EP0225051B1 - The treatment of aqueous systems - Google Patents

The treatment of aqueous systems Download PDF

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EP0225051B1
EP0225051B1 EP86308419A EP86308419A EP0225051B1 EP 0225051 B1 EP0225051 B1 EP 0225051B1 EP 86308419 A EP86308419 A EP 86308419A EP 86308419 A EP86308419 A EP 86308419A EP 0225051 B1 EP0225051 B1 EP 0225051B1
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acid
zinc
hydrogen
methyl
vinyl
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EP0225051A1 (en
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Brian Greaves
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Suez WTS USA Inc
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WR Grace and Co Conn
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    • CCHEMISTRY; METALLURGY
    • C23COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23FNON-MECHANICAL REMOVAL OF METALLIC MATERIAL FROM SURFACE; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL; MULTI-STEP PROCESSES FOR SURFACE TREATMENT OF METALLIC MATERIAL INVOLVING AT LEAST ONE PROCESS PROVIDED FOR IN CLASS C23 AND AT LEAST ONE PROCESS COVERED BY SUBCLASS C21D OR C22F OR CLASS C25
    • C23F11/00Inhibiting corrosion of metallic material by applying inhibitors to the surface in danger of corrosion or adding them to the corrosive agent
    • C23F11/08Inhibiting corrosion of metallic material by applying inhibitors to the surface in danger of corrosion or adding them to the corrosive agent in other liquids

