Ammonia nitrogen treatment process

Abstract

This invention relates to an ammonia nitrogen treatment process, belonging to the field of wastewater treatment technology. The invention utilizes divinylbenzene and 1,2-divinylcyclohexane as crosslinking agents to prepare resin balls. Because the resin ball matrix simultaneously contains rigid benzene rings and cyclohexane structures in both torsion boat and semi-chair configurations, the hardness and surface roughness of the resin matrix can be increased, thereby improving the molding strength of the resin balls and reducing their surface energy. This promotes the approach and adsorption of ammonia nitrogen from wastewater onto the adsorption resin, improving the adsorption effect and rate. Furthermore, this invention simultaneously grafts sulfonic acid groups and phosphate groups onto the resin balls. These two groups can exert a gradient adsorption effect, further improving the adsorption capacity and rate of ammonia nitrogen in wastewater.

Description

Technical Field

[0001] This invention relates to an ammonia nitrogen treatment process, belonging to the field of wastewater treatment technology. Background Technology

[0002] Among numerous polluted water bodies, ammonia-containing wastewater is a major form of sewage, and the increasing discharge of ammonia-containing wastewater has caused serious harm to the ecological balance. High concentrations of nitrogen-containing wastewater are toxic to humans, animals, and plants, severely damaging the ecological environment. Ammonia nitrogen can also be converted into nitrate nitrogen or nitrite nitrogen through microbial degradation; these products have carcinogenic and teratogenic effects, posing significant harm to humans and other organisms. Furthermore, the conversion of ammonia nitrogen consumes dissolved oxygen in the water, leading to mass fish deaths in rivers and lakes, damaging the aquatic environment, and accelerating eutrophication.

[0003] Ion exchange, as an effective method for removing ammonia nitrogen, primarily utilizes the concentration difference between ions and the affinity of functional groups on the exchanger for ions as driving forces to occur at the interface between solid particles and liquid. This reaction is typically reversible. Currently, adsorbents used for ammonia nitrogen wastewater treatment mainly include inorganic adsorbents such as zeolites and organic resin adsorbents. However, the adsorption capacity of these inorganic adsorbents and organic resin adsorbents for ammonia nitrogen wastewater treatment is usually less than 100 mg / g, which cannot meet practical application requirements. Summary of the Invention

[0004] The purpose of this invention is to provide an ammonia nitrogen treatment process to solve the problem that the adsorption capacity of inorganic adsorbents such as zeolite and organic resin adsorbents used in the current treatment of ammonia nitrogen wastewater is too small.

[0005] This invention provides an ammonia nitrogen treatment process, comprising the following steps: adsorbing ammonia nitrogen in wastewater using an adsorption resin, achieving adsorption equilibrium, and then performing solid-liquid separation to complete the treatment of ammonia nitrogen in the wastewater; the adsorption resin is prepared as follows: a monomer mixture is polymerized in a dispersion to obtain resin balls; then the resin balls and grafted monomers are mixed and reacted in a mixed solvent composed of water and an organic solvent to obtain an ion exchange resin; the ion exchange resin is then mixed with an acid solution to obtain the adsorption resin; the monomer mixture consists of divinylbenzene, 1,2-divinylcyclohexane, glycidyl methacrylate, and an initiator; the dispersion consists of water, gelatin, and cellulose; the grafted monomers consist of sodium aminosulfonate and sodium aminoethyl phosphate; and the organic solvent is dioxane.

[0006] Preferably, the molar ratio of divinylbenzene, 1,2-divinylcyclohexane and glycidyl methacrylate is 0.6~0.9:0.3~0.5:1.5~2.5.

[0007] Preferably, the mass fraction of gelatin in the dispersion is 1-3%, and the mass fraction of cellulose is 0.5-1%.

[0008] Preferably, the mass ratio of the monomer mixture to the dispersion is 1:3~5.

