Water treatment agent

Abstract

To provide a water treatment agent which exhibits a high effect of reducing COD components even for wastewater containing salts at high concentrations.SOLUTION: A water treatment agent is used comprising a cationic polymer having a weight average molecular weight of 10,000 to 1,000,000, where essential constitutional monomers of the cationic polymer are a cationic monomer (m1) represented by general formula (1) and an aromatic monomer (m2) represented by general formula (2). Preferably, R1 in general formula (1) and R5 in general formula (2) are the same atom (or group).SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to water treatment chemicals. [Background technology]

[0002] COD components are contained in wastewater generated after the cleaning process in factories that handle various products (chemicals, food, pharmaceuticals, electronic materials, and machinery) and in dry cleaning factories. A method for removing COD components contained in industrial wastewater, etc., is to use water treatment chemicals to remove the COD components. An organic coagulant containing a copolymer of a cationic methacrylate monomer and styrene has been proposed as a water treatment chemical that, with a small amount of addition, improves the clarity of wastewater during treatment and reduces COD (Patent Document 1).

[0003] The cationic polymer contained in the organic coagulant of Patent Document 1 has the function of forming flocs by electrostatically agglomerating negatively charged fine particles, which are contaminants contained in wastewater, and facilitating separation of the contaminants from the water. However, when the wastewater to be treated contains high concentrations of salts (sodium chloride, sodium sulfate, potassium chloride, etc.), the surface charge of the fine particles, which are contaminants, is neutralized by ions derived from the positively charged salts, preventing electrostatic interaction with the cationic polymer and preventing floc formation, resulting in insufficient effectiveness in reducing COD components. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2007-289928 Summary of the Invention [Problem to be solved by the invention]

[0005] An object of the present invention is to provide a water treatment agent that is highly effective in reducing COD components even in wastewater containing high concentrations of salts. [Means for solving the problem]

[0006] The present inventors have conducted extensive research to solve the above problems and have arrived at the present invention. Specifically, the present invention relates to a water treatment agent containing a cationic polymer having a weight-average molecular weight of 10,000 to 1,000,000, and including, as essential constituent monomers, a cationic monomer (m1) represented by general formula (1) and an aromatic monomer (m2) represented by general formula (2).

[0007] [ka] [In general formula (1), R 1 is a hydrogen atom or a methyl group, and R 2 ~R 4 are each independently a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, or a benzyl group; X is an oxygen atom or an imino group; Y - is a monovalent anion, and n1 is an integer of 1 to 3.

[0008] [ka] [In general formula (2), R 5 is a hydrogen atom or a methyl group, X is an oxygen atom or an imino group, Q is a methylene group, an alkyleneoxy group having 1 to 4 carbon atoms, or an alkylenethio group having 1 to 4 carbon atoms, Ar1 is a residue obtained by removing one hydrogen atom from a phenyl group, a benzyl group, a naphthyl group, or a biphenyl group, and n2 is an integer of 1 to 3. DETAILED DESCRIPTION OF THE INVENTION

[0009] The water treatment agent of the present invention contains a cationic polymer having a cationic monomer (m1) and an aromatic monomer (m2) as essential constituent monomers.

[0010] The cationic monomer (m1), which is an essential constituent monomer of the cationic polymer contained in the water treatment agent of the present invention, is represented by the following general formula (1).

[0011] [ka]

[0012] In general formula (1), R 1 is a hydrogen atom or a methyl group, and from the viewpoint of the COD component reduction effect, R in general formula (2) described later 5 is preferably the same as

[0013] In general formula (1), R 2 ~R 4 are each independently a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, or a benzyl group. Examples of alkyl groups having 2 to 4 carbon atoms include linear alkyl groups (ethyl, n-propyl, and n-butyl) and branched alkyl groups (isopropyl, sec-butyl, isobutyl, and tert-butyl). From the viewpoint of the effect of reducing COD components, R 2 ~R 4 It is preferable that all of the groups are alkyl groups having 1 to 4 carbon atoms, and it is more preferable that all of the groups are methyl groups.

[0014] In the general formula (1), X is an oxygen atom or an imino group, and is preferably an oxygen atom from the viewpoint of the effect of reducing COD components.

[0015] In general formula (1), Y - is a monovalent anion. Y - Examples of monovalent anions represented by the formula include the conjugate bases of Bronsted acids. Bronsted acids include inorganic acids and organic acids. Inorganic acids include hydrochloric acid, hydrobromic acid, sulfuric acid, phosphoric acid, and nitric acid, while organic acids include sulfonic acid, carboxylic acid, and phosphonic acid. Examples of organic sulfonic acids include methylsulfonic acid, dodecylbenzenesulfonic acid, and naphthalenesulfonic acid; examples of carboxylic acids include oxalic acid, acetic acid, and maleic acid; and examples of phosphonic acids include methylphosphonic acid and phenylphosphonic acid. As for monovalent anions, from the viewpoint of COD component reduction effect, the conjugate base of hydrochloric acid (Cl - ), the conjugate base of hydrobromic acid (Br - ), or the conjugate base of sulfuric acid (HSO4 - ) is preferred, with the conjugate base of hydrochloric acid being more preferred.

[0016] In the general formula (1), n1 is an integer of 1 to 3, and is preferably 2 from the viewpoint of the effect of reducing COD components.

