oxychem caustic potash handbook ingles... · 2 of 40 introduction caustic potash is manufactured by...

1 of 40

Table of Contents Page

· Introduction ..........................................................2

· Principal Uses of Caustic Potash.........................3

· Manufacturing Process ........................................3

· Forms of Caustic Potash......................................5

· Methods of Shipping Liquid Caustic Potash ........6

· Safety in Handling Caustic Potash.......................7

· Unloading Liquid Caustic Potash from Tank Cars .............................................................9

· Unloading Liquid Caustic Potash from Tank Trucks..........................................................13

· Materials of Construction .....................................16

· Technical Data Section

Tables 1-12.......................................................18

Charts 1-7 ........................................................22

· How to Dilute/Strengthen Caustic Potash............29

· Methods of Analysis .............................................31

OxyChemCaustic PotashHandbook

CAUSTIC POTASHH A N D B O O K

OxyChem ®

KOHKOHAAAA

AAAAAAAAAA

A

AAA

AAA

AA

AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA

A AAAAAAAAAAAAAAAA

AAAAAA

AAAAAAAAA AAAAAAAAAAAAAAAAAAAAA

AAAAAAAAA

AAAAA

AAA

AAA

AAA

AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA

AAA

AAAAAAAAAAAAAAAAAAAAAAAAA

THE INFORMATION PRESENTED HEREIN WAS PREPARED BY TECHNICAL PERSONNEL AND IS TRUE AND ACCURATE TO THE BEST OF OURKNOWLEDGE. OXYCHEM DOES NOT MAKE ANY WARRANTY OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, EXPRESS ORIMPLIED, REGARDING PERFORMANCE, STABILITY OR ANY OTHER CHARACTERISTIC. THE INFORMATION CONTAINED HEREIN IS NOT TO BECONSTRUED AS AN EXPRESS WARRANTY CONCERNING THE PERFORMANCE, STABILITY OR ANY OTHER CHARACTERISTIC OF ANY OXYCHEMPRODUCT. THIS INFORMATION IS NOT INTENDED TO BE ALL-INCLUSIVE AS TO MANNER OR CONDITIONS OF USE. HANDLING, STORAGE, DIS-POSAL AND OTHER ACTIVITIES MAY INVOLVE OTHER OR ADDITIONAL LEGAL, SAFETY OR PERFORMANCE CONSIDERATIONS. WHILE OURTECHNICAL PERSONNEL WILL RESPOND TO ANY QUESTIONS REGARDING SAFE HANDLING AND USE PROCEDURES, SAFE HANDLING ANDUSE REMAINS THE RESPONSIBILITY OF THE CUSTOMER. NO SUGGESTIONS FOR USE ARE INTENDED AS, AND NOTHING HEREIN SHALL BECONSTRUED AS A RECOMMENDATION TO INFRINGE ANY EXISTING PATENT OR TO VIOLATE ANY FEDERAL, STATE OR LOCAL LAW.

Occidental Chemical Corporation 2000

Forward

This handbook details methods for handling,storing, preparing and using caustic potash. Itincludes information on the manufacture, physical properties and analytical methods for testing caus-tic potash.

Additional information and contacts can be foundon the internet at www.oxychem.com

Occidental Chemical CorporationBasic Chemicals GroupOccidental Tower5005 LBJ FreewayDallas, Texas 75244

2 of 40 Introduction

Caustic potash is manufacturedby the electrolysis of potassiumchloride brine in either a mercuryamalgam or membrane electrolyticcell. The co-products are chlorineand hydrogen.

The largest users of causticpotash are the soap and detergent,fertilizer, and chemical industries.Minor uses for caustic potash aremolten salts, dyes, pharmaceuti-cals, and photographic chemicals.

Occidental Chemical Corporationhas played a leading role in provid-ing caustic potash to meet theincreasing demands of industry.OxyChem plants are located to con-veniently and economically serve all

industries. Warehouse stocks ofOxyChem caustic potash and otherproducts are maintained in principalcities. . Distributor stocks are alsoavailable in these and many othercities that form a network of supplyfor the end users’ convenience.

In 1994 Occidental Chemical Cor-poration became the first U.S. pro-ducer of membrane cell causticpotash at its Mobile, AL facility. Thisprocess demonstrates the latest inchlor-alkali technology.

*Acknowledgement is made of thecourtesy of the Sargent-Welch ScientificCompany, of Skokie, IL, in granting per-mission to reproduce in modified formthe potassium, oxygen, and hydrogenportions of the 1979 revised edition ofthe “Periodic Chart of the Atoms.”

3 of 40

Principal Uses andConsumption ofCaustic Potash

ManufacturingProcess

Caustic potash is one of the veryfew chemicals finding almost uni-versal application. Some of the prin-cipal products or processes inwhich caustic potash is used, are:

• A dehydrating agent for drying gases

• A lubricant in the extrusion press-ing of high melting alloys

• A scavenger in a gasoline treatingprocess (dual layer) for removingmercaptans

• A methylating agent

• An alkaline builder in detergentformulations

• In refining petroleum fractions

• In electrolytic stripping baths

• In chemical compounding

• In a molten bath for removingpolyesters and polyurethanes fromsteel objects

• In an absorption cartridge forscavenging carbon dioxide

• As a chemical desiccant

• As a cleaner for eliminating scalefrom the surface of titanium alloyintermediates

• As an agent for lowering the sulfurcontent of coal

• In alkaline batteries

• In removing insulating coatingsfrom wire

• In purifying olefin feedstock con-taining hydrocarbons prior to poly-merization

• In stabilizing synthetic lubricants

• In removing napthenic acids fromgas oils

• In fertilizers

• In descaling ferrous metals

• In sweetening sour petroleumfractions

• In a fused alkaline salt mixtureused for metal cleaning

• In lye peeling

Caustic potash is produced com-mercially by an electrolytic processas shown in the flow diagram on thefollowing page. Brine, preparedfrom potassium chloride, is elec-trolyzed in either a mercury cell or amembrane cell.The co-products arechlorine and hydrogen.

In the mercury cell process, apotassium-mercury amalgam isformed in the cell. The amalgam issent to the decomposer where it is

reacted with water to form liquidKOH, hydrogen and free mercury.The free mercury is returned to theelectrolytic cell. The resulting caus-tic potash solution is either invento-ried in storage tanks as 45% or50% solutions or concentrated byevaporation to a 90% anhydrousform. The liquid is shipped in tanktrucks, tank cars, barges or ships.The anhydrous forms are briquette,

flake and crystal. These forms areshipped in drums, bags or mini bulkbags

In the membrane process, a solu-tion of approximately 30% instrength is formed. This solution isthen sent to evaporators which con-centrate it to a strength of 45% or50% by removing the appropriateamount of water. The resultingcaustic potash solution is invento-ried in storage tanks prior to ship-ment.

4 of 40

Flow Diagram ofManufacturing

KCl + H2O = Brine

Brine Treatment

Mercury Cell

Chlorine

Electricity Membrane Cell

Hydrogen Chlorine

28-32% liq. KOH

H2O Evaporators

45 or 50% liq. KOH

Decomposers H2O

Hydrogen

ConcentratorDehydrator

Anh. KOH(Flake, Crystal or

Briquette)

45% liq. KOH50% liq. KOH

Tank Trucks

Tank Cars

Barge or Ship

Drums

Bags

Bulk Bags

5 of 40Forms of Caustic Potash

Liquid caustic potash is availablein two concentrations, 45% and50% and in four grades, Commer-cial, Membrane, Industrial and LowSodium.

Anhydrous caustic potash is mar-keted in three forms, briquette, flakeand crystal. Drum packages includesizes of 100, 400 and 450 pounds.Each of the three forms is available

as a special order in 2000 poundbulk bags. Also, the flake form isavailable in 50 pound bags.

ANHYDROUS (DRY) FORM

BRIQUETTE

LIQUID

FLAKE

CRYSTAL

6 of 40Methods of Shipping Liquid Caustic Potash

LIQUIDLiquid caustic potash is available

from OxyChem’s plants and termi-nals in tank truck, tank car, barge orship quantities. Each form of trans-portation has advantages. The typeof service selected will depend onsuch factors as size and location ofstorage, rate of consumption, plantlocation, freight rates, etc. Oxy-Chem’s Technical Service staff cansurvey your present facilities andrecommend the most economicalmethod of transportation for yourrequirements.

Caustic potash, liquid and dry, isregulated by the U.S. Departmentof Transportation (DOT) and is clas-sified as a Corrosive Material.

The DOT I.D. number is UN1814for liquid and UN1813 for dry. Bothliquid and anhydrous are HazardClass 8 and Packing Group II.

7 of 40

Safety in Handling Caustic Potash

Caustic potash in any form mustbe respected by everyone whohandles and uses it. Beforestarting to work with it, the usershould be aware of its proper -ties, know what safety precau -tions to follow, and know how toact in case of contact. Acciden -tal exposure to caustic potashmay occur under several condi -tions. Potentially hazardous situ -ations include handling andpackaging operations, equip -ment cleaning and repair, decon -tamination following spills andequipment failures. Employeeswho may be subject to suchexposure must be provided withproper personal protectiveequipment and trained in its use.Some general guidelines follow.

• Read and understand the latestMaterial Safety Data Sheet.

• Provide eyewash fountains andsafety showers in all areas wherecaustic potash is used or handled.Any caustic potash burn may beserious. DO NOT use any kind ofneutralizing solution particularly inthe eyes. Use only clean water.

• Move the patient to a hospitalemergency room immediatelyafter First-Aid measures areapplied.

FIRST-AID MEASURES

EYES: If for any reason causticpotash contacts the eyes, flood theeyes immediately with plenty ofclean water. Continue flushing forat least 15 minutes. While flushing,hold the eyelids apart to ensureflushing of the entire eye surface.Do not use any kind of neutraliz -ing solution in the eyes.

GET MEDICAL ATTENTIONIMMEDIATELY.

SKIN: If caustic potash comes incontact with skin or clothing, flush

with plenty of clean water for atleast 15 minutes. Remove contam-inated clothing and footwear. Washaffected clothing before reusingand discard footwear. GET MEDI-CAL ATTENTION IMMEDIATELY.

INHALATION: If discomfort isexperienced from exposure tocaustic potash dust, mist, or spray,use respiratory protection or leavethe contaminated area until properventilation is restored.

If a worker is overcome due tothe inhalation of caustic potash,dust, mist, or spray, remove themfrom the contaminated area tofresh air. If breathing hasstopped, start artificial respiration.Administer oxygen if readily avail-able. GET MEDICAL ATTEN -TION IMMEDIATELY.

INGESTION: Although it isunlikely in an industrial situationthat caustic potash would beingested, it could be swallowedaccidentally. If that occurs, DONOT induce vomiting. Give largequantities of water. If available,give several glasses of milk. Ifvomiting occurs spontaneously,position individual’s head to keepairway clear. NEVER GIVE ANY-THING BY MOUTH TO ANUNCONSCIOUS PERSON. GETMEDICAL ATTENTION IMMEDI -ATELY.

PROTECTIVE EQUIPMENT

OSHA requires employers tosupply suitable protective equip-ment for employees. When han-dling caustic potash, the followingprotective equipment is recom-mended:

• Wear suitable goggles for eyeprotection during the handlingof caustic potash in any form.The goggles should be close-fit-ting and wrap-around style. Gog-gles which provide adequate ven-

tilation to prevent fogging, withoutallowing entry of liquids. The useof a face shield may be appropri-ate when splashing can occur.

• Wear rubber gloves or glovescoated with rubber, syntheticelastomers, PVC, or other plas-tics to protect the hands whilehandling caustic potash. Glovesshould be long enough to comewell above the wrist.Sleevesshould be positioned over theglove wrists.

• Caustic potash causes leather todisintegrate quite rapidly. For thisreason, wear rubber boots. Wearthe bottoms of trouser legs out-side the boots. Do NOT tuck in.

• Wear chemical resistant clothingfor protection for the body.

RubberBoots

Face Shield

ChemicalSplashGoggles

ChemicalSuit

RubberGloves

8 of 40

Safety in Handling Caustic Potash

HANDLING ANHYDROUS CAUSTIC POTASH

Extreme care must be exercisedwhen adding anhydrous causticpotash to water or to a solution.Itshigh heat of solution generateslarge amounts of heat which cancause local boiling or spurting.When making solutions, alwaysadd the caustic potash slowly to thewater surface with constant stirring.Never add the water to the caus -tic potash. Always start with luke-warm water (80°-100°F). Neverstart with hot or cold water. Danger-ous boiling and/or splattering canoccur if caustic potash is added torapidly, is not sufficiently agitated oradded to hot or cold liquids. Caremust be exercised to avoid thesesituations.

Anhydrous caustic potash will dis-solve freely in a well agitated solu-tion under proper conditions. With-out agitation, the anhydrous causticpotash will fall to the bottom andform a layer of hydrate which dis-solves quite slowly. Also, localizedboiling can occur causing the solu-tion to spatter.

To operate safely, slowly add theanhydrous caustic potash to thesurface of a well-agitated watersolution. The preferred equipmentis a propeller-type agitator or a cir-culating pump with sufficient mixingcapacity. Avoid agitation with withair because air will cause excessiveformation of potassium carbonate.

