United States Patent Stern

[54] TREATMENT OF HAZARDOUS MATERIALS WITH AQUEOUS AIR FOAM OF P0LYHM)ROXY POLYMER

[75] Inventor: Richard M. Stem, St. Paul, Minn.

[73] Assignee: Minnesota Mining and Manufacturing Company, St. Paul, Minn.

1211 Appl. No.: 537,049

[22] Filed: Jun. 12,1990

Related U.S. Application Data

[63] Continuation of Ser. No. 204,110, Jun. 8, 1988, aban- doned.

................................................ [5 11 Int. ( 3 . 5 C08J 9/06 ........................................ [52] U.S. CI . 521/50; 521/65;

521/68; 521/69; 521/70; 521/78; 52V84.1; 521/85; 521/135; 521/907; 521/9 13; 521/921;

252/3; 252/8.5 14; 252/3 15.3; 252/626; 252/628; 252/631; 210/751

....................... [58] Field of Search 521/50, 65, 68, 69, 521/70, 78, 84.1, 85, 135, 907, 913, 921; 252/3,

8.514, 315.3, 626, 628, 631; 210/751

[561 References Cited U.S. PATENT DOCUMENTS

3,264,245 8/1966 Sinclair et al. ..................... 26W29.6 3,794,115 2/1974 Skagerberg ......................... 166/294 4,021,355 5/1977 Holtmyer et al. ............. 252/8.55 R 4,568,481 2/1986 Harris ............................... 252/315.3 4,579,942 4/1986 Brode et al. .......................... 536/84 4,795,590 1/1989 Kent et al. .......................... 252/307 4,795,764 1/1989 Alm et al. ........................... 521/107

FOREIGN PATENT DOCUMENTS

206548A 12/1986 European Pat. Off. . 3230259 2/1984 Fed. Rep. of Germany 7593879 7/1975 Japan .

[ i l l Patent Number: [45] Date of Patent: Jun. 25, 1991

OTHER PUBLICATIONS

The Wall Street Journal, May 16, 1985, pp. 1-20. Consulting Engineer, Mar. 1984, pp. 35-47. U.S. Defensive Publication T901,022, published in PTO Official Gazette, 901 O.G. 416. Encyclopedia of Chem. Tech., Kirk-Othmer, 3rd Edi- tion, vol. 22, pp. 347-387, John Wiley & Sons (1983). Handbook of Water-Soluble Gums & Resins, R. L. Davidson, McGraw Book Co. (1988) Chaps. 6 and 20. E. Z. Casassa, et a]., J. of Chem. Ed., 63, 57-60.

Primary Examiner-Morton Foelak -

Assktant Examiner-S. A. Acquah Attorney, Agent, or Firm-Gary L. Griswold; Walter N. Kim; Eloise J. Maki

A method of treating hazardous material or other sub- strate with an aqueous air foam, comprising the steps of (1) preparing an aqueous solution or dispersion compris- ing (a) water-soluble polyhydroxy polymer having a plurality of hydrogen-bondable 1,2- and/or 1,3-diol structures capable of complexation with the borate anion, B(OH)4-, (b) polyvalent ionic complexing agent, such as borax, which crosslinks said polymer by hydro- gen-bonding complexation, (c) foaming agent to impart persistence to the fluid air foam generated upon aeration of said solution or dispersion, (d) a pH modifier, such as sodium hydoxide or acetic acid, to impart an appropri- ate pH to the solution or dispersion necessary for time- controlled formation of gelled or viscous air foam from the fluid air foam, and (e) water as the major component of said aqueous solution or dispersion by weight; (2) aerating said aqueous solution or dispersion to form therefrom a fluid, aqueous, aerated or air-entrained, low density foam (or air foam) which is gelable or becomes viscous, generally at least 5 seconds after its formation; and (3) spraying, contacting or otherwise applying said fluid, aqueous air foam to exposed surface of said haz- ardous material or other substrate.

21 Claims, No Drawings

5,026,735 1 2

Further background, though it does not disclose the TREATMENT OF HAZARDOUS MATERIALS treatment of hazardous material, is U.S. Defensive Pub-

WITH AQUEOUS AIR FOAM OF POLYHYDROXY lication T901,022, a U.S. patent application published POLYMER Aug. 8, 1982, by the U.S. Patent and Trademark Office

5 in its Official Gazette, 901 O.G. 416. That publication This is a continuation of application Ser. No. discloses foaming an acidic solution of surfactant and

07/204,110 filed June 8, 1988, now abandoned. hydroxylated polymer, such as a polyvinyl alcohol or This invention relates to water-based compositions guar gum, and contacting the resulting foam, at a point

comprising water-soluble polyhydroxy polymer, such adjacent to the point at which the foam issues from the as guar gum or poly(viny1 alcohol). In another aspect, it 10 foam generator, with an alkaline pH modifying agent, relates to the treatment of hazardous materials and such as ammonia or ammonium hydroxide, to increase other substrates, such as those in hazardous waste sites, the pH of the foam to at least 7 and produce a gelled with water-based air foams. In another aspect, it relates polymeric foam within 2 seconds, said gelled foam to water-based air foams and to their use in such treat- being useful for insulating, packaging, and acoustical ment. 15 purposes.

During recent years the threat of hazardous wastes, Briefly, this invention, in one aspect, provides a hazardous spas, leaks, and accidents of flammable liq- method of treating a substrate with an aqueous air foam, uids, and other hazardous materials to public health and comprising the steps of (1) preparing an aqueous solu- safety and to the environment has received increasing tion or dispersion comprising (a) water-soluble P O ~ Y ~ Y - attention and raised national concerns and issues which 20 droxy polymer having a plurality of hydrogen-bondable are being addressed by a host of local ordinances and d i d Structures or groupings in the polymer chain in the state and federal laws and regulations (see, for example, form of "In the Dumps", The Wallstreet Journal, May 16, 1985, pages 1, 20). Various technologies have been used or proposed for the treatment or control of such materials 25 I I

1,2-dl01 structures, -C(OH)-C(0H)-, (see, for example, Consulting Engineer, Mar., 1984, - -

pag& 35-47). - and/or in the form of There are thousands of hazardous waste sites in the

United States, such as impoundments, burial dump sites, 30 and landfills in which wastes from industrial and com- I mercial operations, research and retail establishments,

I I 1.3-dtol structures, -C(OH)-C-C(0H)-,

educational and hospital laboratories, and military com- I plexes have been stored or disposed. Such sites are either still operating, inactive, or abandoned and the 35 such dial structures being of complexation with emission or release of gases, vapors, odors, liquids, and the borate anion, B(oH)~-, (b) polyvalent ionic corn- dust from such sites and their pollution of the air and plexing agent, such as a water-soluble, polyprotic inor- surface or ground water and contamination of soil are ganic acid salt, for example borax, Na2B407. 10HZO, or

or are Or managed by hydrated, polyvalent metal complex salt, which cross- techniques many of which have disadvantages which 40 links said polymer by hydrogen-bonding complexation, limit their applicability. (c) foaming agent to impart persistence to the fluid,

