Solid composite water purifying agent and preparation method thereof

Abstract

The present application relates to the technical field of water treatment technology, and discloses a solid composite water purifying agent and a preparation method thereof, which comprises the following components in parts by weight: 20-25 parts of corrosion and scale inhibitor, 0.3-0.6 parts of auxiliary agent, and 0.1-0.4 parts of flocculating agent. The corrosion and scale inhibitor is compounded to broaden the removal range of metal ions and strengthen the removal of heavy metal pollution in water. Meanwhile, the auxiliary agent is selected to improve the denitrification of low C / N ratio sewage, and the chelation of heavy metals and the removal of nitrogen and phosphorus are simultaneously realized. At the same time, the flocculating agent with hyperbranched structure and sulfur group strengthens the adsorption of the corrosion and scale inhibitor with metal ions, so that the corrosion and scale inhibitor is more easily separated from water, the migration and diffusion of heavy metals in the environment are reduced, and the risk of groundwater pollution is reduced.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of water treatment, and particularly relates to a solid composite water purifying agent and a preparation method thereof. BACKGROUND

[0002] The water purifying agent has high flocculation, precipitation and adsorption capacity, and can effectively remove suspended solids, heavy metals, organic matter and other pollutants in water, and is widely used in industrial wastewater treatment, drinking water purification and other fields. The origin and development process of solid water purifying agent can be traced back to the mid-to-late 20th century. Initially, the water purifying agent was mainly inorganic water purifying agent. These water purifying agents have good flocculation effect, but have the problem of secondary pollution. With the continuous progress of water treatment technology and the increasing demand for environmental protection, high molecular organic water purifying agent has gradually become a research hotspot. This kind of water purifying agent has the advantages of wide raw material, low price, non-toxicity and easy biodegradation, and the representative products include polyacrylamide (PAM) and polyacrylimide (PAPI) and the like.

[0003] At present, related technical personnel still improve the water purifying agent. For example, patent application CN 108862513 A discloses a composite water purifying agent for sewage purification and a preparation process thereof. The components include active calcium carbonate, polyaluminum ferric chloride, calcium chloride, montmorillonite powder, polyacrylamide and active alumina. The water purifying agent is mainly inorganic flocculant, supplemented by high molecular flocculant, which enriches and strengthens the water treatment effect of the water purifying agent through the compounding of components. For example, patent CN 114230788 B discloses a multivalent polyanion oil-containing sewage water purifying agent and a preparation method. The multivalent polyanion water purifying agent has a tree-shaped macromolecular structure, which can effectively improve the generation of oil sludge, pipeline corrosion and blockage problems in the water purification process. However, due to the strengthening of environmental protection regulations and the change of market demand, the above-mentioned water purifying agent needs to pay more attention to the removal of heavy metal ions and the optimization of non-toxic, harmless and easy biodegradation. SUMMARY

[0004] In order to overcome the shortcomings of the prior art, the present application widens the removal range of metal ions by compounding corrosion and scale inhibitors, and strengthens the removal of heavy metal pollution in water. At the same time, the low C / N ratio of sewage is improved by sodium formate to achieve simultaneous removal of heavy metal chelation and nitrogen and phosphorus. At the same time, the flocculant with hyperbranched structure and sulfur group strengthens the adsorption of corrosion inhibitors complexed with metal ions, 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] To achieve the above purpose, the technical scheme adopted by the present application is:

[0006] The application provides a solid composite water purifying agent, which contains the following components in parts by weight: 20-25 parts of an inhibitor and scale inhibitor, 0.3-0.6 parts of an auxiliary agent, and 0.1-0.4 parts of a flocculant.