Accidental exposure to causticpotash may occur under severalconditions. Potentially hazardoussituations include handling andpackaging operations, equipmentcleaning and repairs, decontamina-tion following spills and equipmentfailures. Employees who may besubject to such exposure must be

provided with proper personal pro-tective equipment (including respi-rators) and trained in its use andcare.

HANDLING LIQUID CAUSTIC POTASH

In handling caustic potash solu-tions, care must be taken to avoidsolidification which will plugpipelines and equipment. For thisreason it is desirable to know atwhat temperature a solution ofknown concentration will freeze.Chart 1, shows the freezing pointsfor solutions of different concentra-tions. Chart 2, shows the boilingpoints for the various concentra-tions of aqueous caustic potash.

There are several methods formeasuring the concentration ofcaustic potash solutions, but themost accurate method is by chemi-cal analysis (see the Methods ofAnalysis section). The strength ofthe solution may also be deter-mined by use of a hydrometer.Three scales for expressing densityof caustic potash solutions are: spe-cific gravity, degrees Baumé, anddegrees Twaddell (Table 1). Thedensity of the solution will vary witha change in temperature as shownon Chart 3.

Impregnated vinyl or rubber suitsare recommended.

• Wear hard hats for some protec-tion for the head, face, and neck.

• Use NIOSH-approved air purifyingrespirators for protection fromdusts and mists.

PROTECTIVE PRACTICES

• Avoid breathing dust, mist, orspray of caustic potash.

• Wear proper protective equip-ment.

• Keep equipment clean by washingoff any accumulation of causticpotash.

• Weld pipelines where practical.Use flanged joints with gasketsmade of caustic-resistant materialsuch as rubber, PTFE, or EPDMrubber. If a screwed fitting is used,apply Teflon® tape to the threads.

• When disconnecting equipmentfor repairs, verify that there is nointernal pressure on the equip-ment and that the equipment hasbeen drained and washed.

• Provide storage tanks with suit-able overflow pipes.

• Shield the packing glands ofpumps to prevent spraying ofcaustic solution in case the pack-ing glands should leak.

• When releasing air pressure froma pressurized system, take everyprecaution to avoid spurts orsprays of caustic solution.

• Exercise extreme care whenbreaking solid caustic potash intosmaller pieces.

• In case of a spill or leak, stop theleak. After containment, shovel upthe spill then transfer it to a chemi-cal waste area. Remove large liq-uid spills by vacuum truck. Neu-tralize residue with dilute acid.Flush spill area with water and fol-low with a liberal covering of sodi-um bicarbonate.

® Trademark of E.I. duPont de Nemours and Company, Inc.

9 of 40

Unloading Liquid Caustic Potash From T ank Cars

It is imperative that tank-car quantitiesof liquid caustic potash be handled in asafe manner. This section includesmany details; all are essential for safe-ty.

Placement of the Car for Unload -ing

DOT requires setting the hand-brake and blocking the wheels afterthe car is properly spotted. Cautionsigns must be placed at both endsof the car being unloaded to warnswitching crews and othersapproaching the car. DOT regula-tions also state that caution signsmust be placed on the track or carto give warning to people approach-ing the car from the open end orends of the siding. Caution signsmust be left up until the car isunloaded and disconnected fromthe discharge connections. Signsmust be made of metal or othersuitable material, at least 12 X 15inches in size, and bear the words,“STOP-TANK CAR CONNECTED,”or, “STOP-MEN AT WORK.” Placederail attachments at the open endor ends of the siding, approximatelyone car length (50 ft.) away.

• Entrust only responsible and well-supervised employees with theunloading of liquid caustic potash.Unloading operations must bemonitored while the car is con-nected

• Provide workers with chemicalsplash goggles, rubber boots, hardhats, vinyl suits and rubber or rub-ber-covered gloves to protectagainst serious burns if Causticpotash contacts the skin. If rubberis not suitable for clothing, cottonoffers some protection. A safetyshower and eye-wash fountainmust be located in the unloadingarea.

• Caution workers to exercise care• Unload a car of caustic potash

only in the daytime or when ade-quate lighting is available.

• Before starting to unload, makecertain that the tank car and thestorage tank are vented and verifythat the storage tank has suffi-cient capacity for the delivery.

• Do not allow entry into the carunder any circumstances.

• If the tank car needs to be movedwhen partially unloaded, DOTregulations require disconnectingall unloading lines and replacingall car closures.

• If compressed air (20 psig max) isused in unloading operations,inspect all fittings for leaks orother defects before unloading.Dome fittings, particularly, mustbe inspected. If leaks are found,suspend unloading operationsuntil they are fixed.

HANDLING IN COLD WEATHER

Since OxyChem tank cars arewell insulated and the liquid causticpotash is at a temperature inexcess of 100°F when loaded, itshould arrive at its destination as aliquid . If for any reason the solutioncools, it is possible that some crys-tallization may take place. (45% liq-uid solutions freezes at –28°F; 50%freezes at 41°F.) The most com-mon source of trouble is not thetemperature of the car but the leak-age of solutions into the outlet legwhere it can solidify. This can beliquefied by the application ofsteam. In case freezing occurs, fol-low these procedures: (refer to Fig-ure 1.)

• Carefully open the tank car man-way cover.

• If a layer of solid caustic potashhas formed, break the crustbefore admitting steam to thejacket around the bottom outlet

valve. Puncturing the crust permitsexpansion of the liquid as itincreases in temperature.

• If no crust is present, determine ifcrystals have formed on the bot-tom of the car by probing the bot-tom with a rubber-capped rodintroduced through the manwayopening. Use only a rubber-capped rod to avoid damaging theliner.

• If freezing has occurred, connect asteam line(10 PSIG or less) to ajacket around the bottom valve atopening (13). Connect a conden-sate return line at opening (16).OxyChem ships liquid causticpotash in specially-lined tank carsequipped with steam coils. The lin-ing in these tank cars will with-stand temperatures up to 225°F.To prevent damage to the liner, donot add water or steam directlyinto the tank car.

• If a condensate return line is notused, connect a valve at opening(16) and open it sufficiently torelieve condensate. Direct thecondensate toward the ground orinto a sewer. As contents liquefy,the valve can be closed further toconserve steam.

• When the contents have liquefiedand operation of the valve rod (18)shows that the bottom outlet valve(11) is free, the solution is readyfor unloading.

• If the above measures do not liq-uefy the contents on the car, con-tact your OxyChem representa-tive.

10 of 40 Figure 1

Details of a Caustic Potash Tank Car

AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA

AAAAAAAAAAAAAAAAAAAAAAAAAA AAA

AAAAAAAAAAAAAAAAAAAAAAA AA

AAPlacard

Handbrake

A

A

Electrical Ground

AAAA

AAAA

Warning Signs

AAA

AAAA

AAAAA

A

2. Manway

A A

AAAAAAAAAAAA

AAAA

AAAAAAAA

AAAAAA

19. 4" Insulation

20. 1/8" Steel Shell

AAAA

7/16" Steel Tank

AAAA AAAAAAAAAAAAAAAAAAAA

AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA

AAAAAA

AA

AAA

AAAAAAAAAAAA

AA

3. Safety Vent AAAAA

AAAAAAAAAA

Bottom Unloading Assembly

10. Steam Coil Inlet & Outlet

18. Outlet Valve Operating Rod

7. 1" Air Connection Valve

5. 2" Unloading Connection

11. Bottom Outlet Valve

12. Steam Chamber

13. Steam Inlet16. Steam Outlet

21. Plug Cock

14. Supplementary Valve

15. Plug in Bottom Outlet

Top Unloading Assembly

6. Protective Housing Cover

8. 2" Eduction Pipe

AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA

AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA

AA

AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA

AAAAAAAAAAAAAAAAA

AAAAAAAAAAAA

AAAAAAAA

8. 2" Induction Pipe17. Heating Coils

9. Pipe Guide

19. 4" Insulation 20. 1/8" Steel Shell

7/16" Steel Tank

AAAAAAAAAA18. Outlet Valve Operating Rod

Eduction Pipe Assembly

Stuffing Box

1. Stuffing Box Cover

Safety Chain & Toggle

4. Manway Cover Safety Guard

11 of 40Figure 2

UNLOADING 45% AND 50% LIQ -UID CAUSTIC POTASH

45%-50% liquid caustic potash canbe top or bottom unloaded. Bothmethods are described in this hand-book.

Bottom Unloading

• Pipe the tank car to the storagetank as shown in the diagramabove (Figure 2).

• Open the manway cover and seeif the caustic potash in the car isliquid. If not, follow the instructionsin “Handling in Cold Weather.”Keep the dome cover at least par-tially open during the entireunloading operation to vent thetank car.

• Refer to the cutaway view of thetank car (Figure 1). See that thebottom outlet valve (11) is closedtightly. The valve rod (18) whichoperates the bottom outlet valve(11) has a handle on it which islocated outside the dome of thecar. The handle can be reversedand serves as a cap in transit (1).

• Remove the pipe and plug (15)and then carefully remove thesupplementary valve (14) in orderto drain out any liquid that mayhave seeped by the bottom outletvalve (11) during transit. If thesupplementary valve (14) cannotbe opened, apply steam from asteam lance on the valve to free itfor opening.

• Check the unloading line to seethat all valves are in the properposition for unloading. A flexiblehose is recommended as theunloading line since the car mayrise as much as two inches.

• Open the bottom outlet valve (11)by turning the valve rod (18) toallow the contents to flow by gravi-ty to the pump or tank. If the valve(11) does not open upon applica-tion of light pressure, frozen caus-tic potash is probably present inthe bottom of the car. Apply steamif necessary. Follow instructions in“Handling in Cold Weather.”

• Compressed air can be used toincrease the flow rate to storageor to transfer the liquid without theuse of a pump. If compressed airis used, check the rupture disk inthe dome to be sure it is intact.Close the dome cover securely.Remove the 1-inch air inlet plug(7) and connect a flexible air line.The air line should be equippedwith a release valve, oil trap, pres-sure relief valve set at 20 psig,pressure-reducing valve set at 18psig, and a shut-off valve. Applyair pressure slowly. Note that thepressure relief device (rupturedisk and/or pressure relief valve)in the dome will relieve at a pres-sure between 65 or 165 psig,depending on the type of car.Refer to the stenciling on the sideof the railcar

• When the car and unloading linesare empty, shut off the air supplyand open the release valve.

• When the tank car is empty and

Unloading Caustic potash Through The Bottom Outlet

Steam jacket

UnionPump

2” Steel pipe

Pump inlet valve

Low line drain valveRail carunloading valve

Vent

Tank inlet valve

To process

Drain

TANK CAR

STORAGE TANK

Steam coils

12 of 40 Figure 3

completely drained, disconnect theair line, if used, and detach theunloading line at the car. Preparethe car for return.Top Unloading with Air Pressure• Pipe the tank car to the storagetank as shown in the diagramabove (Figure 3).

• Open the dome cover and see ifthe contents of the car are liquid. Ifnot, follow instructions in “Handlingin Cold Weather.”

• Close the dome cover and fastensecurely, making certain that it isair-tight. Check the rupture disklocated in the dome to be sure it isintact.

• Check the storage tank to see thatit is vented and has sufficientcapacity.

• Refer to the cutaway view of thetank car (Figure 1). Connect theunloading line to the 2” unloadingconnection (5) on the eductionpipe (8), after removing the cover(6). A flexible steel hose connec-tion for the unloading line is rec-ommended since the car may riseas much as 2" during unloading.

• Connect the flexible air supply lineto the 1" air inlet valve (7). Thisline should be equipped with arelease valve, oil trap, pressure-relief valve set at 20 psig, pres-

sure reducing valve set at 18 psig,and a shut-off valve. The car isequipped with a safety vent orrupture disc. The rating for thedevise is stenciled on the side ofthe car.

• Apply air pressure slowly untilthere is a normal flow of liquid tothe storage tank. The pressureshould be adjusted and main-tained until the tank car is com-pletely empty. A drop in air pres-sure or the sound of air rushingthrough the unloading line indi-cates that the tank car is empty.

• Shut off the air supply, open the

Unloading Caustic Potash Through The Top By Compressed Air

AAAAAAAAAAAAAAAAAAAAAAA

AAAAAAA

TANKCAR

STORAGE TANK

Toprocess

Drain

Vent

2” Steel pipe

EductionPipe

Flexible connections

Tank inlet valve

Release valve

Pressure gauge

Relief valve Pressure reducingvalve

Shut-off valve Compressedgas inlet

Steam coils

13 of 40Unloading Caustic Potash

release valve, and allow the educ-tion pipe to drain.

• When the eduction pipe hasdrained and the tank car is atatmospheric pressure, disconnectthe air supply line at the car.

• Open the manway cover anddetermine if the car is empty. Ifempty, disconnect the unloadingline at the car and tightly replacethe manway cover (2) and thecover over the valves (6).

• Do not enter the car to make aninspection.

• Take care not to spill causticpotash on the car, since it willcause damage to the car and mayendanger workers handling theempty car on its return.

• Prepare the car for return.

PREPARING EMPTY TANK CARSFOR RETURN

For Bottom Unloading

•Close the bottom outlet valve (11)and the supplementary valve (14).

