Preparation process of flocculant applied to wastewater treatment

Abstract

The invention relates to the technical field of wastewater treatment, and discloses a preparation process of a flocculant applied to wastewater treatment.The preparation process comprises the steps that divinyl-containing diphenylethylene triazolyl amide butyric acid, acrylamide and starch are subjected to a cross-linking polymerization reaction, and an acrylamide-starch-based flocculant with a cross-linked network structure is obtained; the cross-linked network structure improves the specific surface area of the flocculant, increases adsorption sites, and improves the adsorption performance of metal ions such as cadmium. The acrylamide-starch-based flocculant contains functional groups such as triazole, carboxyl and Schiff base, nitrogen atoms in the triazole and the Schiff base contain lone pair electrons and can be coordinated and chelated with cadmium ions, and the carboxyl also has a very strong adsorption effect, so that the adsorption capacity and the adsorption rate of the flocculant to the cadmium ions are remarkably improved.

Description

Technical Field

[0001] The invention relates to the technical field of wastewater treatment, in particular to a flocculant preparation process used for wastewater treatment. Background Art

[0002] Flocculants mainly include polyacrylamide, polyacrylic acid, starch, etc., which are widely used in the field of wastewater treatment. Traditional flocculants such as polyacrylamide and starch have the disadvantages of low adsorption capacity and slow adsorption rate for pollutants such as metal ions. Introducing functional groups into flocculants can effectively improve their adsorption and flocculation properties.

[0003] Patent CN113651963B discloses that high molecular weight lignin is modified by carboxymethylation, and a graft reaction is carried out with cationic starch through a crosslinking agent to synthesize a hyperbranched lignin-based cationic starch multifunctional composite flocculant with excellent flocculation performance. Patent CN105944691B discloses that graphene oxide, aminotriazole, 4-chloromethylstyrene, initiator, etc. are reacted to obtain a composite membrane for adsorbing heavy metal ions. The nitrogen with lone pair of electrons in the triazole structure can have an adsorption effect on heavy metal ions, thereby achieving efficient adsorption of heavy metal ions. Therefore, introducing functional groups such as triazole, carboxyl, quaternary ammonium salt into starch and polyacrylamide flocculants is an effective method to improve the adsorption performance of flocculants.

[0004] The invention aims to prepare an acrylamide-starch flocculant containing triazole and carboxyl, and improve the adsorption capacity and adsorption rate of acrylamide and starch flocculants to metal ions such as cadmium. Summary of the invention

[0005] The technical problem solved by the invention is: providing a triazole-carboxyacrylamide-starch flocculant, solving the problem of low metal ion adsorption capacity of acrylamide and starch flocculants.

[0006] The technical scheme of the present invention is: a preparation process of a flocculant, comprising the following steps: adding starch to water, stirring and gelatinizing at a temperature of 75-85°C for 1-2 hours under nitrogen protection, then reducing the temperature to 60-70°C, adding bis(acrylamide) triazole butyric acid, acrylamide and an initiator to prepare a reaction solution, stirring for cross-linking polymerization for 3-7 hours, cooling, adding ethanol to the solution until a precipitate is precipitated, filtering, washing with water, and drying to obtain an acrylamide-starch-based flocculant; the structural formula of the bis(acrylamide) triazole butyric acid ester is: .

[0007] Furthermore, the mass fraction of starch in the reaction solution is (60-120) g / L, the mass fraction of distyryl triazole amide butyric acid is (20-100) g / L, and the mass fraction of acrylamide is (50-180) g / L.

[0008] Furthermore, the mass fraction of the initiator in the reaction solution is (1-1.8) g / L.

[0009] Furthermore, the initiator is potassium persulfate or ammonium persulfate.

[0010] Furthermore, the preparation method of the distyryl triazole amide butyric acid comprises the following steps: (1) Add 4-vinylbenzaldehyde and triethylenetetramine in a molar ratio of 1:(2-2.5) to ethanol, react at 60-70°C for 4-8 h, cool, concentrate, wash with water, add the product to dichloromethane, add chloroacetyl chloride and triethylamine, react at room temperature for 2-5 h, concentrate, and wash with petroleum ether to obtain bis(vinyl)chloroacetamide intermediate 1.

