AU595599B2 - Water treatment polymers and methods of use thereof - Google Patents

Description

A

AUSTRALIA

PATENTS ACT 1952 COMPLETE SPECIFICATION Form

(ORIGINAL)

FOR OFFICE USE 595599 Short Title: Int. Cl: Application Number: -7 Lodged: Complete Specification-Lodged: Accepted: Lapsed: Published: Priority: This document contains the amendments made under Section 49 and is correct for printing.

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I

.n n n I Related Art: *O

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4:ga 00 TO BE COMPLETED BY APPLICANT Name of Applicant: Address of Applicant: Actual Inventor: Address for Service: 1 BETZ INTERNATIONAL, INC., 4636 SOMERTON ROAD TREVOSE 19047 PA., UNITED STATES OF AMERICA CLEMENT HACK CO., 601 St. Kilda Road, Melbourne, Victoria 3004, Australia.

S.

Complete Specification for the invention entitled: WATER TREATMENT POLYMERS AND METHODS OF USE THEREOF The following statement is a full description of this invention including the best method of performing it known to me:j.

1A WATER TREATMENT POLYMERS AND METHODS OF USE THEREOF -6rs-sReferene to Related Apictions The present invention pertains to a composition and method of utiliation of same to inhibit corrosion and control the formation and deposition of scale -imparting compounds in water systems such as cooling, boiler and gas scrubbing systems.

0 BackgrounField of the Invention The present invention pertains to a composition and method of utilization of same to inhibit corrosion and control the formation and deposition of scale imparting compounds in water 0, instance, scale tends to accumulate on internal walls of various water systms, such as boiler and cooling systems, and thereby materially lessens the operational efficiency of the system.

Deposits in lines, heat exchange equipment, etc., may originate from several causes. For example, precipitation of calcium carbonate, calcium sulfate and calcium phosphate in the yl rr i I I

I

t: I' I -2water system leads to an accumulation of these scale imparting compounds along or around the metal surfaces which contact the flowing water circulating through the system. In this manner, heat transfer functions of the particular system are severely impeded.

Corrosion, on the other hand, is a degradative electrochemical reaction of a metal with ;ts environment. Simply stated, it is the reversion of refined metals to their natural state. For example, iron ore is iron oxide. Iron oxide is refined into steel.

When the steel corrodes, it forms iron oxide which, if unattended, may result in failure or destruction of the metal, causing the particular water system to be shut down until the necessary repairs can be made.

S

Sr

S

S

S

S

S

*5

S

Typically, in cooling water systems, the formation of calcium sulfate, calcium phosphate and calcium carbonate, among 15 others, has proven deleterious to the overall efficiency of the cooling water system. Recently, due to the popularity of cooling treatments using high levels of orthophosphate to promote passivation of the metal surfaces in contact with the system water, it has become critically important to control calcium phosphate 20 crystallization so that relatively high levels of orthophosphate may be maintained in the system to achieve the desired passivation without resulting in fouling or impeded heat transfer functions which would normally be caused by calcium phosphate deposition.

Although steam generating systems are somewhat different from cooling water systems, they share a common problem in regard to deposit formation.

As detailed in the Betz Handbook of Industrial Water -3- Conditioning, 8th Edition, 1980, Betz Laboratories, Inc., Trevose, PA Pages 85-96, the formation of scale and sludge deposits on boiler heating surfaces is a serious problem encountered in steam generation. Although current industrial steam producing systems make use of sophisticated external treatments of the boiler feedwater, coagulation, filtration, softening of water prior to its feed into the boiler system, these operations are only moderately effective. In all cases, external treatment does not in itself provide adequate treatment since muds, sludge, silts and hardness-imparting ions escape the treatment, and eventually are introduced into the steam generating system.

In addition to the problems caused by mud, sludge or silts, the industry has also had to contend with boiler scale.

SAlthough external treatment is utilized specifically in an attempt 15 to remove calcium and magnesium from the feedwater, scale formation due to residual hardness, calcium and magnesium salts, is always experienced. Accordingly, internal treatment, i.e., treatment of the water fed to the system, is necessary to prevent, reduce and/or retard formation of the scale imparting compounds and 20 their resultant deposition. The carbonates of magnesium and calcium mo are not the only problem compounds as regards scale, but also waters having high contents of phosphate, sulfate and silicate ions either occurring naturally or added for other purposes cause problems since calcium and magnesium, and any iron or copper present, react with 25 each and deposit as boiler scale. As is obvious, the deposition of scale on the structural parts of a steam generating system causes poorer circulation and lower heat transfer capacity, resulting accordingly in an overall loss in efficiency.

4l -4- Detailed Description of the Invention In accordance with the invention, it has been surprisingly discovered that water soluble copolymers, as shown in Formula I hereinafter, are effective in controlling the formation of mineral deposits and in inhibiting corrosion in various water systems.

The water soluble copolymers of the invention have the structure: FORMULA I

S

S. S

S

S.

*0 S

S

0* S 5* 5* t CH 2

-CH

2

-C-

0

I

R

3 (XZ) a wherein R 1 is H or lower alkyl (C 1

-C

3

R

2 is OH or OM, or

NH

2 M is a water soluble cation; R 3 is a hydroxy substituted alkyl or alkylene radical having from 1 to 6 carbon atoms or a non-substituted alkyl or alkylene radical having from 1 to about 6 carbon atoms; X, when present, is an anionic radical selected from the group consisting of SO 3 P0 3 P0 4 and COO; Z, when present, is H or hydrogens or any water soluble cation or cations which together counterbalance the valence of the anionic radical; a is 0 or 1.

4

II

4 t. ia i j cn9, i The number average molecular weight of the water soluble copolymers of FORMULA I may fall within the range of 1,000 to 1,000,000. Preferably the number average molecular weight will be within the range of from about 1,500 to 500,000, with the range of 5 about 1,500 to about 10,000 being even more highly desirable. The key criterion is that the polymer be water soluble.

The molar ratio x:y of the monomers of FORMULA I may fall within the range of between about 30:1 to 1:20, with the x:y molar ratio range of from about 10:1 to 1:5 being preferred.

V 00 01..

00

S

5S

S

S 55

S.

9

S.

9 At present, the water soluble polymer preferred for use in cooling water systems is: FORMULA II

H

CH

2

C

SOH

OH

H

-CH

2

C-

CH

2 0

CH

2

CHOH

CH

2 S0 3

M

wherein M is the same as given in FORMULA I. This polymer (FORMULA II) is referred to as acrylic acid/allyl hydroxy propyl sulfonate -6ether (AA/AHPSE). The IUPAC nomenclature for AHPSE is 1-propane sulfonic acid, 2-hydroxy-3-(2-propenyl oxy)-mono sodium salt. Heretofore, the AHPSE monomer has been used in the emulsion polymerization of acrylate esters, vinyl acetate and styrene for the manufacture of latex paints. However, to my knowledge, my invention involves the first time this monomer has been polymerized into a water soluble polymer under aqueous solution polymerization techniques.

With respect to both repeat units of the polymers of the present invention, they may exist in acid or water soluble salt form when used in the desired water system.