[0017] Examples of the cationic monomer (m1) represented by the general formula (1) include (meth)acryloyloxyethyl trimethyl ammonium chloride, (meth)acryloyloxypropyl trimethyl ammonium chloride, (meth)acryloyloxyethyl dimethyl benzyl ammonium chloride, (meth)acrylamidoethyl trimethyl ammonium chloride, and (meth)acrylamidopropyl trimethyl ammonium chloride. In this specification, (meth)acryloyl means methacryloyl or acryloyl, and (meth)acrylic means methacrylic or acrylic.

[0018] The aromatic monomer (m2), which is an essential constituent monomer of the cationic polymer contained in the water treatment agent of the present invention, is represented by the following general formula (2).

[0019] [ka]

[0020] In general formula (2), R 5 is a hydrogen atom or a methyl group, and from the viewpoint of the COD component reduction effect, R 1is preferably the same as

[0021] In the general formula (2), X is an oxygen atom or an imino group, and is preferably an oxygen atom from the viewpoint of the effect of reducing COD components.

[0022] In general formula (2), Q is a methylene group, an alkyleneoxy group having 1 to 4 carbon atoms, or an alkylenethio group having 1 to 4 carbon atoms. Preferred examples of the alkyleneoxy group having 1 to 4 carbon atoms include an ethyleneoxy group, a propyleneoxy group, and a butyleneoxy group, and preferred examples of the alkylenethio group having 1 to 4 carbon atoms include an ethylenethio group, a propylenethio group, and a butylenethio group. From the viewpoint of the effect of reducing COD components, Q is preferably an alkyleneoxy group having 1 to 4 carbon atoms, and more preferably an ethyleneoxy group.

[0023] In general formula (2), Ar1 is a residue obtained by removing one hydrogen atom from a phenyl group, a benzyl group, a naphthyl group, or a biphenyl group, and from the viewpoint of the effect of reducing COD components, a phenyl group is preferred.

[0024] In the general formula (2), n2 is an integer of 1 to 3, and is preferably 1 from the viewpoint of the effect of reducing COD components.

[0025] Examples of the aromatic monomer (m2) represented by general formula (2) include benzyl (meth)acrylate, phenoxyethyl (meth)acrylate, diethylene glycol monophenyl ether (meth)acrylate, triethylene glycol monophenyl ether (meth)acrylate, phenylthioethyl (meth)acrylate, naphthylmethyl (meth)acrylate, biphenylmethyl (meth)acrylate, phenylphenoxyethyl (meth)acrylate, and benzyl (meth)acrylamide. In this specification, (meth)acrylate means methacrylate or acrylate.

[0026] In the cationic monomer (m1) represented by the general formula (1) and the aromatic monomer (m2) represented by the general formula (2), R 1 and R in general formula (2) 5 It is preferable that and are the same atom (group). An atom (group) means an atom or an atomic group. That is, R in general formula (1) 1 is a hydrogen atom, R in general formula (2) 5 is preferably a hydrogen atom. 1 is a methyl group, R in general formula (2) 5 is preferably a methyl group. R in general formula (1) 1 and R in general formula (2) 5 When the ratios are the same, the cationic monomer (m1) and the aromatic monomer (m2) are likely to have a structure in which they are adjacent to each other, which is preferable because the COD reduction effect is likely to be good.

[0027] Examples of the combination of the cationic monomer (m1) represented by the general formula (1) and the aromatic monomer (m2) represented by the general formula (2) include a combination in which the cationic monomer (m1) is at least one monomer selected from the group consisting of acryloyloxyethyltrimethylammonium chloride, acrylamidopropyltrimethylammonium chloride, and acrylamidoethyltrimethylammonium chloride, and the aromatic monomer (m2) is at least one monomer selected from the group consisting of phenoxyethyl acrylate, benzyl acrylate, phenylthioethyl acrylate, and diethylene glycol monophenyl ether acrylate, and a combination in which the cationic monomer (m1) is methacryloyloxyethyltrimethylammonium chloride, and a combination in which the aromatic monomer (m2) is at least one monomer selected from the group consisting of phenoxyethyl acrylate, benzyl acrylate, phenylthioethyl acrylate, and diethylene glycol monophenyl ether acrylate.

[0046] A combination in which the cationic monomer (m1) is at least one monomer selected from the group consisting of methacryloyloxyethyltrimethylammonium chloride, methacrylamidepropyltrimethylammonium chloride, and methacrylamideethyltrimethylammonium chloride, and the aromatic monomer (m2) is at least one monomer selected from the group consisting of phenoxyethyl methacrylate, benzyl methacrylate, phenylthioethyl methacrylate, and diethylene glycol monophenyl ether methacrylate is preferred, and a combination in which the cationic monomer (m1) is methacryloyloxyethyltrimethylammonium chloride, and the aromatic monomer (m2) is phenoxyethyl methacrylate is even more preferred. These combinations are preferable because they provide a better COD reduction effect.