[0007] S1, under the protection of nitrogen, acrylamide, N,N-methylenebisacrylamide and 3-phenylmercaptothiocarbonyl propionic acid are stirred to be dissolved in dichloromethane at 45-55 DEG C to obtain a mixed bottom liquid;

[0008] S2, azobis crotonic acid is added into the mixed bottom liquid obtained in step S1, acrylamide and acryloxyethyl trimethyl ammonium chloride are added after stirring for 4-6 h, and the stirring is continued for 7-9 h, then rotary evaporation, washing, filtration are performed to obtain an amide polymer;

[0009] S3, the amide polymer obtained in step S2 is dissolved in water at 50-70 DEG C, then sodium hypochlorite and sodium hydroxide are added, stirring is performed at 20-40 DEG C for 1-3 h, hydrochloric acid is used to adjust the pH to 6-7 to obtain an intermediate product;

[0010] S4, the intermediate product obtained in step S3, sodium hydroxide and carbon disulfide are stirred at 20-30 DEG C for 20-50 min, then the temperature is raised to 50-70 DEG C for stirring for 80-140 min, then cleaning and drying are performed to obtain the flocculant.

[0011] In some embodiments, the inhibitor and scale inhibitor contains hydroxyethyl ethylenediamine triacetic acid trisodium salt and nitrilotriacetic acid sodium salt.

[0012] In some embodiments, the mass ratio of the hydroxyethyl ethylenediamine triacetic acid trisodium salt and nitrilotriacetic acid sodium salt is 1:(0.2-0.3).

[0013] The hydroxyethyl ethylenediamine triacetic acid trisodium salt (HEDTA-3Na) can form stable water-soluble complexes with metal ions such as Ca²⁺, Mg²⁺ and Fe³⁺, effectively prevents scale formation and softens water quality, and the chelating ability of the HEDTA-3Na to Fe³⁺ is particularly prominent in a strong acidic environment, which can control the concentration of iron ions and avoid yellowing of water or secondary pollution.

[0014] The nitrilotriacetic acid sodium salt (NTA-3Na) also has good chelating effect on metal ions, and can also disperse suspended particles, prevent pipeline and equipment from scaling and prolong the service life. When the HEDTA-3Na is used in combination with the NTA-3Na, the removal range of metal ions can be widened.

[0015] In some embodiments, the auxiliary agent is sodium formate.

[0016] The nitrilo group in the NTA-3Na molecule can increase the total nitrogen concentration in the water body, and if the wastewater treatment is not complete, the residual NTA-3Na may release ammonia nitrogen through hydrolysis or microbial metabolism, and aggravate the eutrophication of the water body. In the present application, sodium formate as an easily degradable organic carbon source can provide an electron donor for denitrifying bacteria, improve the denitrification treatment of low C / N ratio wastewater, and solve the afterthoughts of NTA-3Na; and sodium formate and HEDTA-3Na are used in combination, which can simultaneously realize heavy metal chelation and nitrogen and phosphorus removal, and comprehensively reduce the cost and improve the denitrification efficiency.

[0017] In some embodiments, in step S1, the concentration of N,N-methylenebisacrylamide in the mixed bottom liquid is 5-15 mg / L, and the concentration of 3-phenylmercaptothiocarbonyl propionic acid is 40-80 mg / L.

[0018] In some embodiments, in step S2, the molar ratio of acrylamide to acryloxyethyltrimethylammonium chloride is (3-4):1.

[0019] In some embodiments, in step S3, the molar ratio of sodium hypochlorite to the total acrylamide in steps S1 and S2 is (0.8-1.2):1.

[0020] 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.

[0021] Although HEDTA-3Na and NTA-3Na have strong chelation effect on heavy metals, they are both anionic chelating agents containing multiple carboxylate groups. This high charge density leads to a charge neutralization ability that exceeds that of general flocculants, resulting in low adsorption efficiency. The applicant found that when HEDTA-3Na and NTA-3Na form chelates with metal ions, the charge density of the complex is further increased, which makes the formed chelate more stable and has higher charge density, further hindering the adsorption of flocculants.

[0022] In the above case, HEDTA-3Na and NTA-3Na and the formed metal complexes will lead to the migration and diffusion of heavy metals in the environment, increasing the risk of groundwater pollution, if they are not completely degraded or not effectively adsorbed by the flocculants. For the above corrosion inhibitor with strong chelating metal ability, the flocculant prepared by the application strengthens the removal of HEDTA-3Na and NTA-3Na and the formed metal complexes, and the reason is that the amide polymer obtained in step S2 has a hyperbranched structure, which can realize the wrapping adsorption of water-soluble metal complexes through the winding of branches, and the adsorption site density of the hyperbranched flocculant is high, which can simultaneously bridge multiple colloidal particles to form dense flocs. On this basis, the sulfur atom introduced by carbon disulfide and the oxygen atom in the molecule form polydentate coordination, further stabilize the metal complexes through chelation effect, so that the formed chelates have hydrophobicity and insolubility, and thus are more easily separated from water.