•Disconnect the unloading line andreplace the bottom outlet plug(15). Do not replace the closureson steam opening (13, 16).

•Close the manway cover (2) andfasten securely.

For Top Unloading

•Turn off air pressure to the car andclose the air line valve (7).

•Disconnect the air supply hose.•Open the air line valve to vent anyremaining pressure.

•Disconnect the product unloadinghose.

•Install the plug cock (21) and closethe 1 inch air connection valve.

Completion of both top and bottomunloading

•Properly placard the car for return.•Return the empty tank car prompt-ly in accordance with the shipper'sinstructions. Follow the shippersrouting directions in all instances.

UNLOADING LIQUID CAUS -TIC POTASH IN TANKTRUCKS

Responsibility of the Carrier in Transporting Tank Truck Shipments of Liquid Causticpotash

The tank truck driver has receivedthe following instructions regardingequipment and delivery procedures.If any carrier delivering causticpotash to your plant fails to followthese instructions, please contactOccidental Chemical Corporationso that corrective action can betaken.

Equipment

Equipment must meet DOT Reg-ulations, Code of Federal Regula-tions, Title 49.

Tank Truck Specification

Tank trucks should meet all DOTregulations for carrying causticpotash.

Four DOT “CORROSIVE” plac-ards must be permanently affixed tothe cargo tank unless cleaned orloaded with nonregulated product.

Unloading Equipment

If unloading is by gravity to stor-age or customer’s unloading pump,no special equipment is needed.

If unloading is by truck mountedpump, use only an all iron or nickel

unit. The pump can be driven by atractor powered take-off or anauxiliary gasoline engine. Use atleast a two inch pump line.

If unloading is by compressedair, the tank vessel must meet therequirements of the CFR, Title 49.The line used to supply air to thetank truck is required to beequipped with: pressure reducingvalve, pressure release valve,pressure gauge. The relief valveshould be set at a maximum pres-sure of 20 PSIG and the pressurereducing valve should be set at 2-3 pounds lower. Whether thisequipment is attached permanent-ly to the tank or carried as anassembled unit to be attached ateach unloading, it should be prop-erly maintained and periodicallytested. A 40 foot length of air hoseis required if the customer’s airsupply is used. When compressedair is not available from the cus-tomer’s plant, trucks equippedwith pumps or air compressorscan be provided at the customerrequest.

Unloading Lines

Unloading hoses must be con-structed of material resistant tocaustic potash. Hoses should beat least two (2) inches in diameterand 15 to 30 feet in length.

Whether the unloading hose isfitted with a union, pipe flange, ora quick type coupler, the truckdriver should have availablematching fittings and tools to facili-tate a connection to a 2-inch or 3-inch threaded pipe.

14 of 40UnloadingCaustic Potash

PERSONNEL

Truck drivers must be fullyinstructed in caustic potash han-dling prior to being dispatched witha shipment.

Truck drivers must follow anyspecial instructions provided by theshipper for a special delivery.

Truck drivers must obtain permis-sion to unload from the properauthorities and observe any specialinstructions from the consignee.

Truck drivers must wear the pro-tective equipment required by Occi-dental Chemical Company as listedunder Protective Equipment, or fol-low the customer requirements,whichever are more inclusive andat all times follow safe handlingpractices.

The following unloading procedures are recommended:

• Check the operation of the safetyshower and eye-wash fountain.Purge water through each toremove rust that may have accu-mulated.

• If a shower and eyewash are notavailable, a water hose connectedto a source of water is required. Ifthe valve on the line is not conve-niently located near the unloadingarea, leave a stream of waterflowing during unloading

• Connect one end of the unloadinghose to the customer’s storagetank fill line.

• During cold weather and if facili-ties are provided, preheat withsteam, the fill line, the unloadinghose and the truck outlet if need-ed.

• Check the unloading line to besure that it is open.

• Connect the unloading hose to thedischarge outlet on the tank truck.

• Start the pump or start pressuriz-ing the tank depending on the typeof equipment used.

• Open the valves on the truck dis-charge line.

• Stand by until the truck cargo iscompletely unloaded.

• If compressed air is used, allowthe air to flush out the lines to thestorage tank and then cut off theair supply.

• When a pump is used, it is advis-able to flush out the unloading linebefore disconnecting the hose. Ifwater is available, a small quantitycan be added into the truck whilethe pump is running to flush out theline. Air or water can be used toflush the line contents into the stor-age tank or back to the truck. If nowater is available for flushing outlines, exercise great caution whenlines are disconnected.

• Close the valve on the storagetank fill line.

• Close all valves on the tank truck.

• In some installations the cus-tomer’s fill line is fitted with a drainto be used instead of flushing theline before the hose is disconnect-ed.

• Disconnect the hose with cautionand discharge any caustic potashremaining in the hose to a suitablecontainer.

• Unload in an area with adequatesafeguards for spill control. Cleanup all spills and dispose in accor-dance with Federal, State and

Local Regulations.

Responsibilities of the Consigneewhen Receiving Tank Truck Ship -ments of Liquid Caustic Potash

EQUIPMENT

Typical installations of storagevessels for receipt of truck ship-ments are shown in Figure 4.

A storage tank with a minimumcapacity of 1.5 tank cars is recom-mended.

A fill line to the top of the storageis strongly recommended. If a bot-tom fill line is used, the truck drivermust be informed.

A permanent fill line in a closeproximity to the tank truck unloadingarea is required.

A 2-inch or larger fill line is recom-mended.

A 3/4-inch valve connection is rec-ommended on the fill line for use influshing out the line with air, water,or steam. It can also be used as adrain.

Cap or close the end of the fill linewhen not in use.

A source of running water for useduring unloading operations isrequired. A safety shower and eye-wash fountain are recommended.

PERSONNEL RESPONSIBILITIES

Inform truck drivers of any specialinstructions.

Truck unloading should not beunnecessarily delayed. Cooperationwith the unloading operation isappreciated.

It is required that plant personnelhandling liquid caustic Potash befully informed of safe handling prac-tices and in the methods of first aidin the event of an accident.

15 of 40Figure 4

Installation of Tanks

* Steam System is not Required in the Storage of 45% KOH.

TemperatureControlled

Steam Valve

AAAAAAAAAAAA

AAAAAAAAAAAAAAA

AAAAAAAA

AAAAAA

Float

Float Gauge

Inlet

Outlet

Steam Trap

Tank Coil 11/2” SCH 80 StainlessSteel (304, 316) Pipe, 15 psi (max)Saddle

Drain

Outlet Valve

2” Line to PumpSCH 40 Pipe

Threaded EndCap for

Tank Truck Connections

2” Fill LineSCH 40 Pipe

18-24” Manway

Thermowell

AVent

Mild Steel, 6000 GallonHorizontal Storage Tank(16’1” Dia. x 8’0” High)

AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA

AAAAAAAA

2” Fill LineSCH 40 Pipe

Threaded EndCap for

Tank Truck Connections

Vent18-24” Manway

Thermowell

Float

TemperatureControlled

Steam Valve

Inlet

Outlet

Steam Trap

Outlet Valve

DrainReinforced Concrete Support

Float Gauge

Tank Coil 11/2” SCH 80 Stainless Steel (304, 316)

Pipe, 15 psi (max)

Mild Steel, 6000 GallonVertical Storage Tank

(8’0” Dia. x 16’1” High)

A

16 of 40Materials ofConstruction

Corrosion of metals by causticpotash is very similar to that ofcaustic soda. In equal concentra-tions caustic potash has a lower vis-cosity and will penetrate cracks andpin holes more readily than causticsoda.

Aluminum, zinc, brass, bronze,and copper are all readily attackedby caustic potash solutions and arecompletely unsuitable as materialsof construction.

Iron and steel are the two mostcommon construction materialsused for handling and storing caus-tic potash solution even thoughthese metals are attacked by thesesolutions under high temperatureconditions. However, 45% and 50%solutions may be safely handled insteel up to temperatures around120°F.

Nickel resists attack by causticpotash solutions better than mostmetals. Nickel-lined equipment isoften used when minimum contami-nation of the solution by metals isimportant.

Rubber has been used for liningsteel caustic potash storage tanks.However, rubber does not withstandhigh temperatures. A number ofepoxy type linings are preferredbecause of their long life and lowcost. Under the right conditions,FRP, polyethylene or polypropylenecan be used. Contact OxyChemTechnical Service representativesfor recommendations.

PIPELINES

Schedule 40 black iron or stain-less steel are recommended forpipeline construction. Welded jointsare preferred to minimize potentialleakage. Flanged joints are pre-ferred on lines which must be dis-

connected. With flanged joints,maintenance labor costs are kept toa minimum because of the compar-ative ease with which repairs andreplacements can be made. A safe-ty shield of wrap-around polypropy-lene is recommended for all flangedjoints. This will protect againstspraying in case a gasket leaks.Where screwed connections arenecessary, use Teflon® tape on thethreads. To allow lines to draincompletely, install all piping with aslight slope. OPW Kamlok quickcouplings or equivalent are safeand convenient where the couplingof hose to pipe is required. Normal-ly, a two-inch male NPT (NationalPipe Thread) fitting is all that isneeded to accommodate tank truckdeliveries. This pipe should bevalved and capped at the unloadingend and heat traced whereexposed. There should also be aconnection for steam, water, or airto clear the unloading line afterdelivery is complete.

In systems where a slight ironcontamination is objectionable,PVC, Saran-lined steel, Kynar, orFiberglass pipe can be used. Payspecial attention to suitable operat-ing temperatures and pressureswith these materials.

METERS

Caustic potash solutions can bemetered through standard rotame-ters having glass tubes and nickelor stainless steel floats. Magnetic ororifice-type meters are preferred forstrong, hot solutions. They shouldhave all iron or nickel construction.

PUMPS

If a pump is required, use eitheran open-impeller centrifugal, rotary,

positive-displacement, or piston-type pump. Include a by-pass orcirculating line arrangement withthe pump. This reduces wear onthe pump and in many cases canbe used as a means for controllingthe rate of flow. Carefully considerpump location. For ease of opera-tion the suction line must be asshort as possible. Specify a pumpwith a deep packing gland. Specifycaustic potash service when order-ing.

Use graphite-braided asbestos orequivalent for the packing material.

VALVES

For general use, lubricated plugcocks of cast iron or steel construc-tion are recommended for causticpotash service.

To control flow rates and for lineshut-offs, Teflon® sleeve-lined quar-ter-turn plug valves are recom-mended.

STORAGE TANKS

Storage facilities must have ade-quate capacity to accommodateshipments. It is necessary to makeprovision for a reserve supply ofcaustic potash between shipments.In the case of 16,000 gallon tankcar shipments, it is suggested thattotal storage space be at least dou-ble the tank car capacity (32,000gallons). If tank trucks of 4,000 gal-lons are received, it is suggestedthat storage space of at least 6,000gallons be available. Proper designof a storage system will includeadequate containment in case oftank failure. Most tanks have alevel transmitter for measuring liq-uid level.

® Trademark of E.I. duPont de Nemours and Company, Inc.

Materials ofConstruction

Extra heavy metal is preferred inthe construction of caustic potashstorage tanks. Specifications forfabrication call for at least 3/8" wallthickness on the body of units largerthan 10,000 gallon capacity and a1/4" wall for smaller capacities.Design the pipe connection for with-drawing the liquid from storage afew inches above the bottom of thetank. Include a drain connection atthe lowest point of the tank to facili-tate flushing.

The ideal storage temperature for50% caustic potash is 60°F to 80°F.Caustic potash solutions in the 23%to 45% concentration range areeasily handled at ambient tempera-tures because their freezing pointsare below -20°F. Solutions outsidethis range may require heatingand/or insulation. If higher tempera-tures are necessary or if iron con-tamination poses a problem, moreresistant materials such as stainlesssteel, nickel, or nickel-based alloys,should be considered. Steel storagetanks are often lined with a protec-tive epoxy coating. A small coil loopof 1 to 1.25 inch Schedule 80 stain-less steel pipe connected to asource of low pressure steam (12 to15 psi), is adequate to adjust tem-peratures. Avoid storage tempera-tures above 130°F for steel tanks.Insulation of tanks is desirable butnot necessarily a requirement. Themost economical thickness for com-mon types of insulation is two inch-es. Proper design of a storage sys-tem will include adequate contain-ment in case of tank failure. Stateand local regulatory authoritiesshould always be consulted duringthe design phase of construction.

TANK CLEANING ANDPASSIVATION

Tank cleaning, can be divided bythe type of product stored in it previ-ously. A tank that previously con-tained caustic potash would requirescale removal, wall thickness test-ing, rinsing, passivation, squeegee-ing, and immediate filling. A tankpreviously containing another prod-uct would require cleaning with anappropriate solvent or soap, as wellas the other steps mentionedabove.

Scale removal is accomplished byblasting the walls with abrasivesuch as sand or pecan shells. Abra-sives containing high percentagesof metals are not recommended inorder to minimize contamination ofthe caustic potash.

The wall thickness of the tankshould be measured and beapproved for the density of theproduct and the height of product inthe tank.