[0011] (2) Add water, distyryl chloroacetamide intermediate 1, sodium azide and sodium carbonate to tetrahydrofuran, react at room temperature for 6-18 h, concentrate to remove tetrahydrofuran, precipitate, filter and wash the precipitate with water and petroleum ether to obtain distyryl azide intermediate 2.

[0012] (3) Add water, bis(phenylene azide intermediate 2), propargylamide butyric acid, copper sulfate and sodium ascorbate to N,N-dimethylformamide, react at 40-60°C for 24-48 h, cool, add ethyl acetate for extraction, concentrate the extract, wash with petroleum ether, and obtain bis(phenylene triazole amide butyric acid).

[0013] Furthermore, the volume ratio of tetrahydrofuran to water in (2) is 1:(0.2-0.4).

[0014] Furthermore, in said (2), the molar ratio of the bis(vinyl)chloroacetamide intermediate 1, sodium azide and sodium carbonate is 1:(2.4-3):(2.8-3.5).

[0015] Furthermore, the volume ratio of N,N-dimethylformamide to water in (3) is 1:(0.2-0.3).

[0016] Furthermore, the molar ratio of the bis(phenylethylene azide) intermediate 2, propargylamide butyric acid, copper sulfate and sodium ascorbate in (3) is 1:(1.8-2.6):(0.6-0.8):(2.2-2.6).

[0017] The beneficial technical effects of the present invention are: The present invention utilizes bis(vinylbenzene) triazole amide butyric acid containing diene groups to carry out cross-linking polymerization reaction with acrylamide and starch to obtain an acrylamide-starch based flocculant with a cross-linked network structure. The cross-linked network structure increases the specific surface area of ​​the flocculant, increases the adsorption sites, and improves the adsorption performance for metal ions such as cadmium.

[0018] Acrylamide-starch based flocculants contain functional groups such as triazole, carboxyl, and Schiff base. The nitrogen atoms in triazole and Schiff base contain lone pairs of electrons, which can coordinate and chelate with cadmium ions. The carboxyl group also has a strong adsorption effect, which significantly improves the adsorption capacity and adsorption rate of flocculants for cadmium ions and can be well used in wastewater treatment. DETAILED DESCRIPTION

[0019] The technical solution of the present invention is further described below based on the embodiments. In the description of this specification, the content of the embodiments means that the specific technical features described in combination with the embodiments are included in at least one embodiment of the present invention.

[0020] Example 1 (1) Add 20 mmol of 4-vinylbenzaldehyde and 42 mmol of triethylenetetramine in a molar ratio to 40 mL of ethanol, react at 70°C for 4 h, cool, concentrate, and wash with water. Then, add the product to dichloromethane, add 38 mmol of chloroacetyl chloride and 45 mmol of triethylamine, react at room temperature for 4 h, concentrate, and wash with petroleum ether to obtain bis(vinyl)chloroacetamide intermediate 1.

[0021] (2) To 50 mL of tetrahydrofuran, add 15 mL of water, 10 mmol of bis(vinyl)chloroacetamide intermediate 1, 24 mmol of sodium azide and 35 mmol of sodium carbonate. The mixture was reacted at room temperature for 18 h. The tetrahydrofuran was removed by concentration and the precipitate was filtered and washed with water and petroleum ether to obtain bis(vinyl)azide intermediate 2.

[0022] (3) Add 60 mL of water, 30 mmol of bis(phenylene azide intermediate 2), 78 mmol of propargylamide butyric acid, 18 mmol of copper sulfate and 66 mmol of sodium ascorbate to 200 mL of N,N-dimethylformamide, react at 60°C for 36 h, cool, extract with ethyl acetate, concentrate the extract, wash with petroleum ether, and obtain bis(phenylene triazole amide butyric acid). The preparation reaction route is as follows:

[0023] (4) Add 10 g of starch to 100 mL of water, and stir the mixture at 85 °C for 1 h under nitrogen protection to gelatinize. Then, reduce the temperature to 70 °C, add 2 g of distyryl triazole amide butyric acid, 15 g of acrylamide and 0.12 g of initiator potassium persulfate to prepare a reaction solution, stir and perform cross-linking polymerization for 4 h, cool the solution, add ethanol to the solution until a precipitate is precipitated, filter, wash with water, and dry to obtain an acrylamide-starch based flocculant.