Definitions

  • the present invention relates to the treatment of aqueous systems and, more particularly, to reducing or eliminating corrosion in aqueous systems.
  • inorganic salts such as nitrites and chromates, inorganic mono and polyphosphates, certain water soluble polymers including naturally occurring materials such as lignins and starches as well as synthetic materials such as polyacrylates, as well as organic phosphonates.
  • zinc salts for this purpose. Indeed, it is known to use zinc salts in combination with organic type corrosion inhibitors, principally organic phosphonates and polyacrylates.
  • AT-B-332 699 discloses preventing corrosion using a phosphonate and, optionally, a zinc salt.
  • a method of treating an aqueous system which comprises adding thereto a zinc salt, a chelant having the formula set out below and either a product containing at least one phosphorus-containing acid group and at least one carboxylic acid group or an acrylic, vinyl or allyl carboxylic acid polymer.
  • any water soluble zinc salt can be used in the present invention.
  • Typical salts which can be used include zinc sulphate, zinc chloride, zinc nitrate and zinc acetate, zinc sulphate monohydrate and zinc chloride being particularly preferred.
  • the third component used in the present invention will, in general, be a phosphonate.
  • the materials used contain at least two acid groups, one of which is a phosphonate group and the other is a carboxylic acid group, at least the two said acid groups being attached to carbon atoms.
  • Preferred phosphonates include hydroxy phosphonoacetic acid and 2-phosphono butane-1,2,4-tricarboxylic acid, the latter being particularly preferred.
  • these preferred phosphonates possess the general formula wherein R is hydrogen, alkyl, alkenyl or alkynyl having up to 4 carbon atoms; phenyl; cycloalkyl having 3 to 6 carbon atoms; benzyl; phenethyl or wherein R' is hydrogen, alkyl having 1 to 4 carbon atoms or carboxyl, R" is hydrogen or methyl and R''' is carboxyl or phosphonate.
  • a polymeric material and, in particular, carboxylic acid polymers which contain a chain phosphorus atom which forms part of an acid group.
  • the molecular weight of such polymers is relatively low, generally below 5,000, the preferred molecular weight being from 250 to 750, especially about 500.
  • a particularly suitable polymer is that sold as "Belclene 500", a registered Trade Mark of Ciba-Geigy.
  • a synergistic effect although most pronounced when the phosphorus containing materials are used, can also be obtained when a polycarboxylic acid is used, typically one having a molecular weight from 1,000 to 5,000.
  • Such polymers may be derived from acrylic, vinyl or allyl carboxylic monomers, typically acrylic, methacrylic, maleic, fumaric, itaconic, crotonic or cinnamic acid alone or with a suitable comonomer.
  • Such comonomers include acrylamide, (meth)acrylate esters or hydroxy esters e.g.
  • hydroxypropyl esters vinyl pyrrolidone, vinyl acetate, acrylonitrile, vinyl methyl ether, 2-acrylamido-2-methyl-propane sulphonic acid, vinyl or allyl sulphonic acid and styrene sulphonic acid as well as cationic monomers such as diallyl dimethyl ammonium chloride, dimethylamino ethylacrylate or methacrylate, optionally quaternised with, for example, dimethyl sulphate or methyl chloride.
  • cationic monomers such as diallyl dimethyl ammonium chloride, dimethylamino ethylacrylate or methacrylate, optionally quaternised with, for example, dimethyl sulphate or methyl chloride.
  • the chelants which can be used in the method of the present invention possess the formula where R1 is hydrogen, hydroxyethyl or carboxymethyl, preferably carboxymethyl, R2 is hydrogen, hydroxyphenyl, preferably ortho-hydroxyphenyl, which is optionally methyl or sulphonic acid substituted, or carboxyl, R4 is hydrogen or carboxyl, where R1, R2 and R4 are as defined above and X is -(CH2)2- or - (CH2)3 - with the proviso that at least one of R2 and R3 contains a hydroxyphenyl group.
  • the phenyl groups may be substituted, if desired, preferably by one or more halogen atoms.
  • the chelant is to be used in aqueous systems which possess a high pH and a relatively high temperature it is preferred that at least one of R1, R2 and R3 contains a hydroxyl group.
  • the most preferred chelants possess a nitrogen ligand, a carboxylic acid group and a hydroxyl group.
  • Preferred chelants for use in the present invention include N,N'-di(-2-hydroxybenzyl-)trimethylenediamine-N, N'-diacetic acid, N,N'ethylene-bis-[2-(2-hydroxy-4-methyl-phenyl)-glycine], ethylenediamine N, N'-bis-[2-hydroxyphenylacetic acid] and N, N-di(2-hydroxy-5-sulphonic acid benzyl)glycine which is especially preferred not only on account of its effectiveness but also on account of its excellent solubility properties which facilitate the formulation of compositions.
  • the present invention also provides a composition suitable for addition to an aqueous system which comprises a water soluble zinc salt, a product containing at least one phosphorus containing acid group and at least one carboxylic acid group or an acrylic, vinyl or allyl carboxylic acid polymer, and a chelant. In such a situation, it may be desirable to add further quantities of chelant as required.
  • the composition will be an aqueous formulation containing, generally, 1% to 2% by weight of zinc salt (as zinc), 4% to 10% by weight of the phosphorus containing material or polymer and 1% to 25% by weight, especially about 5% by weight, of the chelant.
  • zinc salt as zinc
  • 4% to 10% by weight of the phosphorus containing material or polymer 4% to 10% by weight of the phosphorus containing material or polymer
  • 1% to 25% by weight especially about 5% by weight, of the chelant.
  • a further surprising feature of the present invention is that the presence of the combination of chelant and phosphorus containing compound and/or acrylic vinyl or allyl carboxylic acid polymer enables one to reduce the amount of zinc salt. It is usual in the art to employ amounts of the order of 2 to 5ppm zinc. However, with ever increasing restrictions on concentrations of zinc in discharges there is a constant demand to reduce the amounts of zinc used. It has been found that by using the additional ingredients it is possible to reduce the amount of zinc to, say, about 1ppm for comparable effectiveness. In such circumstances it is preferred to employ about 4ppm of the phosphorus compound and about 2.5 to 5ppm of chelant. If, on the other hand, one uses 2.5ppm of zinc then it is preferred to use about 10ppm of phosphorus compound and about 5ppm of chelant.
  • the combination of the present invention together with other ingredients including phosphates, biocides, yellow metal corrosion inhibitors such as benzotriazole and tolyltriazole as well as other polymers which act as dispersants such as polyacrylic acid, polymaleic acid and copolymers of maleic acid with styrene sulphonic acid.
  • dispersants especially a copolymer of methacrylic acid and acrylamide is particularly advantageous, especially one in which the mole ratio is about 1:3, and further enhances the corrosion protection given by the three component system.
  • the molecular weight of the homopolymers will be 1,000 to 10,000 while that of the copolymers will be 1,000 to 50,000.
  • Examples 15 - 34 were carried out at 54°C.
  • Example 42 in relation to Example 43 shows the effect of using Chelant 2 in enabling one to reduce the concentration of zinc/phosphate.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Preventing Corrosion Or Incrustation Of Metals (AREA)
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  • Compositions Of Macromolecular Compounds (AREA)
  • Chemical Treatment Of Metals (AREA)

Abstract

A method of treating an aqueous system is disclosed which comprises adding thereto a water-soluble zinc salt, a chelant and either a product containing at least one phosphorus-containing acid group and at least one carboxylic acid group or an acrylic, vinyl or allyl carboxylic acid polymer.