[0028] It is known that an intermolecular interaction (hereinafter sometimes referred to as a cation / pi interaction) exists between the aromatic ring with conjugated pi electrons contained in the aromatic monomer (m2) and the cation contained in the cationic monomer (m1). The cationic monomer (m1) and the aromatic monomer (m2) are adjacent to each other due to the cation / pi interaction prior to polymerization. Furthermore, the distance from the cation to the polymerizable double bond in the cationic monomer (m1) is similar to the distance from the aromatic ring to the polymerizable double bond in the aromatic monomer (m2). Therefore, it is believed that polymerizing from this adjacent state produces a cationic polymer in which the cationic monomer (m1) and the aromatic monomer (m2) are bonded adjacent to each other. It is known that adjacent cations and aromatic rings exhibit strong electrostatic interactions even in high-salt environments. Therefore, the water treatment agent of the present invention, which has a structure in which the cationic monomer (m1) and the aromatic monomer (m2) are bonded adjacent to each other, is expected to exhibit a high COD component reduction effect even in wastewater containing high salt concentrations.

[0029] The cationic polymer contained in the water treatment agent of the present invention may contain, as a constituent unit, an unsaturated group-containing monomer (m3) other than the cationic monomer (m1) and the aromatic monomer (m2), as necessary, within a range that does not impair the effects of the present invention. The unsaturated group-containing monomer (m3) includes mono(meth)acrylate (m31), unsaturated carboxylic acid (m32), unsaturated sulfonic acid (m33), (meth)acrylamide (m34), nitrogen atom-containing unsaturated group-containing compound (m35) other than the above (m34), olefin (m36), and divalent unsaturated group-containing compound (m37), etc.

[0030] Examples of the mono(meth)acrylate (m31) include hydroxyl group-containing (meth)acrylates [hydroxyethyl (meth)acrylate, diethylene glycol mono(meth)acrylate, polyethylene glycol (degree of polymerization 3 to 50) mono(meth)acrylate, and (poly)glycerol (degree of polymerization 1 to 10) mono(meth)acrylate], 2-cyanoethyl (meth)acrylate, and methyl (meth)acrylate.

[0031] Examples of the unsaturated carboxylic acid (m32) include (meth)acrylic acid, vinylbenzoic acid, allylacetic acid, maleic acid (anhydride), fumaric acid, and itaconic acid (anhydride).

[0032] Examples of unsaturated sulfonic acids (m33) include vinyl sulfonic acid, (meth)allyl sulfonic acid, styrene sulfonic acid, α-methylstyrene sulfonic acid, sulfosuccinic acid, stearyl (meth)allyl sulfosuccinate, (meth)allyl sulfolaurate, 2-(meth)acryloyloxyethanesulfonic acid, 2- or 3-(meth)acryloyloxypropanesulfonic acid, 2- or 4-(meth)acryloyloxybutanesulfonic acid, 2-(meth)acryloyloxy-2,2-dimethyl Examples of the alkyl acrylates include methyl ethanesulfonic acid, p-(meth)acryloyloxymethyl benzenesulfonic acid, 2-(meth)acryloylaminoethane-, propane-, or butane-sulfonic acid, 3-(meth)acryloylaminopropanesulfonic acid, 4-(meth)acryloylaminobutanesulfonic acid, 2-(meth)acryloylamino-2,2-dimethylethanesulfonic acid, p-(meth)acryloylaminomethyl benzenesulfonic acid, and methyl (meth)allyl sulfosuccinate.

[0033] Examples of the (meth)acrylamide (m34) include (meth)acrylamide, N-methyl(meth)acrylamide, N-ethyl(meth)acrylamide, and N-methylol(meth)acrylamide.

[0034] Examples of the nitrogen atom-containing unsaturated group-containing compound (m35) include acrylonitrile, N-vinylformamide, N-vinyl-2-pyrrolidone, vinylimidazole, N-vinylsuccinimide, N-vinylcarbazole, vinylaniline, (meth)allylamine, di(meth)allylamine, 2-vinylpyridine, 3-vinylpiperidine, vinylpyrazine, and vinylmorpholine.

[0035] Examples of the olefin (m36) include ethylene, propylene, and α-olefins (1-butene, 1-hexene, 1-heptane, etc.).

[0036] Examples of the divalent unsaturated group-containing compound (m37) include divinylbenzene, 1,6-hexanediol di(meth)acrylate, (poly)ethylene glycol di(meth)acrylate, and (poly)propylene glycol di(meth)acrylate.

[0037] The number of moles (M m1 ) and the number of moles of the aromatic monomer (m2) represented by the general formula (2) (M m2 ) is considered to be the most effective in reducing COD. m1 :M m2 is preferably 1:99 to 99:1, more preferably 5:95 to 95:5, particularly preferably 10:90 to 90:10, and most preferably 15:85 to 85:15.

[0038] From the viewpoint of the COD reduction effect, the total weight of the cationic monomer (m1) and aromatic monomer (m2) contained in the constituent monomers of the cationic polymer contained in the water treatment agent of the present invention is most preferably 100% by weight based on the total weight of all constituent monomers.

[0039] The weight-average molecular weight (hereinafter sometimes abbreviated as Mw) of the cationic polymer contained in the water treatment agent of the present invention is 10,000 to 1,000,000, and from the viewpoint of COD reduction effect, it is more preferably 10,000 to 500,000. If Mw is less than 10,000, the COD reduction effect is deteriorated due to a decrease in floc-forming ability, and if Mw exceeds 1,000,000, the COD reduction effect is deteriorated due to a decrease in diffusion ability into water.