Passivation requires penetrationof the steel tank walls with causticpotash. This is usually accom-plished by spraying the cleanedwalls with a hot solution of causticpotash. Temperatures of 100 -140°F and solutions of 5 - 20% arerecommended. While this is more ofan art that a science, a standardrecommendation would be, sprayingthe walls for 2-4 hours with a 10%solution at 140°F. The larger thetank, the longer it should besprayed to complete the passiva-tion. The hotter and the stronger thesolution, the less time should beneeded. One way to achieve thesolution heat necessary is to dilute45% or 50% caustic potash to 20%.

The heat of dilution will cause thecaustic potash temperature to rise.Additional heat may be necessaryto achieve optimal solution tempera-tures. The coating of the tank wallsis best accomplished with an ellipti-cal sprayer. If this type of sprayer isnot available, the spraying may bedone manually with extreme cautiontaken to protect the operator.

After passivation, the tank bottommust be cleaned out as well as pos-sible. The quality of the initial prod-uct stored in the tank will dependgreatly upon the extent to which thetank bottom is cleaned of scale andabrasive compound. If an ellipticalsprayer is used for the cleaning, asqueegee will need to be used toclean the tank bottom. If manualspraying is used for cleaning, thesprayer can be used to push thescale and abrasive toward the sumpfollowed up by use of a squeegee.

After cleaning, the tank should befilled with caustic potash as soon aspossible. This will prevent the tankwalls from losing their passivation. Ifthe tank cleaning is not completelysuccessful, it may be necessary tofilter the initial product from the tankto keep it free from particulate mat-ter. This would require a 5-10micron filter media housed in a unitthat would be acceptable with thetemperature, pressure, and chemi-cal.

17 of 40

Specific Solution Lbs. of SolutionGravity Grams of Lbs. of Density KOH Density15.6°C/ Degrees Degrees KOH KOH Pounds per Lb. per

% KOH %K20 15.6°C Baumé Twaddell per Liter per Gal. per Gal. Cu. Foot Cu. Foot0 0.00 1.000 0.00 0.0 0.00 0.00 8.34 0.00 62.43

(Water)1 0.84 1.009 1.29 1.8 10.09 0.08 8.41 0.63 62.992 1.68 1.018 2.56 3.6 20.36 0.17 8.49 1.27 63.553 2.52 1.027 3.81 5.4 30.81 0.27 8.56 1.92 64.124 3.36 1.036 5.04 7.2 41.44 0.35 8.64 2.58 64.685 4.20 1.045 6.38 9.0 52.25 0.44 8.72 3.26 65.246 5.03 1.055 7.56 11.0 63.30 0.53 8.80 3.95 65.867 5.88 1.064 8.72 12.8 74.48 0.62 8.88 4.65 66.438 6.72 1.073 9.86 14.6 85.84 0.72 8.95 5.35 66.999 7.56 1.083 11.11 16.6 96.57 0.81 9.04 6.08 67.61

10 8.40 1.092 12.22 18.4 109.20 0.91 9.11 6.81 68.1711 9.23 1.102 13.42 20.4 121.22 1.01 9.20 7.56 68.8012 10.07 1.111 14.49 22.2 133.32 1.11 9.27 8.32 69.3613 10.91 1.121 15.65 24.2 145.73 1.22 9.35 9.10 69.9814 11.75 1.131 16.79 26.2 158.34 1.32 9.44 9.88 70.6115 12.59 1.140 17.81 28.0 171.00 1.43 9.51 10.68 71.1716 13.43 1.150 18.91 30.0 184.00 1.54 9.60 11.49 71.7917 14.27 1.160 20.00 32.0 197.20 1.64 9.68 12.31 72.4218 15.11 1.170 21.07 34.0 210.60 1.75 9.76 13.13 73.0419 15.95 1.180 22.12 36.0 224.20 1.87 9.85 14.00 73.6720 16.79 1.190 23.15 38.0 238.00 1.99 9.93 14.84 74.2921 17.63 1.200 24.17 40.0 252.00 2.10 10.01 15.72 74.9222 18.47 1.210 25.16 42.0 266.20 2.22 10.09 16.60 75.5423 19.31 1.220 26.15 44.0 280.60 2.34 10.18 17.50 76.1624 20.15 1.230 27.11 46.0 295.20 2.46 10.26 18.41 76.7925 20.99 1.240 28.06 48.0 310.00 2.59 10.35 19.35 77.4126 21.83 1.250 29.00 50.0 325.00 2.71 10.43 20.27 78.0427 22.67 1.261 30.01 52.2 340.47 2.84 10.52 21.24 78.7228 23.51 1.271 30.92 54.2 355.88 2.97 10.60 22.20 79.3529 24.35 1.282 31.90 56.4 371.78 3.10 10.69 23.19 80.0430 25.19 1.292 32.77 58.4 387.60 3.23 10.78 24.17 80.6631 26.02 1.303 33.72 60.6 403.93 3.37 10.87 25.19 81.3532 26.86 1.314 34.65 62.8 420.48 3.50 10.96 26.22 82.0333 27.70 1.324 35.48 64.8 436.92 3.64 11.05 27.25 82.6634 28.54 1.334 36.30 66.8 453.56 3.78 11.13 28.29 83.2835 29.38 1.345 37.19 69.0 470.75 3.92 11.22 29.36 83.9736 30.22 1.356 38.07 71.2 488.16 4.07 11.31 30.45 84.6637 31.06 1.367 38.93 73.4 505.79 4.22 11.41 31.55 85.3438 31.90 1.378 39.78 75.6 523.64 4.37 11.50 32.66 86.0339 32.74 1.389 40.61 77.8 541.71 4.52 11.59 33.79 86.7240 33.58 1.401 41.50 80.2 560.40 4.67 11.68 34.96 87.4641 34.42 1.412 42.31 82.4 578.92 4.82 11.77 36.11 88.1542 35.26 1.423 43.10 84.6 597.66 4.98 11.87 37.28 88.8443 36.10 1.435 43.95 87.0 617.05 5.14 11.97 38.49 89.5944 36.94 1.446 44.72 89.2 636.24 5.31 12.06 39.68 90.2745 37.78 1.457 45.48 91.4 655.65 5.47 12.16 40.89 90.9646 38.62 1.468 46.23 93.6 675.28 5.63 12.25 42.12 91.6547 39.46 1.480 47.03 96.0 695.60 5.80 12.35 43.39 92.4048 40.30 1.492 47.92 98.4 716.16 5.97 12.45 44.66 93.1549 41.14 1.504 48.59 100.8 736.96 6.14 12.55 45.96 93.8950 41.98 1.516 49.35 103.2 758.00 6.32 12.65 47.28 94.64

18 of 40Technical Data

Table 1—Density and Solids Content of Caustic Potash Solution at 15.6°C (60°F)


Table 2—Specific Conductivity ( G ) of Caustic Potash Solutions

C (Moles KOH/L) G18 G19.1-23.4 G25 G30 G50.5-52.4 G80.1-80.2

10.695 0.4212 — — — — —9.292 0.4790 — — — — —7.978 0.5221 — — — — —6.744 0.5434 — — — — —5.583 0.5403 — — — — —4.491 0.5106 — — — — —4.473 0.5199 — — — — —3.806 — 0.53014 — — 0.79585 1.08619

3.467 0.4558 — — — — —2.510 — 0.40443 — — 0.62027 0.829110

2.508 0.3763 — — — — —2.013 0.3286 — — — — —1.679 — 0.29682 — — 0.45636 0.608910

1.612 0.2723 — — — — —1.005 0.1876 — — — — —0.998 — 0.18701 — — 0.30218 0.39629

0.961 — — — 0.2160 — —0.777 0.1464 — — — — —0.500 0.1001 — — — — —0.480 — — — 0.1165 — —0.2057 0.04334 — — — — —0.1066 0.02309 — — — — —0.05048 — — 0.01284 — — —0.01438 — — 0.003689 — — —0.009451 — — 0.002434 — — —0.007424 — — 0.0019155 — — —0.006455 — — 0.0016723 — — —0.005430 — — 0.0014125 — — —0.003481 — — 0.0009144 — — —0.002145 — — 0.0005675 — — —0.001175 — — 0.0003124 — — —0.0008087 — — 0.00021495 — — —0.0005917 — — 0.00015654 — — —

Note: The exact temperatures for values with superscripts are as follows:

1. 19.1°C 6. 50.6°C2. 20.7°C 7. 51.3°C3. 21.6°C 8. 52.4°C4. 23.4°C 9. 80.1°C5. 50.5°C 10. 80.2°C

The specific conductivity “ G ” is expressed in reciprocal ohms (mhos) per cc.


Table 3 - Dielectric Constants ( E) for Caustic Potash Solutions

C (Moles/L) 0 0.0000858 0.000171 0.000858 0.00171

E20.0°C 80.50 80.28 80.08 78.71 —E21.0°C 80.15 — — 78.30 76.37

Table 4 - Diffusion Coefficient ( D) between Water and Caustic Potash Solutions

C (Moles/L) 0.01 0.02 0.05 0.10 0.20D (cm2/day) 1.903 1.889 1.872 1.854 1.843

C (Moles/L) 0.50 1.00 2.00D (cm2/day) 1.841 1.855 1.892

Table 5 - Dissociation Voltage (E) for Caustic Potash Solutions

C (Moles/L) 0.0125 0.125 1 4 10

E (Volts) 1.46 1.45 1.40 1.38 1.32

Note: A platinum cathode and an amalgamated zinc plated anode were used.

Table 6 - Equivalent Conductance ( PP ) of Caustic Potash Solutions

°C °F PP¥ (mho)

18° 64.4 238.718° 64.4 23925° 77.0 274.925° 77.0 274.925° 77.0 238.9225° 77.0 285.4690° 194.0 599

Table 7 - Heat ( DDH) Evolved in Neutralizing One Mole of Alkali with One Mole of indicated Acid at 20°C

Acid KOH NaOHDH (Calories/100 Moles H2O) DH (Calories/100 Moles H2O)

HCl 14014 13895HBr 13988 13843Hl 13915 13779

HNO3 14086 13836

21 of 40TechnicalData

Table 8 - Heat of Solution of Caustic Potash

Heat of Solution°C °F Moles H2O/Mole KOH kcal/mole BTU/lb

11.4 52.5 260 12.46 399.918 64.4 250 13.29 426.5

100 212.0 260 16.8 539.2

Table 9 - Index of Refraction ( n ) of Caustic Potash Solutions

At 17.5°C (64) At 18°C (21)C (Moles/L) n C (Moles/L) n

0.0321 1.33358 0.1066 1.334400.1658 1.33513 0.2057 1.335520.5116 1.33896 0.5000 1.338720.8770 1.34275 1.005 1.343981.264 1.34650 2.013 1.353661.656 1.35021 4.473 1.373062.055 1.35388 — —2.465 1.35750 — —2.891 1.36109 — —3.324 1.36464 — —3.592 1.36675 — —

Table 10 - Molar Magnetic Rotation for Caustic Potash Solutions (14.78%) at 0°C

Wave Length (Å) 4360 5460 5780[M] 2.88 2.75 2.87

Table 11 - Molar Magnetic Susceptibility of Caustic Potash Solutions

–21.2 x 10 –6 cgs units/mole–22.0 x 10 –6 cgs units/mole

Table 12 - Molar Refraction, R mole (Lorentz-Lorentz), D-Line Sodium, for Caustic Potash Solutions at 18°C (64.4°F)

C (Moles/L) 0 0.2 0.5 1.0 2.0 4.0

Rmole 7.36 7.31 7.28 7.28 7.29 7.19


Chart 1Freezing Points of Aqueous KOH Solutions

-100

-80

-60

-40

-20

0

20

40

60

80

100

120

140

160

180

200

220

240

260

280

300

0 10 20 30 40 50 60 70 80 90 100

Tem

pera

ture

, °F

Concentration, % KOH

30.8% KOH, -85.4°F

44.3% KOH, -27.4°FI

II

III

IV

Roman numerals represent the following:I H2O (Ice)

II KOH × 4H2O

III KOH × 2H2O

IV KOH × H2O

The more important transition points:I to II -85.4°F 30.83% KOHII to III -27.4°F 44.29% KOHIII to IV +90.5°F 56.82% KOH


Chart 2Boiling Points of Aqueous Solutions of KOH at Atmospheric Pressure

200

250

300

350

400

450

500

550

600

650

700

0 10 20 30 40 50 60 70 80 90 100

Tem

pera

ture

, °F



Chart 3Density of KOH at V arious T emperatures

7.00

8.00

9.00

10.00

11.00

12.00

13.00

14.00

20 40 60 80 100 120 140 160 180

Den

sity

, lbs

./gal

lon

Temperature, °F

50% KOH

45% KOH

40% KOH

35% KOH

30% KOH

25% KOH

20% KOH

15% KOH

10% KOH

5% KOH

0% KOH


Chart 4Heat of Dilution for Aqueous KOH Solutions at 64.4°F

0

50

100

150

200

250

300

350

400

450

0 10 20 30 40 50 60 70 80 90 100

∆H o

f D

ilu

tion

, BT

U/lb

. of

100%

KO

H



Chart 5Specific Heat of Aqueous KOH Solutions at 64.4°F


Chart 6

1

10

100

1000

2000

0 50 100 150 200 250

Vap

or P

ress

ure

, mm

Hg

Temperature, °F

0% K

OH

20%

KO

H

30%

KO

H

40%

KO

H

45%

KO

H

50%

KO

H

60%

KO

H


Chart 7Viscosity of Aqueous KOH Solutions

0.3

1

10

40 50 60 70 80 90 100 110 120 130 140 150 160

Vis

cosi

ty, C

enti

pois

es

Temperature, °F

50% KOH

45% KOH

40% KOH

30% KOH

20% KOH

10% KOH

0% KOH


HOW TO DILUTE/STRENGTHEN CAUSTICPOTASH

Sometimes it is necessary todilute or strengthen caustic potashsolutions before it is used, or whenthe potential for freezing exists. Aprocedure for calculating theamount of concentrated caustic andwater required, is given below.