As to preparation of the monomer designated as x above, in FORMULA I, acrylic acid is well known. It may be produced by Shydrolysis of acrylonitrile or via oxidation of acrolein. Other well known vinyl containing monomers such as methacrylic acid and 15 acrylamide may also be utilized as monomer x of FORMULA I in accordance with the invention.

Turning to the allyl containing monomer, monomer y, in the FORMULA I above, these may be produced by reacting allyl alcohol with a non-tertiary alcohol in the temperature range of about 25-150°C as 20 is detailed in U.S. Patent 2,847,477 (the entire disclosure of which is hereby incorporated by reference) followed by, if desired, sulfonation, phosphorylation, phosphonation or carboxylation of the monomer j via well-known techniques.

0 The preferred allyl hydroxy propyl sulfonate ether monomers (monomer y FORMULA II) may conveniently be prepared via a ring opening reaction of the epoxy group of an allyl glycidyl ether precursor. Sulfonation of the epoxy group wi t h sodium sulfite in the presence of a phase transfer catalyst such as tetra-n-butylammonium bisulfite or with fuming sulfuric acid containing sulfur trioxide -7will produce the sulfonic acid group and hydroxy group of the AHPSE.

The resulting monomer can be further neutralized with caustic or other basic material. The reaction is illustrated by the following mechanism:

S

Se'S S S

S.

S

S

S.

0 *5* 5

*SS

CH

2 C CH 2 0 CH 2 C CH 2

SO

3 0 NaOH CH 2 H2CH-CH 2 0 CH 2 CHOH CH 2 S0 3 Na Similar ring opening reactions can be carried out by using 10 phosphorous acid and its derivatives including phosphorous trichloride to obtain the phosphonic acid substituents.

If orthophosphoric acid (H 3 P0 4 and its derivatives are used in the ring opening reaction, phosphoric acid ester substituents may be formed in accordance with the mechanism: I I C CH 2

H

3 P0 4 C -CH 2 1

/OH

0 OH I 0

-P

I OH

S

S

55 04

S.

Such reaction is described in U.S. Patent 2,723,971.

Carboxylate functions can be provided on the allyl hydroxy propyl ether monomer via the reaction of allyl alcohol and chloro-8 hydroxy butanoic acid according to the mechanism: H OH H C C CH 2 OH C-CH 2 CH CH 2

COOH

H I C CH CH 2 0 CH 2 C CH 2

COOH

H H It should be noted that the monomer y 'FORMULA I) may 10 itself be allyl glycidyl ether which is commercially available from several sources.

Z in the allyl monomer, (monomer y of FORMULA I) if present, may be hydrogen, hydrogens or any soluble cation or cations which together counterbalance the valence of the anionic moiety X.

Suitable cations include Na, NH 4 Ca, and K. X, when present, may be chosen from the group consisting of S03' PO 3

PO

4 and COO. I co.

After the desired monomers have been obtained, free radical chain addition polymerization may proceed in accordance with conventional solution polymerization techniques. Polymerization initiators such as persulfate initiators, peroxide initiators, etc. may be used. Preferably the requisite monomers are mixed with water and alcohol (preferably isopropanol). The resulting polymer may be isolated by well-known methods such as distillation, etc. or the polymer may simply be used in its aqueous solution.

-9- It should be mentioned that water soluble terpolymers comprising monomers x and y of FORMULAE I or II may also be prepared for use as deposit control agents and/or corrosion control agents. For instance, AHPSE monomers may be incorporated into a water soluble terpolymer backbone having other repeat units including acrylic acid monomers, alkyl acrylate monomers, methacrylic acid monomers, acrylamide monomers, etc.

The polymers should be added to the aqueous system, for which corrosion inhibiting, and/or deposit control activity is desired, in an amount effective for the purpose. This amount will vary depending upon the particular system for which treatment is m••O aige desired and will be influenced by factors such as, the area subject to corrosion, pH, temperature, water quantity and the respective cono °centrations in the water of the potential scale and deposit forming 15 species. For the most part, the polymers will be effective when used at levels of about 0.1-500 parts per million parts of water, and preferably from about 1.0 to 100 parts per million of water contained in the aqueous system to be treated. The polymers may be added directly into the desired water system in a fixed quantity and in the S• 20 state of an aqueous solution, continuously or intermittently.

o:•o The polymers of the present invention are not limited to use in any specific category of water system. For instance, in addi- 00 09tion to boiler and cooling water systems, the polymers may also be 0 effectively utilized in scrubber systems and the like wherein corro- S 25 sion and/or the formation and deposition of scale forming salts is a proble.. Other possible environments in which the inventive polymers may be used include heat distribution type sea water desalting apparatus and dust collection systems in iron and steel manufacturing industries and as a dispersant in the pulp and paper processing industries. Also the polymers could be used as mineral beneficiation aids such as in iron ore, phosphate, and potash recovery.

I tt The water soluble polymers of the present invention can also be used with topping agent components in order to enhance the corrosion inhibition and scale controlling properties thereof. For instance the polymers may be used in combination with one or more kinds of compounds selected from the group consisting of inorganic phosphoric acids, phosphonic acid salts, organic phosphoric acid esters, and polyvalent metal salts. Such topping agents may be added to the system in an amount of from about 1 to 500 ppm.

Examples of such inorganic phosphoric acids include condensed phosphoric acids and water soluble salts thereof. The phos- I phoric acids include an orthophosphoric acid, a primary phosphoric acid and a secondary phosphoric acid. Inorganic condensed phosphoric acids include polyphosphoric acids such as pyrophosphoric acid, tripolyphosphoric acid and the like, metaphosphoric acids such as tri- 15 metaphosphoric acid, and tetrametaphosphoric acid.

As to the other phosphonic acid derivatives which are to be added in addition to the polymers of the present invention, there may be mentioned aminopolyphosphonic acids such as aminotrimethylene phosphonic acid, ethylene diaminetetramethylene phosphonic acid and 20 the like, methylene diphosphonic acid, hydroxyethylidene diphosphonic acid, 2-phosphonobutane 1,2,4, tricarboxylic acid, etc.

Exemplary organic phosphoric acid esters which may be combined with the polymers of the present invention include phosphoric acid esters of alkyl alcohols such as methyl phosphoric acid ester, ethyl phosphoric acid ester, etc., phosphoric acid esters of methyl cellosolve and ethyl cellosolve, and phosphoric acid esters of polyoxyalkylated polyhydroxy compounds obtained by adding ethylene oxide to polyhydroxy compounds such as glycerol, mannitol, sorbitol, etc.

Other suitable organic phosphoric esters are the phosphoric acid esters of amino alcohols such as mono, di, and tri-ethanol amines.

t i -11- Inorganic phosphoric acid, phosphonic acid, and organic phosphoric acid esters may be salts, preferably salts of alkali metal, ammonia, amine and so forth.

Exemplary polyvalent metal salts which may be combined with the water soluble polymers of the invention include those capable of dissociating polyvalent metal cations in water such as Zn Ni etc., which include zinc chloride, zinc sulfate, nickel sulfate, nickel chloride and so forth.

The water soluble polymers of the present invention may 10 also be used in conjunction with water soluble chromate compounds that are adapted to provide chromate radicals in water solutions.