[0040] The Mw of the cationic polymer is measured by gel permeation chromatography under the following conditions. (conditions) Measurement equipment: HLC-8220GPC, manufactured by Tosoh Corporation. Columns: TSKgel Guardcolumn PWXL-CP, TSKgel 6000-PWXL-CP, and TSKgel 5000-PWXL-CP connected in series. Eluent: Water / methanol = 8 / 2 (volume ratio) (containing 0.05M NaNO3) Flow rate: 1ml / min Sample concentration: 0.25 wt% Injection volume: 100μl

[0041] The colloid equivalent value of the cationic polymer contained in the water treatment agent of the present invention is preferably 0.1 to 5.0 meq / g, more preferably 0.5 to 4.5 meq / g, from the viewpoint of the COD reduction effect. The colloid equivalent value can be adjusted to a predetermined range by adjusting the molecular weight of the cationic monomer (m1) and the molar ratio among the constituent monomers of the cationic polymer.

[0042] The colloid equivalent value of the cationic polymer can be determined by the colloid titration method shown below. The procedure for measuring the colloid equivalent value is carried out in an indoor environment adjusted to 20°C. (1) Accurately weigh out 0.2 g of cationic polymer and place it in a 200 ml Erlenmeyer flask. Add ion-exchanged water so that the total weight (total weight of sample and ion-exchanged water) becomes 100 g. After that, stir with a magnetic stirrer (cylindrical magnet, 40 mm long, 5 mm diameter, 1,000 rpm) for 3 hours to completely dissolve the polymer and prepare a 0.2 wt % solution. Place 10 ml of the prepared solution in a 500 ml beaker, add ion-exchanged water so that the total weight (total weight of 10 ml of solution and ion-exchanged water) becomes 400 g, and stir again with a magnetic stirrer (rotation speed 1,000 to 1,200 rpm) for 30 minutes to prepare the measurement sample. (2) Place 100 g of the prepared measurement sample in a 200 ml conical beaker and, while stirring with a magnetic stirrer (500 rpm), gradually add 0.5 wt % sulfuric acid aqueous solution to adjust the pH to 3. Add 2-3 drops of toluidine blue indicator and titrate using potassium polyvinyl sulfate titrant (N / 400) [hereafter referred to as (N / 400PVSK)]. The titration rate is 2 ml / min, and the endpoint is when the sample changes color from blue to reddish purple and remains reddish purple for 30 seconds. (3) As a blank test, titrate 100 g of ion-exchanged water in the same manner as in (2) above. (4) Calculate the colloidal equivalent of the cationic polymer using the following calculation. Colloid equivalent (meq / g) = (1 / 2) × (titration amount in test sample - titration amount in blank test) × [titer of (N / 400PVSK)]

[0043] The cationic polymer contained in the water treatment agent of the present invention can be produced by known radical polymerization methods (solution dropping polymerization, reversed-phase suspension polymerization, photopolymerization, precipitation polymerization, and reversed-phase emulsion polymerization). Among these, solution dropping polymerization is preferred from the industrial viewpoint and from the viewpoint of molecular weight control. The solution dropping polymerization can be carried out by a method in which a solution of a monomer composition containing a cationic monomer (m1) and an aromatic monomer (m2), a solvent, and a radical polymerization initiator is dropped at the boiling point of the solvent (for example, the method described in JP-A-6-211942). When an organic solvent is used as the solvent, the solvent is usually removed and water is added as necessary from the viewpoints of handling hazards and environmental protection.

[0044] As the solvent used in the solution dropping polymerization, water, alcohols (methanol, ethanol, isopropyl alcohol, etc.), ketones (methyl ethyl ketone, acetone, etc.), tetrahydrofuran (THF), dimethylformamide (DMF), and mixtures thereof can be preferably used, and non-polar solvents such as toluene and xylene can also be used.

[0045] Examples of the radical polymerization initiator used in the polymerization include known azo initiators [azobisamidinopropane (salt), azobiscyanovaleric acid (salt), 2,2'-azobis[2-(5-methyl-2-imidazolin-2-yl)propane] (salt), azobiscyanovaleronitrile, azobisisobutyronitrile, and azobiscyclohexanecarbonitrile, etc.], peroxides [ammonium persulfate, sodium persulfate, hydrogen peroxide, peracetic acid, t-butyl hydroperoxide, benzoyl peroxide, cumene hydroxyperoxide, di-t-butyl peroxide, and di-t-butylperoxyhexahydroterephthalate, etc.]. The above-mentioned peroxides may be used as redox initiators in combination with reducing agents, such as bisulfites (sodium bisulfite, potassium bisulfite, and ammonium bisulfite), reducing metal salts [e.g., iron(II) sulfate], tertiary amines [e.g., dimethylaminobenzoic acid (salt) and dimethylaminoethanol], amine complexes of transition metal salts [e.g., pentamethylenehexamine complex of cobalt(III) chloride and diethylenetriamine complex of copper(II) chloride], and organic reducing agents (e.g., ascorbic acid). The azo initiator, peroxide initiator and redox initiator may be used alone or in combination of two or more kinds.

[0046] The amount of the radical polymerization initiator used is preferably 0.001 to 20% by weight, more preferably 0.005 to 10% by weight, based on the total weight of the constituent monomers.

