Solid composite water purifying agent and preparation method thereof

Abstract

The invention relates to the technical field of water treatment technology, and particularly discloses a solid composite water purifying agent and a preparation method thereof, the solid composite water purifying agent comprises the following components by weight: 20-25 parts of a corrosion and scale inhibitor, 0.3-0.6 part of an auxiliary agent, and 0.1-0.4 part of a flocculant. By compounding the corrosion and scale inhibitor, the removal range of metal ions is widened, and the removal of heavy metal pollution in a water body is enhanced; meanwhile, the nitrogen removal treatment of the sewage with the low C / N ratio is improved through specifically selected auxiliaries, heavy metal chelation and nitrogen and phosphorus removal are synchronously achieved, meanwhile, adsorption of the corrosion and scale inhibitor complexed with metal ions is enhanced through the flocculating agent with a hyperbranched structure and sulfenyl, the corrosion and scale inhibitor is separated from water more easily, migration and diffusion of heavy metal in the environment are reduced, and the service life of the corrosion and scale inhibitor is prolonged. The underground water pollution risk is reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of water treatment, and particularly relates to a solid composite water purifier and a preparation method thereof. Background Art

[0002] Water purifiers possess highly efficient flocculation, precipitation, and adsorption capabilities, effectively removing suspended solids, heavy metals, organic matter, and other pollutants from water. They are widely used in industrial wastewater treatment, drinking water purification, and other fields. The origins and development of solid water purifiers can be traced back to the mid-to-late 20th century. Initially, water purifiers were primarily inorganic, offering good flocculation effects but also posing secondary pollution challenges. With the continuous advancement of water treatment technology and increasing environmental protection demands, polymeric organic water purifiers have gradually become a research hotspot. These water purifiers offer advantages such as a wide range of raw materials, low cost, non-toxicity, and easy biodegradability. Representative products include polyacrylamide (PAM) and polyacrylimide (PAPI).

[0003] At present, relevant technical personnel are still improving water purifiers. For example, patent application CN 108862513 A discloses a composite water purifier for sewage purification and its preparation process. Its components include activated calcium carbonate, polyaluminum chloride ferric, calcium chloride, montmorillonite powder, polyacrylamide and activated alumina. The water purifier is mainly composed of inorganic flocculants, supplemented by polymer flocculants. The water treatment effect of the water purifier is enriched and enhanced by the compounding between the components. For example, patent CN 114230788B discloses a multivalent polyanion oily sewage water purifier and its preparation method. The multivalent polyanion water purifier has a tree-shaped macromolecular structure and can effectively improve the generation of oil sludge in the water purification process and the problems of pipeline corrosion and blockage. However, due to the strengthening of environmental protection regulations and changes in market demand, the above-mentioned water purifiers need to pay more attention to the removal of heavy metal ions and the optimization of non-toxicity, harmlessness, and easy biodegradability. Summary of the Invention

[0004] In order to overcome the deficiencies of the above-mentioned prior art, the present invention broadens the scope of metal ion removal by compounding corrosion and scale inhibitors, thereby strengthening the removal of heavy metal pollution in water bodies; at the same time, the denitrification treatment of low C / N ratio wastewater is improved by specially selected sodium formate, and heavy metal chelation and nitrogen and phosphorus removal are simultaneously achieved. At the same time, the adsorption of corrosion inhibitors complexed with metal ions is enhanced by a flocculant with a hyperbranched structure and sulfur group, making it easier to separate from water, reducing the migration and diffusion of heavy metals in the environment, and reducing the risk of groundwater pollution.