Illustrative water soluble chromate compounds include sodium chromate dihydrate, sodium chromate anhydrous, sodium chromate tetrahydrate, sodium chromate hexahydrate, sodium chromate decahydrate, potassium 15 dichromate, potassium chromate, ammonium dichromate and chromic acid.

In addition, water soluble azole compounds can be used in combination with the water soluble polymers herein disclosed. Such azoles have the formula

H

N

5 2 N 4. I II 4 3 N Included within the scope of the invention are N-alkyl substituted 1,2,3-triazole, or a substituted water soluble 1,2,3-triazole where substitution occurs at the 4 and/or 5 position of the ring. The preferred 1,2,3-triazole is 1,2,3-tolyltriazole of the formula

I

1 -12- Other exemplary 1,2,3-triazoles include benzotriazole, 4-phenol-1,2,3triazole, 4-methyl-1,2,3-triazole, 4-ethyl-1,2,3-triazole, 5 methyl- 1,2,3-triazole, 5- thyl-l,2,3-triazole, 5-propyl-l,2,3-triazole, and 5-butyl-1,2,3-triazole. Alkali metal or ammonium salts of these compounds may be used.

sea* 0 be..

6*BO 9 6 &9IS r S a a 0O 4 0 0O :4 0 0* .r os..

0 Other azole compounds include thiazole compounds of the formul a:

S

HC CH II II HC_ N Suitable thiazoles include thiazole, 2-mercaptothiazole, 2-mercaptobenzothiazole, benzothiazole and the like.

The water soluble polymers may also be used in conjunction with molybdates such as, inter alia, sodium molybdate, potassium 20 molybdate, lithium molybdate, ammonium molybdate, etc.

When the water soluble polymer of the invention (FORMULA I) is added to the aqueous system in combination with a topping agent component selected from the group consisting of inorganic phosphoric acids, phosphonic acids, organic phosphoric acids esters, their water-soluble salts (all being referred to

S-

1 3hereinafter as phosphoric compounds), polyvalent metal salts, chromates, molybdates, and azoles, a fixed quantity of said polymer may be added separately and in the state of aqueous solution into the system. The water soluble polymers may be added either continuously or intermittently. Alternatively, the polymer may be blended with the above noted topping agent compounds and then added in the state of aqueous solution into the water system either continuously or intermittently. The topping agents are utilized in the usual manner for corrosion and scale preventing purposes. For instance, the phosphoric compounds or polyvalent metal salts may be added to a water system continuously or intermittently to maintain their j necessary concentrations.

I Generally, the phosphoric compounds should be present in the aqueous system in an amount of about 1-100 ppm (as PO 4 or the I 15 polyvalent metal salts should be present in an amount of about 1 to 50 ppm (as metal cation).

As is conventional in the art, the phosphoric compounds or polyvalent metal salts may be added, as pretreatment dosages, to the water system in an amount of about 20 to about 500 ppm, and thereafter a small quantity of chemicals may be added, as maintenance .dosages.

The polymers may be used in combination with yet other topping agents including corrosion inhibitors for iron, steel, copper, copper alloys or other metals, conventional scale and contamination inhibitors, metal ion sequestering agents, and other conventional water treating agents. Other corrosion inhibitors comprise tungstate, nitrites, borates, silicates, oxycarboxylic acids, amino acids, catechols, aliphatic amino surface active agents, benzotriazole, and mercaptobenzothiazole. Other scale and contamination C -14inhibitors include lignin derivatives, tannic acids, starch, polyacrylic soda, polyacrylic amide, etc. Metal ion sequestering agents include polyamines, such as ethylene diamine, diethylene triamine and the like and polyamino carboxylic acids, such as nitrilo triacetic acid, ethylene diamine tetraacetic acid, and diethylene triamine pentaacetic acid.

Examples The invention will now be further described with reference to a number of specific examples which are to be regarded solely as 10 illustrative, and not as restricting the scope of the invention.

Example 1 Preparation of Acrylic Acid/ SAllyl Hydroxylpropyl Sulfonate Ether Copolymer A suitable reaction flask was equipped with a mechanical agitator, a thermometer, a reflux condenser, a nitrogen inlet and two 15 addition inlets for the initiator and monomer solutions. The flask was charged with 200g of deionized water and 26g of isopropanol. The resulting solution was then heated to reflux under a nitrogen blanket. 72g of acrylic acid (1 mole) and 136g of 1-propane sulfonic acid, 2,',ydroxy-3-(2-propenyl oxy) mono sodium salt [AHPSE] 0.25 mole) were mixed in a separate flask so as to provide a mixed monoer solution. The mixed monomer solution was then transferred to an addition funnel. An initiator solution containing 27.3% of sodium persulfate in deionized water was prepared separately and sparged with nitrogen. The initiator solution (20 ml) was then added to the reaction flask along with the mixed monomer solution over a period of 2 hours. After this addition, the resulting mixture was heated for 2 more hours at 85C and subsequently, 66.5g of the isopropanol/water solution was stripped off. The reaction mixture was r then cooled to less than 40C and 60g of 50% caustic solution was then added.

The structure of the resulting copolymer was verified by Carbon 13 NMR. The polymer solution, after being diluted to solids with water, had a Brookfield viscosity of 14.5 cps at 25C. It was a stable solution with a slightly yellow color.

Example 2 *.s0 000* Do@* 0 S s *5

S..

S.

S

S .5 *5 Utilizing both apparatus and procedure similar to that described in Example 1, 200g of deionized water and 13g of iso- 10 propanol were charged to a reaction flask. The solution was then heated to reflux temperature under a nitrogen blanket. 72g of acrylic acid and 136g of AHPSE were added to a separate flask so as to provide a mixed monomer solution. The mixed monomer solution was then added to the reaction flask along with an initiator 15 solution comprising sodium persulfate over a 2 hour period. The reaction mixture was heated for 2 more hours and subsequently, 36.4g of isopropanol/water solution was stripped off. The mixture was cooled to lower than 40C and 60g of 50% caustic solution was added.

The resulting polymer solution, after being diluted to with water, had a Brookfield viscosity of 19.8 cps (at 0 0 *0 0 *o 55 Example 3 Utilizing both apparatus and procedure similar to that described in Example 1, 15g of isopropanol and 228g of water were added to a reaction flask. 72g of acrylic acid (1 mole) and 180g of AHPSE (40% solution, 0.33 mole) were added to an addition funnel so as to provide a mixed monomer solution. The mixed monomer solution r -16was then added to the reaction flask along with a sodium persulfate containing initiator solution over a 2 hour period. One hour after this addition, a solution of t-butyl hydroperoxide (0.2g in 10 ml of water) was added to the reaction mixture. The mixture was heated for 1 more hour and subsequently, 39.4g of isopropanol/water solution was stripped off. The mixture was cooled to lower than 40C and 60g of caustic was added.

The resulting copolymer solution, after being diluted to solids, had a Brookfield viscosity of 15.9 cps at 10 Example 4 oo Utilizing the apparatus and procedure described in Example 1, 72g of acrylic acid (1 mole) and 90.8g of AHPSE 0.167 mole) S were used for copolymerization. The resulting polymer solution, (at 25'C). The structure of the copolymer was verified by Carbon 13

NMR.