[0047] When producing a cationic polymer by radical polymerization, a known chain transfer agent may be used. Examples of the chain transfer agent include methanol, ethanol, isopropyl alcohol, ethylene glycol, propylene glycol, polyethylene glycol, (poly)ethylene (poly)propylene glycol, ammonia, methylamine, dimethylamine, triethylamine, propanolamine, methanethiol, ethanethiol, propanethiol, n-octanethiol, n-dodecanethiol, hexadecanethiol, n-octadecanethiol, 2-mercaptoethanol, mercaptoacetic acid, 3-mercaptopropionic acid, 1-thioglycerol, and monoethanolamine thioglycolate. amine, 1-thioglycerol, thioglycolic acid monoethanolamine, thiomaleic acid, cysteine, 2-mercaptoethylamine, cyclopentanethiol, cyclohexanethiol, benzenethiol, benzyl mercaptan, thiosalicylic acid, ethanedithiol, diethylenedithiol, triethylenedithiol, propanedithiol, 1,3- or 1,4-butanedithiol, 1,6-hexanedithiol, neopentanedithiol, cyclopentanedithiol, cyclohexanedithiol, benzenedithiol, and biphenyldithiol.

[0048] When a chain transfer agent is used, the amount used is preferably 0.001 to 10% by weight, more preferably 0.005 to 5% by weight, based on the total weight of the constituent monomers.

[0049] The polymerization temperature in the solution dropwise polymerization is preferably controlled so as to maintain a predetermined constant temperature (preferably within ±5°C of the predetermined temperature) from the viewpoint of molecular weight control, and dropwise polymerization below the boiling point of the solvent is preferred from the viewpoint of facilitating maintenance of a predetermined constant temperature. The boiling point of the solvent can be adjusted by the type of solvent and the pressure inside the reaction vessel in which the polymerization reaction is carried out, and is preferably 40 to 190°C, more preferably 60 to 170°C.

[0050] In solution dropping polymerization, polymerization can be carried out by dropping a monomer composition below the boiling point of a solvent. The start of the polymerization reaction can be confirmed by the generation of heat due to polymerization, and the end of the polymerization reaction can be confirmed by the disappearance of the heat generated by polymerization. The polymerization reaction in the solution dropping polymerization is preferably carried out for 1 to 24 hours from the start of the polymerization reaction (start of dropping of the monomer composition), and after confirming the completion of the polymerization reaction (cessation of heat generation), the temperature is preferably maintained and the polymerization reaction is continued for another 2 to 12 hours. Continuing the polymerization reaction after the completion of the polymerization reaction is preferable because it allows the reduction of residual monomers.

[0051] When an organic solvent is used as the solvent during polymerization, it is preferred to remove the organic solvent by a known method and then replace the organic solvent with water.

[0052] If necessary, the water treatment agent of the present invention can be used in combination with known additives such as antifoaming agents, chelating agents, pH adjusters, antioxidants, ultraviolet absorbers, and preservatives, within the scope that does not impair the effects of the present invention.

[0053] The water treatment agent of the present invention is preferably an aqueous solution of the cationic polymer. The content (wt%) of the cationic polymer in the aqueous solution is preferably 5 to 80%, more preferably 10 to 75%, and particularly preferably 15 to 70%, based on the weight of the aqueous solution. When the water treatment agent of the present invention is an aqueous solution of a cationic polymer, the aqueous solution obtained by polymerization using only water as the polymerization solvent may be used as the water treatment agent, or the polymerization solvent may be replaced with water by a known method and the resulting solution may be used as the water treatment agent. The aqueous solution obtained by polymerization or solvent substitution may be further diluted with water to prepare the water treatment agent of the present invention.

[0054] When added to industrial wastewater (wastewater from factories in the paper pulp, dyeing, automobile, metal processing, steelmaking, food, gravel extraction, semiconductor-related, and cleaning industries, etc.), sewage, and organic or inorganic sludge generated in the treatment of industrial wastewater, the water treatment agent of the present invention exerts coagulation and flocculation effects and improves the clarity of the filtrate (COD reduction, decolorization), and is also effective in reducing the amount of cake generated and the moisture content of the cake.

[0055] By adding the water treatment chemical of the present invention to wastewater, the pollutant components are coagulated and precipitated. When water treatment is performed using the water treatment chemical of the present invention, a known coagulant can be used in combination to further improve the coagulation effect. Among the coagulants, organic coagulants include polycondensates of epichlorohydrin and dimethylamine (hydrochloride), polyallylamine (hydrochloride), polyethyleneimine (hydrochloride), polyallylamine hydrochloride, polydiallyldimethylammonium chloride, polydiallylmethylamine hydrochloride, copolymers of diallyldimethylammonium chloride and sulfur dioxide, copolymers of diallyldimethylammonium chloride and acrylamide, and copolymers of diallylamine hydrochloride and sulfur dioxide, and two or more types can also be used in combination. Examples of inorganic coagulants include aluminum sulfate, polyaluminum chloride, ferric chloride, polyferric sulfate, and hydrated lime, and two or more of these can be used in combination. When an organic coagulant and / or an inorganic coagulant are used in combination, either one may be added first separately, or they may be added simultaneously, or they may be mixed in advance and then added. Alternatively, a mixture of the water treatment agent of the present invention may be added.

[0056] When water treatment is carried out using the water treatment chemical of the present invention, known cationic polymer flocculants, nonionic polymer flocculants, anionic polymer flocculants and amphoteric polymer flocculants can be used in combination.