[0005] In order to achieve the above object, the technical solution adopted by the present invention is: In one aspect, the present invention provides a solid composite water purifier comprising the following components, in parts by weight: 20 to 25 parts of a corrosion and scale inhibitor, 0.3 to 0.6 parts of an additive, and 0.1 to 0.4 parts of a flocculant; wherein the flocculant is prepared in the following steps: S1. Under nitrogen protection, acrylamide, N,N-methylenebisacrylamide, and 3-phenylmethylmercaptothiocarbonylpropionic acid are stirred at 45-55° C. until dissolved in dichloromethane to obtain a mixed base solution; S2. Add azobiscyanovaleric acid to the mixed base liquid obtained in step S1, stir for 4 to 6 hours, then add acrylamide and acryloyloxyethyltrimethylammonium chloride, continue stirring for 7 to 9 hours, rotary evaporate, wash, and filter to obtain an amide polymer; S3, dissolving the amide polymer obtained in step S2 in water at 50-70° C., then adding sodium hypochlorite and sodium hydroxide, stirring at 20-40° C. for 1-3 hours, and adjusting the pH to 6-7 with hydrochloric acid to obtain an intermediate product; S4. Stirring the intermediate product obtained in step S3, sodium hydroxide and carbon disulfide at 20-30° C. for 20-50 min, then heating to 50-70° C. and stirring for 80-140 min, washing and drying to obtain a flocculant.

[0006] In some embodiments, the corrosion and scale inhibitor comprises trisodium salt of hydroxyethylethylenediaminetriacetic acid and sodium salt of nitrilotriacetic acid.

[0007] In some embodiments, the mass ratio of the trisodium salt of hydroxyethylethylenediaminetriacetic acid to the sodium salt of nitrilotriacetic acid is 1:(0.2-0.3).

[0008] Trisodium salt of hydroxyethylethylenediaminetriacetic acid (HEDTA-3Na) can form stable water-soluble complexes with metal ions such as Ca²⁺, Mg²⁺, and Fe³⁺, effectively preventing scale formation and softening water quality. Its chelating ability for Fe³⁺ is particularly outstanding in strongly acidic environments, which can control the concentration of iron ions and avoid yellowing or secondary pollution of water bodies.

[0009] Nitrilotriacetic acid sodium salt (NTA-3Na) also has excellent chelating properties for metal ions and can disperse suspended particles, preventing scaling in pipes and equipment and extending their service life. When used in combination with HEDTA-3Na, the range of metal ion removal can be broadened.

[0010] In some embodiments, the auxiliary agent is sodium formate.

[0011] The nitro group in the NTA-3Na molecule increases the total nitrogen concentration in the water. If wastewater treatment is not thorough, the residual NTA-3Na may release ammonia nitrogen through hydrolysis or microbial metabolism, exacerbating eutrophication. In this application, sodium formate, as a readily degradable organic carbon source, can provide an electron donor for denitrifying bacteria, improving the denitrification treatment of low C / N ratio wastewater and resolving the concerns about NTA-3Na. Furthermore, sodium formate is used in combination with HEDTA-3Na to simultaneously achieve heavy metal chelation and nitrogen and phosphorus removal, comprehensively reducing costs and improving denitrification efficiency.

[0012] In some embodiments, in step S1, the concentration of N,N-methylenebisacrylamide in the mixed base solution is 5-15 mg / L, and the concentration of 3-benzylmercaptothiocarbonylpropionic acid is 40-80 mg / L.

[0013] In some embodiments, in step S2, the molar ratio of acrylamide to acryloyloxyethyltrimethylammonium chloride is (3-4):1.

[0014] In some embodiments, in step S3, the molar ratio of the sodium hypochlorite to the total acrylamide in steps S1 and S2 is (0.8-1.2):1.

[0015] In some embodiments, in step S4, the molar ratio of carbon disulfide to the total acrylamide in steps S1 and S2 is (1.9-2.6):1.

[0016] Although HEDTA-3Na and NTA-3Na have strong chelating effects on heavy metals, they are both anionic chelating agents containing multiple carboxylate groups. This high charge density causes them to exceed the charge neutralization capacity of general flocculants, resulting in low adsorption efficiency. In addition, the applicant has found that when HEDTA-3Na and NTA-3Na form chelates with metal ions, the charge density of the complexes is further increased, which makes the formed chelates more stable and has a higher charge density, further hindering the adsorption of flocculants.