Refer to Table 1 for densitiesDILUTING A SOLUTION

Problem:To dilute 1,000 gallons of 45%

KOH to a 20% solution. How muchwater is needed to accomplish thistask?Solution:

(The specific gravity of 45% KOHsolution is 1.457 @ 60°F, takenfrom Table 1).

The dilution can be simplified byusing the following formula:D = V(A(B-C)/C) Where:A = Sp. Gr. of strong solutionB = Concentration of strong solution

(% KOH)C = Concentration of desired solu-

tion (% KOH)D = Volume of water to be added V = Volume of strong solutionAnd it Follows:D = 1,000((1.457)(45-20)/20)D = 1,000(1.82) = 1,820 gallonsResult:

It will take 1,820 gallons of waterto dilute 1,000 gallons of 45% KOHto a 20% solution.

VOLUME OF FINAL SOLUTIONProblem:

What is the final volume of thesolution in the problem above?

In diluting caustic potash the vol-umes are not additive, so the dilut-ed solution will not be the sum ofthe water and strong solution.Solution:

The final volume is calculated byadding the weight of the originalsolution to the weight of the wateradded, then dividing by the density(in lbs./gal. from Table 1) of thedesired solution:

Density of Desired Solution (20%)= 9.93 lbs./gal.1,000 gallons of 45% KOHweighs = 12,160.0 lbs. [1,000

x12.16 lbs./gal.]1820 gallons of H2O weighs =15,178.8 lbs. [1,820 x 8.34lbs./gal.]

15,178.8 lbs. H2O+12,160.0 lbs. 45% KOH

27,338.8 lbs. ÷ 9.93 lbs./gal. =2,753 gallons of 20% solutionResult:The actual volume is 2,753 gal-

lons of 20% KOH solution, not the2,820 gallons that might be expect-ed by simply adding the volume ofingredients.

STRENGTHENING A SOLUTIONProblem:

How many gallons of 45% KOHmust be added to 3,000 gallons of20% solution to obtain a 30% solu-tion?Solution:Y = X/SX = ((C)(B)-A)/(D-C)Where:A = Weight of KOH in weak

solutionB = Total Weight of weak

solutionC = Percent of desired

solution/100D = Percent of strong

solution/100S = Density of strong solutionW = Density of the weak solutionY = Gallons of strong solution nec-

essary to produce desired solu-tion

X = Weight of strong solution nec-essary to produce desired solu-tion

For the example:A = (9.93 lbs./gal.) x 3,000 gallons x

0.20A = 5,958 lb. KOHB = (9.93 lbs./gal.) x 3,000 gallons B = 29,790 lb. of solutionC = 30/100 = 0.3D = 45/100 = 0.45Substituting:X = ((0.3)(29790) - 5,958)

(0.45 - 0.3) X = 19,860 lb.Y = 19,860 / 12.16 lb./gal.Y = 1,633 gallonsResult:

1,633 gallons of 45% KOH areneeded to strengthen 3000 gallonsof a 20% solution to 30%.

DISSOLVING ANHYDROUS (DRY)FORMS OF KOHProblem:

What amount of anhydrous caus-tic potash and what amount ofwater must be added to obtain1,000 gallons of a 20% solution?Solution:Using the equation above:X = ((C)(B)-A)/(D-C)Where:A = 0, since there is no KOH in the

waterB = (8.34)(Z)C = 20/100 = 0.2D = 90/100 = 0.9 (For all forms of

anhydrous KOH the purity is90%)

F = Density of desired solutionZ = Volume of water necessary to

produce the 1,000 gal. ofdesired solution

Substituting:X = ((0.2)[(8.34)(Z)] - 0)/(0.9 - 0.2)X = 2.383(Z)

Since volumes are not additive forKOH solutions, the final volume ofthe desired solution is equal to theweight of the KOH added to theweight of the water, divided by thedensity of the desired solution.Final volume of solution: = 1,000gallons = (X + B)/FSubstituting:1,000 = (X + B)/9.93 X = 9,930 - BSince B = 8.34(Z)X = 9,930 - 8.34(Z), from above we

also know X = 2.383(Z)Solving for Z: 2.383Z = 9,930 -8.34(Z) Z = 926 gallonsSolving for X:X = 9,930 - 8.34(926) X = 2,207 lbs of KOHResult:

Add 2,207 lbs. of KOH to 926gallons of water to produce 1,000gallons of a 20% solution.


Chart 8Dilution of 45% KOH

0

100

200

300

400

500

600

700

800

900

1000

1000

900

800

700

600

500

400

300

200

100

0

0.0 1.0 2.0 3.0 4.0 5.0 6.0

Vol

um

e of

45%

KO

H r

equ

ired

, gal

lon

s

Vol

um

e of

Wat

er r

equ

ired

, gal

lon

s

Concentraton of KOH in diluted solution, lbs./gal.

Volume of 45% KOH

Volume of Water

31 of 40Methods of Analysis

DETERMINATION OF THETOTAL ALKALINITY OFCAUSTIC POTASHPURPOSE AND THEORY

The accurate determination of thetotal alkalinity value for causticpotash is necessary for calculatingthe correct billing concentrations ofthis product.

Total alkalinity in caustic potashproducts is determined by titrationof a sample with a standardizedsolution of 1N hydrochloric acid.Modified methyl orange indicator isused to determine the titration end-point.APPARATUS

100 ml Buret; Class A Volumet-ric, Fisher Scientific Cat #: 03-775or equivalent.

Analytical Balance; capable ofweighing to 0.001 grams.

250 ml Erlenmeyer Flasks; widemouth, Fisher Cat#: 10-090B orequivalent.

Magnetic Stirrer; Fisher Cat#:14-493-120MR or equivalent.

Magnetic stirring bars; 1 1/2" x5/16" dia. Fisher Cat#: 14-511-64 orequivalent.REAGENTS

1N Hydrochloric Acid; measure 83.0 ml of ACS Reagentgrade concentrated hydrochloricacid into a graduated cylinder andtransfer it to a one liter volumetricflask containing approximately 500ml of deionized water. Dilute to vol-ume with additional water, mix welland store in a tightly closed contain-er. A prepared solution of 1N HClcan also be purchased (Fisher Sci-entific Cat# SA48-20 or equivalent)Hydrochloric Acid must be stan-dardized to ±0.0001N before use.

Sodium Carbonate; anhydrous, volumetric grade (EMScience Cat#: 6394-2 or equiva-lent.) Dry at 250°C in a platinum orporcelain crucible for 4 hours. Store in a dessicator.

Modified methyl orange indica -tor; dissolve 0.14 grams of methylorange (Fisher Cat#: M216-25) and0.12 grams of xylene cyanolle FF(Fisher Cat#: BP125-50) in deion-

ized water and dilute to 100 ml.Water, Deionized & Carbon Diox -

ide free; boil and cool the deionizedwater or purge it with nitrogen for twohours.SAFETY

Refer to the MSDS for the properhandling procedures for each of thechemicals listed in this procedure.

Caustic potash is a strong base.Hydrochloric acid is a strong acid.These chemicals are corrosive tobody tissue and can cause immedi-ate and severe burns to eyes. Wearproper gloves, proper eye protectionand other protective clothing whenhandling these chemicals.A. STANDARDIZATION OF 1N

HYDROCHLORIC ACID1. Weigh 4.2 grams of sodium car-

bonate to the nearest 0.0001gram into a weighing dish. Care-fully transfer to an Erlenmeyerflask. Add 75 ml of deionizedwater and swirl to dissolve. Addthree drops of the modifiedmethyl orange indicator andtitrate with the HCl solution to amagenta color change.

2. The following formula is used tocalculate the normality of theHCl.Let:N = Normality of HClW = Weight (g) of Na2CO usedV= Volume (ml) of HCl required

to endpoint.Milliequivalent weight of

Na2CO3= 0.053

N = W/V x 0.0533. Determine the normality by aver-

aging the result of at least threetitrations.

B. ANALYSIS

1. To a clean, dry Erlenmeyer flask,accurately weigh to the nearest0.001 grams an amount ofsample as determined in thetable below. Weighing should beperformed as rapidly as possible.The sample sizes are:45% KOH................8 - 9 g50% KOH............... 7 - 8 gAnhydrous KOH..... 3 - 4 g

2. Immediately add 50 ml of deion-

ized water, making sure thesides of the beaker are washeddown.

3. Add 3 to 4 drops of modifiedmethyl orange indicator andcarefully add the magnetic stir-ring bar.

4. Titrate the sample to a steelgray color with 1N HCl. Sam-ples should be titrated as soonas possible to avoid pick up ofcarbon dioxide from the air.

5. Record the volume of acidrequired to reach this color.Estimate the buret reading tothe nearest 0.02 ml.

C. CALCULATIONSThe following are formulas used

to calculate total alkalinity.Let:W = Weight (g) of sample titratedN = Normality of HClV = Volume (ml) of HCl requiredMilliequivalent wt. of KOH =0.05611

% KOH = (V) (N) (0.05611)(100)W

% K2O = 0.8394 (%KOH)EXAMPLE

8.470 grams of caustic potashrequired the addition of 68.62 ml of1.0011N HCl to reach the modifiedmethyl orange endpoint.

% KOH= (V) (N) (0.05611) (100)W

% KOH = (68.62)(1.0011)(5.611) 8.470

% KOH = 45.51%% K2O= (0.8394) (45.51)% K2O= 38.20%

QUALITY ASSURANCEWith each batch of samples being

analyzed, at least one of the sam-ples should be analyzed in dupli-cate. On a regular basis, samplesthat have been previously analyzedfor total alkalinity should be reana-lyzed and the results compared.

Alkalinity values obtained foreach sample should be comparedwith OxyChem specifications forthat product.

Hydrochloric acid should berestandardized at least monthly.


DETERMINATION OFPOTASSIUM HYDROXIDEIN CAUSTIC POTASHPURPOSE AND THEORY

The potassium hydroxide contentof caustic potash is determined byadding barium chloride to a pre-pared sample and titrating with 1 NHCl to the phenolphthalein endpoint. The results are reported asper cent KOH on a sample-weightbasis.APPARATUS

100 ml Buret; Class A Volumet-ric, Fisher Scientific Cat #: 03-775or equivalent.


250 ml Erlenmeyer Flasks; widemouth, Fisher Cat#:10-090B orequivalent.

Magnetic Stirrer; Fisher Cat#:14-493-120MR or equivalent.

Magnetic stirring bars; 1 1/2" x5/16" dia. Fisher Cat#: 14-511-64 orequivalent.REAGENTS

1N Hydrochloric Acid; the preparation of this reagent isdescribed in the method for: “Deter-mination of Total Alkalinity”.

1% Phenolphthalein Indicator; dissolve one gram ofphenolphthalein (Aldrich Cat#:10,594-5 or equivalent) in 100 ml ofmethanol.

10% Barium Chloride; Dissolve 120 g of reagent gradeBaCl2.2H2O (Fisher Cat#: Bi34-500)in 880 ml of deionized water.

Water, Deionized & CarbonDioxide free; boil and cool thedeionized water or purge it withnitrogen for two hours.SAFETY

Refer to the MSDS for the properhandling procedures for each of thechemicals listed in this procedure.caustic potash is a strong base.Hydrochloric acid is a strong acid.These chemicals are corrosive tobody tissue and can cause immedi-ate and severe burns to eyes. Wearproper gloves, proper eye protec-

tion and other protective clothingwhen handling these chemicals.Barium chloride is highly toxic.Avoid inhaling barium chloride dust.A. STANDARDIZATION OF 1N

HYDROCHLORIC ACIDStandardization procedure is

described in the method for: “Deter-mination of Total Alkalinity”.B. ANALYSIS1. To a clean, dry Erlenmeyer

flask, accurately weigh to thenearest 0.001 grams an amountof sample described in the tablebelow. Weighing should be per-formed as rapidly as possible.The sample sizes are:45% KOH................ 8 - 9 g50% KOH................ 7 - 8 gAnhydrous KOH...... 3 - 4 g

2. Immediately add 100 ml of bari-um chloride solution, makingsure the sides of the beaker arewashed down.

3. Add 3 to 4 drops of phenolph-thalein indicator and carefullyadd the magnetic stirring bar.

4. Titrate the sample with 1N HCluntil the pink color changes towater white. The sample shouldbe titrated as soon as possibleto avoid pick up of carbon diox-ide from the air.

5. Record the volume of acidrequired to reach this color.Estimate the buret reading tothe nearest 0.02 ml.

C. CALCULATIONSThe following are formulas used

to calculate % KOH.Let:W = Weight (g) of sample titratedN = Normality of HClV = Volume (ml) of HCl requiredMilliequivalent wt. of KOH =0.05611

% KOH = (V) (N) (0.05611) (100)W

EXAMPLE8.470 grams of caustic potash

required the addition of 68.52 ml of1.0011N HCl to reach the phe-nolphthalein endpoint.