[0057] Examples of the cationic polymer flocculant include (co)polymers excluding cationic polymers having the cationic monomer (m1) and the aromatic monomer (m2) as essential constituent monomers and having a weight average molecular weight of 10,000 to 1,000,000, and include homopolymers of polyethyleneimine, Mannich-modified poly(meth)acrylamide, and quaternized dialkylaminoethyl (meth)acrylate, or copolymers with other monomers such as (meth)acrylamide.

[0058] Examples of nonionic polymer flocculants include polyacrylamide.

[0059] Examples of anionic polymer flocculants include sodium poly(meth)acrylate, hydrolyzed poly(meth)acrylamide, (meth)acrylamide-sodium (meth)acrylate copolymer, copolymer of (meth)acrylamide, sodium (meth)acrylate and sodium 2-acrylamido-2-methylpropane-1-sulfonate, and copolymer of (meth)acrylamide and sodium 2-acrylamido-2-methylpropane-1-sulfonate.

[0060] Among polymer flocculants, amphoteric polymer flocculants include copolymers whose essential constituent monomers are cationic monomers [such as dialkylaminoethyl (meth)acrylate quaternized products] and anionic monomers [such as (meth)acrylic acid (salts) and 2-acrylamido-2-methylpropane-1-sulfonic acid (salts)].

[0061] Examples of methods for treating wastewater using the water treatment agent of the present invention include the following methods. (1) A method in which the water treatment agent of the present invention is added to wastewater, and the pH is adjusted (preferably to 5.8 to 8.6) while stirring to precipitate a flocculant, followed by solid-liquid separation. (2) A method in which an organic coagulant and an inorganic coagulant are added to wastewater, and then the water treatment chemical of the present invention is further added, and the pH is adjusted (preferably to 5.8 to 8.6) while stirring to precipitate coagulates, thereby performing solid-liquid separation. (3) A method in which an organic coagulant and an inorganic coagulant are added to wastewater, and then the water treatment chemical of the present invention is further added, and the pH is adjusted while stirring (preferably to 5.8 to 8.6) to precipitate a flocculant, and then a polymer coagulant is added to perform solid-liquid separation.

[0062] As a method for solid-liquid separation, gravity settling, membrane filtration, column filtration, pressure flotation, concentrators (thickeners, etc.), dehydrators (centrifuges, belt press dehydrators, filter press dehydrators, etc.), etc. can be used.

[0063] From the viewpoint of the COD reduction effect, the wastewater to be treated with the water treatment agent of the present invention preferably has a pH of 2.0 to 10.0, more preferably 3.0 to 9.0, and even more preferably 3.5 to 8.0, before the water treatment agent of the present invention, organic coagulant, and inorganic coagulant are added. If the pH of the wastewater to be treated is not within this range, it is preferable to adjust the pH using a pH adjuster.

[0064] Examples of pH adjusters that can be used include inorganic acids (hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid, etc.), inorganic solid acidic substances (acidic sodium phosphate, acidic sulfuric acid, ammonium chloride, ammonium sulfate, ammonium bisulfate, sulfamic acid, etc.), organic acids (oxalic acid, succinic acid, malic acid, etc.), inorganic alkaline substances (e.g., sodium hydroxide, potassium hydroxide, ammonia, etc.), and organic alkaline substances (e.g., guanidine, etc.). The pH is measured at 25±1°C using the object to be measured as is without dilution. [Example]

[0065] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. In the examples, "parts" means "parts by weight."

[0066] Example 1 A four-neck flask equipped with a stirrer, temperature sensor, condenser, dropping funnel, and heating mantle was charged with 190 parts of isopropyl alcohol (IPA) and 189 parts of ion-exchanged water and heated to reflux with stirring. While refluxing the IPA, the temperature in the flask was maintained at 80-85°C. An initiator solution (80 parts IPA, 20 parts ion-exchanged water, and 0.8 parts azobisisobutyronitrile (AIBN)) and a monomer solution (252 parts methacryloyloxyethyl trimethylammonium chloride (m1), 28 parts phenoxyethyl methacrylate (m2), 180 parts IPA, and 60 parts ion-exchanged water) were simultaneously added dropwise over 4 hours using separate dropping funnels. After the dropwise addition was completed, the temperature inside the flask was maintained at 80-85°C for 2 hours. A mixture of 80 parts IPA, 20 parts ion-exchanged water, and 2.0 parts AIBN was then added dropwise to the flask, which was maintained at 80-85°C, over 1 hour. The temperature inside the flask was then maintained at 80-85°C for an additional 180 minutes. Next, 151 parts ion-exchanged water for solvent substitution was added to the flask, and the temperature was raised to 100°C to distill off the IPA, yielding a water treatment agent 1 of the present invention containing a cationic polymer (P-1) at a concentration of 40% by weight. The Mw of the cationic polymer (P-1) contained in the water treatment agent 1 was 20,000, and the colloidal equivalent value was 4.3.

[0067] <Example 2> A water treatment agent 2 of the present invention containing a cationic polymer (P-2) at a concentration of 40 wt% was obtained in the same manner as in Example 1, except that the amount of methacryloyloxyethyltrimethylammonium chloride was changed from 252 parts to 196 parts and the amount of phenoxyethyl methacrylate was changed from 28 parts to 84 parts. The Mw of the cationic polymer (P-2) contained in water treatment agent 2 was 20,000, and the colloid equivalent value was 3.4.