[0017] In the above case, HEDTA-3Na and NTA-3Na and the metal complex formed, if not completely degraded or not effectively adsorbed by the flocculant, will cause heavy metals to migrate and diffuse in the environment, increasing the risk of groundwater pollution. For the above-mentioned corrosion inhibitor with strong metal chelating ability, the flocculant prepared by the present application strengthens the removal of HEDTA-3Na and NTA-3Na and the metal complex formed, and the reason is that: the amide polymer obtained in step S2 of the present application has a hyperbranched structure, which can achieve wrapped adsorption of water-soluble metal complexes by side chain winding, and the adsorption site density of the hyperbranched flocculant is high, and multiple colloidal particles can be bridged at the same time to form dense flocs. On this basis, the sulfur atoms introduced by carbon disulfide and the oxygen atoms in the molecule of the present application form multidentate coordination, and the metal complex is further stabilized by the chelating effect, so that the formed chelate has hydrophobicity and insolubility, thereby being easier to separate from water.

[0018] In some embodiments, the solid composite water purifier further comprises 2 to 5 parts by weight of tetrasodium glutamate diacetate.

[0019] HEDTA-3Na is classified as a specific target organ toxicant, which may enhance the chronic toxicity to aquatic organisms. The applicant enhanced the biodegradability by adding tetrasodium glutamate diacetate in conjunction with HEDTA-3Na.

[0020] Another aspect of the present invention provides a method for preparing the solid composite water purifier, which comprises the following steps: uniformly mixing the corrosion and scale inhibitor, the auxiliary agent and the flocculant.

[0021] Compared with the prior art, the present invention has the following beneficial effects: The solid composite water purifier provided by the present invention adopts a compound corrosion inhibitor and scale inhibitor to broaden the scope of metal ion removal and strengthen the removal of heavy metal pollution in water bodies. At the same time, the denitrification treatment of low C / N ratio sewage is improved by specially selected sodium formate, and heavy metal chelation and nitrogen and phosphorus removal are simultaneously achieved, which comprehensively reduces costs and improves denitrification efficiency. On this basis, the applicant strengthens the adsorption of corrosion inhibitors complexed with metal ions by using a flocculant with a hyperbranched structure and a sulfur group, making it easier to separate from water, reducing the migration and diffusion of heavy metals in the environment, and reducing the risk of groundwater pollution; and uses tetrasodium glutamate diacetate and HEDTA-3Na to synergize and enhance biodegradability. DETAILED DESCRIPTION

[0022] The present invention will be described below in conjunction with specific embodiments. It should be noted that the following examples are illustrative of the present invention and are intended only to illustrate the present invention and are not intended to limit the present invention. Other combinations and various modifications within the scope of the present invention may be made without departing from the spirit or scope of the present invention.

[0023] It is worth noting that the raw materials used in the following preparation examples and embodiments, unless otherwise specified, are all from any commercially available manufacturers.

[0024] Preparation Example 1 The preparation steps of flocculant A are as follows: S1. Under nitrogen protection, 1 mol of acrylamide, 40 mg of N,N-methylenebisacrylamide, and 240 mg of 3-phenylmethylmercaptothiocarbonylpropionic acid were stirred at 50°C until dissolved in 4 L of dichloromethane to obtain a mixed base solution; S2. Add 30 mg of azobiscyanovaleric acid to the mixed base solution obtained in step S1, stir for 5 h, then add 7 mol of acrylamide and 2 mol of acryloyloxyethyltrimethylammonium chloride, continue stirring for 8 h, rotary evaporate, wash, and filter to obtain an amide polymer; S3, dissolving the amide polymer obtained in step S2 in 10 L of water at 60° C., then adding 8 mol of sodium hypochlorite and 16 mol of sodium hydroxide, stirring at 30° C. for 2 h, and adjusting the pH to 6.5 with hydrochloric acid to obtain an intermediate product; S4. Stir the intermediate product obtained in step S3, 22 mol of sodium hydroxide and 18 mol of carbon disulfide at 25° C. for 40 min, then heat to 60° C. and stir for 120 min, wash and dry to obtain flocculant A.

[0025] Preparation Example 2 The preparation steps of flocculant B are different from those of Preparation Example 1 in that the amount of acryloyloxyethyltrimethylammonium chloride used in step S2 is 1.6 mol.

[0026] Preparation Example 3 The preparation steps of flocculant C differ from those of Preparation Example 1 in that the amount of acryloyloxyethyltrimethylammonium chloride used in step S2 is 2.4 mol.

