eletrochemical corrosion (kor) laboratory chemical engineering fti - itb modul korosi elektrokimiawi...

EXPERIMENT MODULE

CHEMICAL ENGINEERING EDUCATION LABORATORY

ELETROCHEMICAL CORROSION

(KOR)

CHEMICAL ENGINEERING

FACULTY OF INDUSTRIAL TECHNOLOGY

INSTITUT TEKNOLOGI BANDUNG

2018

INSTRUCTIONAL LABORATORY

CHEMICAL ENGINEERING FTI - ITB

MODUL KOROSI ELEKTROKIMIAWI (KOR)

KOR – 2018 2

Contributors:

Dr. Isdiriayani Nurdin, Dr. Hary Devianto, Dr. Ardiyan Harimawan, Robby Sukma

Dharmawan, Jeffrey Pradipta W, Darien Theodric




KOR – 2018 i

TABLE OF CONTENTS

TABLE OF CONTENTS ............................................................................................................ i

LIST OF FIGURES ................................................................................................................... ii

LIST OF TABLES ................................................................................................................... iii

CHAPTER I PREFACE ............................................................................................................ 1

CHAPTER II EXPERIMENT GOALS AND OBJECTIVES ................................................... 2

2.1. Experiment Goals............................................................................................................ 2

2.2. Experiment Objectives .................................................................................................... 2

CHAPTER III EXPERIMENTAL DESIGN ............................................................................. 3

3.1. Perangkat dan Alat Ukur ................................................................................................. 3

3.2. Materials/Chemical Substance ........................................................................................ 3

3.3. Experimental Condition .................................................................................................. 3

3.3.1. Constant Variables ....................................................................................................... 3

3.3.2. Free Variables .............................................................................................................. 4

3.3.3. Bound Variables........................................................................................................... 4

3.4. Equipment Layout ........................................................................................................... 4

CHAPTER IV WORKING PROCEDURE ............................................................................... 5

4.1. Preparation ...................................................................................................................... 5

4.4. Main Experiment ............................................................................................................ 6

Bibliography .............................................................................................................................. 7

APPENDIX ................................................................................................................................ 8

APPENDIX A RAW DATA TABLE ....................................................................................... 9

APPENDIX B CALCULATION PROCEDURE .................................................................... 10

APPENDIX C LITERATURE SPECIFICATION .................................................................. 11

APPENDIX D .......................................................................................................................... 12




KOR – 2018 ii

LIST OF FIGURES

Figure 1. Equipment layout........................................................................................................ 4

Figure 2. Experimental flow diagram. ....................................................................................... 6

Figure 3. Experiment result (a) Fe-Zn (b) Fe-Cr. .................................................................... 10




KOR – 2018 iii

LIST OF TABLES

Table 1. Experimental data. ....................................................................................................... 9

Table 2. Standard potentials of some metals. .......................................................................... 11




KOR – 2018 1

CHAPTER I

PREFACE

Corrosion is an event where material is damaged due to its interaction with its surroundings.

Industrial equipment made from metal if exposed to various aggressive environments can get

corroded. Corrosion in a chemical plant can cause substantial losses such as equipment

damage, halt of processes during equipment maintenance due to corrosion, leakage of raw

materials/intermediate products/end products with additional potential for environmental and

plant-related hazards. Therefore, the corrosion process needs to be studied to determine the

proper way of control.

Naturally, metals in oxidative environments tend to oxidize. This tendency is expressed as a

standard equilibrium potential of cation-metal reduction/oxidation reactions. The comparison

of various metal tendency to oxidize is expressed by standard potential series (electromotive

force, emf-series)

There are several methods of corrosion control that can be applied to metal equipments.

Corrosion control methods that apply basic electrochemical principles are cathodic protection,

anodic protection, and addition of inhibitors. The working principle of cathodic protection

and anodic protection is to change the metal potential to reduce the corrosion rate which is

proportional to the flow of electric current. The addition of inhibitors aims to reduce the

active surface area of the anode or cathode.




KOR – 2018 2

CHAPTER II

EXPERIMENT GOALS AND OBJECTIVES

2.1. Experiment Goals

The goal of the experiment is to understand eletrochemical corrosion on metal and how to

control it.

2.2. Experiment Objectives

In this practicum, students are expected to identify:

1. Potential-Current Diagram (Evans Diagram) from pair of electrodes in certain

solution, also determination of metals’ function as cathode or anode.