Description

  • The present invention relates to the treatment of aqueous systems and, more particularly, to reducing or eliminating corrosion in aqueous systems.
  • Many different types of material have been employed to prevent or inhibit corrosion in aqueous systems. These include inorganic salts such as nitrites and chromates, inorganic mono and polyphosphates, certain water soluble polymers including naturally occurring materials such as lignins and starches as well as synthetic materials such as polyacrylates, as well as organic phosphonates. In addition, it is well known to use zinc salts for this purpose. Indeed, it is known to use zinc salts in combination with organic type corrosion inhibitors, principally organic phosphonates and polyacrylates.
  • The use of zinc salts enables one to passivate corrosion of the metal in contact with the system. It is generally believed that localised high concentrations of hydroxide ions arise at sites of corrosion on the metal surface because, due to the galvanic cell effect, oxygen present in the water is reduced to hydroxide ions at the cathodic sites. These hydroxide ions then react with zinc ions of the zinc salt to give zinc hydroxide which in turn yields a protective film on the metal surface.
  • While this passivation system works reasonably satisfactorily in some aqueous media it is known that the use of zinc salts, with or without the organic type corrosion inhibitor, is ineffective when the pH of the system is high, for example at pH from 8.2 to 9.0. Such a pH can be present when the water is hard, or is otherwise alkaline ie of low hardness and high alkalinity as can be the case with base exchanged water. Under such circumstances, the zinc hydroxide precipitates prematurely in the system water and therefore does not form a protective film over the metal. Thus in such systems the zinc actually becomes a foulant of the system. Similar problems arise when the temperature of the aqueous system is raised, for example to at least 40°C as can occur when the aqueous system is used as cooling water which comes into contact with hot metal surfaces. AT-B-332 699 discloses preventing corrosion using a phosphonate and, optionally, a zinc salt.
  • It has now surprisingly been found, according to the present invention, that more effective corrosion inhibition can be obtained when a zinc salt is used together with a class of phosphonate or similar material and, in addition, a specific class of chelant. It has been found that this combination is capable of being effective under a combination of severe pH and temperature conditions. It is considerably more effective than existing zinc/organic products on pre-corroded mild steel surfaces since the combination is capable of stifling existing corrosion as well as enabling much faster passivation of the rusty surface to be brought about. Thus the combination, as well as inhibiting corrosion, also acts as an on line cleaning agent by removing old rust.
  • According to the present invention there is provided a method of treating an aqueous system which comprises adding thereto a zinc salt, a chelant having the formula set out below and either a product containing at least one phosphorus-containing acid group and at least one carboxylic acid group or an acrylic, vinyl or allyl carboxylic acid polymer.
  • Generally, any water soluble zinc salt can be used in the present invention. Typical salts which can be used include zinc sulphate, zinc chloride, zinc nitrate and zinc acetate, zinc sulphate monohydrate and zinc chloride being particularly preferred.
  • The third component used in the present invention will, in general, be a phosphonate. Preferably, the materials used contain at least two acid groups, one of which is a phosphonate group and the other is a carboxylic acid group, at least the two said acid groups being attached to carbon atoms.
  • Preferred phosphonates include hydroxy phosphonoacetic acid and 2-phosphono butane-1,2,4-tricarboxylic acid, the latter being particularly preferred. Thus these preferred phosphonates possess the general formula
    Figure imgb0001

    wherein R is hydrogen, alkyl, alkenyl or alkynyl having up to 4 carbon atoms; phenyl; cycloalkyl having 3 to 6 carbon atoms; benzyl; phenethyl or
    Figure imgb0002

    wherein R' is hydrogen, alkyl having 1 to 4 carbon atoms or carboxyl, R" is hydrogen or methyl and R''' is carboxyl or phosphonate.
  • It is also possible to employ as the third component in the method a polymeric material and, in particular, carboxylic acid polymers which contain a chain phosphorus atom which forms part of an acid group. Thus these polymeric materials are preferably phosphino polycarboxylic acids, typically those having the formula
    Figure imgb0003