[0027] Preparation Example 4 The preparation steps of flocculant D are as follows: S1. Under nitrogen protection, 1 mol of acrylamide, 40 mg of N,N-methylenebisacrylamide, and 240 mg of 3-phenylmethylmercaptothiocarbonylpropionic acid were stirred at 50°C until dissolved in 4 L of dichloromethane to obtain a mixed base solution; S2. Add 30 mg of azobiscyanovaleric acid to the mixed base liquid obtained in step S1, stir for 5 h, then add 7 mol of acrylamide and 2 mol of acryloyloxyethyltrimethylammonium chloride, continue stirring for 8 h, rotary evaporate, wash, filter, and dry to obtain flocculant D.

[0028] Preparation Example 5 The preparation steps of flocculant E differ from those of Preparation Example 1 in that the amount of sodium hypochlorite used in step S3 is 6 mol.

[0029] Preparation Example 6 The preparation steps of flocculant F differ from those of Preparation Example 1 in that the amount of sodium hypochlorite used in step S3 is 10 mol.

[0030] Example 1 A solid composite water purifier, comprising the following components, calculated by weight: 22.5 parts of a corrosion and scale inhibitor, 0.5 parts of sodium formate, 0.3 parts of a flocculant A, and 3 parts of tetrasodium glutamate diacetate; The corrosion and scale inhibitor comprises 18 parts of trisodium salt of hydroxyethylethylenediaminetriacetic acid and 4.5 parts of sodium salt of nitrilotriacetic acid.

[0031] The preparation steps of the solid composite water purifier in this embodiment are as follows: uniformly mix the corrosion and scale inhibitor, sodium formate, flocculant A and tetrasodium glutamate diacetate.

[0032] Example 2 A solid composite water purifier, comprising the following components, calculated by weight: 20 parts of corrosion and scale inhibitor, 0.3 parts of sodium formate, 0.3 parts of flocculant A, and 2 parts of tetrasodium glutamate diacetate; The corrosion and scale inhibitor comprises 16.6 parts of trisodium salt of hydroxyethylethylenediaminetriacetic acid and 3.4 parts of sodium salt of nitrilotriacetic acid.

[0033] The preparation steps of the solid composite water purifier in this embodiment are the same as those in Example 1.

[0034] Example 3 A solid composite water purifier, comprising the following components, calculated by weight: 25 parts of a corrosion and scale inhibitor, 0.6 parts of sodium formate, 0.4 parts of a flocculant A, and 5 parts of tetrasodium glutamate diacetate; The corrosion and scale inhibitor comprises 19.3 parts of trisodium salt of hydroxyethylethylenediaminetriacetic acid and 5.7 parts of sodium salt of nitrilotriacetic acid.

[0035] The preparation steps of the solid composite water purifier in this embodiment are the same as those in Example 1.

[0036] Example 4 This embodiment provides a solid composite water purifier and a preparation method thereof. The specific implementation method is the same as that of Example 1, except that flocculant A is replaced by an equal amount of flocculant B.

[0037] Example 5 This embodiment provides a solid composite water purifier and a preparation method thereof. The specific implementation method is the same as that of Example 1, except that flocculant A is replaced by an equal amount of flocculant C.

[0038] Example 6 This embodiment provides a solid composite water purifier and a preparation method thereof. The specific implementation method is the same as that of Example 1, except that flocculant A is replaced by an equal amount of flocculant E.

[0039] Example 7 This embodiment provides a solid composite water purifier and a preparation method thereof. The specific implementation method is the same as that of Example 1, except that flocculant A is replaced by an equal amount of flocculant F.

[0040] Example 8 A solid composite water purifier, comprising the following components, by weight: 22.5 parts of corrosion and scale inhibitor, 0.5 parts of sodium formate, and 0.3 parts of flocculant A; The corrosion and scale inhibitor comprises 18 parts of trisodium salt of hydroxyethylethylenediaminetriacetic acid and 4.5 parts of sodium salt of nitrilotriacetic acid.

[0041] The preparation steps of the solid composite water purifier in this embodiment are as follows: the corrosion inhibitor and scale inhibitor, sodium formate, and flocculant A are mixed evenly.

