MXPA01001778A - Media for water treatment - Google Patents

Abstract

The invention relates to media for water treatment which are based on biodegradable polymers containing recurring succinyl units, oxidation media with a biocide activity and possibly substituted sulfamic acid, uses of said media for conditioning water of cooling systems and corresponding method.

Description

COMPOSITIONS FOR WATER TREATMENT Description of the Invention The present invention relates to water treatment compositions based on biodegradable polymers containing repeated succinyl units, biocidal oxidizing agents and a substituted or unsubstituted amidosulfonic acid, their use in, and the process for, conditioning water circuits. Cooling. When natural waters are used for industrial purposes, for example as cooling water, the water used is changed physically and / or possibly also chemically, specifically or unintentionally. Thus, for example, in open recirculation cooling systems, changes in temperature, concentration and an increase in pH due to the discharge of carbon dioxide into the cooling tower are unavoidable. Due to the concentration and increase of pH by the discharge of C02, the concentration of hardness constituents increases, in particular calcium ions and carbonate ions. If natural waters were in equilibrium before use (carbon-carbon dioxide balance), an increase in the concentration of I-tef: 127057 constituents of hardness leads to supersaturation. In order to avoid the deposition of scale (scale), in particular on heat transfer surfaces, the treatment of the water is necessary by the addition of additives ("scale inhibitors"). An additional purpose, sometimes also the predominant one, of the use of additives in water treatment is the protection of metallic materials against corrosion. For example, when unalloyed carbon steels are used in open recirculating cooling systems, adequate corrosion inhibition is desired, since the conditions prevailing in such systems (oxygen saturation, salt accumulation) lead to an acceleration of the corrosion. WO 97/39078 proposes the use of biodegradable polymers, such as, for example, polyaspartic acid, or other polymers containing aspartic acid in combination with oxidizing agents that act biocide to condition water in cooling circuits. Descriptions are given, inter alia, of experiments in which 10 mg / l of polyaspartic acid, having a molecular weight of about 3000, were tested in the presence of 0.4 mg / 1 of sodium hypochlorite for scale-inhibiting activity, and a decrease in scale inhibition activity was observed during the 4 hour measurement period. When 0.4 mg / 1 of a mixture of sodium hypochlorite and sodium hypobromite was added in a weight ratio of 1: 1, 95% of the initial activity was present even after 4 hours. In addition, in a cooling circuit having a cooling tower, the concentration of polyaspartic acid was tested without and with the addition of 0.2 mg / 1 of chlorine in the form of sodium hypochlorite for one month: without the addition of chlorine, With daily doses of 20 to 50 mg / 1 of polyaspartic acid, a concentration of between 11 mg / 1 and 2 mg / 1 was established, with the addition of chlorine a concentration of approximately 20 mg / 1 was established. A disadvantage of the mixtures of WO 97/39078 is the fact that the polymers used there react to a considerable degree with microbicides such as chlorine, bromine or halogen releasing products, which is observed by a decrease in the concentration of the biocide. It should be expected that due to the reaction with the biocide, portions of polyaspartic acid will also be destroyed, and that, as a result, the desired scale inhibition and / or corrosion inhibition activity will no longer be achieved. In many cases, although it would be possible to create compensation at least to a certain degree by means of a higher dosage of the polyaspartic acid, the economic efficiency of the use of polyaspartic acid would be affected. Therefore, the object of the present invention is to provide a composition for water treatment based on polymers containing succinyl units that are repeated, the components of these polymers remain stable for a long period, so the use is economically justifiable, even in cooling systems, especially in those that have relatively long residence times.