Example Utilizing the apparatus and procedure as described in Example 1, 72g of acrylic acid (1 mole) and 68.1g of AHPSE 0.125 mole) were used for copolymerization. The resulting polymer solution, after being diluted to 25% had a Brookfield viscosity of 15.1 cps (at -17- Example 6 Apparatus, procedure and reagent charge similar to that described in Example 3 were used, except that this time, AHPSE (180g, solution) was initially charged into a reaction flask along with isopropanol and water. Acrylic acid (72g) and sodium persulfate solution were then added to the reaction flask over a 2 hour period.

The resulting copolymer solution, after isopropanol distillation, caustic addition and water dilution (to 25% solids) had a Brookfield viscosity of 22.5 cps at 10 Example 7 eas Apparatus, procedure and reagent charge similar to that described in Example 4 were used except that this time AHPSE (90.8g, 40% solution) was charged initially into the reaction flask along with isopropanol and water. Acrylic acid (72g) and sodium persulfate solution were thin added to the reaction mixture over a 2 hour period. The resulting copolymer solution, after isopropanol distillation, caustic addition, and water dilution, (to 25% solids) had a *Brookfield viscosity of 15.4 cps (at Table I hereinbelow presents a summary of the physical properties of the copolymers produced in accordance with Examples 1 through 6.

oo

S

5* 1 -18- Table I Viscosity (Brookfield Example AA/AHPSE 25% Soln.

Number Molar Ratio 25°C) _n pH 1 4:1 14.5 2,550 5.9 2 4:1 19.8 3,600 3 3:1 15.9 2,900 5.7 4 6:1 14.5 2,080 6.1 5 8:1 15.1 2,260 6.7 6 3:1 22.5 3,760 6.1 f* 6:1 15.4 2,217 6.2 AA acrylic acid AHPSE allyl hydroxypropyl sulfonate ether; IUPAC 1-propane sulfonic acid, 2-hydroxy-3-(2-propenyl oxy)-mono sodium salt.

Deposit Control Activity One method of evaluating deposit control activity of a material consists of measuring its ability to prevent bulk phase precipitation of a salt at conditions for which the salt would normally precipitate. It is additionally important to recognize that the material being evaluated is tested at "substoichiometric" concen- S. trations. That is, typical molar ratios of precipitating cation to the material being evaluated are on the order of 20:1 and much greater. Consequently, stoichiometric sequestration is not the route through which bulk phase precipitation is prevented. This well known phenomenon is also called "threshold" treatment and is widely practiced in water treatment technology for the prevention of scale -19- (salt) deposits from forming on various surfaces. In the results that follow calcium phosphate, calcium carbonate, and calcium sulfate salts commonly found in industrial water systems under various conditions have been selected as precipitants. The polymers of the present invention has been evaluated for their ability to prevent prej cipitation inhibit crystallization) of these salts. Zinc hydroxide and calcium phosphonate precipitation studies were also undertaken as these particular deposit forming species are also commonly encountered as a result of the use of zinc based corrosion prevention treatments and phosphonate containing deposit control treatments. The results are expressed as "percent inhibition", positive values indicate that the stated percentage of precipitate was prevented from being formed. Except as where noted to the contrary, the following conditions, solutions, and testing procedure were utilized 15 to perform the inhibition tests, the results of which are reported herein in Tables II to VIII.

4 t 9• rr Q o S* ct' i -JW *5 T T-T/ T CALCIUM CARBONATE INHIBITION Conditions PH 8.5 T 70 0

C

5 hour equilibrium 105 ppm Ca 2 as CaCO 3 702 ppm CO 3 -2 Sol utions 3.25g CaCl 2 '2H 2 0/liter DI H 2 0 2.489 Na 2 C0 3 /liter DI H 2 020 Procedure

I

0@*S a I 1 SI 0 OgO as I a a.

I~

lap :01.5 6) 7) 8) 0 11 Add 50 ml CaCl 2 '2H 2 0 pre-adjusted to pH Add 40 ml of Na 2 HPO 4 solution.

Add 50 ml Na 2 CO 3 pre-adjusted to pH Heat 5 hours at 70 0 C water bath. Remove and cool to room temperature.

Filter 5 mis through 0.2u filters.

Adjust samples to pH 1.0 with conc. HCl lg Conc. HCl).

Allow to stand at least 15 minutes.

Dilute to 50 mis with DI H 2 0.

Bring pH to 12.0 with NaOH.

Add Ca 2 indicator 01 level).

Titrate with EDTA to purple-violet endpoint.

Cal cul ation: 01 0* a, S 0 0 a.

a a a.

Inhibition =ml EDTA titrated (treated) ml EDTA titrated (control) x 100 ml EDTA titrated (Ca-4 stock-mi EDTA titrated (contr-ol r 1 I -21- CALCIUM PHOSPHATE INHIBITION PROCEDURE Conditions Solutions T 70'C 36.76 CaC12 2H 2 0/liter pH 8.5 0.4482g Na 2

HPO

4 /liter 17 hour equilibration Ca 2 250 ppm as CaCO 3 -33 -3

PO

4 6 ppm Procedure 1) To about 1800 ml DIH20 in a 2 liter volumetric flask, add 20 ml 10 of CaC1 2 2H 2 0 solution followed by 2 drops of conc. HC1.

2) Add 40 ml of Na 2

HPO

4 solution.

3) Bring volume to 2 liters with DI water.

4) Place 100 ml aliquots of solution in 4 oz glass bottles.

S 5) Add treatment.

6} Adjust pH as desired.

7) Place in 70°C water bath and equilibrate for 17 hours.

8) Remove samples and filter while hot through 0.2 u filters.

j 9) Cool to room temperature and take Absorbance measurements using Leitz photometer (640 nm).

Preparation for Leitz S, a. 5 mls filtrate b. 10 mls Molybdate Reagent c. 1 dipper Stannous Reagent d. Swirl 1 minute, pour into Leitz cuvette; wait 1 minute before reading.

3 Using current calibration curve (Absorbance vs ppm PO -3) -3 find ppm PO 4 3 of each sample.

Calculation: Inhibition m P4 3 (treated) ppm P 4 (control) x 100 ppm 4 3 (stock) ppm P04 3 Control) 1 l l r l not -22- CALCIUM SULFATE INHIBITION PROCEDURE Conditions Chemical s pH 7.0 T =50 0

C

24 hour equilibration Ca+ 2 =2000 ppm S0 4 -2 4800 ppm 1 x 10- M CaCl 2 '2H 2 0 1 x 10- 1 M N' 2 so 4 14 Procedure orb.

0 0@

S

15 *0

OS

OSO

0

S.

0SS0 .2Q.

S

0e S

OS

*0 1) Add 50 ml of 10-1 M to a 4 oz. bottle.

2) Add treatment.

3) Add 50 ml of 10-1 M 4) Heat samples for 24 Cool for 30 minutes, 6) Filter 5 ml through 7) Add NaOH to pH 12.0 CaCl 2 '2H 2 0 pre-adjusted to pH Na 2 so 4 preadjusted to hours in a 50'C water bath.

at least.

0.45 u filters.

and dilute to 50 ml with DI H 2 0.

Add Ca~f- indicator (1 level).