~n example of a particularly serious hazardous waste aqueous air foam generated upon aeration of said solu- dump is the McColl Dump in Orange County, Calif., an tion or dispersion, (d) a pH modifier, such as sodium abandoned world War 11 dump containing acid Petro- hydroxide or acetic acid, to impart an appropriate pH to leum sludges, oil field drilling muds* waste hydrocar- 45 the solution or dispersion necessary for time-controlled bons, sulfur dioxide, and benzene, which dump is in formation of gelled or viscous air foam from the fluid close proximity to a residential area of more than 800 air foam, and (e) water as the major component of said homes. A cleanup solution proposed for that site is aqueous solution or dispersion by weight; (2) aerating excavation of the hazardous waste material by workers said aqueous solution or dispersion to form therefrom a in protective clothing and hauling by trucks of the a c a - 50 fluid, aqueous, aerated or air-entrained, low density vated material elsewhere, with the possible evacuation foam (or air foam) which becomes gelled or viscous, of people from the neighborhood if emissions of gases generally at least 5 seconds after its formation; and (3) and odors cannot be controlled. spraying, contacting or otherwise applying said fluid,

A significant advance in the treatment of hazardous aqueous air foam as a wet, three-dimensional coating, material is that described in European Patent Applica- 55 blanket, or layer to exposed surface of a substrate, such tion, EP 206548A, published Dec. 30,1986. That appli- as a body of hazardous material, for example a hazard- cation discloses aerating an aqueous solution of surfac- ous waste dump, a pool of a spilled, volatile, flammable tant and poly(oxyalkylene)isocyanate prepolymer, pre- liquid, or other substrate to be protected from giving pared from polyether polyols and polyisocyanates, to rise to a hazard, e.g. fire. The applied fluid foam gels, or form a fluid, water-based air foam which is sprayed or 60 increases in viscosity without gelling, generally at least otherwise applied to the exposed surface of a substrate, 5 seconds after its formation, and thus stabilizes in situ such as a body of hazardous material, the applied foam and forms a wet, persistent or long-lasting, sealing or gelling or increasing in viscosity, due to the reaction of vapor suppressing, gelled, aqueous air foam or a vis- the isocyanate prepolymer with water to form a poly- cous, aqueous air foam, in the form of a highly vapor- (oxyalkylene) polyurea polymer, and forming a persis- 65 impermeable coating, blanket, or layer on the substrate. tent, gelled air foam or viscous air foam in the form of Such a coating results in minimizing, suppressing, con- a coating on the exposed surface, thus sealing or other- trolling, reducing or preventing the emission, spread- wise protecting or controlling the substrate. ing, or release of gases, vapors, odors, dusts, or liquids

5,026,735 3 4

that may be present in the hazardous material or sub- sion of polyhydroxy polymer, for example by pumping strate and physically immobilizing, constraining, con- the solution to air-aspirating, foam-producing equip- solidating, sealing, or inactivating the exposed surface ment and applying, for example by spraying, the result- so-coated. ing fluid, low-density air foam onto the hazardous mate-

(The term "air foam" is used in its industr~-acce~ted rial or substrate. The starting solution or dispersion can sense mean a foam made physically mixing air into b, at the time of application by bringing to- a liquid, and thus the term is distinct from chemical or gether two liquid from separate sources, one carbon dioxide foam or halocarbon blown foam.)

The foam as prepared and applied is initially a fluid, stream comprising water, complexing agent, pH modi-

two phase-system (an agglomeration of air bubbles) of a 10 fier~ and foaming agent and the stream being in discontinuous or dispersed gas phase, viz. air, and a the form of a concentrate comprising ~ o l ~ h ~ d r o x ~ continuous, aqueous, polymer liquid phase, viz. bubble polymer dissolved or dispersed in an anhydrous, water-

or lamellae, comprising water in which is dis- soluble or -dispersible, non-reactive organic solvent, solved or dispersed small amounts of polyhydroxy p l y - such as mineral oil or diethylene glycol monoethyl mer, foaming agent, pH modifier, and the complexing 15 ether acetate. agent such as the disassociated or ionized polyprotic Advantages of the treatment, control, or management inorganic acid salt. The water of the liquid phase can of hazardous materials or substrates with foam in accor- also contain dissolved or dispersed optional compo- dance with this invention include: the use of an inexpen- nents, such as rubber or polymeric latex particles, fire sive and readily available raw material, namely water, retardant, pigment, dye, etc. The liquid phase of the 20 which can be tepid (as is often found in field conditions) foam is the Or predominant phase by weight- and is either fresh water, brackish water, or sea water, Upon Or of the fluid foam to the the water being the bulk of the weight of the foam; the hazardous material or substrate, and as a consequence of use of foaming agent, pH modifier, and complexing the Of the by the agent, each of which is used in a relatively small amount complexing agent, the three-dimensional structure of 25 applied fluid air foam is thus stabilized in said time-con- and many types of which are commercially available; a

trolled manner in the form of either a non-fluid, gelled, p0lrner which is also used in relatively small amounts

aqueous air foam or a viscous, aqueous air foam. The and is environmentally acceptable, many types of such gelled air foam is a two-phase system of discontinuous polymer being commercially available; a treatment gas (air) phase and a continuous, soft, semi-solid hydro- 30 which can use equipment that is not particularly energy gel phase comprising bound water and water-insoluble, intensive or expensive and can be conventional or easi- crosslinked, hydrated polyhydroxy polymer. The vis- ly-modified conventional equipment, namely, pumps, cous air foam is a two-phase system of discontinuous gas valves, regulators, mixers, tanks, hoses, and foam- (air) phase and continuous aqueous polymer phase com- generating nozzles such as air-aspirating or air-injecting prising water and p o l ~ h ~ d r o x ~ polymer. The polymer 35 nozzles, etc., the operation of which can be carried out in both the gelled and viscous foams comprises a plural- without specialized labor; the fact that the gelled or ity of hydrated diol-containing polymer chains. 'I'he viscous foam can be formed in a time-controlled manner gelled or phase is the major or predominant from the fluid foam, which is particularly meaningful phase by weight. The lamellae or liquid film of the air when the fluid foam is applied to a vertical or inclined

in the fluid foam is gelled, Or 40 surface; the fact that the gelled or viscous foam does not viscous, thus minimizing, reducing, or preventing the significantly increase the weight and volume of the drainage of liquid from the lamellae and the consequent rupture of the bubbles and collapse of the foam struc- hazardous material or substrate to which it is applied,

ture. D~~ to the hydrophilic nature of the po~y~ydroxy that is, there is a high substrate-to-foam weight or vol- water in the foam is retained or bound and the 45 ume ratio; and the facts that the gelled or viscous foam