[0068] Example 3 A water treatment agent 3 of the present invention containing a cationic polymer (P-3) at a concentration of 40 wt% was obtained in the same manner as in Example 1, except that the amount of methacryloyloxyethyltrimethylammonium chloride was changed from 252 parts to 141 parts and the amount of phenoxyethyl methacrylate was changed from 28 parts to 139 parts. The Mw of the cationic polymer (P-3) contained in water treatment agent 3 was 20,000, and the colloid equivalent value was 2.4.

[0069] Example 4 The same procedure as in Example 1 was repeated except that the amount of ion-exchanged water charged into the four-neck flask before the start of polymerization was changed from 189 parts to 70 parts, azobisisobutyronitrile from 0.8 parts to 2.0 parts, methacryloyloxyethyltrimethylammonium chloride from 252 parts to 320 parts, phenoxyethyl methacrylate from 28 parts to 80 parts, and ion-exchanged water for solvent substitution was changed from 151 parts to 449 parts, to obtain a water treatment agent 4 of the present invention containing a cationic polymer (P-4) at a concentration of 40 wt%. The Mw of the cationic polymer (P-4) contained in water treatment agent 4 was 250,000, and the colloid equivalent value was 3.9.

[0070] <Example 5> Water treatment agent 5 of the present invention containing cationic polymer (P-5) at a concentration of 40 wt% was obtained in the same manner as in Example 1, except that the amount of ion-exchanged water charged into the four-neck flask before the start of polymerization was changed from 189 parts to 70 parts, azobisisobutyronitrile from 0.8 parts to 1.7 parts, methacryloyloxyethyl trimethylammonium chloride from 252 parts to 320 parts to acryloyloxyethyl trimethylammonium chloride, phenoxyethyl methacrylate from 28 parts to 80 parts to phenoxyethyl acrylate, and ion-exchanged water for solvent substitution from 151 parts to 449 parts. The Mw of the cationic polymer (P-5) contained in water treatment agent 5 was 650,000, and the colloid equivalent value was 4.1.

[0071] Example 6 A water treatment agent 6 of the present invention containing a cationic polymer (P-6) at a concentration of 40 wt% was obtained in the same manner as in Example 1, except that 252 parts of methacryloyloxyethyltrimethylammonium chloride was changed to 227 parts of acrylamidopropyltrimethylammonium chloride and 28 parts of phenoxyethyl methacrylate was changed to 53 parts of phenoxyethyl acrylate. The Mw of the cationic polymer (P-6) contained in water treatment agent 6 was 80,000, and the colloid equivalent value was 3.9.

[0072] Example 7 Water treatment agent 7 of the present invention, containing cationic polymer (P-7) at a concentration of 40 wt%, was obtained in the same manner as in Example 1, except that 252 parts of methacryloyloxyethyltrimethylammonium chloride was changed to 227 parts of methacrylamidepropyltrimethylammonium chloride and the amount of phenoxyethyl methacrylate was changed from 28 parts to 53 parts. The Mw of the cationic polymer (P-7) contained in water treatment agent 2 was 15,000, and the colloid equivalent value was 3.7.

[0073] Example 8 Water treatment agent 8 of the present invention, containing cationic polymer (P-8) at a concentration of 40 wt%, was obtained in the same manner as in Example 1, except that the amount of methacryloyloxyethyltrimethylammonium chloride was changed from 252 parts to 237 parts, the amount of phenoxyethyl methacrylate was changed from 28 parts to 43 parts, and the amount of AIBN was changed from 0.8 parts to 0.3 parts. The Mw of the cationic polymer (P-8) contained in water treatment agent 8 was 50,000, and the colloid equivalent value was 4.1.

[0074] Example 9 A water treatment agent 9 of the present invention containing a cationic polymer (P-9) at a concentration of 40 wt% was obtained in the same manner as in Example 8, except that the AIBN was changed from 0.3 parts to 0.15 parts. The Mw of the cationic polymer (P-9) contained in the water treatment agent 9 was 100,000, and the colloid equivalent value was 4.1.

[0075] Example 10 A water treatment agent 10 of the present invention containing a cationic polymer (P-10) at a concentration of 40 wt% was obtained in the same manner as in Example 8, except that the AIBN was changed from 0.3 parts to 0.05 parts. The Mw of the cationic polymer (P-10) contained in the water treatment agent 10 was 300,000, and the colloid equivalent value was 4.1.

[0076] Example 11 A water treatment agent 11 of the present invention containing a cationic polymer (P-11) at a concentration of 40 wt% was obtained in the same manner as in Example 8, except that the AIBN was changed from 0.3 parts to 0.03 parts. The Mw of the cationic polymer (P-11) contained in the water treatment agent 11 was 500,000, and the colloid equivalent value was 4.1.

[0077] Example 12 Water treatment agent 12 of the present invention containing cationic polymer (P-12) at a concentration of 40 wt% was obtained in the same manner as in Example 6, except that the amount of acrylamidopropyltrimethylammonium chloride was changed from 227 parts to 45 parts, the amount of phenoxyethyl acrylate was changed from 53 parts to 235 parts, and the amount of AIBN was changed from 0.8 parts to 2.0 parts. The Mw of the cationic polymer (P-12) contained in water treatment agent 12 was 200,000, and the colloid equivalent value was 0.8.