Titrate to purple-violet endpoint with EDTA.

Cal cul ati on: Inhibition ml s titrant (treated) ml s titrant (control) mls titrant (Ca+ 2 stock) mlis ti't-rant (control) x 1 00 :I i 1 i*C*~Y- I I -23- CALCIUM PHOSPHONATE PRECIPITATION INHIBITION PROCEDURE Conditions: Static Beaker Study; 750 ppm Ca 2 as CaCO 3 pH 8.7; T 158F; 18 hour Equilibration Time; 10 ppm l-hydroxyethylidene 1,1-diphosphonic acid (HEDP) Experimental Prepare following solutions: Stock Sol'n 2.206g CaCl 2 2H 2 0 0.033g HEDP/2 liters.

Treatment 1,000 ppa active solutions Procedure fe 10 1) To clean 4 oz bottle add 100 ml of stock solution.

S2) Add treatment with stirring.

3) Adjust pH to 8.7 with a dilute NaOH sol'n.

4) Place samples in water bath at T 158 0 F, for 18 hours, after which time filter aliquot through 0.2 u filter paper.

15 5) Analyze filtrate for organic phosphate (TP).

*eo **e Calculation of Inhibition Inh. ppm TP in Treated Sample ppm TP in Untreated Control x 100 ppm FP Initial ppm TP in Untreated Control

I

-24- ZINC HYDROXIDE INHIBITION PROCEDURE Conditions T 120"F; Static Beaker Study; Equilibration Time 18 hours; Ca 2 170 ppm as CaCO3; Mg 2 110 ppm as CaC03; Si0 2 15 ppm; Zn 2 5 ppm; treatment level 5 ppm active.

Sol utions 1000 ppm Treatment Solution Stock Solution Preparation of Stock Solution 10 15

B

*0* 20 1) 2) 3) 4) 5) 6) To approximately 9 liters DI water, add 0.5357g Na 2 SiO 3 5H20.

Adjust pH 6 with concentrated HC1.

Add 2.4996g CaC1 2 2H 2 0.

Add 2.7114g MgSO 4 7H20.

Add 0.1374g ZnSO 4 Bring volume to 10 liters with DI water.

Procedure To 800 ml stock solution, add 4 ml treatment solution.

Adjust pH with dilute NaOH.

As each desired pH is reached, place 100 ml of solution in clean 4 oz. bottle.

Place in water bath at 120"F and equilibrate for 18 hours.

Remove samples and filter through 0.2 u filter.

Analyze filtrate for soluble zinc.

Measure and record pH of cooled unfiltered solution.

4) 6) 7)

I

1:1 T,i-ble II CaC03 Precipitation Inhibition Treatment Inhibition Treatment Concentrations (ppm active) 1 3 5 7.5 30.0 63.2 73.7 77.9 78.9 Polyacrylic acid MW z 5,000 Acrylic acid/2-hydroxy propylacrylate copolymer Mn 2,000 10 AA/HPA molar ratio 3:1 1.7 45.1 56.6 65.3 42.2

S

S

S S. S 5 0*

S

S.

S

SSS

S5

S

*5 Exampl e Exampl e Exampl e Copolymer Copolymer Co polymer 36.4 38.2 30.6 45.1 50.9 42.2 56.6 53.8 48.0 62.4 57.8 45.1 15 Polyacrylic acid MW 5,000 12.4 71.4 75.7 84.9 86.5 Exampl e Exampl e Copolymer Copolymer 10.8 8.1 56.8 54.1 68.6 67.6 75.7 73.0 75.7 78.4 S. S. S

S

5* 0

S.

-26- Table III -Ca 3 (P0 4 2 Precipitation Inhibition Inhibition Treatment Concentrations (ppm active) Treatment 5 10 1 Acrylic acid/2-hydroxy 59.3 88.9 90.7 propylacrylate copolymer Mn 2,000; AA/HPA Molar ratio 3:1 Sulfonated styrene/ 50.0 81.5 90.7 10 maleic anhydride ojes copolymer 1j Exml 1 ooye 42.6 90.7 9.

Emn ple 2,00 Copmr4.A90.

4 molar ratio 3:1 *Example 4 Copolymver 22.2 84.1 93.7 Example 5 Copolymer 12.7 84.1 90.5 -27- Table IV Calcium Phosphonate Inhibition inhibition Treatment Concentration (ppm active) Treatment 5 10 15 Sulfonated styrene/ 2.9 4.4 26.5 72.1 maleic anhydride copolymer MW 1 ,500 SS/MA molar ratio 3:1 *1 *Example 1 Copolymer 0.0 0.0 17.6 76.5 Example 2 Copolymer 0.0 0.0 33.8 69.1 Example 3 Copolymer 0.0 2.9 51.5 82.4 Sulfonated styrene/ 4.2 5.6 25.4 69.0 4 copolymer MW Z 1,500 SS/MA molar ratio 3:1 Example 4 Copolymer 0.0 0.0 0.0 2.8 Example 5 Copolymer 0.0 0.0 0.0 0.0 A -28- Table V Zinc Hydroxide Inhibition Treatment No treatment Final pH 7.42 7.60 8.10 8.47 8.79 9.09 7.12 7.55 7.93 8.15 8.64 9.04 Gos* 0 ~0* 0S S Go* 't 9 60 *1 a 9 go.

Acrylic acid/2-hydroxy propyl acryl ate copolymer Mn '%12,000; AA/HPA molar ratio 3:1 ppm Soluble Zinc after 18 Hours 3.3 0.3 0.1 0.1 0.1 4.3 3.8 3.7 3.8 3.8 3.6 3.8 3.9 4.2 4.3 4.6 4.6 4.2 4.2 p d Sul fonated styrene/ maleic anhydride copolymer MW 1 ,500 SS/MA molar ratio 3:1 00 00 4. 0 p OS S 00 0 #0 7.40 7.68 8.06 8.35 8.77 9.08 7.03 7.62 7.96 8.29 8.64 8.96 Example 1 Copolymier -29- Table V Zinc Hydroxide Inhibition (Continued) Treatment Example 2 Copolymner Example 3 Copolymer it

I

I

9 a6 torn Final pH 7.12 7.64 7.90 8.29 8.57 9.10 7.20 7.64 7.94 8.33 8.67 9.06 7.27 7.63 8.03 8.48 8.73 9.05 ppm Soluble Zinc after 18 Hours 4.2 4.6 3.7 4.2 4.6 4.6 4.3 4.4 4.2 1.6 0.3 0.1 0.1 0.1 No treatment Table V Zinc Hydroxide Inhibition Con ti-nued)T Treatment Example 4 Copolymer Ii a a \jJ a 0 Final pH 7.22 7.65 8.02 8.43 8.73 9.05 7.24 7.60 8.01 8.37 8.72 9.03 Example 5 Copolymer ppm Soluble Zinc after 18 Hours 3.7 3.8 3.7 3.4 4.1 4.1 3.8 3.3 3.6 3.9 4.1 -31- Table VI Ca 3 (P0 4 2 Precipitation inhibition Inhibition Treatmrent Concentration (ppm active) 70 ppm Treatment AcryIi c aci d/2-hydroxy propylacry late Mn AA/HPA molar ratio 3:1 Example 1 Copolymer Example 2 Copolymer Example 3 Copolymer 70.4 90.7 94.4 94.4

