Ammonia nitrogen treatment process

Abstract

The invention relates to an ammonia nitrogen treatment process, and belongs to the technical field of wastewater treatment. According to the invention, divinyl benzene and 1, 2-divinyl cyclohexane are used as cross-linking agents to prepare the resin ball, and a resin ball matrix simultaneously contains rigid benzene rings and is of a twisted boat type and half-chair type cyclohexane structure, so that the hardness and the surface roughness of the resin matrix can be simultaneously improved; further, the forming strength of the resin ball is improved, the surface energy of the resin ball is reduced, ammonia nitrogen in wastewater is promoted to approach and be adsorbed to adsorption resin, and the adsorption effect and the adsorption rate are improved. In addition, the sulfonic acid group and the phosphate group are grafted to the resin ball at the same time, the two groups can play a gradient adsorption role, and the adsorption capacity and the adsorption rate of ammonia nitrogen in wastewater are further improved.

Description

Technical Field

[0001] The invention relates to an ammonia nitrogen treatment process and belongs to the technical field of wastewater treatment. Background Art

[0002] Among the many polluted water bodies, ammonia-nitrogen wastewater is a major form of wastewater. The increasing discharge of ammonia-containing wastewater poses a serious threat to the ecological balance. High-concentration nitrogen-containing wastewater is toxic to humans, animals, and plants, severely harming the ecological environment. Microbial degradation of ammonia-nitrogen also converts it into nitrate or nitrite nitrogen. These products are carcinogenic and teratogenic, posing significant risks to humans and other organisms. Furthermore, the conversion of ammonia-nitrogen depletes dissolved oxygen in the water, leading to mass fish deaths in rivers, damaging the aquatic environment, and accelerating eutrophication.

[0003] Ion exchange is an effective method for removing ammonia nitrogen. Its mass transfer mechanism primarily involves utilizing the concentration difference between ions and the affinity of functional groups on the exchanger for the ions as the driving force for ion exchange at the interface between solid particles and liquid. This reaction is generally a reversible process. Currently, adsorbents used for treating ammonia nitrogen wastewater primarily include inorganic adsorbents such as zeolites and organic resins. However, the ammonia nitrogen adsorption capacity of these inorganic adsorbents, such as zeolites, and organic resins used in ammonia nitrogen wastewater treatment is typically less than 100 mg / g, which does not meet practical application requirements. Summary of the Invention

[0004] The purpose of the present invention is to provide an ammonia nitrogen treatment process to solve the problem that the inorganic adsorbents such as zeolite and organic resin adsorbents currently used for ammonia nitrogen wastewater treatment have low adsorption capacity for ammonia nitrogen.

[0005] The invention provides an ammonia nitrogen treatment process, comprising the following steps: using an adsorption resin to adsorb ammonia nitrogen in wastewater, and after reaching adsorption equilibrium, performing solid-liquid separation to complete the treatment of ammonia nitrogen in the wastewater; the preparation method of the adsorption resin is as follows: subjecting a monomer mixture to a polymerization reaction in a dispersion to obtain resin balls; then subjecting the resin balls and a grafted monomer to a mixed reaction in a mixed solvent consisting of water and an organic solvent to obtain an ion exchange resin; and then mixing the ion exchange resin with an acid solution to obtain the adsorption resin; the monomer mixture is composed of divinylbenzene, 1,2-divinylcyclohexane, glycidyl methacrylate and an initiator; the dispersion is composed of water, gelatin and cellulose; the grafted monomer is composed of sodium sulfamate 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 temperature is 85-90° C., and the time is 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 resin balls and the grafting monomer are mixed and reacted as follows: the grafting monomer, water, sodium hydroxide and an organic solvent are uniformly mixed to obtain a grafting solution, and then the resin balls and the grafting solution are mixed and reacted at a temperature of 80-95° C. for 18-24 hours.

[0012] Preferably, the mass fraction of sodium hydroxide in the grafting solution is 4-6%, and the mass fraction of the grafting monomer is 20-25%.

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

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

[0015] Compared with the prior art, the beneficial effects of the present invention are as follows: The present invention utilizes divinylbenzene and 1,2-divinylcyclohexane as cross-linking agents to prepare resin balls. Since the resin ball matrix contains both rigid benzene rings and cyclohexane structures in the form of twisted boats and half-chairs, the hardness and surface roughness of the resin matrix can be improved at the same time, thereby improving the molding strength of the resin balls and reducing the surface energy of the resin balls, promoting the ammonia nitrogen in the wastewater to approach and be adsorbed on the adsorption resin, and improving the adsorption effect and adsorption rate. In addition, the present invention simultaneously grafts sulfonic acid groups and phosphoric acid groups onto the resin balls. The two groups can exert a gradient adsorption effect, further improving the adsorption capacity and adsorption rate of ammonia nitrogen in the wastewater. The adsorption resin used in the present invention has a saturated adsorption capacity of more than 248 mg / g for ammonia nitrogen and an adsorption rate of more than 4.9 mg / g·min, which can quickly and efficiently treat ammonia nitrogen in wastewater. DETAILED DESCRIPTION

[0016] The following examples are intended to further illustrate the present invention, but are not intended to limit the scope of protection of the present invention.