[0009] Preferably, the polymerization reaction is carried out at a temperature of 85-90°C for 4-6 hours.

[0010] Preferably, the initiator is benzoyl peroxide, and the mass fraction of benzoyl peroxide in the monomer mixture is 3-5%.

[0011] Preferably, the method for mixing and reacting the resin balls and grafting monomers is as follows: the grafting monomers, water, sodium hydroxide and organic solvent are mixed evenly to obtain a grafting solution, and then the resin balls and grafting solution are mixed and reacted at a temperature of 80~95℃ for 18~24h.

[0012] Preferably, the grafting solution contains 4-6% sodium hydroxide by mass and 20-25% grafting monomer by mass.

[0013] Preferably, the mass ratio of water to organic solvent in the grafting solution is 6~7:3~4.

[0014] Preferably, the molar ratio of amino groups in the grafted monomer to the molar ratio of epoxy groups on the surface of the resin ball is 1.3 to 1.5:1.

[0015] Compared to existing technologies, the beneficial effects of this invention are as follows: This invention utilizes divinylbenzene and 1,2-divinylcyclohexane as crosslinking agents to prepare resin balls. Because the resin ball matrix simultaneously contains rigid benzene rings and cyclohexane structures in both torsion boat and semi-chair configurations, it can simultaneously improve the hardness and surface roughness of the resin matrix, thereby increasing the molding strength of the resin balls and reducing their surface energy. This promotes the approach and adsorption of ammonia nitrogen from wastewater onto the adsorption resin, improving the adsorption effect and rate. Furthermore, this invention simultaneously grafts sulfonic acid groups and phosphate groups onto the resin balls. These two groups can exert a gradient adsorption effect, further improving the adsorption capacity and rate of ammonia nitrogen in wastewater. The adsorption resin used in this invention achieves a saturated adsorption capacity of over 248 mg / g for ammonia nitrogen and an adsorption rate of over 4.9 mg / g·min, enabling rapid and efficient treatment of ammonia nitrogen in wastewater. Detailed Implementation

[0016] The following examples are intended to further illustrate the content of the present invention, rather than to limit the scope of protection of the present invention.

[0017] The preparation method of sodium aminoethyl phosphate used in the various embodiments and comparative examples of the present invention is as follows: aminoethyl phosphate, sodium hydroxide solution and ethanol are added to a reaction vessel, heated to 40°C, stirred and reacted for 1.5 h, and dried to obtain sodium aminoethyl phosphate; wherein, the concentration of sodium hydroxide solution is 2 mol / L, the molar ratio of sodium hydroxide in aminoethyl phosphate and sodium hydroxide solution is 1:1, and the mass ratio of aminoethyl phosphate to ethanol is 1:0.8.

[0018] Example 1

[0019] The ammonia nitrogen treatment process in this embodiment includes the following steps:

[0020] (1) Add gelatin, cellulose and distilled water to a stirring vessel and stir evenly to obtain a dispersion; the mass fraction of gelatin in the dispersion is 1% and the mass fraction of cellulose is 0.5%; add the monomer mixture to the dispersion, stir evenly, heat to 85℃, keep warm for 4h, cool to room temperature and filter, wash the filtered solid with water to obtain resin balls; wherein, the monomer mixture is composed of divinylbenzene, 1,2-divinylcyclohexane, glycidyl methacrylate and benzoyl peroxide, the molar ratio of divinylbenzene, 1,2-divinylcyclohexane and glycidyl methacrylate is 0.6:0.3:1.5, the mass fraction of benzoyl peroxide in the monomer mixture is 3%; the mass ratio of monomer mixture to dispersion is 1:3.