I

V

~jIV ;i~A 0 *0* 0000 0@ 0e 0 000 0*S 0 00 0 000 00 0 .00 00 0

GO

@000 000 0* 00 0 0 0 00 0 0 S* 0 00 -32- Table VIa Ca-I(P0 4 2 Precipitation inhibition Treatment Treatment Level (ppm) Inhibition Example I Copolymer *see ,so:% f* 00 S. 0 0* s** 0 0 0 60 Example 1 Copolymer Example 2 Copolymer 10 Examp-2e 3 Copolymer Acrylic acid/ 2-hydroxypropyl acrylate copolymer Mn '-2,000; AA:HPA molar ratio 3:1 5.0 10.0 20.0 2.5 10.0 20.0 2.5 5.0 10.0 20.0 2.5 5.0 10.0 20.0 25.9 46.3 90.7 100.0 18.5 44.4 94.4 100.0 38.9 42.6 94.4 10010 31.5 44.4 70.4 98.1 I -33- Table VII Calcium Carbonate Precipitation Inhibition Treatment tjI ii Example 1 Copolymer Example 2 Copolymer

S..

S

S

OS S

*SSSSS

S

0S

S

SSS

S.

S

SS

S

S.

6S*S S. 55 5 0 0 SS S S S

SS

Treatment Level (ppm) 0.5 0.5 1 .0 3.0 5.0 0.5 1.0 3.0 1.0 3.0 5.0 1 0.0 Inhibition 25.0 53.6 70.3 74.5 27.1 55.7 63.0 71 .4 26.6 47.9 66.7 65.6 31 .0 61 .0 59.7 66.7 Example 3 Copolymer Polyacrylic acid MW4 5, 000 -34- Table VIII Calcium Sulfate Inhibition Treatment Treatment Level (ppm) Inhibition Example 1 Copolymer Example 2 Copolymer

S

S.

10.4 24.3 88.4 98.6 8.1 18.9 97.3 97.5 16.5 92.9 97.2 97.0 98.0 98.0 Example 3 Copolymer 0.5 1.0 3.0 Polyacrylic acid MW 5, 000

I

Ferric Oxide Dispersion In order to demonstrate the effectiveness of the polymers of the invention in dispersing suspended particulate matter, the following procedure, using Fe 2 0 3 as suspended solids, was undertaken. Results appear in Table IX. In the results, it is noted that increasing A%T values indicate better treatment as more particles remain suspended in the aqueous medium.

FeO, Dispersion Procedure Conditions: Oe** 0 0000 0 0*S S e

I

Solutions: 0.1% solution Fe 2 0 3 in D.I. H 2 0 3.68g CaC1 2 2H 2 0/100 ml DI H 2 0 T 25°C pH 7.5 +2 200 ppm Ca as CaCO 3

S*

15 Procedure Prepare a suspension of 0.1% Fe 2 0 3 in DI H 2 0.

+2 Adjust hardness to 200 ppm Ca as CaCO 3 using CaC2 2H 2 0 solution 8 ml/1000 ml of Fe 2 0 3 solution.

Using overhead mixer, mix suspension 1/2 hour at 1000 rpms.

Remove solution to magnetic stirrer and adjust to pH 7.5 (about 20 minutes to stabilize pH).

00 00

S

0 0@ S 50 55 Return solution to overhead mixer.

Take 90 ml aliquots of suspension and place 4 oz. glass bottle.

ruPn.

7) (8) 9) (10) Add treatment and DI water to bring total volume to 100 ml.

Cap bottle, invert several times and place on recip-""ating shaker at a moderate speed of about 40 spm for 1/2 nour.

Place on vibration-proof surface and allow to stand 18 hours.

Without disturbing settled phase, pipet the top 40 mls off the sample. Place in a cell and read %T (at 415 nm).

Calculation A%T %T (control) %T (treated) i +znra 0*0 0 a 0 5 04 0 0.

a 0 0 0 0 00000 00000 000 00 0 0e 0 50 Treatment Example 1 Copolymer Table IX Treatment Level (ppm) 2.5 5.0 10.0 20.0 2.5 5.0 10.0 20.0 A %T 20.7 21.2 20.7 12.0 10.0 10.2 10.7 Example 2 Copolymer

L

i I~ -37- Table IX (Continued) Treatment Example 3 Copolymer Treatment Level (ppm) 2.5 10.0 20.0 15.1 23.1 25.9 25.4 9.3 15.4 15.1 16.4 16.9 i 5

S

500 *5 *5 0 *5 0 0@ S Acrylic acid/2-hydroxy 10 propyl acrylate Mn 2,000 molar ratio AA:HPA 3:1 2.5 5.0 10.0 20.0 30.0 Recirculator Studies In order to approximate those conditions experienced in a cooling tower, tests were conducted under recirculatory conditions with heat transfer provided.

These conditions closely simulate the environment in a field cooling system. In this test system treated water is circulated by a centrifugal pump through a corrosion coupon by-pass into which corrosion coupons are inserted, and past a mild steel (AISI- 1010) heat exchanger tube contained in a plexiglass block. The inside of the exchanger tube is filled with silicone oil and heated with an electric heater. The temperature of the silicone oil can be regulated. The water velocity past the corrosion coupons and heat exchanger tube can be controlled anywhere from 0 to 4.5 ft/sec.

i

I

-38- The pH and temperature of the bulk water are automatically controlled. The treated water is prepared by chemical addition to deionized water. Provisions for continuous make-up and blowdown are made by pumping fresh treated water from supply tanks to the sump, with overflow from the sump serving as blowdown.

Corrosion rates are determined by exposing precleaned and weighed metal specimens for a specified period of time, after which they are removed, cleaned and reweighed. Corrosion rates are calculated by dividing the total coupon weight loss by the number of days of exposure.

The conditions used were: Heat Flux 8000 BTU/ft /hr; Water Velocity 3 ft/sec; Water Temperature 120'F; Retention Time 1.3 days; Mild Steel Heat Transfer Surface.

*2 Water Chemistry: 600 ppm Ca as CaC03; 300 ppm Mg as 15 CaCO 3 83 ppm NaHC03; pH 7.3 0.2: Treatment: 12.5 ppm active polymer; 3.0 ppm tolyltriazole; 10.5 ppm tetrapotassium pyrophosphate; 15.2 ppm monosodium phosphate; S* HEDP 4.0 ppm.

The following results were obtained: i 20 Table X Pretreated Mild Steel Mild Steel Admiralty Treatment Corrosion Corrosion Corrosion Remarks Example 1 Copolymer 1.2 mpy 0.1 mpy 0.1 mpy No significant corrosion or deposition on steel surfaces.

Y 7t--.

-39- (Continued) Pretreated Mild Steel Mild Steel Admiralty Treatment Corrosion Corrosion Corrosion Remarks Example 2 Copolymer 1.2 mpy 0.9 mpy 0.5 mpy No significant corrosion or deposition on mild steel surfaces.

Example 3 Copolymer 1.1 mpy 0.8 mpy 0.5 mpy No significant corrosion or deposition on mild steel surfaces.