[0024] Example 2 (1) Add 20 mmol of 4-vinylbenzaldehyde and 40 mmol of triethylenetetramine in a molar ratio to 40 mL of ethanol, react at 70°C for 6 h, cool, concentrate, and wash with water. Then, add the product to dichloromethane, add 35 mmol of chloroacetyl chloride and 42 mmol of triethylamine, react at room temperature for 4 h, concentrate, and wash with petroleum ether to obtain bis(vinyl)chloroacetamide intermediate 1.

[0025] (2) To 50 mL of tetrahydrofuran, add 20 mL of water, 10 mmol of bis(vinyl)chloroacetamide intermediate 1, 26 mmol of sodium azide and 28 mmol of sodium carbonate. The mixture was reacted at room temperature for 12 h. The tetrahydrofuran was removed by concentration and the precipitate was filtered and washed with water and petroleum ether to obtain bis(vinyl)azide intermediate 2.

[0026] (3) To 200 mL of N,N-dimethylformamide, 60 mL of water, 30 mmol of bis(phenylene azide intermediate 2), 60 mmol of propargylamide butyric acid, 20 mmol of copper sulfate and 78 mmol of sodium ascorbate were added. The mixture was reacted at 50 °C for 36 h. After cooling, ethyl acetate was added for extraction. The extract was concentrated and washed with petroleum ether to obtain bis(phenylene triazole amide butyric acid).

[0027] (4) Add 10 g of starch to 100 mL of water, and stir the mixture at 80 °C for gelatinization for 1 h under nitrogen protection. Then reduce the temperature to 65 °C, add 5 g of distyryl triazole amide butyric acid, 15 g of acrylamide and 0.14 g of initiator potassium persulfate to prepare a reaction solution, stir and perform cross-linking polymerization for 7 h, cool the solution, add ethanol to the solution until a precipitate is precipitated, filter, wash with water, and dry to obtain an acrylamide-starch based flocculant.

[0028] Example 3 (1) Add 20 mmol of 4-vinylbenzaldehyde and 45 mmol of triethylenetetramine in a molar ratio to 80 mL of ethanol, react at 60°C for 6 h, cool, concentrate, and wash with water. Then, add the product to dichloromethane, add 40 mmol of chloroacetyl chloride and 45 mmol of triethylamine, react at room temperature for 4 h, concentrate, and wash with petroleum ether to obtain bis(vinyl)chloroacetamide intermediate 1.

[0029] (2) To 50 mL of tetrahydrofuran, add 15 mL of water, 10 mmol of distyryl chloroacetamide intermediate 1, 30 mmol of sodium azide and 28 mmol of sodium carbonate. The mixture was reacted at room temperature for 12 h. The tetrahydrofuran was removed by concentration and the precipitate was filtered and washed with water and petroleum ether to obtain distyryl azide intermediate 2.

[0030] (3) To 200 mL of N,N-dimethylformamide, 60 mL of water, 30 mmol of bis(phenylene azide intermediate 2), 65 mmol of propargylamide butyric acid, 18 mmol of copper sulfate and 70 mmol of sodium ascorbate were added. The mixture was reacted at 60 °C for 36 h. After cooling, ethyl acetate was added for extraction. The extract was concentrated and washed with petroleum ether to obtain bis(phenylene triazole amide butyric acid).

[0031] (4) Add 10 g of starch to 100 mL of water, and stir the mixture at 80 °C for gelatinization for 1 h under nitrogen protection. Then reduce the temperature to 65 °C, add 7 g of distyryl triazole amide butyric acid, 15 g of acrylamide and 0.14 g of initiator ammonium persulfate to prepare a reaction solution, stir and perform cross-linking polymerization for 4 h, cool the solution, add ethanol to the solution until a precipitate is precipitated, filter, wash with water, and dry to obtain an acrylamide-starch based flocculant.

[0032] Example 4 (1) Add 20 mmol of 4-vinylbenzaldehyde and 48 mmol of triethylenetetramine in a molar ratio to 60 mL of ethanol, react at 60°C for 8 h, cool, concentrate, and wash with water. Then, add the product to dichloromethane, add 45 mmol of chloroacetyl chloride and 40 mmol of triethylamine, react at room temperature for 2 h, concentrate, and wash with petroleum ether to obtain bis(vinyl)chloroacetamide intermediate 1.