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

[0018] Example 1

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

[0020] (1) Add gelatin, cellulose and distilled water into a stirring tank and stir them 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 a monomer mixture into the dispersion, stir it evenly, heat it to 85°C, keep it warm for 4 hours, cool it to room temperature and filter it, wash the filtered solid with water to obtain resin balls; wherein the monomer mixture consists 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, and the mass fraction of benzoyl peroxide in the monomer mixture is 3%; the mass ratio of the monomer mixture to the dispersion is 1:3.

[0021] (2) Grafting monomer, water, sodium hydroxide and organic solvent are added to a stirred reactor and stirred evenly to obtain a grafting solution (the mass fraction of sodium hydroxide in the grafting solution is 4%, the mass fraction of grafting monomer is 20%, and the mass ratio of water to organic solvent is 6:3). The solution is heated to 80°C and, under stirring, resin balls are added to the stirred reactor. The mixture is stirred for 18 hours and filtered after cooling to room temperature. The filtered solid is washed with water and dried to obtain an ion exchange resin. The grafting monomer is composed of sodium aminosulfonate and sodium aminoethylphosphate in a molar ratio of 2:1, the organic solvent is dioxane, and the ratio of the molar amount of amino groups in the grafting monomer to the molar amount of epoxy groups on the surface of the resin balls is 1.3:1.

[0022] (3) Immerse the ion exchange resin in hydrochloric acid and filter it after 24 hours. Wash the filtered solid with water to obtain an 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 filtered solid with 0.4 mol / L dilute sulfuric acid until the ammonium ion concentration no longer changes, filter it again, and wash the filtered solid with distilled water to complete the regeneration of the adsorption resin.

[0023] Example 2

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

[0025] (1) Add gelatin, cellulose and distilled water into a stirring tank and stir them 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 a monomer mixture into the dispersion, stir it evenly, heat it to 88°C, keep it warm for 5 hours, cool it to room temperature and filter it, wash the filtered solid with water to obtain resin balls; wherein the monomer mixture consists 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, and the mass fraction of benzoyl peroxide in the monomer mixture is 4%; the mass ratio of the monomer mixture to the dispersion is 1:4.

[0026] (2) Grafting monomer, water, sodium hydroxide and organic solvent are added to a stirred reactor and stirred evenly to obtain a grafting solution (the mass fraction of sodium hydroxide in the grafting solution is 5%, the mass fraction of grafting monomer is 22%, and the mass ratio of water to organic solvent is 6:4), which is heated to 85°C. Under stirring conditions, resin balls are added to the stirred reactor and stirred for 20 hours. After cooling to room temperature, the mixture is filtered and the filtered solid is washed with water and dried to obtain an ion exchange resin; wherein the grafting monomer is composed of sodium aminosulfonate and sodium aminoethylphosphate in a molar ratio of 3:2, the organic solvent is dioxane, and the ratio of the molar amount of amino groups in the grafting monomer to the molar amount of epoxy groups on the surface of the resin balls is 1.4:1.

[0027] (3) Immerse the ion exchange resin in hydrochloric acid and filter it after 24 hours. Wash the filtered solid with water to obtain an 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 filtered solid with 0.5 mol / L dilute sulfuric acid until the ammonium ion concentration no longer changes, filter it again, and wash the filtered solid with distilled water to complete the regeneration of the adsorption resin.

[0028] Example 3

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

[0030] (1) Add gelatin, cellulose and distilled water into a stirring tank and stir them evenly to obtain a dispersion; the mass fraction of gelatin in the dispersion is 3%, and the mass fraction of cellulose is 1%; add a monomer mixture into the dispersion, stir it evenly, heat it to 90°C, keep it warm for 6 hours, cool it to room temperature and filter it, wash the filtered solid with water to obtain resin balls; wherein the monomer mixture consists 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, and the mass fraction of benzoyl peroxide in the monomer mixture is 5%; the mass ratio of the monomer mixture to the dispersion is 1:5.

[0031] (2) Grafting monomer, water, sodium hydroxide and organic solvent are added to a stirred reactor and stirred evenly to obtain a grafting solution (the mass fraction of sodium hydroxide in the grafting solution is 6%, the mass fraction of grafting monomer is 25%, and the mass ratio of water to organic solvent is 7:4). The solution is heated to 95°C and resin balls are added to the stirred reactor under stirring conditions. The mixture is stirred for 24 hours and filtered after cooling to room temperature. The filtered solid is washed with water and dried to obtain an ion exchange resin. The grafting monomer is composed of sodium aminosulfonate and sodium aminoethylphosphate in a molar ratio of 4:3, the organic solvent is dioxane, and the ratio of the molar amount of amino groups in the grafting monomer to the molar amount of epoxy groups on the surface of the resin balls is 1.5:1.