Example 8 Copolymer of Methacrylic Acid and AHPSE a Utilizing both apparatus and procedure similar to that Sdescribed in Example 1, 228 g. of water and 180 g of AHPSE S* solution, 0.33 mole) were added to a reaction flask, 86 g. of methacrylic acid (1 mole) and sodium persulfate solution were then separately added to the reaction mixture over a two hour period at The resulting polymer solution was further neutralized with g of caustic and diluted to a 25% solids solution. The final solution had a Brookfield viscosity of 28.2 cps at 25°C. The molecular weight Mn of the copolymer was 3,400.

Boiler Studies In order to assess the efficacy of the polymers of the present invention in inhibiting scale formation in steam generating systems, research boilers were fitted with two 4,000 watt electrical heater probes, giving 185,000 BTU/ft 2 /hr and about 8 Kg/hr steam.

The boiler feedwater contained the contaminants and treatment agents given hereinbelow. The boilers were operated for 44 hours per run at i i an average of 15 cycles of concentration. At the conclusion of each run, the deposts were cl;aned from the probes with an acid solution and the deposit densities were then calculated.

Boiler Test Conditions Condition Condition 'Oh' d *r

S

.4 *9 4 *0

U

4a 904e *h *O *0 4 4@ 0* 84 sodium sulfite oxygen scavenger, 900 psig, contaminants 4/1/1 ppm Ca/Mg/Fe in feedwater, stoichiometric amount of EDTA added chelant/ polymer program.

sodium sulfite oxygen scavenger, 900 psig, contaminants 4/1 ppm Ca/Mg in feedwater, phosphate added to produce 30 ppm PO 4 as Ca phosphate precipitation/polymer program.

hydrazine oxygen scavenger, 1450 psig, contaminant ppm Fe in feedwater, phosphate added to produce 7 ppm

PO

4 as Ca coordinated phosphate/pH/polymer.

Condition c _1 I -41- The results appear hereinbelow in Table XI.

Table XI Treatment Dosage Average Condi- ppm polymer Deposit tion Polymer (actives) (g/ft 2 A Polymethacrylic acid 5 0.18 Mw 12,000 (sodium salt) A Example 8 5 0.19 Copolymer B Sulfonated Polystyrene 7.5 0.23 Maleic Anhydride Copolymer MW 3,000 5,000 SSMA (3:1) B Example 8 7.5 0.23 Copolymer 15 C Polymethacrylic acid MI 12,000 5 0.93 (Sodium Salt) C Example 8 5 2.55 Copolymer Discussion 20 The examples demonstrate that the copolymers of the present invention are effective in inhibiting the formation of those deposits normally encountered in industrial water systems such as cooling and *boiler systems. Further, the copolymers are effective in dispersing iron oxide which is sometimes encountered as a troublesome fouling species.

The demonstrated efficacy of the copolymers in inhibiting calcium phosphate, and calcium phosphonate precipitation is very t -42important. For instance, one successfully established cooling water treatment method provides a passivated oxide film on metal surfaces in contact with the aqueous medium via addition of orthophosphate, organo-phosphonate and an acrylic acid/hydroxylated alkyl acrylate copolymer. Details of such method are disclosed in U.S. Patent 4,303,568 (May et al). The entire content of this patent is hereby incorporated by reference. Based upon the deposit control efficacy shown by the instant copolymers, as well as the minimum corrosion rates displayed herein in the recirculator studies, it is thought that the subject copolymers can be substituted for the polymers .disclosed in the aforementioned May et al patent so as to provide the *important passivated oxide film on the desired metal surfaces.

As the copolymers are effective in inhibiting calcium phosphate formation, they would also be effective in gas scrubbing systems where scrubbing mediums such as sewage treatment effluents contain high phosphate levels. Such systems would have the prerequisite for i ;the formation and deposition of calcium phosphate which is to be avoided. Additional areas of application' such as the phosphate production and processing field, fertilizer field, automotive 20 metallic part pretreatment field, etc. will be apparent to those skilled in the art.

I 40 The fact that the instant copolymers provide for increased j *soluble zinc concentrations in solution (Table V) is important in that more zinc is left in the system water so as to provide its well 25 known corrosion protection. Without the use of the copolymers of the present invention, more zinc precipitates in the form of zinc hydroxide, thus leaving less zinc available for its all important anti-corrosion protection. As such, it is postulated that the present copolymers can be successfully employed in zinc-based corrosion protection systems such as those disclosed in U.S. Patent 3,510,436

I

I

-43- (Silverstein), the content of which is hereby incorporated by reference.

The boiler studies demonstrate that a polymethacrylic acid/ AHPSE copolymer in accordance with the invention is comparable to the well-known polymethacrylic acid and polysulfonated styrene/maleic anhydride polymeric treatments in inhibiting deposits in boilers. Accordingly, the polymethacrylic acid/AHPSE copolymer of Example 8 is preferred for use in boiler environments.

In a particularly unique aspect of the invention, a high pH, simultaneous corrosion inhibition and scale control protection treatment may be provided in cooling water systems when the preferred water soluble copolymer is used conjointly with a water soluble phosphonate, e.g. HEDP, and a source of Zn++ ions.

Specifically, the polymer has the formula es.,

S

C

S..

S.

C.

C C

CH

2

C-

C 0 C=O

I

OH

S. t*

C

S

C S C C

I

CH

2 C

CH

2 0

CH

2

CHOH

CH

2

SO

3

M

-i y

(AA/AHPSE)

-44- Presently, for commercial purposes in such high pH system methods, the copolymer has a molar ratio x:y of from about 3:1 to 6:1 and a molecular weight (Mn) of around 5,000 to 10,000. The copolymer presently commercially used for this purpose has an x:y molar ratio of 6:1 and a Mn of 6,400 to 6,800.

In accordance with these high pH cooling water system programs, the system water is supersaturated with respect to CaCO 3 The pH is maintained in a high range 7.5-9.0) with a 1 minimum M alkalinity of 150 ppm and a maximum M alkalinity of 400 S 10 ppm. Due to such high alkalinity, the system water is not conducive to corrosion but does present a significant calcium carbonate deposition potential. Heretofore, sulfonated styrene/maleic S. anhydride (SS/MA) copolymers have been successfully employed in such high pH systems that are supersaturated with respect to calcium carbonate. However, substitution of the AA/AHPSE copolymers for the SS/MA copolymers lends even better calcium carbonate scale control to the treatment method. In addition to the superior calcium carbonate inhibition occasioned by use of the AA/AHPSE polymers, they also function to maintain the zinc component of the treatment in soluble ion form so it can perform its intended corrosion inhibiting function even at the high pH range of the S* treatment method.

The following process parameters are to be employed in the cooling water system: pH 7.5-9.0 M-alk 150 ppm 400 ppm (as CaCO 3 LSI (Langelier Saturation Index-see 1.0 p 177-178 Betz Handbook of Industrial Water Conditioning, Eighth Edition, 1980) Phosphonate hydroxy ethylidene .2 50 ppm disphosphonic acid HEDP) Zinc compound (as Zn ion) .1 15 ppm AA/AHPSE copolymer .5 50 ppm As to the zinc compound which is to be employed, exemplary G* 10 compounds include zinc oxide, zinc sulfate, zinc acetate, zinc chloride, zinc formate, zinc nitrate, zinc borate, zinc chromate, and zinc dichromate may be mentioned.