[0042] Comparative Example 1 This comparative example provides a solid composite water purifier and a preparation method thereof. The specific implementation method is the same as that of Example 1, except that flocculant A is replaced by an equal amount of flocculant D.

[0043] Comparative Example 2 A solid composite water purifier, comprising the following components, calculated by weight: 22.5 parts of a corrosion and scale inhibitor, 0.3 parts of a flocculant A, and 3 parts of tetrasodium glutamate diacetate; The corrosion and scale inhibitor comprises 18 parts of trisodium salt of hydroxyethylethylenediaminetriacetic acid and 4.5 parts of sodium salt of nitrilotriacetic acid.

[0044] The preparation steps of the solid composite water purifier in this embodiment are as follows: uniformly mix the corrosion and scale inhibitor, flocculant A and tetrasodium glutamate diacetate.

[0045] Performance testing: 1. Wastewater denitrification experiment under low C / N ratio: This experiment uses an integrated sewage treatment equipment with a total volume of 15m 3 , the equipment processing capacity is 1m 3 / h, at 300 mg / m 3The ratio of the water purifiers obtained in Examples 1 to 8 and Comparative Examples 1 to 2 was added to the sewage treatment equipment respectively; the experimental water was taken from the domestic sewage pumping station, in order to achieve the expected 1 <C / N<2比例,根据实际废水指标情况,通过添加硝态氮(NaNO3,AR)进行调配。污水处理完毕后,对进水与出水中的NO3 - -N concentration was measured by ultraviolet spectrophotometry and the removal rate was calculated.

[0046] 2. Water purification experiment: Take a water sample containing Cu(II) with an initial concentration of 25 mg / L of Cu(II), adjust the pH value to 6.0, and use a program-controlled coagulation test mixer at a concentration of 300 mg / m 3 The water purifiers obtained in Examples 1 to 8 and Comparative Examples 1 to 2 were added respectively, and the mixture was stirred at a speed of 120 r / min for 2 min, then at a speed of 40 r / min for 10 min, and then allowed to settle for 15 min. The supernatant was removed to determine the residual concentrations of HEDTA-3Na and Cu(II), and the removal rate was calculated.

[0047] 3. Biodegradability test: Using the shaking table test method, the water purifiers of Examples 1 to 8 and Comparative Examples 1 to 2 were continuously cultured with a mixed solution of microorganisms, and the COD value of the mixed solution was regularly measured. The steps are as follows: Preparation of inoculum: Dissolve 100 g of garden soil in 1000 mL of distilled water, stir thoroughly and let it settle for 2 h, filter, discard about 200 mL of the upper filtrate, and set aside the rest.

[0048] Specific implementation: Add 500mL of water sample (add water purifier at 300mg / L) and 0.5mL of inoculum into a conical flask, cover the bottle cap, and place it in a 25℃ constant temperature shaker for shaking. Measure the COD of the sample on the 28th day after the start of the experiment. The degradation rate formula of the sample is as follows: ρ t =[(1-(C t -C bt ) / (C0-C b0 )]×100%, where C t COD of the inoculated reaction solution after adding the reagent on day t, C bt is the COD of the blank control inoculation reaction solution on day t, C0 is the initial COD of the inoculation reaction solution containing the agent, C b0 The initial COD of the inoculated reaction solution is the blank control.

[0049] The above test results are shown in Table 1.

[0050] Table 1 It can be seen from the data in Table 1 that the composite water purifiers of Examples 1 to 3 have good biodegradability and metal ion removal rate, and also show excellent nitrogen removal rate at a low C / N ratio. In combination with the removal rate of HEDTA-3Na in the supernatant, it can be seen that the flocculant in the water purifier can effectively precipitate HEDTA-3Na and the metal complex formed therefrom, thereby reducing the migration and diffusion of heavy metals in the environment.

[0051] Compared with Example 1, the flocculants used in Examples 4 to 5 changed the amount of acryloyloxyethyltrimethylammonium chloride during the preparation process, which did not affect the nitrogen removal rate and metal ion removal rate, but mainly affected the cationic degree of the flocculant, thereby interfering with the precipitation effect of the corrosion and scale inhibitor.