% KOH= (V) (N) (0.05611) (100)W

% KOH = (68.52) (1.0011) 5.611) 8.470

% KOH = 45.44%

QUALITY ASSURANCE

For each batch of samples beinganalyzed, at least one of the sam-ples should be analyzed in dupli-cate. On a regular basis, samplesthat have been previously analyzedfor total alkalinity should be reana-lyzed and the results compared.Alkalinity values obtained for eachsample should be compared withOxyChem specifications.

Hydrochloric Acid should berestandardized at least monthly.

DETERMINATION OFPOTASSIUM CARBONA TEIN CAUSTIC POTASH(Gravimetric)PURPOSE AND THEORY

The potassium carbonate contentof a sample of caustic potash isdetermined by a direct gravimetricmethod. The method involves acidi-fication of the caustic potash sam-ple with dilute sulfuric acid, boiling,and weighing the carbon dioxideevolved. Accurate results can beobtained when the potassium car-bonate content is 0.01% or greater.This method should be used to ana-lyze samples of 45% or 50% caus-tic potash containing 0.01% to0.25% K2CO3.

APPARATUSSee the CO2 train sketch below.Air for sweep is drawn in through

“A.” This air must be scrubbed freeof CO2. The ground-glass jointedtube fitted into the top of “A” shouldbe packed with 8-20 mesh ascaritewith a layer of anhydrous granularcopper sulfate on top.U-tube “D”

Add a few glass beads and 5 to10 ml of concentrated H2SO4. Theacid takes up the bulk of the mois-


ture passing through condenser “C”and should be changed oftendepending on frequency of use.U-tube “E”

Pack with dehydrated copper sul-fate pumice. This packing materialis prepared by soaking pulverizedpumice having the grain size ofwheat in saturated copper sulfatesolution drying at 150°F to 180°F.The product must be kept in a well-stoppered bottle.

U-tube “F”Pack with anhydrous magnesium

perchlorate. This removes all finaltraces of moisture carried throughthe system.

Ascarite - Absorbing Tower “G”Pack inside tube with 8-20 mesh

ascarite. Over the top layer addabout 0.25 inch of magnesium per-chlorate and cover with absorbentcotton. The cotton will prevent lossof weight due to carry-over of dustparticles. After tower is packed, itshould be hooked into the systemand swept with CO2-free air for aperiod of 15 to 20 minutes.U-tube “H”

Pack with 8-20 mesh ascarite.REAGENTS

Sulfuric Acid; 12 N with 27.8 g.FeSO4

.7H2O per liter.Sulfuric Acid, concentrated.Ascarite II; 8-20 mesh (sodium

hydroxide coated silica.)Magnesium perchlorate, anhy -

drous.Copper (II) Sulfate, anhydrous.Water, Deionized & Carbon

Dioxide free; boil and cool thedeionized water or purge it withnitrogen for two hours.SAFETY

caustic potash as dust or mist isintensely irritating to the respiratorysystem, skin, and eyes. Becomefamiliar with the first-aid measuresrecommended in this Handbook(pgs. 7 - 8).

When preparing 12 N sulfuricacid, the concentrated acid must bepoured slowly into water with con-stant stirring.

Wear safety glasses with sideshields when handling causticpotash samples or acids solutions.PROCEDURE

1. Sample PreparationThe 50% liquid caustic potash will

solidify at 40°F. If the sample issolidified at the time of analysis, itmay be thawed out by placing thecontainer in hot water until no solidsare present. The lip of the bottlemay be wiped before the sample ispoured into a weighing bottle.

No special preparation is requiredfor anhydrous samples. Carbonateand moisture pickup should beavoided by rapid sample handling.

In all cases, samples for carbon-ate analysis should be the firsttaken from the sample bottle to min-

imize carbon dioxide pickup fromthe atmosphere.2. Analysis

The train must be conditioneddaily before any samples are run.This is done by making a regulardetermination using a sample thatcontains carbonate. Following this,a blank should be run on the trainto make sure that the train is leakfree. This is done by making a reg-ular determination but omitting thesample. If the ascarite weighingtower gains more than 0.2 mg inweight during the blank run, thetrain probably has a leak.

After the train has been condi-tioned and found to be leak free,the samples are run as follows:1. Two absorbing towers (G) must

be conditioned and weighedprior to analysis. These will becalled G1 and G2 in the proce-dure. The use of two towerswill enable the analyst to con-serve time when performingmore than one analysis.

2. Weigh a sample of at least 20g. (50% basis) or large enoughto contain 5 mg of CO2 into aflask “B” using an analyticalbalance. Add 4 or 5 glassbeads and 80 ml of CO2-freedeionized water and immedi-ately place the flask into itsproper position in the train.

3. Add 50 ml of 12 N sulfuric acidto funnel “A”.

4. Place tared tower G1 betweenU-tubes “F” and “H”.

5. Open the system starting at U-tube “H” and working back to“D”.

6. Open cock on funnel “A” andallow acid to run into flask “B”and immediately hook vacuumline to tube “H”. Adjust the flowof air to 4 to 5 bubbles per sec-ond through the tip of the stemof funnel “A”.

7. Apply heat to flask “B” andbring to a boil. Hold “B” con-tents to boiling point for 3 min-utes and remove heat.

8. Sweep the system for 20 min-utes. While this is being done,the next sample can be

34 of 40Methodsof Analysis

weighed into another flask (B),and the beads and distilledwater added. This flask is thenstoppered and set aside untilneeded.

9. At the end of 20 minutes, thevacuum line is removed, towerG1 is shut off and removed andtower G2 placed into position.The cock on funnel “A” isclosed and 50 ml of 12 N sulfu-ric acid is again added to funnel“A”.

10. Flask “B” is removed, the stemof funnel “A” is washed downwith deionized water and thenew sample is placed into posi-tion.

11. Tower G2 is opened and theprocedure is repeated begin-ning at Step 6.

12. When G1 is removed from thetrain, a period of 20 minutes willcondition the sample for weigh-ing. During this 20 minutesweep time, another sample isprepared and tower G1 isreweighed in order to determinethe weight of CO2 found in thefirst sample. Tower G1 is thenready for Run No. 3.

CALCULATIONS

Report results as per cent K2CO3calculated to the nearest 0.01. Let:W(CO2) = Weight of CO2 evolvedW(S) = Weight of sample% K2CO3 = (W(CO2))(3.140)(100)

W(S)EXAMPLEIf a 25 gram sample was used and

the weight of CO2 absorbed intower “G” = 0.0125 grams, then:% K2CO3 = (0.0125)(3.140)(100)

25% K2CO3 = 0.12%

DETERMINATION OFPOTASSIUM CHLORIDE INCAUSTIC POTASHPURPOSE AND THEORY

Chloride is a contaminant in allgrades of caustic potash. Potassi-um chloride is present at < 60 ppmin 45% caustic potash. Higher con-centrations of this compound canhave undesirable effects in manyapplications of the product. Conse-

quently, accurate determination ofthis impurity is most important.

When acid solutions of silver ionand an alkali thiocyanate are mixedin the presence of a ferric salt, thethiocyanate has a selective actiontoward silver, resulting in the forma-tion of silver thiocyanate. Anyexcess of thiocyanate not requiredby the silver reacts with ferric salt toform reddish-brown ferric thio-cyanate. This color indicates thecompletion of the reaction.

An excess of silver nitrate and theferric indicator is added to a sampleof caustic potash that has beenacidified with nitric acid. Any chlo-ride that is contained in the samplewill react with the silver nitrate toform a silver chloride precipitate.The silver nitrate that is remaining inthe sample solution after this reac-tion is titrated with a standardizedsolution of ammonium thiocyanate.The equations involved are:AgNO3 + KCl Þ AgCl + KNO3Excess AgNO3 + NH4SCN ÞAgSCN + NH4NO36NH4SCN + Fe2(SO4)3 Þ2Fe(SCN)3 + 3(NH4)2SO4(reddish brown color)APPARATUS

25ml Buret; Class A Volumetric,Fisher Scientific Cat#:03-724-10Aor equivalent.

20ml Pipet; Class A Volumetric,Fisher Cat#: 13-650-2N

500ml Erlenmeyer flasks; widemouth, Fisher Cat#: 10-090C orequivalent.

Magnetic stirrer; Fisher Cat#:14-493-120MR or equivalent.

Magnetic stirring bars; 1 1/2" x5/16" dia, Fisher Cat#: 14-511-64 orequivalent.

Analytical Balance; capable ofweighing to 0.001 grams.REAGENTS

Water, Deionized.0.1N Silver Nitrate; accurately

weigh 16.99 grams of ACS Reagentgrade silver nitrate (dried at 110°Cfor 1 hr) and transfer to a 1L volu-metric flask. Dilute to volume withdeionized water, mix well and storein a tightly closed amber container.Silver nitrate and its aqueous solu-tions are photodecomposed by light

and should be stored in a darkplace.

0.1N Ammonium Thiocyanate;accurately weigh 7.612 grams ofACS Reagent grade ammoniumthiocyanate and transfer to a onevolumetric flask. Dilute to volumewith deionized water, mix well andstore in a tightly stoppered glassbottle. The thiocyanate solutionmust be standardized to within±0.0001N prior to use.

Ferric Indicator; prepare a satu-rated aqueous solution of ferricammonium sulfate [FeNH4(SO4)2],Aldrich Cat# 22,126-0 or equivalent.

1% Phenolphthalein Indicator; dissolve one gram ofphenolphthalein (Aldrich Cat#:10,594-5 or equivalent) in 100 ml ofmethanol.

Nitric acid, 1:1 (v/v); slowly pour500 ml of ACS Reagent grade nitricacid in 500 ml of deionized water asit is stirring. Allow the solution tocool.SAFETY

Refer to the MSDS for the properhandling procedures for each of thechemicals listed in this method.

Caustic potash is a strong baseand nitric acid is a strong acid.These chemicals are corrosive tobody tissue and can cause immedi-ate and severe burns to eyes. Wearproper gloves, proper eye protec-tion and other protective clothingwhen handling these chemicals.

Silver Nitrate is a strong oxidizingagent. Wear rubber gloves whenhandling. Contact with skin causesa black discoloration. Keep awayfrom heat, sparks and open flames.METHOD

A. STANDARDIZATION OF 0.1NSILVER NITRATE

Since this procedure determinesthe chloride content of a sample bycomparing the amount of unreactedsilver nitrate remaining in a samplewith the amount that is remaining ina reagent blank, the exact normalityof the silver nitrate need not beknown. If a reagent blank is notused, silver nitrate standardizationis essential. A manual titrationmethod is described in “ASTM


Standard Practice for Preparation,Standardization and Storage ofStandard Solutions for ChemicalAnalysis”, Vol 15.05; E200-86, 44-48.B. STANDARDIZATION

OF 0.1N AMMONIUM THIOCYANATE

1. Use a volumetric pipet to trans-fer 20.00 ml of freshly standard-ized 0.1 N silver nitrate into a250 ml Erlenmeyer flask con-taining 50 ml deionized water, 5ml of 1:1 nitric acid and 1 ml offerric indicator. Titrate theAgNO3 with the NH4SCN solu-tion until the first permanentreddish-brown color appearsand persists after vigorousshaking for 15 seconds. Recordthe volume of NH4SCNrequired. Repeat the above pro-cedure on at least three moresolutions of silver nitrate.

2. Use the following formula tocalculate the normality of theammonium thiocyanate solu-tion:N1 = (N2)(V2)/(V1)where:N1 = Normality of NH4SCNN2 = Normality of AgNO3V1 = Volume of NH4SCN

requiredV2 = Volume of AgNO3 added

3. Determine the normality byaveraging the results of at leastthree titrations.

C. PROCEDURE1. To a clean dry Erlenmeyer

flask, accurately weigh, to thenearest 0.01 g, 80 g of 45% liq-uid caustic potash or 40 to 80 gof dry caustic potash. Weighingshould be performed as rapidlyas possible.

2. Immediately add 100 ml ofdeionized water, making surethe sides of the beaker arewashed down.

3. Add 2 drops of 1% phenolph-thalein indicator and carefullyneutralize the sample with 1:1nitric acid. Caution: The sam-ple solutions generate consider-able heat when being neutral-ized with acid. The flask should

be continu-ously cooled in anice bath while the acid is slowlyadded. After the phenolph-thalein endpoint has beenreached (color changes frompink to colorless), add an addi-tional 5.0 ml of acid.

4. Allow the solution to cool toroom temperature and add astirring bar to the flask.

5. Using a volumetric pipet add20.00 ml of 0.1N silver nitrate,also add approximately 1 ml ofthe ferric indicator solution (seeNote 1).

6. Prepare a reagent blank byadding two drops of phenol-phthalein, 5ml nitric acid, 20.00ml silver nitrate solution and1ml of ferric indica-tor to a flaskcontaining 100 ml of deionizedwater and a stirring bar.