[0078] Example 13 Water treatment agent 13 of the present invention containing cationic polymer (P-13) at a concentration of 40 wt% was obtained in the same manner as in Example 6, except that the amount of acrylamidopropyltrimethylammonium chloride was changed from 227 parts to 90 parts, the amount of phenoxyethyl acrylate was changed from 53 parts to 190 parts, and the amount of AIBN was changed from 0.8 parts to 2.0 parts. The Mw of the cationic polymer (P-13) contained in water treatment agent 13 was 300,000, and the colloid equivalent value was 1.6.

[0079] <Comparative Example 1> 112 parts of IPA and 28 parts of ion-exchanged water were placed in a four-neck flask similar to that used in Example 1, and the mixture was heated with stirring until the IPA refluxed. While refluxing the IPA, the temperature inside the flask was maintained at 80 to 85°C, and an initiator solution prepared by mixing 179 parts of IPA, 45 parts of ion-exchanged water, and 2.2 parts of AIBN, and a monomer solution prepared by mixing 132 parts of dimethylaminoethyl methacrylate and 148 parts of styrene were simultaneously added dropwise over a period of 4 hours using separate dropping funnels. After the dropwise addition was completed, the temperature inside the flask was maintained at 80-85°C for 2 hours. A mixture of 76 parts IPA and 3.6 parts AIBN was then added dropwise over 1 hour to the flask, which was maintained at 80-85°C. The temperature inside the flask was then maintained at 80-85°C for another 180 minutes. 87 parts of hydrochloric acid (hydrogen chloride concentration: 35% by weight) was then added dropwise over 1 hour, and the temperature was raised to 100°C while adding 250 parts of ion-exchanged water to distill off the IPA. When IPA no longer distilled off, 95 parts of a 5% by weight aqueous solution of sodium hydroxide was added to obtain a comparative water treatment agent H1 containing a 40% by weight concentration of cationic polymer (PH-1). The Mn of the cationic polymer (PH-1) was 9,000.

[0080] Water treatment tests were carried out using the methods described below for the water treatment agents 1 to 13 obtained in Examples 1 to 13 and Comparative Example 1, and the comparative water treatment agent H1. The CODMn and COD reduction rates after the tests are shown in Table 1.

[0081] <Water treatment test> Sodium chloride was dissolved at a concentration of 10% by weight in an aqueous solution (CODMn = 500 mg / L) of sodium lauryl sulfonate, a COD component, dissolved in ion-exchanged water to prepare simulated wastewater for testing. 1 L of the prepared simulated wastewater was placed in a beaker, and 5,000 mg of a 10 wt % aqueous solution of aluminum sulfate, an inorganic flocculant, was added while stirring the simulated wastewater. After the addition of the inorganic flocculant, the mixture was further stirred for 5 minutes, and 250 mg of a water treatment agent (100 mg as the cationic polymer contained in the water treatment agent) was added. After stirring for another 5 minutes, the pH of the simulated wastewater was adjusted by adding 10 wt % aqueous sodium hydroxide solution dropwise while stirring until the pH reached 7.0. After stirring for 5 minutes, the stirring was stopped and the mixture was allowed to stand for 5 minutes. The supernatant separated by standing was filtered using filter paper (No. 5C), and the CODMn of the obtained filtrate was measured in accordance with JIS K0102:2016 to obtain the CODMn after treatment (referred to as CODMn of the filtrate in Table 1). Furthermore, the difference between CODMn (500 mg / L) before water treatment and CODMn after treatment was calculated, and the ratio of the difference between CODMn before water treatment and CODMn after treatment to the CODMn of the simulated wastewater before water treatment was defined as the COD reduction rate.

[0082] [Table 1]

[0083] The examples using the water treatment chemicals of the present invention showed a higher COD reduction rate than the comparative examples, and also showed an excellent COD reduction effect even in water with a high salt concentration. [Industrial Applicability]

[0084] The water treatment chemical of the present invention is highly effective in removing COD components from wastewater containing high concentrations of salts, and is therefore useful for treating wastewater from chemical plants, food factories, etc., which generate wastewater containing high concentrations of salts. It can also be suitably used for treating muddy water at civil engineering sites where the soil contains a large amount of salt, treating muddy water generated during dredging and landfilling at port facilities, etc., and treating wastewater from papermaking processes.

Claims

1. A water treatment agent comprising a cationic polymer having a weight average molecular weight of 10,000 to 1,000,000, wherein the cationic polymer comprises, as essential constituent monomers, a cationic monomer (m1) represented by general formula (1) and an aromatic monomer (m2) represented by general formula (2). [Chemical 1] [In general formula (1), R １ is a hydrogen atom or a methyl group, and R ２ ~R ４ are each independently a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, or a benzyl group; X is an oxygen atom or an imino group; Y － is a monovalent anion, and n １ is an integer from 1 to 3. 【Chemistry 2】 [In general formula (2), R ５ is a hydrogen atom or a methyl group, X is an oxygen atom or an imino group, Q is a methylene group, an alkyleneoxy group having 1 to 4 carbon atoms, or an alkylenethio group having 1 to 4 carbon atoms, and Ar １ is a residue obtained by removing one hydrogen atom from a phenyl group, a benzyl group, a naphthyl group, or a biphenyl group, and n ２ is an integer from 1 to 3.

2. R in general formula (1) １ and R in general formula (2) ５ The water treatment chemical according to claim 1, wherein and are the same atom (group).

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