If desired, addition corrosion protection may be provided by adding between about 1-50 ppm chromate (as Cr 2 0 4 to the cooling water system. As is disclosed in Kahler et al U.S. Patent 2,900,222, acceptable chromate compounds include alkali metal a..

chromates or any water soluble compound that contains hexavalent chromate and provides chromate radicals in water solutions.

Illustrative water-soluble chromate compounds include sodium chromate dihydrate, sodium chromate anhydrous, sodium chromate tetrahydrate, sodium chromate hexahydrate, sodium chromate decahydrate, potassium dichromate, potassium chromate, ammonium h dichromate and chromic acid.

Use of the AA/AHPSE copolymer in the high pH cooling treatment system also provides significant commercial advantage over the use of acrylic acid/hydroxylated lower alkyl acrylate AA/HLAA copolymers in similar methods, since the latter copolymers cannot be sold in combination with the other treatment components in a stable one drum product. Use of the AA/AHPSE copolymers allows -46for such commercially desirable one drum packaging and sale.

In addition to the other high pH cooling water system +2 treatment components AA/AHPSE copolymer, Zn 2

HEDP,

optional chromate), especially in those cooling systems comprising copper, such as admiralty, binary brasses, binary bronzes, etc., it is desirable to add from about .2 to 30 ppm of an azole compound.

Exemplary azole compounds include 1,2,3-tolytriazole; benzotriazole; 4-phenol-1,2,3-triazole; 4-methyl-l,2,3-triazole; 4-ethyl-1,2,3-triazole; 5-methyl-1,2,3-triazole; 5-ethyl-1,2,3-triazole; 10 1,2,3-triazole; and 5-butyl-1,2,3-triazole.

Other exemplary azole copper corrosion inhibitors comprise thiazole, 2-mercaptothiazole, 2-mercaptobenzothiazole, benzothiazole and the like.

Exemplary single drum AA/AHPSE containing compositions for 15 use in the high pH cooling water system program comprise aqueous solutions of *go AA/AHPSE 3-10 wt% Zn compound .3-2 wt% (as Zn 20 Phosphonate .5-4 wt% Azole .75-2 wt% (when present) Chromate 5-10 wt% (when present) Remainder water -47- In order to demonstrate the efficacy of the AA/AHPSE copolymers in simultaneously inhibiting corrosion and scale formation at high pHs, recirculator tests, similar to those reported in Table X hereinabove, were run under the high pH process parameters referred to above. Exact water chemistry and test results are reported in Table XII.

If ii TABLE XII 0S** 5

S*

S

*5*4

S

Test Conditions: Test Water: 120F bulk water temperature, 1.4 ft/sec water velocity (2 gpm), pH 8.5, 15600 Btu/hr-ft 2 heat flux, 160F skin temperature, 4-5 day test, 1.3 day retention time 600 ppm Ca 2 as CaCO 3 200 ppm Mg 2 as CaCO 3 357 ppm NaHC0 3 M-alk 220-250 ppm (as CaCO 3 15 ppm AA/AHPSE (AA:AHPSE 6:1, Fn 6800) 6 ppm HEDP as P0 4 3 ppm TTA (Tolytriazole) 2 ppm Zinc Treatment: Corrosion Rates: (mpy) 0.7 Coupon/Heat Exchange Tube Appearance: Coupons clean. Tube predominantly clean with streaks of corrosion products and a small patch of thin, white deposit on back of tube.

LCS Low Carbon Steel ADM Admiralty Brass While this invention has been described with respect to particular embodiments thereof, it is apparent that numerous other forms and modifications of this invention will be obvious to those skilled in the art. The appended claims and this invention -48generally should be construed to cover all such obvious forms and modifications which are within the true spirit and scope of the present invention.

0e@* S. 0

S

S.

S

S*S

S

0** 5*

S

*ISSS

S* 55 5 *5 S S 5 05

Claims (10)

1. A method for simultaneously inhibiting corrosion and scale formation in a cooling water system, comprising a) maintaining the pH of said cooling water system within the pH range of about 7.5 to auet b) maintaining the cooling water system in a state of supersaturation with respect to calcium carbonate; c) adding from abet- .5-50 ppm of a water soluble acrylic acid/allylhydroxypropylsulfonate ether copolymer or water soluble salt form thereof to said cooling water system, based upon one million parts of water in said system; said copolymer having the formula: CH 2 H C CH 2 C 0 OH 0 9 H 1 C CH 2 0 I CH 2 I CHOH I CH2 SO 3 M S4 wherein M is a water soluble cation; wherein the molar ratio x:y is from 3:1-6:1 and wherein the number average molecular weight of said copolymer is from 5,000 to 10,000; d) adding to said cooling water system from .2-50 ppm of water soluble phosphonate compound to said cooling water; and e) adding to said cooling water system from .1-15 ppm of a zinc compound adapted to 2+ Sliberate Zn ions in water. o.. %oo:•

2. A method as recited in claim 1 further I comprising maintaining the M-alkalinity of said cooling water system within the range of from 150 ppm 400 ppm (as CaCO 3 and maintaining the Langelier Saturation f Index of said cooling water system within the range of I from 1.0 to

3. A method as recited in claim 1 wherein said o copolymer has a molar ration x:y of 6:1. i

4. A method as recited in claim 1 wherein said s phosphonate comprises hydroxyethylidene diphosphonic t acid.

A method as recited in claim 1 further comprising adding from 1-50 ppm (as Cr20 4 of a water soluble chromate compound containing hexavalent chromium ions. i ii i i i :li Y -51

6. A method as recited in claim 1 further comprising adding from aeot- .2-30 ppm of azole compound to said cooling water system.

7. Composition for simultaneously inhibiting corrosion and deposit formation comprising: a) from &be- 3-10 wt% of a water soluble acrylic acid/allylhydroxypropylsulfonate ether copolymer or water soluble salt form thereof, said copolymer having the formula t .040 too* a.. t 0:91 9 a a. *0 *4 a.. CH 2 H C C=O I OH CH 2 C CH 2 0 CH 2 CHOH I CH 2 SO 3 M ft U wherein M is a water soluble cation, the mola ratio x:y being from about 3:1-6:1 and wherein the number average molecular weight of said copolymer is from -abo 5,000 to 10,000; b) from about .3-2 wt% of a zinc compound adapted to liberate Zn2+ ions in water; -52- c) from 44ot .5-4 wt% of a water soluble phosphonate compound; d) remainder water.

8. Composition as recited in claim 7 wherein said phosphonate c) comprises hydroxyethylidene diphosphonic acid or water soluble salt. a

9. Composition as recited in claim 7 further comprising from a .75-2 wt% of azole compound. a j tests:

10. Composition as recited in claim 7 further comprising 10 aeLk 5-10 wt% of a water soluble chromate compound containing hexavalent chromium ions. DATED THIS 23RD DAY OF APRIL 1987 BETZ INTERNATIONAL, INC. p By its Patent Attorneys: CLEMENT HACK CO. SFellows Institute of Patent Attorneys of Australia.