[0033] (2) Add 20 mL of water, 10 mmol of distyryl chloroacetamide intermediate 1, 30 mmol of sodium azide and 28 mmol of sodium carbonate to 50 mL of tetrahydrofuran and react at room temperature for 12 h. Concentrate to remove tetrahydrofuran and precipitate. After filtering, wash the precipitate with water and petroleum ether in turn to obtain distyryl azide intermediate 2.

[0034] (3) To 200 mL of N,N-dimethylformamide, 50 mL of water, 30 mmol of bis(phenylene azide intermediate 2), 78 mmol of propargylamide butyric acid, 24 mmol of copper sulfate and 70 mmol of sodium ascorbate were added. The mixture was reacted at 40 °C for 24 h. After cooling, ethyl acetate was added for extraction. The extract was concentrated and washed with petroleum ether to obtain bis(phenylene triazole amide butyric acid).

[0035] (4) Add 10 g of starch to 100 mL of water, and stir the mixture at 85 °C for 1 h under nitrogen protection to gelatinize. Then, reduce the temperature to 70 °C, add 10 g of distyryl triazole amide butyric acid, 15 g of acrylamide and 0.18 g of initiator potassium persulfate to prepare a reaction solution, stir and perform cross-linking polymerization for 7 h, cool the solution, add ethanol to the solution until a precipitate is precipitated, filter, wash with water, and dry to obtain an acrylamide-starch based flocculant.

[0036] Comparative Example 1 The difference between Comparative Example 1 and Example 1 is that no bis(phenylethylene triazole)amide butyric acid is added in the polymerization reaction.

[0037] Comparative Example 2 The difference between Comparative Example 2 and Example 1 is that the distyryl chloroacetamide intermediate 1 is used in the polymerization reaction instead of distyryl triazole amide butyric acid to carry out the polymerization reaction.

[0038] Comparative Example 3 The difference between Comparative Example 3 and Example 1 is that the bisphenylethylene azide intermediate 2 is used in the polymerization reaction instead of bisphenylethylene triazole amide butyric acid to carry out the polymerization reaction.

[0039] Prepare 0.5 L of cadmium nitrate solution with different concentrations, add 100 mg of acrylamide-starch-based flocculant, and adsorb for 5 h at room temperature. After adsorption, remove the upper solution and use an atomic absorption spectrophotometer to detect the concentration of cadmium. Calculate the equilibrium adsorption capacity W of the flocculant for cadmium ions, W = (C 0 -C) × V ÷ M, C 0 The initial concentration of cadmium ions in the solution, C 0 where V is the volume of the solution and M is the mass of the acrylamide-starch based flocculant.

[0040]

[0041] After adsorption experiments, when Cd 2+ The starting concentration C 0 When the concentration of Cd was 250 mg / L, the acrylamide-starch-based flocculants prepared in each example had a significant effect on the concentration of Cd 2+The equilibrium adsorption capacity of the adsorbent is the largest, reaching 0.362-0.536 g / g. It has the advantage of high adsorption capacity because the addition of distyryl triazole amide butyric acid, acrylamide and starch undergo cross-linking polymerization to form a cross-linked network structure with a larger specific surface area. It also contains functional groups such as triazole and carboxyl, which can react with Cd 2+ Carry out coordination chelation to enhance the Cd 2+ adsorption capacity and adsorption ability.

[0042] Comparative Example 1 did not add styrene triazole amide butyric acid, acrylamide-starch-based flocculant did not form a cross-linked network structure, and did not contain triazole, carboxyl and other functional groups, and had no effect on Cd 2+ The equilibrium adsorption capacity is the lowest.

[0043] Comparative Examples 2 and 3 respectively added bis(vinyl chloride)acetamide intermediate 1 and bis(vinyl chloride)azide intermediate to carry out cross-linking polymerization. Although the acrylamide-starch-based flocculant formed a cross-linked network structure, it did not contain functional groups such as triazole and carboxyl, and had no effect on Cd 2+ The equilibrium adsorption capacity of is not good, but the equilibrium adsorption capacity is higher than that of Comparative Example 1.