[0023] In some embodiments, the solid composite water purifying agent further comprises 2-5 parts by weight of tetrasodium glutamate diacetate.

[0024] HEDTA-3Na is classified as a specific target organ system toxicant, which can enhance the chronic toxicity to aquatic organisms, and the applicant adds tetrasodium glutamate diacetate to synergize with HEDTA-3Na, thereby strengthening the biodegradability.

[0025] Another aspect of the application provides a preparation method of the above solid composite water purifying agent, and the specific steps are as follows: uniformly mixing the corrosion and scale inhibitors, the additives and the flocculant.

[0026] Compared with the prior art, the application has the following beneficial effects:

[0027] The solid composite water purifying agent provided by the application widens the removal range of metal ions by using the compounded corrosion and scale inhibitors, and strengthens the removal of heavy metal pollution in water bodies. At the same time, the low C / N ratio sewage denitrification treatment is improved by using the specifically selected sodium formate, and the heavy metal chelation and nitrogen and phosphorus removal are simultaneously realized, thereby comprehensively reducing the cost and improving the denitrification efficiency. On this basis, the flocculant with a hyperbranched structure and a sulfur group prepared by the applicant strengthens the adsorption of the corrosion inhibitor with metal ions, so that the corrosion inhibitor is more easily separated from water, the migration and diffusion of heavy metals in the environment are reduced, and the risk of groundwater pollution is reduced; and the biodegradability is strengthened by using tetrasodium glutamate diacetate to synergize with HEDTA-3Na. DETAILED DESCRIPTION

[0028] The application will be described below in conjunction with specific embodiments. It should be noted that the following examples are examples of the application and are only used to illustrate the application, but not to limit the application. Other combinations and various modifications within the concept of the application can be made without departing from the spirit or scope of the application.

[0029] It is worth noting that the raw materials used in the following preparation examples and examples are from any manufacturer unless otherwise specified.

[0030] Preparation Example 1

[0031] The preparation steps of flocculant A are as follows:

[0032] S1, under nitrogen protection, 1 mol of acrylamide, 40 mg of N, N-methylene bisacrylamide and 240 mg of 3-phenylmercaptothiocarbonyl propionic acid were stirred to dissolve in 4 L of dichloromethane at 50°C to obtain a mixed bottom liquid;

[0033] S2, 30 mg of azobis-dicyanopentanoic acid was added to the mixed bottom liquid obtained in step S1, and after stirring for 5 h, 7 mol of acrylamide and 2 mol of acryloyloxyethyl trimethyl ammonium chloride were added, and the stirring was continued for 8 h. Rotary evaporation, washing, filtration, to obtain an amide polymer;

[0034] S3, the amide polymer obtained in step S2 was dissolved in 10 L of water at 60°C, then 8 mol of sodium hypochlorite and 16 mol of sodium hydroxide were added, and stirred at 30°C for 2 h. The pH was adjusted to 6.5 with hydrochloric acid to obtain an intermediate product;

[0035] S4, the intermediate product obtained in step S3, 22 mol of sodium hydroxide and 18 mol of carbon disulfide were stirred at 25°C for 40 min, then the temperature was raised to 60°C and stirred for 120 min. Cleaning and drying, to obtain flocculant A.

[0036] Preparation Example 2

[0037] The preparation steps of flocculant B are different from those of Preparation Example 1, and the difference is that the amount of acryloyloxyethyl trimethyl ammonium chloride in step S2 is 1.6 mol.

[0038] Preparation Example 3

[0039] The preparation steps of flocculant C are different from those of Preparation Example 1, and the difference is that the amount of acryloyloxyethyl trimethyl ammonium chloride in step S2 is 2.4 mol.