water, together with the highly vapor-impermeable is conformable and adheres to many types of substrates, nature of the resulting gelled or viscous foam, provides is relatively innocuous, environmentally acceptable, a stable, persistent or long-lasting, sealing or vapor noncorrosive, nonflammable, relatively stable and per- suppressing blanket or barrier on the exposed, treated sistent or long-lasting, inherently white or light-colored surface of the hazardous material or substrate. Such a 50 and can be dyed (thus the extent of application is visu- foam blanket excludes oxygen or air from the treated ally perceptible), does not require high application tem- hazardous material, or h ~ e r s the vaporization rate of peratures or drying, and rapidly covers, traps, immobi- liquid in the hazardous material or substrate SO-treated, lizes, restrains, or consolidates the hazardous material and greatly facilitates clean-UP procedures, such as ex- or substrate, is quickly effective as a control measure, cavation and hauling of excavated material by reducing 55 ,d .,, in many cases, be cleaned up. the risk of ignition of flammable vapors or other corn- me water-soluble, polyhydroxy polymers used in bustible material, reducing the concentration of toxic this invention are known organic materials (see, for vapors in the work area, and reducing the environmen- example, Davidson, R. L., of Water-Solu- tal impact of the hazardous material. For purposes of clean-up, the applied foam in the case of borate-cross- 60 ble Gums and Resins," McGraw-Hill Book Co., (1988),

linked polymer, after it serves its purpose, can be e.g. and 20). An example of as~nthetic, water-

sprayed or otherwise treated with a foam-collapsing or P ~ ~ Y ~ Y ~ ~ ~ ~ Y polymer useful in the practice of -breaking agent, such as dilute aqueous acid, the are- this invention is poly(viny1 alcohol), which is typically versible" nature of such a foam system being an impor- manufactured by the hydrolysis of ~olY(vinY1 acetate). tant and useful property thereof. 65 It is sometimes described in the art as a polyhydric

The fluid, aqueous air foam can be conveniently alcohol with secondary hydroxyl groups on alternate formed by mechanically or physically entraining or carbon atoms in the form of 1,3-diol structures, and dispersing air in the starting aqueous solution or disper- represented structurally as:

5,026,735 5 6

range of molar substitution, e.g. with hydroxypropyl groups, is 0.1 to 2, most preferably from 0.2 to 0.6. An especially useful guar gum derivative is hydroxypropyl guar gum, a commercially available example of which is

5 JAGUAR Q HP-11, with an average of 0.35 to 0.45 moles of hydroxypropylation per each anhydrohexose

Preferred poly(viny1 alcohol) materials are those de- dt of the guar gum. rived from F'Ol~(vin~l acetate) by at least 98% h~droly- The polyvalent ionic complexing agents useful in this sis thereof and having a weight at least invention include known crosslinking agents for the 10yOOO, preferably greater than 5090009 and most prefer- 10 polyhydroxy polymers and representatively include

greater than 75,000. Lower weight alkali meta] brates such as sodium and pomsium b- P ~ ~ Y ( ~ ~ ~ Y ~ e'g' with weights rates, alkali metal pyroantimonates such as sodium and 10,00Q-50,000, preferably be loo% potassium pyroantimonates, titanates such as sodium P ' Y ( ~ Y ' acetate)' The lower the weight, and potassium fluorotitanates and potassium the larger the amount of the polymer needed for achiev- 15 ing desired foam properties. oxalate, chromates such as sodium and potassium chro-

A of naturally-occurring, water-soluble polyhy- mates and dichromates, vanadates such as ammonium

droxy polymers useful in the practice ofthis invention is vanadate, and the like (see, for example, said U.S. De-

the class of water-soluble polysaccharides with high fensive Publication T901,022 and U.S. Pat. Nos. molecuJar weight (generally at least 100,000) and hav- 20 4,021,355, 495689481, 392649245, and 3,794,115 for fur- ing cis 1,Zdiol structures in one or more monosaccha- ther disclosure of such crosslinking agents). c or ax, ride units in the polymer chain, preferred polysaccha- Na2B407*10H20, the salt of a strong base and a weak rides being galactomannan gums, such as guar gum and acid, hydrolyzes in aqueous solution to form a boric locust bean gum, (See, for example, U.S. Pat. NO. acid-borate buffer having a pH of around 9. The borate 4,579,942 (Brode et al) for a disclosure of such polysac- 25 anion, B(OH)4-, present in alkaline solutions, is capable charides, which disclosure is incorporated herein by of complexation, through hydrogen bonding, with the reference.) Guar gum has long been known to be useful cis 12-diol or the 1,3diol groupings in the polyhydroxy as a thickening agent for water and is approved as a polymer, leading to crosslinking thereof, which com- direct food additive by the U.S. Food and Drug Admin- plexation may be illustrated as follows: istration. The structure of guar gum has been accepted as being that of a linear, alternating copolymer (e.g. see 30 H H p. 6-3 and 6-4 of "Handbook of Water-Soluble Gums I

0 - H - - - 0 I

and Resins," supra) having cis 1,2-diol groupings in the anhydrohexose units, and can be structurally repre- \ f

H-C C-H sented as 35 I /

\ B - /O-H---O I

(CH21.x / \

(CH21x I I byGI{ hydroxypropyl where gum such x is as zero, guar guar e.g. gum gum, as in or or the a derivative x case is 1, e.g. of a as thereof galactomannan in the such case of as

45 poly(viny1 alcohol). E. Z. Casassa et a]., .I of Chem. Ed. H HO OH 63, 57-60 (1986) illustrates such complexation.

H The foaming agents useful in this invention are sur- face active agents or surfactants which are synthetic or

H H H H ,I natural organic compounds or materials capable of guar gum repeating unit 50 foaming water, and which are compatible with the

polyhydroxy polymers, the polyvalent ionic complex- A commercially available guar gum useful in the prac- ing agents, and pH modifiers used in this invention. tice of this invention is JAGUAR Q 6003. Suitable surfactants can be nonionic, cationic, anionic,

Also useful in the practice of this invention are the or amphoteric, and compatible mixtures thereof. Classes derivatives of guar gum, such as those formed by etheri- 55 of surfactants which are useful include: soaps or the fication and esterification reactions with the hydroxy salts of fatty acids, such as those having the general functionalities. The commercially significant deriva- formula RCOOM, where R is a fatty aliphatic group tives are mainly those prepared by etherification, e.g. and M is an alkali metal, e.g., sodium oleate, laurate, hydroxyethylation with ethylene oxide, hydroxypropy- palmitate, or stearate; fatty alkyl sulfates, such as those lation with propylene oxide, carboxymethylation with 60 of the general formula ROS020M, e.g., sodium octyl, monochloroacetic acid, and quaternization with various decyl, lauryl, tetradecyl, hexadecyl, heptadecyl, or oc- quaternary amine compounds containing reactive tadecyl sulfate; salts of alkarylsulfonic acids, such as chloro or epoxy sites. In the case of guar gum, each those of the general formula RC6H4S03M, e.g., sodium saccharide ring or anhydrohexose unit contain an aver- octylbenzene sulfonate; ethylene oxide adducts, such as age of 3 hydroxy groups. For the guar gum derivatives, 65 those of the general formula R(CH2CH20),H where R molar substitution of the hydroxy groups should prefer- is a fatty aliphatic radical, e.g., where R is CloH2lO to ably not exceed an average of one substitution of hy- C16H330 and n is 10 to 60; those of the general formula droxy groups per anhydrohexose unit. A preferred R(OCH2CH2),OS03M, where R is a Clo to Clg alkyl, n