    where N + M = 4 to 20
       The molecular weight of such polymers is relatively low, generally below 5,000, the preferred molecular weight being from 250 to 750, especially about 500. A particularly suitable polymer is that sold as "Belclene 500", a registered Trade Mark of Ciba-Geigy.
  • It has also been found that a synergistic effect, although most pronounced when the phosphorus containing materials are used, can also be obtained when a polycarboxylic acid is used, typically one having a molecular weight from 1,000 to 5,000. Such polymers may be derived from acrylic, vinyl or allyl carboxylic monomers, typically acrylic, methacrylic, maleic, fumaric, itaconic, crotonic or cinnamic acid alone or with a suitable comonomer. Such comonomers include acrylamide, (meth)acrylate esters or hydroxy esters e.g. hydroxypropyl esters, vinyl pyrrolidone, vinyl acetate, acrylonitrile, vinyl methyl ether, 2-acrylamido-2-methyl-propane sulphonic acid, vinyl or allyl sulphonic acid and styrene sulphonic acid as well as cationic monomers such as diallyl dimethyl ammonium chloride, dimethylamino ethylacrylate or methacrylate, optionally quaternised with, for example, dimethyl sulphate or methyl chloride.
    The chelants which can be used in the method of the present invention possess the formula
    Figure imgb0004

    where R¹ is hydrogen, hydroxyethyl or carboxymethyl, preferably carboxymethyl, R² is hydrogen, hydroxyphenyl, preferably ortho-hydroxyphenyl, which is optionally methyl or sulphonic acid substituted, or carboxyl, R⁴ is hydrogen or carboxyl,
    Figure imgb0005