[0040] Preparation Example 4

[0041] The preparation steps of flocculant D are as follows:

[0042] S1, under nitrogen protection, 1 mol of acrylamide, 40 mg of N, N-methylene bisacrylamide and 240 mg of 3-phenylmercaptothiocarbonyl propionic acid were stirred to dissolve in 4 L of dichloromethane at 50°C to obtain a mixed bottom liquid;

[0043] S2, 30 mg of azobis cyanovaleric acid was added into the mixed solution obtained in step S1, and stirred for 5 h, then 7 mol of acrylamide and 2 mol of acryloyloxyethyl trimethyl ammonium chloride were added, and stirred for 8 h, and then the product was obtained by rotary evaporation, washing, filtration and drying.

[0044] Preparation Example 5

[0045] The preparation steps of flocculant E are different from those of Preparation Example 1 in that the amount of sodium hypochlorite in step S3 is 6 mol.

[0046] Preparation Example 6

[0047] The preparation steps of flocculant F are different from those of Preparation Example 1 in that the amount of sodium hypochlorite in step S3 is 10 mol.

[0048] Example 1

[0049] A solid composite water purifying agent, comprising the following components by weight parts: 22.5 parts of corrosion and scale inhibitor, 0.5 parts of sodium formate, 0.3 parts of flocculant A, 3 parts of tetrasodium glutamate diacetate;

[0050] The corrosion and scale inhibitor comprises 18 parts of hydroxyethyl ethylenediamine triacetic acid trisodium salt and 4.5 parts of nitrilotriacetic acid sodium salt.

[0051] The preparation steps of the solid composite water purifying agent in this example are as follows: the corrosion and scale inhibitor, sodium formate, flocculant A and tetrasodium glutamate diacetate are mixed uniformly.

[0052] Example 2

[0053] A solid composite water purifying agent, comprising the following components by weight parts: 22.5 parts of corrosion and scale inhibitor, 0.5 parts of sodium formate, 0.3 parts of flocculant A, 3 parts of tetrasodium glutamate diacetate;

[0054] The corrosion and scale inhibitor comprises 16.6 parts of hydroxyethyl ethylenediamine triacetic acid trisodium salt and 3.4 parts of nitrilotriacetic acid sodium salt.

[0055] The preparation steps of the solid composite water purifying agent in this example are the same as those of Example 1.

[0056] Example 3

[0057] A solid composite water purifying agent, comprising the following components by weight parts: 22.5 parts of corrosion and scale inhibitor, 0.5 parts of sodium formate, 0.3 parts of flocculant A, 3 parts of tetrasodium glutamate diacetate;

[0058] The corrosion and scale inhibitor comprises 19.3 parts of tri-sodium salt of hydroxyethyl ethylenediamine triacetate and 5.7 parts of sodium salt of nitrilotriacetate.

[0059] The preparation steps of the solid composite water purifying agent in this example are the same as those in Example 1.

[0060] Example 4

[0061] The example provides a solid composite water purifying agent and a preparation method thereof, and the specific implementation manner is the same as that in Example 1, and the difference lies in that the flocculating agent A is replaced by the same proportion of flocculating agent B.

[0062] Example 5

[0063] The example provides a solid composite water purifying agent and a preparation method thereof, and the specific implementation manner is the same as that in Example 1, and the difference lies in that the flocculating agent A is replaced by the same proportion of flocculating agent C.

[0064] Example 6

[0065] The example provides a solid composite water purifying agent and a preparation method thereof, and the specific implementation manner is the same as that in Example 1, and the difference lies in that the flocculating agent A is replaced by the same proportion of flocculating agent E.

[0066] Example 7

[0067] The example provides a solid composite water purifying agent and a preparation method thereof, and the specific implementation manner is the same as that in Example 1, and the difference lies in that the flocculating agent A is replaced by the same proportion of flocculating agent F.

[0068] Example 8

[0069] A solid composite water purifying agent comprises the following components in parts by weight: 22.5 parts of corrosion and scale inhibitor, 0.5 parts of sodium formate, and 0.3 parts of flocculating agent A.

[0070] The corrosion and scale inhibitor comprises 18 parts of tri-sodium salt of hydroxyethyl ethylenediamine triacetate and 4.5 parts of sodium salt of nitrilotriacetate.