is 1 to 3, and M is sodium; and salts of dialkyl Sulfosuc- That time generally is at least 5 seconds, and can be as ch ic acids, e.g., sodium dioctyl sulfosuccinate. Also see long as 20 minutes or longer, after the fluid, aqueous air Encyclopedia of Chemical Technology, Kirk-Othmer, 3rd foam is formed, depending, for example, on the chemi- Ed., Vol. 22, pages 347-387, John Wiley & Sons (1983) cal structures of the polyhydroxy polymer and the poly- for other surfactants useful in this invention. Many of 5 valent ionic complexing agent and their amounts and these hydrocarbon surfactants are biodegradable, mak- especially on the pH of the foamable solution or disper- ing the foams of this invention made therefrom particu- sion, on the desired extent or nature of the application, larly advantageous where their biodegradability is de- e.g. how large an area is to be covered with the fluid sired, e.g. in treating municipal waste sites and sanitary foam before it gels or reaches its desired increase in landfills or in protecting combustible material from fire. 10 viscosity, on whether the substrate is horizontal, verti- Said European Patent Application E P 206548A dis- cal, or inclined, and on the particular hazard to be con- closes a host of fluoroaliphatic surfactants, e.g. trolled, etc. Generally, the amount of the polyhydroxy C8F17S03K9 Cfil3SO2N(CH2CH(0H)CH- polymer (excluding its organic solvent or dispersing 2S03-)C3H6N+(CH3)2C2H40H, and agent) will be a small amount, about 0.2 to 3 weight C6F13S02N(C3H6S03-)C3H6N+(CH3)2C2&OH, 15 percent, preferably about 0.5 to 2 weight percent, of the which can likewise be used in this invention. FLuoroali- foamable aqueous solution or dispersion; thus, the solids phatic surfactants can be used in this invention alone or content of the foams of this invention which is attributa- in combination as mixtures, and they can be used in ble to the crosslinked polyhydroxy polymer will be combination with the hydrocarbon surfactants, and the low. When the polyhydroxy polymer (particularly ga- disclosure of foaming surfactants in E P 206548A are 20 lactomannan gum) is used in the form of a concentrate incorporated herein by reference for purposes of brev- dispersion in an organic solvent, e.g. mineral oil or ity. diethylene glycol monoethyl ether acetate, such disper-

The pH modifiers used in preparation of the starting sion will have a concentration generally about 30 to 50 aqueous solution or dispersion of this invention can be weight percent of the polymer, depending upon the acids to lower the pH such as organic acids, e.g. acetic, 25 molecular weight and chemical nature of the polymer. oxalic, or citric acid, or mineral acids, e.g. hydrochloric Generally, the amount of such organic solvent in the acid, or can be bases to raise the pH, such as organic foamable aqueous solution or dispersion and foam bases, e.g. triethanolamine, or inorganic bases, e.g. so- thereof will be less than about 5 weight percent, prefer- dium or ammonium hydroxide, the particular pH modi- ably less than about 3 weight percent. fier to be used for a particular foam system being depen- 30 The amount of water to be used will be that amount dent on the particular polyvalent ionic complexing to provide sufficiently low viscosity to the foamable agent chosen and the amount of pH modifier to be used aqueous solution or dispersion to enable its efficient being dependent on the pH necessary for the formation handling and to enable the fluid foam formed therefrom of the foam and the type thereof (gelled or viscous). For to have sufficient expansion and quality and flow and a foam system where borax is used as the crosslinking 35 cover the desired substrate area. In any case, however, agent, gelation would be premature, that is, occur too the amount of water to be used will be such that it is the fast and before adequate air is entrained, if the pH of the major component by weight, i.e. greater than 50 weight starting aqueous solution or dispersion is too low and a percent and generally about 55 to 99.5 weight percent, base pH modifier is not included in the formulation to preferably 75 to 99.5 weight percent, of the aqueous raise its pH. For a foam system where a crosslinking 40 foamable solution or dispersion (as well as of the fluid agent such as potassium pyroantimonate is used, desired foam and gelled or viscous foam produced therefrom). gelation or viscosity build-up would not occur or The amount of air to be entrained in the aqueous foam- readily occur if the pH of the starting aqueous solution able solution or dispersion will be that necessary to or dispersion is too high and an acid pH modifier is not obtain a sufficient expansion value. However, the included in the formulation to lower its pH. 45 amount of air to be entrained generally will be such that

The relative amounts of the various components of the fluid air foam and the gelled or viscous air foam the foamable aqueous solutions or dispersions and foams formed therefrom will have the aforementioned expan- of this invention can vary widely. Functionally ex- sion value, and preferably the entrained air will be the pressed, the amount of surfactant foaming agent to be major component of the foam thereof by volume, i.e. used will be that sufficient, to cause the aqueous foam- 50 greater than 50 volume percent, and even as high as 98 able solution or dispersion, upon aeration, to form a volume percent or higher, and more preferably in the foam having a density of less than 1 g/cc or having an range of 75 to 98 volume percent. expansion value (i.e., the ratio of the volume of aqueous The particular foam formulation components and air foam to the volume of starting aqueous solution or relative amounts thereof to be used for a foam system of dispersion) generally greater than about 1.5, and prefer- 55 this invention, having the desired expansion value, gela- ably 2 to 20 (a range which can be characterized as tion or viscosity increase time, and other foam proper- "low expansion") and which can be as high as 200 or ties, can be readily determined in the laboratory using a even 1000. Such a foam will thus float on water and is Waring blender or other laboratory mixer for mixing less dense than most other liquids, e.g. flammable liq- the components and for mechanically entraining air. uids, and thus is generally buoyant. Generally, the sur- 60 For a gelled foam of this invention, gel time is defined factant will be about 0.05 to 2 weight percent, prefera- as the time required for the freshly prepared fluid aque- bly about 0.2 to 0.5 weight percent, of the foamable ous air foam to become non-flowable, which can be aqueous solution or dispersion. The amount of polyhy- determined conveniently in the laboratory by pouring droxy polymer in the aqueous foamable solution will be the fluid foam repeatedly from one beaker to another that sufficient upon crosslinking to cause the fluid foam 65 beaker until it is no longer pourable. to gel or merely increase the viscosity of the fluid foam, For a preferred gelled foam system based on guar whichever is desired, at a desired time after application gum or hydroxypropyl guar gum as the polyhydroxy of the fluid foam to the hazardous material or substrate. polymer and borax as the crosslinking agent, an aqueous