The objective was achieved by the fact that repeated succinyl units containing the polymers are mixed with oxidizing agents acting biocide and unsubstituted or substituted amidosulfonic acid is added as a stabilizer. The stabilizer here has the task of substantially avoiding or reducing the reaction between the polymer and the oxidizing agent. Although the use of ammonia, amines, amides or amidosulfonic acids as stabilizers for chlorine is described in US-P 4,711,724 and US-P 3,1 / 0,883, and US-P 4,642,194 describes the use of amidosulfonic acids and organic sulfonamides (EP- A 0 569 220) as stabilizers for specific phosphonic acids with respect to chlorine and also US-P 4,759,852 with respect to bromine, the use of amidosulfonic acid and organic derivatives of amidosulfonic acid to stabilize polyaspartic acid with regarding chlorine and bromine. The high efficiency of amidosulfonic acid to stabilize halogens with respect to repeated succinyl units containing the polymers is surprising to those skilled in the art, since amide structures occur in the same polymers. Therefore, the addition of an additional amide should give rise to the expectation of little activity. Surprisingly, by these means, the reaction between the oxidizing biocide and the polymer was considerably reduced. Therefore the present invention relates to the use of repeated succinyl units containing the polymers, in particular polyaspartic acids, as compositions for water treatment in combination with a biocide and amidosulfonic acid H-.NSO3H or organic derivatives of amidosulfonic acid, and to the use of these compositions for water conditioning of cooling circuits. The polymers used according to the invention have repeated succinyl units having one of the following structures: CH2 - CO CH - CO, preferably form ß form In addition, as a result of the suitable reaction procedure and the selection of initiation materials, additional repeating units, e.g. a) maleic acid units of the formula b) units of maleic acid and fumaric acid of the formula The chemical structure is preferably analyzed by 13 C-NMR, FT-IR and, after total hydrolysis, by CLAP, GC and GC / MS. Many preparation processes do not produce the pure acids, but initially the corresponding anhydrides, for example polysuccinimide (= PSI). Polymerization products of this type can be converted to a PAA salt by reaction with a base in the presence or absence of water. This conversion of polymers PSI to polymers PAA is carried out subsequently in a suitable apparatus by means of hydrolysis. Preference is given here to a pH between 5 and 14. Particularly preferably, a pH of 7 to 12 is selected, in particular by adding a base. Suitable bases are alkali metal hydroxides and alkali metal hydroxides, or alkali metal carbonates and alkaline earth metal carbonates, such as sodium hydroxide solution, potassium hydroxide solution, sodium or potassium carbonate, ammonia and amines. such as triethylamine, triethanolamine, diethylamine, diethanolamine, alkylamines, etc. Particular preference is given, in addition to the free acids, to their Na, K or Ca salts. The temperature during hydrolysis is suitably in a range of up to and including the boiling point of the PSI suspension, and is preferably from 20 to 150 ° C. The hydrolysis is carried out under pressure, if appropriate. However, it is also possible to obtain the free polyaspartic acid merely by aqueous hydrolysis or by treating the salt with acids or ionic acid exchangers. The term "polyaspartic acid" (= P7? A) for the purposes of the present invention also includes the salts, unless explicitly stated otherwise. The final polyaspartic acid or the polyaspartic acid salts are obtained by drying, preferably by spray drying. Preferred polymers have a molecular weight, according to gel diffusion chromatography, of MW = 500 to 10,000, preferably 700 to 5000, particularly preferably 1000 to 4500. In general, the content of beta form is more than 50%, preferably more than 70%. The concentration of the polyaspartic acids to be used for the water treatment is usually about 0.5 to 100 mg / 1 of active compound in the aqueous phase, but mainly in the range of about 2 to 50 mg / 1. In addition, biocides are used to achieve the objective of the present invention. Preferably, use is made of biocidal oxidizing agents having a standard redox potential more positive than oxygen. The standard redox potentials, also called standard potentials, are in general terms known thermodynamic terms, which are described in physics or general chemistry textbooks. An example that could be mentioned is chapter 11 of the textbook: H.R. Christen "Grundlagen der allgemeinen und anorganischen Chemie" [Principles of General and Inorganic Chemistry], Verlag Sauerlander-Salle, 1973. This textbook, on pages 692 to 697, contains a list of different standard potentials, which can also be found in many other textbooks and tabulations. The magnitude of the standard redox potential is usually expressed in volts. Preferably, for the application according to the invention, oxidizing agents having a standard redox potential greater than 0.4 volts are used. Preferably, the selected oxidizing agent is hydrogen peroxide, chlorine, bromine, chlorine dioxide, hypochlorites, hypobromites or ozone. Since these chemicals in the presence of water can participate in acid-base reactions and / or disproportionation reactions, the aforementioned oxidizing agents are also taken to indicate their reaction products with water. The biocides are used in the compositions according to the invention for water treatment in concentrations of 0.05 to 20 mg / 1. Preferably 0.05 to 10 mg / 1, especially preferably 0.1 to 5 mg / 1 of biocide are used.