[0071] The preparation steps of the solid composite water purifying agent in this example are as follows: the corrosion and scale inhibitor, the sodium formate and the flocculating agent A are uniformly mixed.

[0072] Comparative Example 1

[0073] The example provides a solid composite water purifying agent and a preparation method thereof, and the specific implementation manner is the same as that in Example 1, and the difference lies in that the flocculating agent A is replaced by the same proportion of flocculating agent D.

[0074] Comparative Example 2

[0075] A solid composite water purifying agent, comprising the following components in parts by weight: 22.5 parts of corrosion and scale inhibitor, 0.3 parts of flocculant A, 3 parts of tetrasodium glutamate diacetate;

[0076] The corrosion and scale inhibitor comprises 18 parts of hydroxyethyl ethylenediamine triacetic acid trisodium salt and 4.5 parts of nitrilotriacetic acid sodium salt.

[0077] The preparation steps of the solid composite water purifying agent in the embodiment are as follows: the corrosion and scale inhibitor, the flocculant A and the tetrasodium glutamate diacetate are uniformly mixed.

[0078] Performance test:

[0079] 1. Nitrogen removal experiment of sewage under low C / N ratio: The integrated sewage treatment equipment is used in the experiment, the total volume of the equipment is 15 m 3 , the processing capacity of the equipment is 1 m 3 / h, and the water purifying agent obtained from examples 1-8 and comparative examples 1-2 is added to the sewage treatment equipment at a ratio of 300 mg / m 3 ; the influent water is taken from the domestic sewage collection pump station, in order to achieve the expected ratio of 1<C / N<2, according to the actual wastewater index, the nitrate nitrogen (NaNO3, AR) is added for adjustment. After the sewage treatment is completed, the concentration of NO3 - -N in the influent and effluent is determined by ultraviolet spectrophotometry, and the removal rate is calculated.

[0080] 2. Water purification experiment: take Cu(II) water sample with initial concentration of 25 mg / L, adjust pH value to 6.0, add water purifying agent obtained from examples 1-8 and comparative examples 1-2 to the water sample at a ratio of 300 mg / m 3 , first stir at a speed of 120 r / min for 2 min, then stir at a speed of 40 r / min for 10 min, and then stand for 15 min, remove the supernatant to determine the residual concentration of HEDTA-3Na and Cu(II), and calculate the removal rate.

[0081] 3. Biodegradability test: the water purifying agent of examples 1-8 and comparative examples 1-2 is respectively mixed with microbial mixture for continuous culture by using the shaking bed method, and the COD value of the mixture is determined periodically, and the steps are as follows:

[0082] Preparation of inoculum: 100 g of garden soil is dissolved in 1000 mL of distilled water, stirred thoroughly, and then precipitated for 2 h, filtered, and the upper filtrate is discarded about 200 mL, and the rest is reserved.

[0083] Specific implementation: add 500 mL of water sample (add 300 mg / L of water purifying agent) and 0.5 mL of inoculum into a conical flask, cover the flask, place it in a constant temperature shaker at 25°C, and measure the COD of the sample on the 28th day of the experiment. The degradation rate of the sample is calculated as follows: ρ t =[(1-(C t -C bt ) / (C0-C b0 )]×100%, wherein C t is the COD of the inoculated reaction liquid added with the agent on the tth day, C bt is the COD of the blank control inoculated reaction liquid on the tth day, C0is the initial COD of the inoculated reaction liquid containing the agent, and C b0 is the initial COD of the blank control inoculated reaction liquid.

[0084] The test results are shown in Table 1.

[0085] Table 1

[0086]

[0087] As can be seen from the data in Table 1, the composite water purifying agent of Examples 1-3 has good biodegradability and metal ion removal rate, and also shows 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 flocculating agent in the water purifying agent can effectively precipitate HEDTA-3Na and the metal complexes formed therefrom, reducing the migration and diffusion of heavy metals in the environment.