5,026,735 9 10

solution having a pH of about 9 to 10.5, preferably 9 to application apparatus which is useful as well in making 10 (which alkaline pH control can be obtained by add- the foam products of this invention, such disclosure ing appropriate amounts of a base, e.g. NaOH, Na2C03, being incorporated herein by reference. or NI&OH), containing 0.2 to 2 weight percent, prefer- The hazardous materials which can be treated or ably 0.5 to 1 weight percent, of the gum, and containing 5 controlled with the foam in accordance with this inven- 0.2 to 0.5 weight percent of a surfactant as a foaming tion include the various materials present in hazardous agent, can be gelled with borax, using a borax:gum waste sites described at the beginning of this specifica- weight ratio of 120 to 1:1, preferably 1:10 to 1:s. In tion, such as land burial dumps, impoundments, and preparing the foamable, aqueous solution or dispersion lagoons. Such materials can be organic or inorganic for this foam system, the borax is added to the formula- 10 liquids, semi-liquids, or solids, such as synthetic or natu- tion after the Par component has been in contact with ral organic chemicals, heavy or toxic metals, solvents, the Water of the fontdation for a residence hydration efluents, household garbage and trash, discarded prod- time of 15 to 600 seconds or as long as 3 hours or longer, u c t ~ , spent raw materials, contaminated containers, preferably at least 30 seconds. If the hydration time is sludges, mill tailings, burn residues, contaminated soil, less than 15 seconds, the solution or dispersion generally 15 flammable and volatile liquids, etc., disposed in such does not gel. If the PH of the foalnable aqueous sites from industrial and commercial operations, etc. solution or dispersion is alkaline but lower than about 9, such wastes can be toxic, noxious, ignitable, flammable, the Or will generally gel before combustible, corrosive, or dangerously reactive. The foaming or before sufficient air is entrained. If the pH is body of such materials can be treated in situ with the greater than about 10.5, the desired gelation or viscosi- 20 or as excavated or removed from such sites. Spills ty-buildup may be too long or not occur. or leaks of hazardous liquids from pipelines or contain-

For a preferred gelled foam system based On guar ers such as tanks or vehicles can also be treated. gum 0' h ~ d r o x ~ ~ r o ~ ~ l gum as the ~ o l ~ h ~ d r o x ~ ~h~ foams of this invention are particularly useful polymer and potassium pyroantimonate, K~H2Sb207~ as during or in connection with the excavation of material the crosslinking agent, an aqueous solution or dispersion 25 from hazardous waste sites (e.g. sites,,), a having a pH of 3.5 5'5 and preferably to 4.5 (which type of clean-up operation which many believe is the pH can be obtained by adding appropriate best solution to the problems posed by such sites. amounts of an acid, e.g. acetic acid, oxalic acid, citric acid, HCl, H2S04, H4P04, HN03, KHS04, or KHS04 Materials which are not wastes, spills, or the like but

in combination with NaOCOCH3), containing 0.4 to 3 30 rather have utility and are innately harmful, have toxic-

weight percent, preferably 0.75 to 2.5 weight percent, ity, or are potentially hazardous, can also be treated

gum, and containing 0.2 to 0.5 weight percent ofa sur- with the foam, for example coal in transport by train

factant foaming agent, can be gelled with potassium cars or barges or the coal in mine tunnels, to seal the

pyroantimonate using a pyroant~monate:gum weight exposed surfaces from air and minimize or prevent fires ratio of 1:50 to 1~20, preferably 1:40 to 1:30. ~f the p~ of 35 or to control such fires. Combustible material, such as the aqueous solution or dispersion of polymer is lower wooden structures like houses and vegetation like than about 3, the initially-fomed foam generally col- brush, grass fields, and forests, can be treated to prevent lapses quickly, and if the pH is greater than about 6, the 0' control fires Or fire damage thereof. ~ h u s , the term solution generally does not foam readily. "hazardous" in its broader sense is used in this applica-

optional components of the foam systems of this 4 tion to include present or imminent hazards due to exist- invention include: foam stabilizers, such as ethylene ing exposure as well as potential hazards due to the glycol, diethylene glycol, glycerol, CEL- innate harmful or toxic effects of a material which be- LOSOLVE @, and butyl CARBITOL @; foam tough- comes hazardous upon exposure. The amount or thick- eners and shrink control agents, such as aqueous rubber ness of foam applied to the h~Zardous material or sub- or polymeric latices, e.g. styrene-butadiene rubber lati- 45 Strate or the extent of its application can vary depending ces, poly(ch1oroprene) rubber latices, poly(chlor0- 0" factors as the nature, magnitude, location, and prene-co-methacrylic acid) rubber latices, and the poly- Permanency of the hazardous material or substrates, the mer latices described in U.S. Pat. No. 4,315,703; dyes, presence of environmental factors such as wind, rain, and pigments, such as titanium dioxide; fire retardants, drainage, etc., and the particular threat to health, safety, such as diammonium phosphate, ammonium phosphate, 50 and environment that the material poses. The thickness ammonium sulfate, and ammonium polyphosphate; and of the foam applied to the material thus can vary, for other additives or components such as electrolytes, example from about 1 cm to 30 cm or higher, e.g. up to corrosion inhibitors, and biocides. Such optional corn- 1 meter or more. In any event, the thickness of the foam ponents should be compatible with the other compo- will generally be sufficient to alleviate or prevent the nents in the systems and are used in amounts which do 55 threat posed by the material. Where the material not disadvantageously affect the desired properties, evolves or releases volatile or superficial products such such as foamability, and function, such as the sealing as gases, fumes, vapors, dust, etc., or it is desired to seal capability, of the foam system. The total amount of a material from ambient air to control or prevent com- solids attributable to said optional components in the bustion or oxidation of the material, the amount or case of the foam systems will be such that the aqueous 60 thickness of the foam will be such as to suppress the tolution or dispersion is still foamable and the density of volatilization or escape of the material to the atmo- !he foam prepared therefrom is less than 1 g/cc. Gener- sphere or suppress its contact with atmosphere, the high ally, the amount of solids attributable to said optional degree of vapor impermeability of the foam due to its components will be less than about 40 weight percent, large amount of water and foam cell structure signifi- preferably less than about 30 weight percent, of the 65 cantly contributing to such suppression. foamable aqueous solution or dispersion. Objects and advantages of this invention are illus-

Said European Patent Application EP 206548A dis- trated in the following examples, in which the prepara- closes a proportioning, foam-generating and foam- tion of various aqueous, air foams of this invention are

5,026,735 11 12

described as well as some tests thereof indicative of A repeat of this example with 0.70 g (instead of 0.80 their utility in the treatment of various substrates. g) glacial acetic acid gave an aqueous air foam with a

EXAMPLE 1 gel time between 60 and 120 seconds.