[0021] (2) Add the grafting monomer, water, sodium hydroxide and organic solvent to a stirred reactor and stir until homogeneous to obtain a grafting solution (the mass fraction of sodium hydroxide in the grafting solution is 4%, the mass fraction of the grafting monomer is 20%, and the mass ratio of water to organic solvent is 6:3). Heat to 80°C, and under stirring conditions, add the resin balls to the stirred reactor and stir for 18 hours. After cooling to room temperature, filter the solution, wash the filtered solid with water, and dry it to obtain the ion exchange resin. The grafting monomer is composed of sodium aminosulfonate and sodium aminoethyl phosphate in a molar ratio of 2:1, the organic solvent is dioxane, and the molar ratio of the amino group in the grafting monomer to the epoxy group on the surface of the resin ball is 1.3:1.

[0022] (3) Immerse the ion exchange resin in hydrochloric acid for 24 hours and then filter it. Wash the solid obtained by filtration with water to obtain the adsorption resin. Then use the adsorption resin to adsorb ammonia nitrogen in the wastewater. After reaching adsorption equilibrium, filter it to complete the treatment of ammonia nitrogen in the wastewater. At the same time, stir and mix the solid obtained by filtration with 0.4 mol / L dilute sulfuric acid until the concentration of ammonium ions no longer changes. Filter it again and wash the solid obtained by filtration with distilled water to complete the regeneration of the adsorption resin.

[0023] Example 2

[0024] The ammonia nitrogen treatment process in this embodiment includes the following steps:

[0025] (1) Add gelatin, cellulose and distilled water to a stirring vessel and stir evenly to obtain a dispersion; the mass fraction of gelatin in the dispersion is 2% and the mass fraction of cellulose is 0.8%; add the monomer mixture to the dispersion, stir evenly, heat to 88℃, keep warm for 5h, cool to room temperature and filter, wash the filtered solid with water to obtain resin balls; wherein, the monomer mixture is composed of divinylbenzene, 1,2-divinylcyclohexane, glycidyl methacrylate and benzoyl peroxide, the molar ratio of divinylbenzene, 1,2-divinylcyclohexane and glycidyl methacrylate is 0.7:0.4:1.9, the mass fraction of benzoyl peroxide in the monomer mixture is 4%; the mass ratio of monomer mixture to dispersion is 1:4.

[0026] (2) Add the grafting monomer, water, sodium hydroxide and organic solvent to a stirred reactor and stir until homogeneous to obtain a grafting solution (the mass fraction of sodium hydroxide in the grafting solution is 5%, the mass fraction of the grafting monomer is 22%, and the mass ratio of water to organic solvent is 6:4). Heat to 85°C, and under stirring conditions, add the resin balls to the stirred reactor and stir for 20 hours. After cooling to room temperature, filter the solution, wash the filtered solid with water, and dry it to obtain the ion exchange resin. The grafting monomer is composed of sodium aminosulfonate and sodium aminoethyl phosphate in a molar ratio of 3:2, the organic solvent is dioxane, and the molar ratio of the amino group in the grafting monomer to the epoxy group on the surface of the resin ball is 1.4:1.

[0027] (3) Immerse the ion exchange resin in hydrochloric acid for 24 hours and then filter it. Wash the solid obtained by filtration with water to obtain the adsorption resin. Then use the adsorption resin to adsorb ammonia nitrogen in the wastewater. After reaching adsorption equilibrium, filter it to complete the treatment of ammonia nitrogen in the wastewater. At the same time, stir and mix the solid obtained by filtration with 0.5 mol / L dilute sulfuric acid until the concentration of ammonium ions no longer changes. Filter it again and wash the solid obtained by filtration with distilled water to complete the regeneration of the adsorption resin.

[0028] Example 3

[0029] The ammonia nitrogen treatment process in this embodiment includes the following steps:

[0030] (1) Add gelatin, cellulose and distilled water to a stirring vessel and stir evenly to obtain a dispersion; the mass fraction of gelatin in the dispersion is 3% and the mass fraction of cellulose is 1%; add the monomer mixture to the dispersion, stir evenly, heat to 90℃, keep warm for 6h, cool to room temperature and filter, wash the filtered solid with water to obtain resin balls; wherein, the monomer mixture is composed of divinylbenzene, 1,2-divinylcyclohexane, glycidyl methacrylate and benzoyl peroxide, the molar ratio of divinylbenzene, 1,2-divinylcyclohexane and glycidyl methacrylate is 0.9:0.5:2.5, the mass fraction of benzoyl peroxide in the monomer mixture is 5%; the mass ratio of monomer mixture to dispersion is 1:5.