[0088] Compared with Example 1, the amount of acryloyloxyethyl trimethyl ammonium chloride used in the preparation process of the flocculating agent of Examples 4-5 is changed, which does not affect the nitrogen removal rate and the metal ion removal rate, but mainly affects the cationic degree of the flocculating agent, thereby interfering with the precipitation effect of the corrosion and scale inhibitor.

[0089] Compared with Example 1, the amount of sodium hypochlorite used in the synthesis of the flocculating agent of Examples 6-7 is changed, which may affect the subsequent introduction of the sulfur group, resulting in a decrease in the precipitation effect of the corrosion inhibitor. In combination with the lack of tetrasodium glutamate diacetate in Example 8, it can be seen that the self-degradation rate of HEDTA-3Na is slow. Compared with Example 1, the flocculating agent in Comparative Example 1 only retains the branched structure, resulting in a decrease in the precipitation effect of the corrosion inhibitor; and in Comparative Example 2, sodium formate is lacking, which is not conducive to nitrogen removal at a low C / N ratio.

[0090] The above examples and comparative examples do not limit the present application in any form, although the present application has been disclosed as above with preferred embodiments, however, not intended to limit the present application, any skilled person in the art, without departing from the technical solution of the present application, can make some changes or modifications as equivalent embodiments with the above disclosed technical content, but as long as it does not deviate from the technical solution of the present application, any simple modification, equivalent change and modification of the above examples according to the technical essence of the present application, still belongs to the scope of the technical solution of the present application.

Claims

1. A solid composite water purifying agent, characterized by comprising: The corrosion and scale inhibitor comprises 20-25 parts by weight of corrosion and scale inhibitor, 0.3-0.6 parts by weight of auxiliary agent, and 0.1-0.4 parts by weight of flocculating agent. S1, under nitrogen protection, acrylamide, N,N-methylene bisacrylamide and 3-phenyl mercaptothiocarbonyl propionic acid are stirred to dissolve in dichloromethane at 45-55 DEG C to obtain a mixed bottom liquid; S2, azobis cyanovaleric acid is added to the mixed bottom liquid obtained in step S1, and after stirring for 4-6 h, acrylamide and acryloyloxyethyl trimethyl ammonium chloride are added, and stirring is continued for 7-9 h, and then rotary evaporation, washing, filtration are performed to obtain an amide polymer; S3, the amide polymer obtained in step S2 is dissolved in water at 50-70 DEG C, and then sodium hypochlorite and sodium hydroxide are added, and stirring is performed at 20-40 DEG C for 1-3 h, and then hydrochloric acid is used to adjust the pH to 6-7 to obtain an intermediate product; S4, the intermediate product obtained in step S3, sodium hydroxide and carbon disulfide are stirred at 20-30 DEG C for 20-50 min, and then the temperature is raised to 50-70 DEG C and stirring is performed for 80-140 min, and then washing and drying are performed to obtain the flocculating agent.

2. The solid composite water purifying agent according to claim 1, characterized in that, The corrosion and scale inhibitor comprises hydroxyethyl ethylenediamine triacetic acid trisodium salt and sodium nitrilotriacetate.

3. The solid composite water purifying agent according to claim 2, characterized in that, The mass ratio of the hydroxyethyl ethylenediamine triacetic acid trisodium salt and the sodium nitrilotriacetate is 1:(0.2-0.3).

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

5. The solid composite water purifier according to claim 1, wherein In step S1, the concentration of N,N-methylene bisacrylamide in the mixed bottom liquid is 5-15 mg / L, and the concentration of 3-phenyl mercaptothiocarbonyl propionic acid is 40-80 mg / L.

6. The solid composite water purifier according to claim 1, wherein In step S2, the molar ratio of acrylamide to acryloyloxyethyl trimethyl ammonium chloride is (3-4):

1.

7. The solid composite water purifier according to claim 1, wherein In step S3, the molar ratio of 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, wherein 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 purifying agent according to any one of claims 1 to 8, characterized by, The solid composite water purifying agent further comprises 2-5 parts by weight of glutamic acid diacetate tetrasodium salt.

10. A method for preparing the solid composite water purification agent according to any one of claims 1-8, characterized in that, The specific steps are as follows: the corrosion and scale inhibitor, the auxiliary agent and the flocculating agent are mixed uniformly.

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