A 1.0 wt. % aqueous solution of powdered guar gum 5 EXAMPLE 5

(JAGUAR Q 6003) was prepared by adding a concen- A suspension in mineral oil of 33 wt. % JAGUAR Q trate dispersion of 160 g of the guar powder in 240 g of HP-11 and 3.3 wt. % glacial acetic acid was metered by diethylene glycol monoethyl ether acetate to 15.6 liters eduction at a rate of approximately 5 wt. % into an of slowly stirred water. aqueous stream (flowing in a rubber hose, about 2.5 cm

After about 2 hours, a gelable aqueous air foam was 10 diameter, from a pressurized, 20-liter tank) consisting of prepared by mixing in a Waring blender, for 15 seconds 1.5 wt. % of the foaming agent used in Example 2, and at medium speed, 50 g of the above aqueous guar gum 0.5 wt. % gelling agent used in Example 4. The com- solution, 50 g of water, 1.25 g of a 10 wt. % aqueous bined aqueous stream was mixed with air by passing the sodium hydroxide solution as a pH modifier, 0.4 g so- stream through a low-expansion, air-aspirating nozzle, dium lauryl sulfate as a foaming agent, and 2.5 g of a 4.0 l5 "PYRENE Foam Playpipe", Model PP16-6, to provide wt. 9% aqueous solution of borax, Na2B407. 10H20, as a an aqueous air foam with an expansion value of 5 and a crosslinking agent. The resulting fluid, aqueous air gel time of less than 180 seconds. foam, having an appearance similar to freshly dis- charged aerosol shaving cream and having an expansion EXAMPLES 6 and 7

value of 4 to 5, gelled in about 30 seconds to form a 20 These examples illustrate the suppression of a body of gelled, aqueous air foam. triethylamine with a gelled foam of this invention.

EXAMPLE 2 In such example, in the lower half of a disassembled

two-piece, 25 cm diameter, cylindrical, glass chamber, In a Waring blender was placed 100 g of water and having a total volume of about 5100 cc, was placed

0.50 g of a hydroxypropyl guar gum derivative (JA- 25 triethylamine to a depth of about 5 cm. The upper half G U A R Q HP-11). After blending this mixture at me- of the glass chamber, containing a foam entry port and dium speed setting for 30 seconds, 1.5 g of a 25 wt. % nitrogen gas inlet and outlet openings, was then placed aqueous solution of C6F13S02N(CH2CH(OH)CH- on top of the lower half of the chamber containing the 2S03-)C3H6N+(CH3)2C2&OH foaming agent, 0.3 g 30 triethylamine. An aqueous, fluid air foam (compositions of 10 wt. % aqueous sodium hydroxide solution, 1.25 g described in Table 1 below) was added to the chamber of a 4.0 wt. % aqueous solution of borax were added and the latter purged with nitrogen, as described below. and the total mixture blended an additional 15 seconds A gas-tight seal between the upper and lower halves of to provide an aqueous, fluid air foam with an expansion the chamber was achieved by lubrication of the ground value of 4 to 5 and a gel time of about 30 seconds. glass, mating edges of the two halves with a silicone

A repeat of this example with 1.25 g of a 40 wt. % 35 grease before assembly. dispersion of JAGUAR Q HP-11 in mineral oil (instead In each example, a nitrogen gas Purge of about 340 cc of 0.50 g of the neat hydroxypropyl guar gum) gave an per minute was established and maintained in the cham- aqueous air foam with an expansion value of 4 to 5 and ber before and after adding the fluid foam. Immediately a gel time of about 30 seconds. 40 after foam generation, the fluid foam was added to the

chamber through the foam port, covering the triethyl- EXAMPLE 3 amine to a depth of about 2.5 to 5.0 cm with foam,

In a Waring blender was placed 90 g of water and 0.5 which subsequently gelled. The foam Port was then g of JAGUAR @ HP-I I. After blending this mixture closed and the exiting nitrogen Purge gas analyzed by for 30 seconds at medium speed setting, 1.5 g of a hy- 45 gas chromatography (gc) for the Presence of trieth~l- drocarbon foaming agent, 1.0 g of 10 wt. % aqueous amine. sodium hydroxide solution, 2.5 g of a 4.0 wt. % aqueous The suppression of trieth~lamine vapor by the gelled solution of borax, and 10 of 50 wt. % aqueous latex of foam was calculated at various time intervals by com- styrene-butadiene rubber ("DOW 633A") were added paring trieth~lamine gc peak areas ("counts") with and the total mixture blended an additional 15 seconds 50 foam Present to trieth~lamine gc peak areas measured to provide a rubber-reinforced, fluid, aqueous air foam before adding foam to the trieth~lamine layer. The with an expansion value of 3 to 4 and a gel time of 30 to results are shown in Table 2. 60 seconds. The hydrocarbon foaming agent used was a The foamable com~ositions A and B, set forth in solution of 21.2 wt. % sodium decyl sulfate, 5.3 wt. % Table '9 were employed to generate the aqueous air N,N-dimethyl dodecylamine oxide, 26.5 wt. % diethyl- 55 foams used in these examples. Aqueous air foams A' and ene glycol monobutyl ether, and 47 wt. % water. B' were generated from compositions A and B, respec-

tively, by combining the ingredients in a large Waring EXAMPLE 4 blender and mixing for 15 to 30 seconds on a medium

In a Waring blender were placed 100 g of water, 2.5 setting. The foams had an expansion value of 4 to 5 and g of 40 wt. % JAGUAR Q HP-11 suspension in mineral 60 a gel time of about 30 to 60 seconds. oil, 0.2 g pyroantimonate gelling agent ("DW-3", Hi- TABLE 1 Tek Polymers, Inc., a 13 wt. % potassium pyroantimo-

Foamable Solut~on nate in an ethylene glycol, potassium hydroxide and Ingredient, A B water solution), 2.0 g of the foaming agent of EXAM- PLE 2, and 0.80 g of glacial acetic acid. This mixture 65 PO1yhydroxy was blended 30 seconds at a medium speed setting to ~ ~ ~ Y P ' O P Y I guar gum, JAGUAR @ 350

provide an aqueous air foam with an expansion value of 1% ,,. % aqueous solution 4 and a gel time of about 60 seconds. Poly(vinyl alcohol), 14,000 MW,

TABLE 1-continued In each of two 800 mL beakers was placed about 50

Foamable Solution g of liquid ammonia mixed with 50 g of SUPER-

Ingredient, g A B CELL @ diatomaceous earth (to absorb the ammonia).

Into one of these beakers (Beaker A) was poured an 100% hydrolyzed poly(viny1 acetate) 20% ~ t . % aqueous solution aqueous air foam (immediately after generation) pre- Water 436 350 pared by mixing for 30 seconds in a Waring blender at Foaming agent medium speed setting the following ingredients: 50 g of LIGHT WATER Q AFFF/ATC FC-600 26 40 a 1.0 wt. % aqueous solution of JAGUAR @ HP-11,60 surfactant 7 wt. % aqueous solution g of water, 7 g of the foaming agent used in Examples 6 Croslinking agent and 7,0.25 g 25 wt. % aqueous sodium hydroxide, 10 g Borax 8.75 25 of 50 wt. % aqueous styrene-butadiene rubber latex 4 wt. % aqueous solution pH Modifying agent Sodium hydroxide, 50 w. % aqueous solution Reinforcing agent Stvmnchutadiene rubber latex.

("DOW 638A") reinforcing agent, and 2.0 g of a 4.0 wt. % aqueous solution of borax gelling agent. The foam

1.05 7.5 1s expansion value was 3 to 4 and the gel time was about 60 seconds.

70 200 The initial foam thickness placed on the liquid am- OW 638A" monia-diatomaceous earth mixture in ~eaker- A was 5 0 8 aqueous solution about 2.5 cm. The second beaker (Beaker B) was a

20 comparative example in which no foam cover was used.