[0052] Compared to Example 1, Examples 6-7 varied the amount of sodium hypochlorite used during flocculant synthesis, potentially impacting the subsequent introduction of sulfide groups and resulting in reduced inhibitor precipitation. The absence of tetrasodium glutamate diacetate in Example 8 suggests a slower autonomous degradation of HEDTA-3Na. Compared to Example 1, the flocculant in Comparative Example 1 retained only a branched structure, resulting in a reduced inhibitor precipitation effect. Furthermore, the absence of sodium formate in Comparative Example 2, as the data indicates, was detrimental to nitrogen removal at low C / N ratios.

[0053] The embodiments and comparative examples described above do not impose any form of limitation on the present invention. Although the present invention has been disclosed as a preferred embodiment as above, it is not intended to limit the present invention. Any technician familiar with the present profession can make some changes or modifications to equivalent embodiments of equivalent changes using the technical content disclosed above without departing from the scope of the technical solution of the present invention. However, any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention still fall within the scope of the technical solution of the present invention.

Claims

1. A solid composite water purifier, characterized in that: The composition comprises the following components by weight: 20 to 25 parts of corrosion inhibitor and scale inhibitor, 0.3 to 0.6 parts of auxiliary agent, and 0.1 to 0.4 parts of flocculant; wherein the preparation steps of the flocculant are as follows: S1. Under nitrogen protection, acrylamide, N,N-methylenebisacrylamide, and 3-phenylmethylmercaptothiocarbonylpropionic acid are stirred at 45-55° C. until dissolved in dichloromethane to obtain a mixed base solution; S2. Add azobiscyanovaleric acid to the mixed base liquid obtained in step S1, stir for 4 to 6 hours, then add acrylamide and acryloyloxyethyltrimethylammonium chloride, continue stirring for 7 to 9 hours, rotary evaporate, wash, and filter to obtain an amide polymer; S3, dissolving the amide polymer obtained in step S2 in water at 50-70° C., then adding sodium hypochlorite and sodium hydroxide, stirring at 20-40° C. for 1-3 hours, and adjusting the pH to 6-7 with hydrochloric acid to obtain an intermediate product; S4. Stirring the intermediate product obtained in step S3, sodium hydroxide and carbon disulfide at 20-30° C. for 20-50 min, then heating to 50-70° C. and stirring for 80-140 min, washing and drying to obtain a flocculant.

2. The solid composite water purifier according to claim 1, characterized in that The corrosion and scale inhibitor comprises trisodium salt of hydroxyethylethylenediaminetriacetic acid and sodium salt of nitrilotriacetic acid.

3. The solid composite water purifier according to claim 2, characterized in that: The mass ratio of the trisodium salt of hydroxyethylethylenediaminetriacetic acid to the sodium salt of nitrilotriacetic acid is 1:(0.2-0.3).

4. The solid composite water purifier according to claim 1, characterized in that The auxiliary agent is sodium formate.

5. The solid composite water purifier according to claim 1, characterized in that: In step S1, the concentration of N,N-methylenebisacrylamide in the mixed base solution is 5-15 mg / L, and the concentration of 3-benzylmercaptothiocarbonylpropionic acid is 40-80 mg / L.

6. The solid composite water purifier according to claim 1, characterized in that: In step S2, the molar ratio of acrylamide to acryloyloxyethyltrimethylammonium chloride is (3-4):

1.

7. The solid composite water purifier according to claim 1, characterized in that In step S3, the molar ratio of the sodium hypochlorite to the total acrylamide in steps S1 and S2 is (0.8-1.2):

1.

8. The solid composite water purifier according to claim 1, characterized in that: In step S4, the molar ratio of carbon disulfide to the total acrylamide in steps S1 and S2 is (1.9-2.6):

1.

9. The solid composite water purifier according to any one of claims 1 to 8, characterized in that: The solid composite water purifier further comprises 2 to 5 parts by weight of tetrasodium glutamate diacetate.

10. A method for preparing the solid composite water purifier according to any one of claims 1 to 8, characterized in that: The specific steps are as follows: Mix the corrosion inhibitor, scale inhibitor, additive and flocculant evenly.

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