2. Corrosion control method (cathodic/anodic protection, or mixed)

3. Influence of cathode/anode cross-sectional area and variation of electrolyte

concentration to corrosion rate




KOR – 2018 3

CHAPTER III

EXPERIMENTAL DESIGN

3.1. Perangkat dan Alat Ukur

Equipments used in the experiments are:

a. Beaker glass (500 mL)

b. Plate electrode of carbon steel, aluminum, copper, and stainless steel, each with cross-

sectional area of 0,25 (0,5 x 0,5) cm2 dan 25 (5 x 5) cm

2

c. Variable resistance 0 – 10 k

d. Amperemeter

e. Voltmeter

f. Copper cable

g. Saturated standard electrode of Cu/CuSO4

h. Volumetric flash (1000 mL)

i. Measuring pipette 5-10 mL (as needed)

j. Funnel

3.2. Materials/Chemical Substance

Followings are materials/substance needed:

a. H2SO4 98%

b. Solid KOH/NaOH

c. Aqua dm

d. CuSO4

e. Isolator Tape

3.3. Experimental Condition

Experimental condition consists of constant, free, and bound variables.

3.3.1. Constant Variables

a. Room ambient pressure (660 – 700 mmHg)

b. Room temperature (23 – 28 oC)

c. Electrolyte volume (250 mL)




KOR – 2018 4

d. Distance between electrodes (1 cm)

e. Types of electrodes and electrolytes

3.3.2. Free Variables

a. Electrolyte type and concentration (H2SO4 and NaOH solution with various

concentrations)

b. Coupling of different electrode types (carbon steel, aluminum, copper, stainless

steel)

c. Comparison of electrode cross-sectional area (anode area/cathode area : 1/1, 1/25,

25/1)

3.3.3. Bound Variables

a. Current

b. Electrode potential differences (cathode and anodes)

3.4. Equipment Layout

The layout of equipments used in this experiment is show by Figure 1. The layout consists of

intentiostatic layout with variation of resistance.

Figure 1. Equipment layout.




KOR – 2018 5

CHAPTER IV

WORKING PROCEDURE

The working procedure of electrochemical corrosion module consists of two main steps:

1. Preparation

a. Preparation of electrodes

b. Preparaton of electrolyte solutions

c. Equipment assembly

2. Main Experiment

Includes the making of Evans diagram and the analysis.

4.1. Preparation

a. Preparation of electrodes

Two electrodes (according to assignment) along with Cu standard electrodes are

cleaned using abrasive paper from the lowest grade up to 1200 CW under flowing

water. Then the electrodes are washed with aqua dm and dried before use.

b. Making of Electrolyte Solutions

The steps of electrolyte preparation depend on the type of electrolyte used (as

assigned).

i. H2SO4 Solution

H2SO4 solution is made by taking a volume of H2SO4 using a measuring

pipette and filler. The solution is then fed into a quantity of water in a 500 mL

beaker glass The H2SO4 solution is introduced into the aqua dm slowly. Then

put the solution into the flask and add aqua dm until the solution reaches the

boundary mark in the flash.

REMEMBER : Pour H2SO4 to water, not the other way around!

ii. KOH/NaOH Solution

The solid KOH/NaOH is weighed as needed. The solid is then fed into a

beaker containing a certain amount of water. The KOH solution is put into a

flask and aqua dm is added until the solution reaches the boundary mark of

flask.

c. Equipment Assembly




KOR – 2018 6

The equipments are assembled according to the layout in Figure 1.

4.4. Main Experiment

Record the voltage of the cell and electric current when the variable resistance is set to zero.

After that, the current is decreased by slowly increasing the variable resistance. Do changes

in cell resistance several times until the current is no longer readable by the amperemeter.

Record the current and voltage of the cell each time its resistance changes. After that, plot the

experiment result as Evans diagram. The experimental flow diagram is shown in Figure 2.

Start

Preparation of Equipments

Scrub electrodes with abrasive paper

Scrub standard electrodes with abrasive paper

Take H2SO4 96% using pipette

Wash with aqua dmFill tube with saturated CuSO4

solutionAdd an amount of aqua dm to

beaker glass

Add aqua dm until the boundary mark of volumetric

flask

Assemble the equipment

Set resistance to 0

Read starting V & I

Do variations on the resistance

Read V & I

Selesai

n-sequence of i reading?

Figure 2. Experimental flow diagram.




KOR – 2018 7

Bibliography

Jean Besson et Jacques Guitton, 1972, Manipulations d’electrochimie, introduction a la

theorie et a la pratique de la cinetique electrochimique, Paris: MASSON & CIE.

Jones, D.A., 1992, Principles and Prevention of CORROSION, Macmillan Publishing

Company.

Prentice, G., 1991, Electrochemical Engineering Principles, Prentice-Hall International, Inc.




KOR – 2018 8

APPENDIX




KOR – 2018 9

APPENDIX A

RAW DATA TABLE

Example of experimental table used in the experiment is shown below.

EXAMPLE

Run number :

Electrode 1 (area) :

Electrode 2 (area) :

Electrolyte type and concentration :

Table 1. Experimental data.