TABLE 2 The rate of evaporation of ammonia vapor was mea-

Elapsed tlme after Percent Vapor Suppress~on sured by weight loss from the beakers at room tempera-

foam application to Ex. 6 Ex. 7 ture (about 22" C.) in a fume hood. The results are sum-

tnethylamine, hours Foam A' Foam B' No Foam marized in Table 4. 25

1 97 98 o TABLE 4 4 75 94 0 6 72 90 0 Percent We~ght Loss

16 70 72 0 Elapsed ttme after Ex. 9 Comparative foam application, mlnutes Beaker A example Beaker B

30 0 0 0

EXAMPLE 8 2 0 2 2 5 0 5 6

This example illustrates the use of a foam of the in- 9 o 9 10 vention to suppress the vapors of benzene. The same 15 2.0 17 apparatus and general procedure used for Examples 6 35 40 9.8 -

75 26.2 - and 7 were used. Benzene was placed on a pool of water in the bottom

half of the glass chamber described in Examples 6 and 7. A foam was generated from the following ingredients: EXAMPLE 10

hydroxypropyl guar gum, JAGUAR Q HP-11 (200 g 40 This example illustrates the reversibility of a borate- of 1 wt. % aqueous solution) gelled, aqueous air foam of this invention based upon

water (250 g) guar gum polymers. sodium lauryl sulfate (2.8 g) A 0 75 wt. % aqueous solution of JAGUAR@ borax (5.1 g of a 4.0 wt. % aqueous solution) HP-11 was prepared by adding a suspension of 120 g of sodium (1.7 g of a 50 wt. % aqueous solution) 45 the guar powder in 180 g of diethylene glycol mono- styrene-butadiene latex YDoW 638A") (@ g. of a 50 ethyl ether acetate to 15.7 liters of slowly stirred water.

wt. % aqueous suspension) After about 2 hours, a gelable, aqueous air foam was The foam was generated as described in prepared by mixing in a Waring blender for 15 seconds and 7 and immediately applied to the benzene layer

through foam port of the upper chamber. Vapor sup- at medium speed 100 g of the above aqueous guar solu-

pression data obtained by monitoring the nitrogen gas 50 tion, 1.25 g of a 10 wt. % aqueous sodium hydroxide

sweep through the chamber, before and at various time g the foaming agent used in 2,

intervals after adding the foam, are reported in Table 3 and 2.5 g a 4.0 wt. % aqueous borax solution. The

below. resulting foam, having an expansion value of 4 to 5, was

TABLE 3 immediately poured into a 1 0 ~ 13 cm aluminum con-

s' tainer to give a 4 cm thick foam which gelled in about Elapsed time after foam Percent Vapor Suppression 30 ( F ~ ~ ~ A).

applicat~on to benzene, hours Ex. 8 No foam An identical foam was prepared in another container 0.5 92.5 o (Foam B). 2 95 0 6 94 0 60 100 mL of water was poured onto Foam A from a

16 92 o height of about 30 cm with no penetration or disruption 120 89 o of the gelled foam.

100 mL of 2 wt. % aqueous acetic acid was poured from a height of about 30 cm onto Foam B which re-

EXAMPLE 9 65 sulted in penetration and collapse of the gelled foam :n this example, an aqueous air foam of this invention where it was contacted by the acid solution. Use of an

was used to suppress the evaporation of ammonia vapor underivatized guar gum (JAGUAR Q 6003) in a similar from a body of liquid ammonia. . example gave similar results.

5,026,735 15 16

EXAMPLE 1 I surface, but the combustion of the foam was not sus- tained when the lighted match was removed. A dupli-

This example illustrates the reversibility of a borate- cate foam made without use of the diammonium phos- gelled, aqueous air foam of this invention based on phate did support combustion, the total surface of such poly(viny1 alcohol). 5 foam igniting and most of it charring.

A 2.0 wt. % aqueous solution of poly(viny1 alcohol) (VINOL Q, a 100% hydrolyzed poly(viny1 acetate, EXAMPLES 14 AND 15

average mol. wt. about 78,000), was prepared by heat- These examples illustrate the preparation and use of ing to about 95' C. a stirred mixture of 20 g of the poly- guar gum-based aqueous air foams as fue-retardants. mer and 980 g of water for about 15 minutes and allow- 10 The foams were prepared using the ingredients listed ing the resulting solution to cool to room temperature. in TABLE 5. The components were mixed for 15 sec-

Two identical foam samples were prepared by com- onds in a Waring blender on medium speed setting just bining in a Waring blender 100 g of the above 2.0 wt. % prior to use. poly(viny1 alcohol) solution, 1.0 g of the foaming agent used in Example 2,1.25 g of a 10 wt. % aqueous solution 15

TABLE 5

of sodium hydroxide, and 2.5 g of a 4.0 wt. % aqueous Foamable Solut~ons

solution of borax, and immediately mixed for about 15 lngred'entp C D E F G

seconds using a medium setting on the blender. The JAGUAR @ HP-11, 0 o 100 100 100 resulting foams were poured into a 10 c m x 13 cm alu- ~~~,~~ % aqueOuS minum trays. The foams which had an expansion value 20 water 100 100 o o o of about 4.5, gelled in about 30 seconds. Foaming agent (same

The first foam was subjected to twenty sprays (total as used in

volume about 20 mL) of tap water from a plastic spray EXAMPLE 2,

bottle from a distance of 8 to 10 cm. The foam remained :;u:z aqueous 1.0 1.0 1.0 1.0 1.0

intact. 25 Crossl~nkin a ent Using a similar procedure, the second foam sample BO,, 4.0 z.:o o o o 2.5 2.5

was subjected to twenty sprays (total volume about 20 aqueous solution mL) of a 0.5 wt. % aqueous acetic acid solution (pre- PH modlfyin~ agent

pared by diluting 10 mL of household vinegar, Red Owl sodium hydroxide, o o o 1.25 11.0 Brand apple cider vinegar, with 90 mL water). The 30 ~ ~ u ~ u ~ s o l u t i o n gelled foam collapsed. Flame retardant

Essentially identical results were obtained when this D~~~~~~~~~ o 1 0 o o 1 .o example was repeated using 100 g of 0.75 wt. % of an phosphate aqueous solution of JAGUAR Q HP-11 in place of the Foam prope*les

100 g of 2.0 wt. % aqueous poly(viny1 alcohol) solution. 35 Foam ex~anslon value 6.5 7 4 5 4 4 Gel time, seconds NG* NG NG 40 40

EXAMPLE 12 *NG = no gelallon

This example further illustrates the reversible proper- ties of an aqueous air foam of this invention. Immediately after foam generation, approximately 50 g