7. Place the flask containing thereagent blank on a magneticstirrer and titrate the solutionwith 0.1N ammonium thio-cyanate until a reddish-browncolor persists for at least 15seconds (see Note 2). Recordthe volume of NH4SCN requiredto reach the color change.

8. Titrate the sample solution with0.1N ammonium thiocyanateuntil the same color change isreached and record the volumeof NH4SCN (see Notes 3 and4).

D. CALCULATIONSThe following is the formula used

to calculate the percent chloride inthe sample.Let:W = Weight of sample titratedN = Normality of NH4SCNV1= Volume of NH4SCN required to

titrate blankV2= Volume of NH4SCN required to

titrate sampleMilliequivalent wt. of Cl = 0.03545% Cl = (V1-V2)(N)(0.03545)(100)

WCalculate the percentage of

potassium chloride as follows:%KCl = (%Cl)(2.1029)EXAMPLE

79.28 grams of 45% KOHrequired the addition of 19.54 ml of

0.1005 N NH4SCN to reach thetitration endpoint while the reagentblank required 19.95 ml of NH4SCNto reach the same endpoint.% Cl = (V1-V2)(N)(0.03545)(100)

W= (19.95-19.54)(0.1005)(3.545)

79.28% Cl = 0.00180% KCl = (% Cl)(2.1029)% KCl = (0.00180)(2.1029)% KCl = 0.00378 or 37.8 ppmNOTES1. Sample solutions should be

titrated within several minutesof adding the silver nitrate. Thesilver chloride has a tendencyto decompose with exposure tolight giving the solution a pur-plish color. This color can inter-fere with an accurate determi-nation of the endpoint colorchange.

2. From the outset of the back-titration with ammonium thio-cyanate, an appreciable quanti-ty of silver ions are absorbed onthe surface of the precipitates.Because of this, there is a ten-dency for a premature appear-ance of the end point color. Vig-orous stirring or shaking of thesolution is essential to bringabout desorption of silver ionsfrom the precipitates so theycan react with the thiocyanate.

3. As the endpoint is approached,increasing amounts of silverthiocyanate precipitating out ofsolution will actually increasethe solubility of silver chloride.Silver chloride that has precipi-tated will redissolve, allowingadditional silver ions to reactwith the thiocyanate. This caus-es a fading endpoint and resultsin low chloride values. For sam-ples containing concentrationsof chloride greater than 0.01%,it is advisable to filter the sam-ple solution through semi-quan-titative paper after the additionof silver nitrate but prior to titra-tion with thiocyanate. Removingmost of this precipitate willgreatly decrease the amount ofsilver that can be redissolvedduring the titration.


4. The white precipitate of silverthiocyanate interferes withobservation of the color changeat the titration endpoint. It issometimes helpful to stop thestirring or shaking of the sampleand allow the precipitate to set-tle, in order to observe the colorof the sample solution. If it isdetermined during this observa-tion that the endpoint has notyet been reached, resume vig-orous stirring before addition ofmore NH4SCN.

QUALITY ASSURANCEBecause of difficulties in deter-

mining the exact endpoint whenusing this method, only skilled labo-ratory personnel should attempt toperform these titrations.

On a regular basis, samples thathave been previously analyzed forchloride content should be reana-lyzed and the results compared.

Chloride values should bechecked against OxyChem specifi-cations.

DETERMINATION OF IRONIN CAUSTIC POTASHPURPOSE AND THEORY

Iron can result from contamina-tion during storage or transport ofthe product. Since iron is oftendetrimental to the end use of theproduct, accurate quantitation ofthis element is essential.

Ferric ion in an acidic mediumreacts with thiocyanate ions to pro-duce a red color complex. Theintensity of the color is proportionalto the amount of iron present. Bymeasuring the color intensity with aspectrophotometer, the concentra-tion of iron in a sample of causticpotash can be determined.APPARATUS

Visible Spectrophotometer;able to perform absorbance or %transmittance measurements at awavelength of 480 nanometers.


100 ml Volumetric Flasks; Fis-cher Scientific Cat# 10-210-8C orequivalent.

Pipets, Class A Volumetric;0.50 ml, Fischer Cat#: 13-650A orequivalent.1.00 ml, Fischer Cat#: 13-650B orequivalent. 2.00 ml, Fischer Cat#: 13-650C orequivalent. 5.00 ml, Fischer Cat#: 13-650F orequivalent. 10.00 ml, Fischer Cat#: 13-650L orequivalent. 20.00 ml, Fischer Cat#: 13-50N orequivalent.

Spectrophotometer Cells, stan-dard silica windows, 1 cm path-length; Fischer Cat#: 14-385-910Cor equivalent.

REAGENTSDeionized Water.Hydrochloric Acid; ACS

Reagent grade concentrated acid,Fisher Cat# A144 or equivalent.

1.5N Potassium Thiocyanate;add 145.77 grams of ACS Reagentgrade KSCN (Fischer Cat#: P317-500 or equivalent) to a one liter vol-umetric flask, dilute to volume withdeionized water and mix thorough-ly.

Potassium Chloride, 240 g/L;add 240.0 grams of ACS Reagentgrade KCl (Fisher Cat# P217-500or equivalent) to a one liter volumet-ric flask, dilute to volume withdeionized water and mix thorough-ly.

Hydrogen Peroxide, 30%; Fisch-er Cat#: H325-500 or equivalent.

Iron Reference Standard Solu -tion, 1000 ppm; Fischer Cat#:SI124-500 or equivalent.

pH Test Ribbons; Fischer Cat#:A979 or equivalent.SAFETY

Refer to the MSDS for the properhandling procedures for each of thechemicals listed in this procedure.

Caustic potash is a strong base.Hydrochloric acid is a strong acid.Hydrogen Peroxide is a strong oxi-dizing agent. The Iron ReferenceSolution is acidified with HCl. All ofthese chemicals are corrosive tobody tissue and can cause immedi-ate and severe burns to eyes. Wearproper gloves, proper eye protec-

tion and other protective clothingwhen handling these materials.

Refer to instrument manual forthe proper use of equipmentdescribed in this method.METHOD

A. CALIBRATION OF THE SPEC -TROPHOTOMETER

1. Prepare a stock iron standardby diluting 1.00 ml of the 1000ppm iron reference solution to100.0 ml with deionized water.This standard will have an ironconcentration of 10 µg/ml.

2. From the stock standard, trans-fer 0.50, 1.00, 2.00, 5.00, 10.0and 20.0 ml aliquots to 100 mlvolumetrics containing 50 ml of240 g/L KCl. To the volumet-rics, add 2.5 ml of conc. HCland one drop of 30% hydrogenperoxide and allow to set forapproximately one minute. Afterthe minute, add 10.0 ml of 1.5NKSCN, fill the flasks to the 100ml mark with deionized waterand mix thoroughly. These cali-bration standards will contain5.0, 10.0, 20.0, 50.0, 100, and200 µg/100 ml of iron, respec-tively (see Notes 1,2 and 3).

3. A reagent blank is prepared inthe same manner although noiron solution is added to theblank.

4. Refer to the instruction manualsupplied with the spectropho-tometer for specific instructionson the proper use of the instru-ment.

5. Set the wavelength on thespectrophotometer to 480nanometers.

6. Fill two matched 1 cm spec-trophotometer cells with thereagent blank. Place one cell inthe reference compartment andone cell in the sample compart-ment if the instrument is a dou-ble beam type or place thereagent blank in just the samplecompartment if it is a singlebeam unit. Adjust theabsorbance reading obtainedby the spectrophotometer tozero.


7. Proceed by taking absorbancereadings for each of the calibra-tion solutions, leaving thereagent blank in the referencecell of the spectrophotometer(double beam instrument).Absorbance readings must betaken within 15 minutes ofadding the KSCN to the solu-tions since the color complexthat is formed has limited stabil-ity.

8. Insert the concentrations of theiron standards (µg/100 ml) andtheir absorbance readings intoa linear regression formula(available on many hand heldcalculators). Determine the bestfit straight line for this data andthe correlation coefficient (r2)for the line. The correlationcoefficient indicates how wellthe data conforms to the best fitline that has been calculated. Itshould be greater than 0.99. Asan alternative to using a linearregression formula, the concen-trations and absorbance read-ings of the calibration standardscan be plotted on quadrilineargraph paper and the beststraight line drawn through thedata points.

B. ANALYSIS OF SAMPLES1. Weigh to the nearest 0.1 gram,

10 grams of anhydrous or 20grams of liquid caustic potashinto a 100 ml volumetric.

2. Add 20 ml of deionized waterand a 0.25 inch piece of pH testribbon.

3. Slowly add conc. HCl until thetest ribbon turns red, then addan additional 2.5ml of acid.

4. Cool the solution in a waterbath until it has reached roomtemperature.

5. Add one drop of 30% hydrogenperoxide and mix. The purposeof the peroxide is to oxidize anyferrous ion that may be presentin the sample to its ferric statesince the KSCN only reactswith ferric ion.

6. Add 10 ml of 1.5N KSCN. Diluteto volume with deionized waterand mix thoroughly.

7. Carefully transfer a portion ofthe sample solution to a 1 cmcell and measure the

absorbance on the spectropho-tometer at a wavelength of 480nm. Use the reagent blank inthe reference cell of the spec-trophotometer (double beaminstrument only). Absorbancereading should be taken within15 minutes after the KSCN hasbeen added to the sample.

8. Insert the absorbance readingfor the sample into the linearregression program establishedwith the calibration standardsand obtain the concentration ofFe in µg/100 ml of the solution.

CALCULATIONSReport results as ppm Fe, based

on the weight of the sample. Let:C = concentration of Fe in µg/100ml solutionW = weight of sample in grams

ppm Fe = C/W

NOTES1. If a 20 gram sample of liquid

product is used, the calibrationstandards will correspond toconcentrations of 0.25 - 20.0ppm of iron in the sample. Ifmore or less iron is expected tobe found in the products, theamount of iron in the standardsshould be adjusted accordingly.

2. If concentrations of less than0.25 ppm iron are expected, thesensitivity of this method can beincreased. The instrument canbe calibrated with more diluteiron standards while usingspectrophotometer cells with a5 cm rather than 1 cm path-length. Increasing the path-length will proportionallyincrease the absorbance read-ings.

3. When caustic potash samplesare neutralized with HCl, theresulting solutions contain KCl.Calibration standards andreagent blanks should thereforecontain this compound. Adding50 ml of 240 g/L KCl to thestandards and blanks approxi-mates the amount of KClformed in neutralized samples ifa 20 gram sample of liquidproduct is used. If a samplesize other than 20 grams isused, the amount of KCl addedshould be adjusted accordingly.

QUALITY ASSURANCEWith each batch of samples, ana-

lyze at least one of the samples induplicate. On a regular basis, rean-alyze samples that have been pre-viously tested and compare results.

Concentrations of iron found inthe analyzed samples should becompared with OxyChem specifica-tions.

Perform duplicate and samplespike analyses on a minimum of10% of all samples analyzed. Dupli-cate analyses should be repro-ducible within 15%. Samples shouldbe spiked with iron at approximately1 to 2 times the concentration thatis expected to be in the sample.

DETERMINATION OF SODI-UM IN CAUSTIC POTASHATOMIC ABSORPTION METHOD

PURPOSE AND THEORYSodium may be present in caustic

potash products. If sodium is detri-mental to the end use of the prod-uct, the concentration should bedetermined.APPARATUS

Atomic Absorption Spec -trophotometer.

100-ml Volumetric Flasks;Polypropylene, CMS Cat.# 253-260or equivalent.

10-ml Volumetric Pipets ;; FisherCat.# 13-650-2L or equivalent.

Adjustable Pipetter; with disposable plastic tips, EppendorfModel 4810 (100 to 1000 µl), CMSCat.# 382-283 or equivalent.

Analytical Balance; accurate to0.001 grams.REAGENTS

Sodium Reference StandardSolution, 1000 ppm; transfer 2.542grams of NaCl (dried at 110 °C fortwo hours) to a one liter volumetricflask. Dilute to volume with deion-ized water and mix. Transfer to aplastic bottle. Standards are com-mercially available (CMS Cat.# 737-631).

Sodium Working StandardSolution, 100 µg/ml; transfer 10.00ml of the reference standard to a


100 ml volumetric. Dilute to volumewith deionized water and mix. Pre-pare a fresh standard daily.SAFETY

Refer to the MSDS for the properhandling procedures for eachchemical.

Caustic potash and hydrochloricacid are corrosive solutions. Thesechemicals are corrosive to body tis-sue and may cause severe andimmediate burns. Wear propergloves, eye protection and otherprotective clothing.

Improper operation of the AA cancause a flashback or explosion.Refer to the instrument manual forproper use procedures.ANALYSIS1. Weigh 1.25 grams of caustic

potash to 0.001 grams into a100-ml volumetric flask. Diluteto volume and mix. This will bethe stock sample solution fromwhich dilutions are made andanalyzed.

2. Pipet 10 ml of the diluted caus-tic potash sample (if low sodiumgrade) or 1 ml (if commercialgrade) into each of three 100-ml volumetric flasks.

3. Dilute the contents of one flaskto volume and mix.

4. To the second and third flask,add aliquots of the workingsodium standard solution sothat the amounts of Na addedto the flasks will be approxi-mately 100% and 200%,respectively, of the anticipatedsodium concentration. Typical-ly, aliquots of 0.20 ml and 0.40ml will be appropriate. (Seenotes 2 and 3.)