[0031] (2) Add the grafting monomer, water, sodium hydroxide and organic solvent to a stirred reactor and stir until homogeneous to obtain a grafting solution (the mass fraction of sodium hydroxide in the grafting solution is 6%, the mass fraction of the grafting monomer is 25%, and the mass ratio of water to organic solvent is 7:4). Heat to 95°C, and under stirring conditions, add the resin balls to the stirred reactor and stir for 24 hours. After cooling to room temperature, filter the solution, wash the filtered solid with water, and dry it to obtain the ion exchange resin. The grafting monomer is composed of sodium aminosulfonate and sodium aminoethyl phosphate in a molar ratio of 4:3, the organic solvent is dioxane, and the molar ratio of the amino group in the grafting monomer to the molar ratio of the epoxy group on the surface of the resin ball is 1.5:1.

[0032] (3) Immerse the ion exchange resin in hydrochloric acid and filter it after 24 hours. Wash the solid obtained by filtration with water to obtain the adsorption resin. Then use the adsorption resin to adsorb ammonia nitrogen in the wastewater. After reaching adsorption equilibrium, filter it to complete the treatment of ammonia nitrogen in the wastewater. At the same time, stir and mix the solid obtained by filtration with 0.6 mol / L dilute sulfuric acid until the concentration of ammonium ions no longer changes. Filter it again and wash the solid obtained by filtration with distilled water to complete the regeneration of the adsorption resin.

[0033] Comparative Example 1

[0034] The only difference between the ammonia nitrogen treatment process of this comparative example and the ammonia nitrogen treatment process of Example 1 is that in step (1) of the ammonia nitrogen treatment process of this comparative example, the monomer mixture is composed of divinylbenzene, glycidyl methacrylate and benzoyl peroxide, the molar ratio of divinylbenzene and glycidyl methacrylate is 0.9:1.5, and the mass fraction of benzoyl peroxide in the monomer mixture is 3%.

[0035] Comparative Example 2

[0036] The only difference between the ammonia nitrogen treatment process of this comparative example and the ammonia nitrogen treatment process of Example 1 is that in step (1) of the ammonia nitrogen treatment process of this comparative example, the monomer mixture consists of 1,2-divinylcyclohexane, glycidyl methacrylate and benzoyl peroxide, the molar ratio of 1,2-divinylcyclohexane and glycidyl methacrylate is 0.9:1.5, and the mass fraction of benzoyl peroxide in the monomer mixture is 3%.

[0037] Comparative Example 3

[0038] The only difference between the ammonia nitrogen treatment process of this comparative example and the ammonia nitrogen treatment process of Example 1 is that the grafting monomer in step (2) of the ammonia nitrogen treatment process of this comparative example is sodium aminosulfonate.

[0039] Comparative Example 4

[0040] The only difference between the ammonia nitrogen treatment process of this comparative example and the ammonia nitrogen treatment process of Example 1 is that the grafted monomer in step (2) of the ammonia nitrogen treatment process of this comparative example is sodium aminoethyl phosphate.

[0041] Comparative Example 5

[0042] The only difference between the ammonia nitrogen treatment process of this comparative example and the ammonia nitrogen treatment process of Example 1 is that the organic solvent used in step (2) of the ammonia nitrogen treatment process of this comparative example is dimethyl sulfoxide.

[0043] Comparative Example 6

[0044] The only difference between the ammonia nitrogen treatment process of this comparative example and the ammonia nitrogen treatment process of Example 1 is that the organic solvent used in step (2) of the ammonia nitrogen treatment process of this comparative example is tetrahydrofuran.