A guar gum-based, gelled foam was prepared in a 40 of each foam was poured over a wooden tongue de~res- Waring blender from 100 of 0.75 wt. % aqueous solu- SOT bent into a triangular shape. About 60 seconds after tion of JAGUAR @ HP-1 1 using the ingredients and the foam was in place, the flame from a Meker burner (4 procedure described in EXAMPLE 10. A gelled aque- cm diameter flame) was held 1 to 2 cm from the surface ous air foam having a p~ of about 10, an expansion of the foam. The time for the following events were value of about 4.5, and a gel time of about 30 seconds 45 noted: (1) initial charring or burning, (2) approximate was thus obtained. T~ this foam in the blender was 50% destruction, and (3) 100% destruction. The results added 1.0 g of glacial acetic acid and the blender con- are summarized in TABLE 6, where the letter of each tents mixed for about 15 seconds to yield a non-gelled foam corresponds to the letter of the foamable solution fluid foam having a pH of 4.5. T o this fluid foam was from which it was prepared. added 9.5 g of 10 wt. %,aqueous sodium hydroxide 50 TABLE 6 solution and the blender contents stirred again for about Time in seconds 15 seconds to yield a foam (pH 10) which gelled in COMPARATIVE about 30 seconds. EXAMPLES

EXAMPLE 13 1 2 3 4 EX. 14 EX. 15 No Foam Foam Foam Foam Foam - -

This example illustrates the preparation and use of a Even': foam c D E F G guar gum-based, fire-retardant, aaueous air foam con- Initial charring 5 10 15 60 330 600' taining diammonium phosphate. or burning

50% I5 60 120 180 510 - In a Waring blender was placed 40 mL water, 50 g of datruction a 1.0 wt. % aqueous solution of JAGUAR @ HP-11,2.5 60 100% 30 180 250 480 - - g of 4.0 wt. % aqueous solution,, of borax,2.0 g of the destruction foaming agent used in EXAMPLE 3, 11 er of 10 wt. % *very slxahtlv charred . - - - - aqueous P ~ H , and 1.0 g of diammonium phosphate. The resulting foam was poured into a 10X 13 cm alumi- TABLE 6 shows that a guar gum-based foam (Foam num tray and allowed to stand in a laboratory fume 65 E), although containing no gelling agent, gave good hood for about 24 hours, the top surface of the gelled flame resistance over foams containing no guar gum foam layer becoming dry to the touch. A lighted match (Foams C and D). However, the wood substrate cov- was placed on the surface of the foam layer igniting the ered with a gelled guar gum-based foam of this inven-

5,026,735 17 18

tion (Foam F) required 5 times longer for initial char- 10. The method of claim 1 wherein said aqueous ring or burning of the foam-covered wooden substrate solution or dispersion further comprises rubber or poly- than the wood protected by non-gelled guar gum-based meric latices. foam (Foam E). 11. A method of treating a substrate with aqueous air

Also, it is especially noteworthy that the wooden 5 foam, comprising the steps of substrate protected with the gelled guar gum-based (1) preparing an aqueous solution or dispersion com- foam containing diammonium phosphate (Foam G) prising (a) guar gum or hydroxypropyl guar gum required 2 times longer for initial charring or burning derivative, (b) borax, (c) foaming agent, (d) alkaline than the wood substrate covered with a gelled guar pH modifier, and (e) water as the major component gum-based foam containing no flame retarder (Foam F) 10 by weight; and 10 times longer than wood substrate covered with a (2) aerating said aqueous solution or dispersion to non-gelled guar gum-based foam (Foam E). form an aqueous fluid air foam therefrom; and

Various modifications and alterations of this inven- (3) applying said fluid air foam to exposed surface of tion will become apparent to those skilled in the art said substrate, the resulting foam forming, at least 5 without departing from the scope and spirit of this in- 15 seconds after its formation, a gelled, aqueous air vention. foam in the form of a highly vapor impermeable

What is claimed is: coating on said surface. 1. A method of treating a substrate with an aqueous 12. The method of claim 11, wherein the amount of

air foam, comprising the steps of gum is 0.2 to 2 weight percent, the amount of borax is (1) preparing an aqueous solution or dispersion com- 20 sufficient to provide a boraxgum weight ratio of 1:20 to

prising (a) water-soluble polyhydroxy polymer 1:1, and the amount of pH modifier is sufficient to pro- .

having a plurality of hydrogen-bondable diol struc- vide a pH of about 9 to 10.5, said pH modifier being tures in the polymer chain in the form of 1,2-diol NaOH, Na2C03, or NH40H. and/or 1,3-diol structures which are capable of 13. The method of claim 11, further comprising the complexation with borate anion, (b) water-soluble 25 step of contacting said gelled air foam coating with a polyprotic inorganic acid salt which crosslinks said dilute aqueous acid solution to collapse said coating. polymer by hydrogen-bonding complexation said 14. The method of treating a substrate with aqueous salt comprising alkali metal borate, (c) foaming air foam, comprising the steps of agent to impart persistence to the fluid air foam (1) preparing an aqueous solution or dispersion com- generated upon aeration of said solution or disper- 30 prising (a) water-soluble poly(viny1 alcohol) capa- sion, (d) pH modifier to impart an' appropriate pH

' ble of complexation with borate anion, (b) borax, to said solution or dispersion necessary for time- (c) foaming agent, (d) pH modifier, and (e) water as controlled formation of gelled or viscous foam the major component by weight; from said fluid air foam, and (e) water as the major (2) aerating said aqueous solution or dispersion to component by weight; 35 form an aqueous fluid air foam therefrom; and

(2) aerating said aqueous solution or dispersion to (3) applying said fluid air foam to exposed surface of form an aqueous fluid air foam therefrom; and said substrate.

(3) applying said fluid air foam to exposed surface of 15. The method of claim 2, wherein said substrate is a said substrate, the resulting applied foam forming a body of hazardous material or waste. gelled, aqueous air foam or viscous, aqueous air 40 16. The method of claim 15, wherein said substrate is foam in the form of a highly vapor-impermeable a body of flammable liquid. coating on said surface. 17. The method of claim 15, wherein said substrate is

2. The method of claim 1, wherein said polymer is a a body of combustible material. polysaccharide containing cis 1,2-diol structures. 18. The method of claim 17 wherein said combustible

3. The method of claim 2 wherein said polymer is 45 material is wooden structures of vegetation. gcilactomannan gum. 19. A method according to claim 2 wherein the fluid

4. The method of claim 2 wherein said polymer is air foam, at least 30 seconds after its formation, forms a guar gum. gelled or viscous aqueous air foam in the form of a

5. The method of claim 2 wherein said polymer is a highly vapor impermeable coating on said surface. guar gum derivative. 50 20. A method according to claim 2 wherein the fluid

6. The method of claim 2 wherein said polymer is a air foam, at least 60 seconds after its formation, forms a hydroxypropyl guar gum derivative. gelled or viscous air foam in the form of a highly vapor

7. The method of claim 1 wherein said polymer is impermeable coating on said surface. poly(viny1 alcohol). 21. A method according to claim 2 wherein the fluid

8. The method of claim 1, wherein said polyprotic 55 air foam, at least 20 minutes after its formation, forms a inorganic acid salt is borax. gelled or viscous air foam in the form of a highly vapor

9. The method of claim 1 wherein said aqueous solu- impermeable coating on said surface. tion or dispersion further comprises fire retardant. 1 * * * *

60