5. Dilute the contents of flasks 2and 3 to volume.

6. Optimize the AA for sodiumanalysis. The 589.0 nm wave-length is the most sensitive andstable wavelength for sodium.Refer to the instrument manualfor specific instructions.

7. Aspirate the unspiked samplesolution into the AA flame andrecord the absorbance.

8. Aspirate the standard additionsamples from flasks two andthree into the flame and recordthe absorbances.

9. Calculate the micrograms of Nain the working sample solutionusing the standard additionmethod. Consult the instrumentmanual for details.

10. Taking into account the dilutionfactor, calculate the µg of Na inthe stock sample solution. Todetermine ppm Na in the prod-uct, let:C = concentration of Na in thestock solutionW = weight of sampleppm Na = C/W

EXAMPLE45% caustic potash is to be ana-

lyzed for sodium by flame AA. It isexpected to contain approximately200 ppm.

If 1.25 g of the sample is dilutedto 100 ml and a 10 ml aliquot of thesolution is diluted to 100 ml, thefinal dilution will contain:= (200ppm)(1.25g/100 ml) x 10 =25 µg Na/100 ml

Standard addition samples shouldthen be prepared to give an addi-tional 25 µg and 50 µg of sodium in100 ml samples.

These spikes can be prepared byadding 0.25 and 0.50 ml aliquots ofa 100 µg Na/ml working standard tothe second and third flasks, respec-tively.NOTES1. Sodium is extremely sensitive

to atomic absorption. Theremay be enough sodium in thesample to cause an extremelyhigh readout. If this shouldoccur, rotate the burner head.This has the same effect asdiluting the sample.

2. Store all reagents in plastic bot-tles to avoid either sodium pick-up from the glass or absorptionon the glass container walls.

3. Once the samples have beenprepared, they should be run assoon as possible to avoid sodi-um contamination from the airor the surroundings.a. Several rinses with hot tap

water.b. Several rinses with sodium-

free distilled water.Initial glassware cleaning maybe done with acid chromate

cleaning solution.4. The amount of diluted standard

prepared is for a limited numberof samples. If many samplesare to be analyzed, a larger vol-ume of diluted standard may beprepared.

5. The diluted standard should beprepared fresh daily. This isnecessary to avoid either sodi-um pickup from the glassware,the surroundings, or sodiumabsorption on the walls of theglassware.

6. Use distilled water from thesame supply for any one analy-sis.

DETERMINATION OF NICK-EL IN CAUSTIC POTASHPURPOSE AND THEORY

Nickel may be present at varyingconcentrations in caustic potashproducts. Nickel can be detrimentalto the end use of the product. Whenit is present at concentrations ofless than 1 ppm in liquid causticpotash, the heptoxime method canbe used for accurately determininglevels of at least 0.1 ppm. By reduc-ing the sample size, higher concen-trations of nickel can be measured,making this method applicable forall grades of caustic potash prod-ucts. This procedure has beenfound to be faster than methodswhich require the nickel to beextracted by an ion exchange resinor an organic solvent.

Nickel in caustic matrices can bequantified by using a visible spec-trometer (at 445 nm) to measurethe intensity of the orange colorformed by the addition of heptoxime(cycloheptanedionedioxime). Nick-el/heptoxime complexes are similarto those formed with dimethylgly-oxime, however, the heptoximecomplex is reported to be more sta-ble (Ref. 1). Divalent nickel forms apink color complex with heptoximewhich is less intense than theorange colored complex at higheroxidation states. To insure nickel isoxidized to a higher valence state,bromine is added as an oxidizingagent prior to addition of the hep-


toxime. Citric acid is also added tothe sample solution to complex anyiron which would interfere with theanalysis.APPARATUS

Visible Spectrophotometer;capable of measuring absorbanceor % transmittance at a wavelengthof 445 nanometers.

Spectrophotometer Cells; stan-dard silica windows, 5 cm path-length; Fisher Cat#: 14-385932E orequivalent.

Analytical Balance; capable ofweighing 100 +/- .01 grams.

100 ml Volumetric Flasks; ClassA Volumetric, Fisher Scientific Cat#10-210-8C or equivalent.

Pipets, Class A Volumetric;2.00 ml, Fisher Cat#: 13-650-2C orequivalent. 4.00 ml, Fisher Cat#: 13-650-2E orequivalent. 6.00 ml, Fisher Cat#: 13-650-2G orequivalent. 10.00 ml, Fisher Cat#: 13-650-2L orequivalent. 20.00 ml, Fisher Cat#: 13-650-2Nor equivalent.REAGENTS

Water, Deionized.Hydrochloric Acid, Concentrat -

ed; Trace Metal grade, FisherCat#: A508.

Citric Acid, 10%; dissolve 10 gcitric acid (Aldrich Cat#: 24,062-1 orequivalent) into water and dilute to100 ml.

Heptoxime (1,2-Cycloheptane -dionedioxime), 0.1%: dissolve0.1g of cycloheptanedionedioxime(CAS# 530-97-2) (Pfaltz & Bauer.Cat#: C29880 or ICN Cat#: 204213)into 100 ml of ethanol.

Ammonium Hydroxide, Con -centrated; Trace Metal grade,Fisher Cat#: A144.

Nickel Reference StandardSolution, 1000 ppm; AtomicAbsorption standard, Fisher Cat#:SN70-100 or equivalent.

Bromine water, saturated; addapproximately 4-5 ml. of ACSReagent Grade bromine. (AldrichCat#: 27,757-6) to 100 ml of deion-ized water and mix.

pH Test Paper; pH range 1-12,Fisher Cat#: 14-850-llB or equiva-lent.

SAFETYRefer to the MSDS for the proper

handling procedures for each of thechemicals listed in this procedure.

Caustic potash and ammoniumhydroxide are strong bases andhydrochloric acid is a strong acid.These chemicals are corrosive tobody tissue and can cause immedi-ate and severe burns to eyes. Wearproper gloves, proper eye protec-tion and other protective clothingwhen handling these materials.

Bromine is highly toxic, very cor-rosive and a strong oxidizing agent.Use only in a well ventilated fumehood. Wear proper gloves, propereye protection and other protectiveclothing when handling this materi-al.

Refer to the instrument manualfor the proper use of equipmentdescribed in this method.CALIBRATION OF THE SPECTROPHOTOMETER1. Transfer 1.00 ml of the 1000

ppm nickel reference standardsolution to a 1 L volumetricflask and dilute to volume withdeionized water. This stockstandard will have nickel con-centration of 1.00 µg/ml.

2. Transfer 2.00, 4.00, 6.00,10.00, and 20.00 ml aliquots ofthe 1.00 µg/l nickel stock stan-dard to 100 ml volumetrics con-taining approximately 50 ml ofdeionized water. Add one drophydrochloric acid and mix. Add5 ml of the citric acid solutionand mix. Add 2 ml. of saturatedbromine water and mix. Add 3ml of conc. ammonium hydrox-ide and mix. Add 2 ml. of hep-toxime solution, mix and dilutethe flask to volume. Note: These standard concen-trations will be equivalent to0.1, 0.2, 0.3, 0.5 and 1.0 ppm ofnickel if a 20 gram sample ofcaustic potash is used.

3. A reagent blank is prepared inthe same manner although nonickel solution is added to theblank.

4. The solutions should set for 20minutes from the time the hep-toxime is added to allow for fullcolor development.

5. Set the spectrophotometerwavelength to 445 nm. Refer tothe instruction manual suppliedwith the spectrophotometer forspecific instructions on theproper use of the instrument.

6. Transfer portions of the reagentblank solution to matched spec-trophotometer cells and placethem in both the reference andsample cell holders of the spec-trophotometer if it is a doublebeam instrument or just thesample cell holder if it is a sin-gle beam instrument. Zero theabsorbance reading of theinstrument.

7. With the blank solution remain-ing in the reference compart-ment (double beam instrumentonly), record the absorbancereadings for each calibrationstandard. Plot absorbance vs.nickel amount (µg) using a lin-ear regression program to gen-erate a calibration curve.

ANALYSIS OF SAMPLES1. Into a 100 ml volumetric flask,

weigh to the nearest 0.01grams, the amount of causticpotash product needed to accu-rately determine its nickel con-centration. After addition of theproduct, add 20 ml of deionizedwater. Use the table below as aguideline for the correct samplesize.Expected Ni Sample Concentration Size0.0-0.1 ppm................20 g0.1-0.2 ppm.................10g0.2-0.4 ppm..................5 g0.4-0.8 ppm................2.5g

2. Place the flask in an ice bath tocool the contents. Slowly neu-tralize the sample with concen-trated hydrochloric acid. Checkthe pH of the solution with pHtest paper. The paper can betouched to the flask’s stopperafter HCl addition and somemixing. Do not add a piece ofpH paper to the flask itself. Thepaper can dissolve and theresulting turbidity can affect thefinal colorimetric reading. For

40 of 40 Methodsof Analysis

every gram of 45% causticpotash, 0.66 ml of conc. HCl willbe required. When the neutral-ization point is near, the solutioncan be adjusted to neutral bythe addition of more dilute HCl.After the sample is pH neutral,add one additional drop of con-centrated hydrochloric acid.CAUTION: Neutralization ofthese products with concentrat-ed acid will generate a consider-able amount of heat. Add theacid in small increments andcool in between additions to pre-vent splashing and excessiveheating.

3. After the solution has reachedroom temperature, add 5 ml ofthe citric acid solution and mixwell. The purpose of the citricacid is to complex any iron thatmight be present so that is doesnot compete with the nickel forconsumption of the complexingreagent. If concentration of ironin these samples is known to below, it may not be necessary toadd this reagent.

4. Add 2 ml of saturated brominewater and mix thoroughly.

5. Add 3 ml of conc. NH40H andmix.

6. Add 2 ml of heptoxime solutionand mix.

7. Dilute the flask to volume withdeionized H2O and mix thor-oughly.

8. Allow the flasks to set for 20minutes from the time the hep-toxime was added for full colordevelopment.

9. Carefully transfer a portion ofthe sample solution to a 5 cmcell, stopper the cell and placein the sample compartment ofthe spectrophotometer. (Fordouble beam instruments, thereagent blank should be placedin the reference compartment.)Read the absorbance of thesample solution at a wavelengthof 445 nm.

10. Use the absorbance reading toobtain the amount (µg) of nickelin the sample solution from thecalibration curve.

11. Calculate the concentration ofnickel in the original product andreport as ppm.

CALCULATIONSLet:C = concentration of Ni in

µg/100 ml of solutionW = weight of sample in grams

ppm Ni = C/W

EXAMPLE20.11 g of caustic potash was

analyzed by the above procedure fornickel. An absorbance reading of0.1000 was obtained on the samplesolution. Standards containing 2 µgto 20 µg Ni were prepared and a cal-ibration curve generated using Pro-cedure A.Standard AbsorbanceConcentration Reading2.00 µg. Ni.................... 0.02584.00 µg. Ni.................... 0.05106.00 µg. Ni.....................0.077510.00 µg. Ni...................0.128720.00 µg. Ni...................0.2610

A calibration curve was generatedby performing a linear regressionanalysis on these readings. In thisexample the coefficient of correlationis 1.000. Coefficients of correlationgreater than 0.99 are acceptable.

From the linear regression equa-tion, the absorbance readingobtained for the sample is 0.1000which is equivalent to 7.72 µg Ni.ppm Ni = 7.72 µg Ni/20.11 g ppm Ni= 0.38 ppm NiQUALITY ASSURANCE

Perform duplicate and samplespike analyses on a minimum of10% of all samples analyzed. Dupli-cate analyses should be repro-ducible within 15%. Spike sampleswith nickel at approximately 1 to 2times the concentration that isexpected.

Compare concentrations of nickelfound in the analyzed samples toOxyChem specifications.

REFERENCES1. APHA, AWWA, WPCF; Stan-

dard Methods for the Examina-tion of Water and Wastewater;17th ed.; pp 3-121-123.

2. Vogel, Arthur I., A Text-book ofQuantitative Inorganic Analysis,3rd edition, 1961.

3. Kolthoff, Sandell, Meehan &Bruckenstein; QuantitativeChemical Analysis; 4th ed.;Macmillan Co.

DETERMINATION OF MER-CURY IN CAUSTIC POTASHPURPOSE AND THEORY

Mercury is a toxic material andmust be monitored as a pollutant. Itcan cause adverse effects if pre-sent in caustic potash used in cer-tain manufacturing processes.

Mercury is converted to mercuricion by oxidation with potassium per-manganate, then reduced to metal-lic mercury which is aerated fromthe solution and determined byflameless (cold vapor) atomicabsorption spectroscopy.PROCEDURE

ASTM E 538: “Standard TestMethod for Mercury in caustic Soda(Sodium Hydroxide)” is the proce-dure used for analyzing mercury incaustic potash products and is pub-lished in the Annual Book of ASTMStandards, Vol. 15.05. For a copyof this test procedure, contact:ASTM, 1916 Race St., Philadelphia,PA 19103 or OxyChem’s TechnicalService Dept.

oxychem caustic potash handbook ingles... · 2 of 40 introduction caustic potash is manufactured by...

Documents