[0045] Example of effect

[0046] To evaluate the treatment effect and cost of the ammonia nitrogen treatment processes in each embodiment and comparative example, the adsorption resins prepared in each embodiment and comparative example were added to conical flasks. Simulated ammonia nitrogen wastewater (ammonia nitrogen concentration of 5000 mg / L, pH 7.8) was then added to the conical flasks. The flasks were then placed in a constant-temperature water bath shaking chamber and shaken at a constant speed (temperature 30℃, speed 100 rpm). The ammonia nitrogen concentration in the wastewater was measured and analyzed at regular intervals until the ammonia nitrogen concentration no longer changed. The initial concentration C0 and the final concentration C of the ammonia nitrogen in the wastewater were then used as the basis for the determination of the ammonia nitrogen concentration. Z Calculate the adsorption rate of ammonia nitrogen by the adsorption resin. Adsorption rate = (C0 - C) Z ) / C0×100%, and based on the wastewater volume V, the initial concentration of ammonia nitrogen in the wastewater C0, and the final concentration C ZGiven the mass m of the adsorption resin, calculate the saturated adsorption capacity of ammonia nitrogen per unit mass of adsorption resin. Saturated adsorption capacity = V × (C0 - C) Z Finally, based on the ammonia nitrogen saturation adsorption capacity and the time t required for the adsorption resin to reach the ammonia nitrogen saturation adsorption capacity, the ammonia nitrogen adsorption rate (adsorption rate = ammonia nitrogen saturation adsorption capacity / t) was calculated. The experimental results are shown in Table 1.

[0047] Table 1. Adsorption rate, saturated adsorption capacity, and adsorption rate of ammonia nitrogen by the adsorption resin in the ammonia nitrogen treatment processes of each embodiment and comparative example.

[0048]

[0049] As shown in Table 1, the adsorption resin used in the ammonia nitrogen treatment process of the present invention has a large adsorption capacity, adsorption rate and fast adsorption speed for ammonia nitrogen, and has good treatment effect and low treatment cost when treating ammonia nitrogen wastewater.

[0050] As shown in Example 1 and Comparative Examples 1-2, when divinylbenzene and 1,2-divinylcyclohexane are used simultaneously to prepare the adsorption resin, the presence of both rigid benzene rings and torsion boat and semi-chair cyclohexane structures in the resin ball matrix simultaneously increases the hardness and surface roughness of the resin matrix. This, in turn, improves the molding strength of the resin balls and reduces their surface energy, promoting the approach and adsorption of ammonia nitrogen from the wastewater onto the adsorption resin, thus enhancing the adsorption effect and rate. However, when divinylbenzene or 1,2-divinylcyclohexane is used alone, the lack of rigid benzene rings or torsion boat and semi-chair cyclohexane structures leads to a decrease in the adsorption effect of the adsorption resin.

[0051] As shown in Example 1 and Comparative Examples 3-4, when sodium aminosulfonate and sodium aminophosphate are grafted onto the surface of the resin balls simultaneously, the adsorption resin matrix contains uniformly distributed sulfonic acid groups and phosphate groups. These sulfonic acid and phosphate groups can exert a gradient adsorption effect, thereby increasing the adsorption capacity and rate of ammonia nitrogen in wastewater. When sodium aminosulfonate and sodium aminophosphate are used alone, the adsorption resin contains only phosphate groups or sulfonic acid groups, which cannot exert a gradient adsorption effect, resulting in a significant decrease in adsorption capacity and rate.