As stabilizers of the biocides, unsubstituted or substituted amidosulfonic acids of formula (I) are used wherein Z represents hydrogen, lithium, sodium, potassium, magnesium or calcium, and R represents an unsubstituted or substituted radical from the group consisting of OH, CJ-C alquilo alkyl, C-C4 alkoxy, amino, mono (Cj-Cj alkyl) ) amino, di (C 1 -C 6 alkyl, formylamino, -NHC (O) alkyl -NHC (0) 0 C 1 -C 6 alkyl, C 2 -C 6 alkenyl, C 2 -C 6 alkynyl, C 3 -C 7 cycloalkyl, unsubstituted or substituted phenyl , naphthyl, pyridyl, pyrimidyl, pyrazyl, pyridazyl, pyrrolyl, imidazolyl, pyrazolyl, triazolyl, tetrazolyl, the substituents suitable in each case are: C 1 -C 6 alkyl, C 1 alkoxy, C 1 -C 6 alkoxycarbonyl, halogen, nitro , nitrile, carboxyl, -S (0) n Ct-C4 alkyl where n = 2 and each of which is optionally substituted on the nitrogen by one or two alkyl groups Cj-Cj, sulfamoyl, -S02N (R1) R2 where R.sub.1 and R.sub.2 each denote C.sub.1 -C.sub.4 alkyl, Preferably, use is made of an unsubstituted or substituted amidosulphonic acid of formula (I) wherein R.sub.OH, C.sub.6 H.sub.4 -CH.sub.3 (tolyl) and OCH.sub.3, and Z. It was hydrogen, sodium and potassium. In particular, preference is given to the aminosulfonic acid of formula (I) wherein R represents OH and Z represents hydrogen. Stabilizers are used in amounts of 0.02 to 15 mg / 1. Preferably, from 1 to 0.1 to 10 mg of stabilizer, in particular from 0.2 to 5 mg of stabilizer, are used. It is customary, and preferred for purposes of the invention, that the water phase of the aqueous cooling system further comprises other components which may have an inhibiting action on corrosion or scale, or a dispersive action. Those that could be mentioned by way of example are: 1 to 10 mg / 1 of zinc ions, 1 to 200 mg / 1 of monomeric or oligomeric molybdate ions, organic phosphates in a concentration such that the phosphorus content, calculated as phosphate, is in the range of 1 to 20 mg / 1 of phosphate, monomeric, oligomeric or polymeric inorganic phosphates in a concentration such that the phosphorus content, calculated as phosphate, is in the range of 1 to 20 mg / 1 of phosphate, and inhibitors of non-ferrous metal, such as triazoles As additional anti-corrosion components, the water phase can comprise known active compounds, such as alkanolamines, in particular triethanolamine, borates, sorbitol, nitrites, nitrates and silicates. As further additives having corrosion and / or dispersive inhibiting action, use may be made of: phosphate esters, polyphosphoric esters, aminophosphates, aminomethylene phosphonic acids, phosphonates, in particular hydroxyalkane diphosphonic acids, hydroxyphosphonoacetic acid, aminoalkylene phosphonic acids, phosphonocarboxylic acids, succinamide, gluconates, polyoxycarboxylic acids and their copolymers, derivatives of tannins, lignosulfates, sulfonated condensation products of naphthalene with formaldehyde, polyacrylates, polymethacrylates, polyacrylamides, polymaleates, copolymers of acrylic acid or methacrylic acid, maleic acid and acrylamide, homopolymers containing phosphinic acid and copolymers of acrylic acid and acrylamide, phosphonous co-oligomeric acid compounds, sulphomethylated or sulfoethylated polyacrylamides, and copolymers or terpolymers with acrylic acid, maleic acid, N-butylacrylamide, ac acid rilamidopropionosulfonic, polymers and copolymers of maleic anhydride and copolymers, polymers of phosphinoalkylated acrylamide and copolymers with acrylic acid, citric acid, ether carboxylates or oxidized carbohydrates. To achieve optimum corrosion protection, the water phase of the aqueous cooling systems is preferably adjusted to a pH in the range of about 7 to 9. Biocidal oxidizing agents can be measured in the cooling system continuously or preferably discontinuously in the form of an intermittent treatment. Aqueous cooling systems can be direct flow systems or open or closed circulation systems. The invention is particularly designed for use in open circuit systems, although it is especially suitable to counteract the problems that arise in such systems of scale formation, deposit formation and / or biological contamination. The compositions according to the invention can be used in a versatile manner, for example as scale inhibitors and also corrosion inhibitors and biocides. The fields of use of such compositions can be, for example: water treatment (e.g. treatment of cooling water, treated water, gas scrubbing water, injection water in secondary oil extraction, and water treatment in mining). The present invention also relates to a process for water treatment, characterized in that the composition according to the invention is introduced into the water to be treated. The water treatment process will be illustrated with reference to the following examples: For example, the compositions according to the invention are added to the feed water in concentrations of between approximately 0.1 and 10 mg / 1 of the active compound to avoid depositions. and incrustations when used in cooling systems that use cool water cooling. In cooling circuits, additives are often measured independently of the rate at which water is compensated, for the prevention of scale and / or the prevention of corrosion. The concentrations are between approximately 1 and 100 mg / 1 of active compound in the circulating cooling water.