    where R¹, R² and R⁴ are as defined above and
    X is -(CH₂)₂- or - (CH₂)₃ - with the proviso that at least one of R² and R³ contains a hydroxyphenyl group. The phenyl groups may be substituted, if desired, preferably by one or more halogen atoms.
  • If the chelant is to be used in aqueous systems which possess a high pH and a relatively high temperature it is preferred that at least one of R¹, R² and R³ contains a hydroxyl group. Thus the most preferred chelants possess a nitrogen ligand, a carboxylic acid group and a hydroxyl group.
  • Preferred chelants for use in the present invention include N,N'-di(-2-hydroxybenzyl-)trimethylenediamine-N, N'-diacetic acid, N,N'ethylene-bis-[2-(2-hydroxy-4-methyl-phenyl)-glycine], ethylenediamine N, N'-bis-[2-hydroxyphenylacetic acid] and N, N-di(2-hydroxy-5-sulphonic acid benzyl)glycine which is especially preferred not only on account of its effectiveness but also on account of its excellent solubility properties which facilitate the formulation of compositions.
  • In general, from 1 to 10 parts by weight of chelant and from 4 to 6 parts by weight of the phosphorus containing compound are employed to 1 part of the zinc salt. While in certain circumstances it may be desirable to add the individual components separately, in other situations it will be convenient to add the components together in the form of a composition. Accordingly, the present invention also provides a composition suitable for addition to an aqueous system which comprises a water soluble zinc salt, a product containing at least one phosphorus containing acid group and at least one carboxylic acid group or an acrylic, vinyl or allyl carboxylic acid polymer, and a chelant. In such a situation, it may be desirable to add further quantities of chelant as required. Typically, the composition will be an aqueous formulation containing, generally, 1% to 2% by weight of zinc salt (as zinc), 4% to 10% by weight of the phosphorus containing material or polymer and 1% to 25% by weight, especially about 5% by weight, of the chelant.
  • A further surprising feature of the present invention is that the presence of the combination of chelant and phosphorus containing compound and/or acrylic vinyl or allyl carboxylic acid polymer enables one to reduce the amount of zinc salt. It is usual in the art to employ amounts of the order of 2 to 5ppm zinc. However, with ever increasing restrictions on concentrations of zinc in discharges there is a constant demand to reduce the amounts of zinc used. It has been found that by using the additional ingredients it is possible to reduce the amount of zinc to, say, about 1ppm for comparable effectiveness. In such circumstances it is preferred to employ about 4ppm of the phosphorus compound and about 2.5 to 5ppm of chelant. If, on the other hand, one uses 2.5ppm of zinc then it is preferred to use about 10ppm of phosphorus compound and about 5ppm of chelant.
  • It is also possible to use the combination of the present invention together with other ingredients including phosphates, biocides, yellow metal corrosion inhibitors such as benzotriazole and tolyltriazole as well as other polymers which act as dispersants such as polyacrylic acid, polymaleic acid and copolymers of maleic acid with styrene sulphonic acid. In particular, it has been found that the use of certain dispersants, especially a copolymer of methacrylic acid and acrylamide is particularly advantageous, especially one in which the mole ratio is about 1:3, and further enhances the corrosion protection given by the three component system. In general the molecular weight of the homopolymers will be 1,000 to 10,000 while that of the copolymers will be 1,000 to 50,000.
  • The use of a phosphate is particularly noteworthy since zinc phosphate is effective in low water hardness systems because the zinc phosphate itself gives protection. By using the chelant and phosphorus containing compound as well it is possible, as previously discussed, to use significantly lower quantities of zinc.
  • The following Examples further illustrate the present invention.
  • Examples 1 to 34