I (mA) V1 (mV) V2 (mV)




KOR – 2018 10

APPENDIX B

CALCULATION PROCEDURE

Figure 6 shows the Evans diagram obtained from the experiment. In both cases with Fe-Zn

and Fe-Cr pair electrodes, the corrosion was controlled by cathodic reaction. Note that in the

case of Fe-Cr, the maximum current of 0.23 mA is centered on the Fe anode of 0.03 cm2 to

produce an alarming deep-pit corrosion. In contrast, with Fe - Zn pairs, a current of 0.12 mA

is divided over a 25 cm2 Zn anode. The corrosion that occurs in these electrode pairs is even

corrosion. Therefore, the thickness decrease of electrodes due to corrosion runs very slowly.

Figure 3. Experiment result (a) Fe-Zn (b) Fe-Cr.

In experimental conditions with a closure of 50% cathodic or anodic surface area, a change in

corrosion rate is indicated by a decrease in current. The result can be seen in Figure 6 with

dashed lines.

From Evans diagram, we can conclude that:

a. Corrosion reaction type : cathodic/anodic control

b. Metal that function as anode and cathode

c. Maximum corrosion rate, calculated from ianodic max (= Imax/anode area) using Faraday

equation (

)




KOR – 2018 11

APPENDIX C

LITERATURE SPECIFICATION

C.1. Standard Potential Series

Table 2. Standard potentials of some metals.

½ Cell Reaction Standard Potential (V)

Au3+

+ 3e- Au +1.420

O2 + 4H+ + 4e

- 2H2O +1.229

Pt2+

+ 2e- Pt +1.2

Ag+ + e

- Ag +0.800

Fe3+

+ e- Fe

2+ +0.771

O2 + 2H2O + 4e- 4(OH

-) +0.401

Cu2+

+ 2e- Cu +0.340

2H+ + 2e

- H2 0.000

Pb2+

+ 2e- Pb -0.126

Sn2+

+ 2e- Sn -0.136

Ni2+

+ 2e- Ni -0.250

Co2+

+ 2e- Co -0.277

Cd2+

+ 2e- Cd -0.403

Fe2+

+ 2e- Fe -0.440

Cr3+

+ 3e- Cr -0.744

Zn2+

+ 2e- Zn -0.763

2H2O + 2e- H2 + 2(OH

-) -0.828

Al3+

+ 3e- Al -1.662

Mg2+

+ 2e- Mg -2.363

Na+ + e

- Na -2.714

K+ + e

- K -2.924

C.2. Electrical Conductivity of Metal

Find the conductivity of used metal! (as assigned)




KOR – 2018 12

APPENDIX D

JOB SAFETY ANALYSIS

No Material Material Properties Countermeasures

1 Sulfuric

Acid

(H2SO4)

Very corrosive

Hazardous if

inhaled

Hazardous to

skin (can cause

burn)

Can cause

respiratory

iritation

Very toxic

Dangerous in

aquatic

environment

Boiling point =

270°C

Colorless

Molecular weight

= 98,08 g/mol

Smell = has a

little bit of

character

Solubility in

water : soluble,

exothermic

Inhaled:

Get aids. Wash immediately

with water. If hard to inhaled,

quickly get oxygen. Don’t

use mouth-to-mouth

resuscitation.

Swallowed:

No need to vomit. If victim is

conscious, give 2 – 4 glass

of milk or water. Get aid

immediately.

Skin contact:

If contacted with skin or hair,

immediately wash with soap

and water for 15 minutes. Get

aid.

Eye contact:

Wash with flowing water for

at least 30 minutes. Don’t let

victim close or wipe the eyes.

Work in fume hood

2 Copper

(II)

Sulfate

(CuSO4)

Odorless

Can cause skin

eye, respiratory

and digestive

system

iritation, and

also damage in

internal organ.

Boiling point =

150°C

Solid

Molecular weight

= 249,69 g/mol

If inhaled, get fresh air

immediately

Water contact: Check and

remove any contact lense.

Wash eye with flowing

water for at least 15 minutes.

Can use cold water. Get

medical aid.

Skin contact: wash skin with

large amount of water. Close

iritated skin with emolient.

Clean shoes before use.

Get medical aids.

3 Water Molecular

weight =

18,02 g/mol

Boilig point =

100°C

Density = 1

gr/cm3

Specific gravity

Inflammable

Odorless

Colorless

Clean with dry cloth in case

of spill.




KOR – 2018 13

: 1

pH : 7

Boiling point =

100 oC

Melting point :

0 oC

Accidents that may happen Penanggulangan

Student slip on material spill Treat material carefully, especially sulfuric acid

(H2SO4) and call laboratory assistant for help in

handling the cleaning.

Perlengkapan keselamatan kerja

Gloves Lab coat Mask Goggle

Safety Working Procedure

1. Materials and equipment checking:

Ensure equipments are in good condition

Ensure taking the correct material and closing it well

2. Experiment

Ensure the equipments are assembled as layout

Immediately dry material spill.

3. After experiment

Make sure all equipments are turned off and electrical cables are plugged out.

Make sure tables and floors are cleaned from leakage/spill.

Asisten Pembimbing Koordinator Lab TK

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