Example 1 In a clear glass flask, 11 of cooling water having a total hardness of 3.0 mmol / 1 (&17 ° dGH [German degrees of total hardness]), of which 80 mol% is carbonate hardness, and Ks 4 3 = 3.2 mmol / 1 (&9 ° dKH [German grades of carbonate hardness]) was mixed with 10 mg / 1 of sodium polyaspartate and 5 ml of a diluted bleaching liquor solution containing 1000 mg / 1 as chlorine. The pH was adjusted to 7.0 using hydrochloric acid, the flask was sealed and stored at room temperature for 24 h. Similar samples were prepared which had the following variants: the pH was fixed at 8.5 by the addition of sodium hydroxide solution, addition of sodium bromide (1 mg / 1 Br), addition of 5 mg / 1 amidosulfonic acid . After storage, the chlorine content in the samples was analyzed (Palin DPD method) *: Reference: M. Zimmermann (Editor) Photometrische Metall- und Wasseranalyse [Photometric analysis of metais and water], Wissenschaf11. Verlagsgesellschaft, Stuttgart 1974, Method B-C 1/3, variant 2: Determination of "total active chlorine", including chloramines Comments from Example 1: Under conditions of pH that are frequently found in cooling water, the reaction of polyaspartic acid (10 mg / 1 as sodium salt) with bleaching liquor (5 mg / 1 as chlorine) was studied. During storage at room temperature, as shown in experiments Nos. 1 and 5, the bleach liquor reacted > 80%, both at pH 7 and pH 8.5, after 24 h; only recovered from 0.9 mg / 1 (pH 7) to 0.8 mg / 1 (pH 8), in each case measured as chlorine. The addition of bromide further intensifies the decomposition, especially at pH 8.5. [The bromide is oxidized under the experimental conditions present in this application of the bleaching liquor for hypobromous acid whose biocidal action, especially at pH 8.5, is considerably stronger than that of the bleaching liquor. ] Adding amidosulfonic acid (Experiments Nos. 2, 4, 6, 8), under other identical conditions, the reaction between the polyaspartic acid and the bleaching liquor (or, with the addition of bromide, Experiments Nos. 4 and 8, in the presence of hypobromous acid, was significantly decreased) additional): the residual contents of the oxidizing agent are higher by a factor of 2.67 (comparison of Experiments Nos. 1 and 2) to 7.67 (comparison of Experiments 7 and 8). Since the chemical reaction of chlorine with PAA, whose progress was measured in this application by means of the consumption of the oxidizing agent, not only destroys the biocide, but presumably also the polymer, the degradation reaction is doubly harmful: the biocide is added to protect the polymer from biodegradation it is lost and can no longer protect the polymer, and the polymer alone can not further develop its desired activity (protection from corrosion and protection from scale).

Example 2 (See Example 1 for the experimental procedure) Variant: Storage of the flasks at 60 ° C for 24 h Results It is noted that in relation to this date, the best method known to the applicant to carry out the aforementioned invention, is that which is clear from the present description of the invention.

Claims (7)

CLAIMS Having described the invention as above, the content of the following claims is claimed as property:

1. The composition for water treatment, characterized in that it comprises a) biodegradable organic polymers having repeated succinyl units b) a biocidal oxidizing agent c) an unsubstituted or substituted amidosulfonic acid.

2. The composition for water treatment according to claim 1, characterized in that the amidosulfonic acid of the formula H2NS03H 3 is used.

The composition for water treatment according to claims 1 and 2, characterized in that the biodegradable organic polymers have repeated succinyl units of structures CH2 - CO - CH-CO CH, -CO CH, -CO-NH CH-CO- H- , N- -CH- CO -CH COOH -CH2-COOH form ß form

4. The composition for water treatment according to claims 1 to 3, characterized in that the biodegradable organic polymers contain repeated units of formulas a) maleic acid units of formula b) units of maleic acid and fumaric acid of formula

5. The composition for water treatment according to claims 1 to 4, characterized in that the biocidal oxidizing agent is hydrogen peroxide, chlorine, bromine, chlorine dioxide, hypochlorite, hypobromide, ozone or its reaction products with water.

6. Use of the compositions according to claim 1 to condition water in cooling circuits.

7. The process for conditioning water in cooling circuits, characterized in that the compositions according to claim 1 are used.