  • In these Examples tests were carried out on a laboratory scale recirculating rig consisting of a plastic vessel holding 8 litres of water and connected by tubing to a circulating pump the water passing from the pump through a glass rack holding the metal test coupons ('line') and returning to the plastic vessel. Any evaporation was made up by the addition of de-ionised water. Metal test coupons were also suspended in the plastic vessel ('Pond'). The corrosion rate was calculated from the weight of metal lost during test. The water temperature was maintained by means of a heater/thermostat arrangement. The conditions of the test were as follows:
  • System Water
    : 150ppm Ca hardness/150ppm 'M' Alkalinity
    Water pH
    : 8.8
    Water Temperature
    : 54°C or 40°C (as stated)
    Flow Rate: Line
    : 2 ft/sec
    Pond
    : 0.2 ft/sec
    Duration of Test
    : 3 days
    Initial Passivation
    : 1 day at 3 times normal maintenance dose.
  • Examples No. 1 - 14 were carried out at 40°C.
    Figure imgb0006
  • Examples 1 - 14 illustrate:
    • i) The blend of zinc/chelant/phosphonate is superior to zinc/phosphonate or zinc/chelant.
    • ii) the best chelants are Chelants 1, 2,3 and 9.
    • iii) Phosphonate 1 gives significantly better results than comparative Phosphonate 2.
    Examples 15 - 34 were carried out at 54°C.
  • Figure imgb0007
    Figure imgb0008
    • Chelant 1 = N, N'-di(-2 hydroxybenzyl trimethylenediamine-N,N'-diacetic acid
    • Chelant 2 = N,N' Ethylene-bis- [2(2-hydroxy-4 methyl-phenyl) - glycine]
    • Chelant 3 = Ethylenediamine N, N'bis-[2 hydroxyl phenyl acetic acid]
    • Chelant 4 = Ethylenediamine tetraacetic acid.
    • Chelant 5 = N,N-di (2 hydroxy ethyl) glycine.
    • Chelant 6 = N-Hydroxyethyl,N,N' Ethylenediamine triacetic acid.
    • Chelant 7 = 2-hydroxyethyl iminodiacetic acid.
    • Chelant 8 = Diethylene triamine penta acetic acid.
    • Chelant 9 = N,N-di(2 hydroxy -5-sulphonic acid benzyl) glycine
    • Phosphonate 1 = 2-Phosphonobutane 1,2,4 tricarboxylic acid.
    • Phosphonate 2 = Hydroxy ethylidene di-phosphonic acid.
    • Phosphonate 3 = Hydroxy phosphonoacetic acid.
    • Phosphino 1 = Phosphino polyacrylic acid, M.Wt. approx 500 (sold commercially as "Belclene 500" Ciba Geigy).
    Polymer 1 =
    Copolymer of methacrylic acid/acrylamide, mole ratio 1:3, M.Wt. 35,000.
    Polymer 2 =
    Polyacrylic acid, M.Wt.1000.
    Polymer 3 =
    Polyacrylic acid, M.Wt.4500.
    Examples 15 - 34 indicate:
    • i) The excellent corrosion inhibiting properties of the zinc/chelant/phosphonate combinations are maintained at the higher test temperature; this should be compared with Chelant 8 which does not contain a hydroxy group (Example 32). The excellent corrosion inhibition is also maintained when the phosphonate is replaced by the phosphino-polycarboxylic acid in the 3 component combination.
    • ii) The presence of Polymer 1, (Example 20), enhances the corrosion protection conferred by the 4 component blend over that given by the corresponding 3 component blend, (Example 19), without polymer.
    • iii) The improvement brought about by the presence of the chelant with the zinc/polyacrylic acid combination.
    Examples 35 to 43
  • These Examples illustrate the effect of longer term tests. These were carried out on a laboratory scale simulated open, evaporative, recirculating cooling water system incorporating mild steel heat exchanger together with feed and bleed facilities which enable the system to run at a given concentration factor throughout the 14 day test. The test conditions were as follows:
  • System Water
    : 160ppm Calcium hardness 50ppm Magnesium hardness 200ppm 'M' Alkalinity
    Water Temperature (Pond)
    : 50°C
    pH
    : 8.8
    Flow Rate through heat exchanger
    : 0.3 ft/sec
    Flow Rate through coupon chamber
    : 1.5 ft/sec
    Heat flux on exchanger
    : 75 kj/m⁻²/sec⁻¹
    Duration of test
    : 14 days
    Initial passivation
    : 3 x normal maintenance dose, allowed to decay from start of test.
    Figure imgb0009
  • It was noticed that when Chelant 2 was in use (Examples 35 to 38), the corrosion which initiated on the heat exchanger was rapidly stifled whereas in Example 40 corrosion spread throughout the test. Chelant 4 was largely ineffective; in fact, the results indicate aggression. This shows that this chelant is unsuitable where there is a heat exchanger giving a high surface temperature.
  • Example 42 in relation to Example 43 shows the effect of using Chelant 2 in enabling one to reduce the concentration of zinc/phosphate.