[0044] Prepare 0.5 L cadmium nitrate solution with a concentration of 250 mg / L, add 100 mg acrylamide-starch-based flocculant, and perform adsorption at room temperature. At different adsorption times, remove the upper solution, and use an atomic absorption spectrophotometer to detect the concentration of cadmium. Calculate the equilibrium adsorption capacity W of the flocculant for cadmium ions, W = (C 0 -C) × V ÷ M, C 0 The initial concentration of cadmium ions in the solution, C 0 where V is the volume of the solution and M is the mass of the acrylamide-starch based flocculant.

[0045]

[0046] After adsorption experiments, when Cd 2+ The starting concentration C 0 When the concentration of acrylamide-starch-based flocculants was 250 mg / L, the acrylamide-starch-based flocculants prepared in various embodiments almost reached a balanced adsorption state after 3 h of adsorption, and had the advantage of a fast adsorption rate.

[0047] This specific embodiment is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make modifications to the present embodiment without any creative contribution as needed, but such modifications are protected by the patent law as long as they are within the scope of the claims of the present application.

Claims

1. A process for preparing a flocculant, characterized in that: The preparation process of the flocculant comprises the following steps: adding starch to water, stirring and gelatinizing at a temperature of 75-85°C for 1-2 hours under nitrogen protection, then reducing the temperature to 60-70°C, adding bis(acrylamide) triazole butyric acid, acrylamide and an initiator to prepare a reaction solution, stirring for cross-linking polymerization for 3-7 hours, cooling, adding ethanol to the solution until a precipitate is precipitated, filtering, washing with water, and drying to obtain an acrylamide-starch-based flocculant; the structural formula of the bis(acrylamide) triazole butyric acid ester is: .

2. The flocculant preparation process according to claim 1, characterized in that: The mass fraction of starch in the reaction solution is (60-120) g / L, the mass fraction of distyryl triazole amide butyric acid is (20-100) g / L, and the mass fraction of acrylamide is (50-180) g / L.

3. The flocculant preparation process according to claim 1, characterized in that: The mass fraction of the initiator in the reaction solution is (1-1.8) g / L.

4. The flocculant preparation process according to claim 3, characterized in that: The initiator is potassium persulfate or ammonium persulfate.

5. The flocculant preparation process according to claim 1, characterized in that: The preparation method of the distyryl triazole amide butyric acid comprises the following steps: (1) Add 4-vinylbenzaldehyde and triethylenetetramine in a molar ratio of 1:(2-2.5) to ethanol, react at 60-70°C for 4-8 h, cool, concentrate, wash with water, add the product to dichloromethane, add chloroacetyl chloride and triethylamine, react at room temperature for 2-5 h, concentrate, and wash to obtain bis(vinyl)chloroacetamide intermediate 1; (2) Add water, bis(phenylethylene chloroacetamide) intermediate 1, sodium azide and sodium carbonate to tetrahydrofuran, react at room temperature for 6-18 h, concentrate, precipitate, filter and wash to obtain bis(phenylethylene azide) intermediate 2; (3) Add water, bis(phenylene azide intermediate 2), propargylamide butyric acid, copper sulfate and sodium ascorbate to N,N-dimethylformamide, react at 40-60°C for 24-48 h, cool, extract, concentrate and wash to obtain bis(phenylene triazole amide butyric acid).

6. The flocculant preparation process according to claim 5, characterized in that: The volume ratio of tetrahydrofuran to water in (2) is 1:(0.2-0.4).

7. The flocculant preparation process according to claim 5, characterized in that: The molar ratio of the bis(vinyl)chloroacetamide intermediate 1, sodium azide and sodium carbonate in (2) is 1:(2.4-3):(2.8-3.5).

8. The flocculant preparation process according to claim 5, characterized in that: The volume ratio of N,N-dimethylformamide to water in (3) is 1:(0.2-0.3).

9. The flocculant preparation process according to claim 5, characterized in that: The molar ratio of the bis(phenylethylene azide) intermediate 2, propargylamide butyric acid, copper sulfate and sodium ascorbate in (3) is 1:(1.8-2.6):(0.6-0.8):(2.2-2.6).

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