[0052] As shown in Example 1 and Comparative Examples 5-6, the organic solvent used in the grafting reaction has a significant impact on the performance of the adsorption resin. This is because the reaction between the resin balls and the grafted monomers is a solid-liquid reaction. The organic solvent can promote the migration of the grafted monomers to the resin balls, improving the grafting efficiency, and thus increasing the content of sulfonic acid groups and phosphate groups on the surface of the adsorption resin, thereby increasing the adsorption capacity and adsorption rate. The experimental results of Example 1 and Comparative Examples 5-6 show that, compared with dimethyl sulfoxide and tetrahydrofuran, dioxane can better improve the affinity between the resin balls and the grafted monomers, thereby improving the adsorption effect of the adsorption resin on ammonia nitrogen.

[0053] Therefore, this invention utilizes divinylbenzene and 1,2-divinylcyclohexane as crosslinking agents to prepare resin balls. Because the resin ball matrix simultaneously contains rigid benzene rings and cyclohexane structures in both torsion boat and semi-chair configurations, the hardness and surface roughness of the resin matrix can be increased simultaneously, thereby improving the molding strength of the resin balls and reducing their surface energy. This promotes the approach and adsorption of ammonia nitrogen from wastewater onto the adsorption resin, improving the adsorption effect and rate. Furthermore, this invention simultaneously grafts sulfonic acid groups and phosphate groups onto the resin balls. These two groups can exert a gradient adsorption effect, further improving the adsorption capacity and rate of ammonia nitrogen in wastewater.

Claims

1. An ammonia nitrogen treatment process, characterized in that, Includes the following steps: Ammonia nitrogen in wastewater is adsorbed using an adsorption resin. After adsorption equilibrium is reached, solid-liquid separation is performed to complete the treatment of ammonia nitrogen in the wastewater. The preparation method of the adsorption resin is as follows: a monomer mixture is polymerized in a dispersion to obtain resin balls; then the resin balls and grafted monomers are mixed and reacted in a mixed solvent composed of water and an organic solvent to obtain an ion exchange resin; the ion exchange resin is then mixed with an acid solution to obtain the adsorption resin; the monomer mixture consists of divinylbenzene, 1,2-divinylcyclohexane, glycidyl methacrylate, and an initiator; the dispersion consists of water, gelatin, and cellulose; the grafted monomers consist of sodium aminosulfonate and sodium aminoethyl phosphate; and the organic solvent is dioxane.

2. The ammonia nitrogen treatment process as described in claim 1, characterized in that, The molar ratio of divinylbenzene, 1,2-divinylcyclohexane, and glycidyl methacrylate is 0.6~0.9:0.3~0.5:1.5~2.

5.

3. The ammonia nitrogen treatment process as described in claim 1, characterized in that, The dispersion contains 1-3% gelatin and 0.5-1% cellulose by mass.

4. The ammonia nitrogen treatment process as described in claim 1, characterized in that, The mass ratio of the monomer mixture to the dispersion is 1:3~5.

5. The ammonia nitrogen treatment process according to any one of claims 1-4, characterized in that, The polymerization reaction is carried out at a temperature of 85-90°C for 4-6 hours.

6. The ammonia nitrogen treatment process as described in claim 5, characterized in that, The initiator is benzoyl peroxide, and the mass fraction of benzoyl peroxide in the monomer mixture is 3-5%.

7. The ammonia nitrogen treatment process as described in claim 1, characterized in that, The method for mixing and reacting resin balls and grafting monomers is as follows: mix grafting monomers, water, sodium hydroxide and organic solvent evenly to obtain grafting solution, and then mix and react resin balls and grafting solution at 80~95℃ for 18~24h.

8. The ammonia nitrogen treatment process as described in claim 7, characterized in that, The grafting solution contains 4-6% sodium hydroxide by mass and 20-25% grafting monomer by mass.

9. The ammonia nitrogen treatment process as described in claim 7, characterized in that, The mass ratio of water to organic solvent in the grafting solution is 6~7:3~4.

10. The ammonia nitrogen treatment process as described in claim 7, characterized in that, The molar ratio of amino groups in the grafted monomer to the molar ratio of epoxy groups on the surface of the resin ball is 1.3~1.5:1.

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