Claims (27)

  1. A method of treating an aqueous system which comprises adding thereto a water-soluble zinc salt, a chelant which possesses the formula
    Figure imgb0010
    where R¹ is hydrogen, hydroxyethyl or carboxymethyl, R² is hydrogen, hydroxyphenyl, which is optionally methyl or sulphonic acid substituted, or carboxyl, R⁴ is hydrogen or carboxyl,
    Figure imgb0011
    where R¹, R² and R⁴ are as defined above and X is -(CH₂)₂₋ or -(CH₂)₃-; the phenyl groups being optionally further substituted by one or more halogen atoms, with the proviso that at least one of R² and R³ contains a hydroxyphenyl group, and either a product containing at least one phosphorus-containing acid group and at least one carboxylic acid group or an acrylic, vinyl or allyl carboxylic acid polymer.
  2. A method according to claim 1 in which the zinc salt is zinc sulphate, zinc chloride, zinc nitrate or zinc acetate.
  3. A method according to claim 1 or 2 in which the phosphonate has the general formula
    Figure imgb0012
    wherein R is hydrogen, alkyl, alkenyl or alkynyl having up to 4 carbon atoms; phenyl; cycloalkyl having 3 to 6 carbon atoms; benzyl; phenethyl or
    Figure imgb0013
    wherein R' is hydrogen, alkyl having 1 to 4 carbon atoms or carboxyl, R" is hydrogen or methyl and R''' is carboxyl or phosphonate.
  4. A method according to claim 3 in which the phosphonate is hydroxy-phosphonoacetic acid or 2-phosphonobutane-1,2,4-tricarboxylic acid.
  5. A method according to claim 1 or 2 in which the product containing at least one phosphorus-containing acid group and at least one carboxylic acid group is a phosphino polycarboxylic acid having the formula
    Figure imgb0014
    where N + M = 4 to 20.
  6. A method according to claim 1 or 2 in which the polymer is a copolymer of acrylic, methacrylic, maleic, fumaric, itaconic, crotonic or cinnamic acid with acrylamide, an acrylate or methacrylate ester or hydroxy ester, vinyl pyrrolidone, vinyl acetate, acrylonitrile, vinyl methyl ether, 2-acrylamido-2-methyl-propane sulphonic acid, vinyl, allyl or styrene sulphonic acid, or diallyldimethyl ammonium chloride or dimethylamino ethyl acrylate or methacrylate, optionally quaternised with dimethyl sulphate or methyl chloride.
  7. A method according to claim 1 or 2 in which the polymer is a polymer of acrylic acid, methacrylic acid, maleic acid, fumaric acid, itaconic acid or crotonic acid, having a molecular weight from 1000 to 5000.
  8. A method according to any one of claims 1 to 7 in which R¹ is hydrogen or carboxymethyl, R² is hydroxyphenyl which is optionally methyl or sulphonic acid substituted, R³ is
    Figure imgb0015
    or -CH₂C₆H₃ (OH) (SO₃H), the phenyl groups being optionally further substituted by one or more halogen atoms.
  9. A method according to any one of claims 1 to 7 in which the chelant is N,N'-di(2-hydroxybenzyl)-trimethylenediamine-N,N'-diacetic acid, N,N'ethyenebis-[2(2-hydroxy-4-methyl-phenyl)-glycine}, ethylenediamine N,N'-bis-[2-hydroxyphenylacetic acid] or N,N-di (2-hydroxy-5-sulphonic acid benzyl) glycine.
  10. A method according to any one of the preceding claims in which the zinc salt is added in an amount to provide up to 5 ppm zinc.
  11. A method according to claim 10 in which the zinc salt is added to provide up to 2 ppm zinc.
  12. A method according to any one of the preceding claims in which 1 to 10 parts by weight of chelant are added per part by weight of the zinc salt.
  13. A method according to any one of the preceding claims in which 4 to 6 parts by weight of the phosphorus and carboxylic acid group containing compound are added per part by weight of the zinc salt.
  14. A method according to any one of the preceding claims in which the system water attains a temperature of at least 40° C.
  15. A method according to any one of the preceding claims in which the system water attains a pH of at least 8.2.
  16. A composition suitable for addition to an aqueous system which comprises a water-soluble zinc salt, a product containing at least one phosphorus-containing acid group and at least one carboxylic acid group or an acrylic, vinyl or allyl carboxylic acid polymer, and a chelant which possesses the formula
    Figure imgb0016
    where R¹ is hydrogen, hydroxyethyl or carboxymethyl, R² is hydrogen, hydroxyphenyl, which is optionally methyl or sulphonic acid substituted, or carboxyl, R⁴ is hydrogen or carboxyl,
    Figure imgb0017
    where R¹, R² and R⁴ are as defined above and X is -(CH₂)₂- or -(CH₂)₃-; the phenyl groups being optionally further substituted by one or more halogen atoms, with the proviso that at least one of R² and R³ contains a hydroxyphenyl group.
  17. A composition according to claim 16 in which the zinc salt is zinc sulphate, zinc chloride, zinc nitrate or zinc acetate.
  18. A composition according to claim 16 or 17 which is agueous and contains 1 to 2% by weight of zinc salt (as zinc), 4 to 10% by weight of the phosphorus and carboxylic acid group containing material or polymer and 1 to 25% by weight of the chelant.
  19. A composition according to any one of claims 16 to 18 which also comprises a phosphate, biocide, yellow metal corrosion inhibitor or dispersant.
  20. A composition according to claim 19 in which the dispersant is a copolymer of methacrylic acid and acrylamide.
  21. A composition according to any one of claims 16 to 20 in which the phosphonate has the general formula
    Figure imgb0018
    wherein R is hydrogen, alkyl, alkenyl or alkynyl having up to 4 carbon atoms; phenyl; cycloalkyl having 3 to 6 carbon atoms; benzyl; phenethyl or
    Figure imgb0019
    wherein R' is hydrogen, alkyl having 1 to 4 carbon atoms or carboxyl, R'' is hydrogen or methyl and R''' is carboxyl or phosphonate.
  22. A composition according to claim 21 in which the phosphonate is hydroxy-phosphonoacetic acid or 2-phosphonobutane-1,2,4-tricarboxylic acid.
  23. A composition according to any one of claims 16 and 18 to 20 in which the product containing at least one phosphorus-containing acid group and at least one carboxylic acid group is a phosphino polycarboxylic acid having the formula
    Figure imgb0020
    where N + M = 4 to 20.
  24. A composition according to any one of claims 16 and 18 to 20 in which the polymer is a copolymer of acrylic, methacrylic, maleic, fumaric, itaconic, crotonic or cinnamic acid with acrylamide, an acrylate or methacrylate ester or hydroxy ester, vinyl pyrrolidine, vinyl acetate, acrylonitrile, vinyl methyl ether, 2-acrylamido--2-methyl-propane sulphonic acid, vinyl, allyl or styrene sulphonic acid, or diallyldimethyl ammonium chloride or dimethylamino ethyl acrylate or methacrylate, optionally quaternised with dimethyl sulphate or methyl chloride.
  25. A composition according to any one of claims 16 and 18 to 20 in which the polymer is a polymer of acrylic acid, methacrylic acid, maleic acid, fumaric acid, itaconic acid or crotonic acid, having a molecular weight from 1000 to 5000.
  26. A composition according to any one of claims 16 to 25 in which R¹ is hydrogen or carboxymethyl, R² is hydroxyphenyl which is optionally methyl or sulphonic acid substituted, R³ is
    Figure imgb0021
    or -CH₂C₆H₃ (OH)(SO₃H), the phenyl groups being optionally further substituted by one or more halogen atoms.
  27. A composition according to any one of claims 16 to 26 in which the chelant is N,N'-di(2-hydroxybenzyl)-trimethyl-enediamine-N,N'-diacetic acid, N,N'ethylenebis-[2(2-hydroxy-4-methyl-phenyl)-glycine], ethylenediamine N,N'-bis-[2-hydroxyphenylacetic acid] or N,N-di(2-hydroxy-5-sulphonic acid benzyl) glycine.
EP86308419A 1985-10-29 1986-10-29 The treatment of aqueous systems Expired EP0225051B1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AT86308419T ATE72678T1 (en) 1985-10-29 1986-10-29 TREATMENT OF AQUEOUS SYSTEMS.

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
GB8526590 1985-10-29
GB08526590A GB2184109A (en) 1985-10-29 1985-10-29 The treatment of aqueous systems
GB08623464A GB2183624A (en) 1985-10-29 1986-09-30 Anti-corrosion treatment of aqueous systems
GB8623464 1986-09-30

Publications (2)

Publication Number Publication Date
EP0225051A1 EP0225051A1 (en) 1987-06-10
EP0225051B1 true EP0225051B1 (en) 1992-02-19

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EP (1) EP0225051B1 (en)
AT (1) ATE72678T1 (en)
AU (1) AU6456486A (en)
CA (1) CA1332138C (en)
DE (1) DE3683928D1 (en)
ES (1) ES2038595T3 (en)

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US8765656B2 (en) 2006-08-02 2014-07-01 Ch2O Incorporated Disinfecting/mineral treating composition and methods comprising a chlorite or chlorate salt
CN110158094A (en) * 2019-07-11 2019-08-23 北京中天兰清环境科技有限公司 A kind of formula and preparation method of the without phosphorus carbon steel corrosion inhibitor of composite efficient

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US4717542A (en) * 1987-01-23 1988-01-05 W. R. Grace & Co. Inhibiting corrosion of iron base metals
NZ226331A (en) * 1987-10-05 1991-08-27 Calgon Corp Method of inhibiting corrosion of metallic surfaces in aqueous systems using acrylic polymers and zinc ions; compositions therefor
EP0364030A1 (en) * 1988-10-11 1990-04-18 Calgon Corporation Synergistic compositions and method for inhibiting carbon steel corrosion in aqueous systems
US5171477A (en) * 1991-05-31 1992-12-15 W. R. Grace & Co.-Conn. Corrosion inhibition in chelant solutions
ES2059273B1 (en) * 1993-02-09 1995-10-01 Miret Lab DISPERSING AND INHIBITING COMPOSITIONS OF INCRUSTATION AND / OR CORROSION IN INDUSTRIAL WATER CIRCUITS.
US5518629A (en) * 1993-07-29 1996-05-21 Betz Laboratories, Inc. Methods for controlling scale formation in acqueous systems
WO2000039359A1 (en) * 1998-12-29 2000-07-06 Calgon Corporation Corrosion inhibitor compositions and methods to control metal corrosion in brine systems

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US3669901A (en) * 1970-10-22 1972-06-13 William Bruce Murray Corrosion inhibitor composition containing zinc, sulfamate, and phosphate ions
US3794603A (en) * 1972-01-17 1974-02-26 Sherwin Williams Co Zn++-benzotriazole-h2so4 corrosioninhibitor
AU452099B2 (en) * 1972-08-02 1974-08-29 Applied Chemicals Pty. Limited Aqueous corrosion inhibiting compositions
DE2333353C2 (en) * 1973-06-30 1983-05-19 Bayer Ag, 5090 Leverkusen Process for preventing corrosion in water-bearing systems and anti-corrosion agents for carrying out the process
US4018701A (en) * 1975-07-31 1977-04-19 Calgon Corporation Phosphorous acid and zinc corrosion inhibiting compositions and methods for using same
US4042451A (en) * 1975-08-05 1977-08-16 M&T Chemicals Inc. Selected stripping of nickel-iron alloys from ferrous substrates
DK231879A (en) * 1978-06-05 1979-12-06 Calgon Corp PROCEDURE FOR CORROSION INHIBITION AND PRODUCT FOR USE IN THE PERFORMANCE OF THE PROCEDURE
GB2118159B (en) * 1982-04-20 1985-09-04 Dearborn Chemicals Ltd The treatment of aqueous systems

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US8765656B2 (en) 2006-08-02 2014-07-01 Ch2O Incorporated Disinfecting/mineral treating composition and methods comprising a chlorite or chlorate salt
CN110158094A (en) * 2019-07-11 2019-08-23 北京中天兰清环境科技有限公司 A kind of formula and preparation method of the without phosphorus carbon steel corrosion inhibitor of composite efficient

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DE3683928D1 (en) 1992-03-26
ES2038595T3 (en) 1993-08-01
EP0225051A1 (en) 1987-06-10
CA1332138C (en) 1994-09-27
ATE72678T1 (en) 1992-03-15
AU6456486A (en) 1987-04-30

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