[0032] (3) Immerse the ion exchange resin in hydrochloric acid and filter it after 24 hours. Wash the filtered solid with water to obtain an 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 filtered solid with 0.6 mol / L dilute sulfuric acid until the ammonium ion concentration no longer changes, filter it again, and wash the filtered solid with distilled water to complete the regeneration of the adsorption resin.

[0033] Comparative Example 1

[0034] The 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 divinylbenzene, glycidyl methacrylate and benzoyl peroxide, the molar ratio of divinylbenzene to 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 to 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 grafting 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] Effect Examples

[0046] In order to evaluate the treatment effect and treatment cost of the ammonia nitrogen treatment process of each embodiment and comparative example, the adsorption resin prepared in the ammonia nitrogen treatment process of each embodiment and comparative example was added to a conical flask, and then the simulated ammonia nitrogen wastewater (ammonia nitrogen concentration of 5000 mg / L, pH of 7.8) was added to the conical flask. The conical flask was then placed in a constant temperature water bath oscillating box and oscillated at a constant speed (temperature of 30°C, speed of 100 rpm). The ammonia nitrogen concentration in the wastewater was taken out for testing and analysis at regular intervals until the ammonia nitrogen concentration no longer changed. According to the initial concentration C0 of ammonia nitrogen in the wastewater and the end point concentration C Z , calculate the adsorption rate of ammonia nitrogen by adsorption resin, adsorption rate = (C0-C Z ) / C0×100%, and according to the wastewater volume V, the initial concentration of ammonia nitrogen in the wastewater C0, the end point concentration C Zand the mass m of the adsorption resin, calculate the saturated adsorption capacity of ammonia nitrogen per unit mass of the adsorption resin, saturated adsorption capacity = V × (C0-C Z ) / m, and finally, according to the saturated adsorption capacity of ammonia nitrogen and the time t required for the adsorption resin to reach the saturated adsorption capacity of ammonia nitrogen, the ammonia nitrogen adsorption rate was calculated (adsorption rate = saturated adsorption capacity of ammonia nitrogen / t). 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 process of each embodiment and comparative example

[0048]

[0049] As can be seen from 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 rate for ammonia nitrogen, and has good treatment effect and low treatment cost when treating ammonia nitrogen wastewater.

[0050] As can be seen from Example 1 and Comparative Examples 1-2, when divinylbenzene and 1,2-divinylcyclohexane are used simultaneously to prepare the adsorption resin, the hardness and surface roughness of the resin matrix can be simultaneously improved because the resin ball matrix contains both rigid benzene rings and cyclohexane structures in the form of twisted boats and half-chairs. This increases the molding strength of the resin balls and reduces the surface energy of the resin balls, promoting the ammonia nitrogen in the wastewater to approach and be adsorbed on the adsorption resin, thereby improving the adsorption effect and adsorption rate. However, when divinylbenzene or 1,2-divinylcyclohexane is used alone, the adsorption effect of the adsorption resin is poor due to the lack of rigid benzene rings or cyclohexane structures in the form of twisted boats and half-chairs.

[0051] As shown in Example 1 and Comparative Examples 3-4, when sodium sulfamate and sodium aminophosphate are simultaneously grafted onto the surface of the resin spheres, the adsorption resin matrix contains uniformly distributed sulfonic acid and phosphate groups. These groups can exert a gradient adsorption effect, thereby increasing the adsorption capacity and rate of ammonia nitrogen in the wastewater. When sodium sulfamate and sodium aminophosphate are used alone, the adsorption resin contains only phosphate or sulfonic acid groups, which prevents the gradient adsorption effect and significantly reduces the adsorption capacity and rate.

[0052] As shown in Example 1 and Comparative Examples 5-6, the organic solvent used in the grafting reaction also significantly affects the performance of the adsorption resin. This is because the reaction between the resin spheres and the grafted monomer is a solid-liquid reaction. The organic solvent can promote the migration of the grafted monomer to the resin spheres, improving the grafting efficiency. This in turn increases the content of sulfonic acid and phosphate groups on the adsorption resin surface, thereby improving the adsorption capacity and adsorption rate. The experimental results of Example 1 and Comparative Examples 5-6 show that, compared to dimethyl sulfoxide and tetrahydrofuran, dioxane can further enhance the affinity between the resin spheres and the grafted monomer, thereby improving the adsorption efficiency of the adsorption resin for ammonia nitrogen.

[0053] Therefore, the present invention utilizes divinylbenzene and 1,2-divinylcyclohexane as cross-linking agents to prepare resin spheres. Because the resin sphere matrix contains both rigid benzene rings and twisted boat and half-chair cyclohexane structures, the hardness and surface roughness of the resin matrix can be simultaneously increased, thereby improving the molding strength of the resin spheres and reducing their surface energy, promoting the approach and adsorption of ammonia nitrogen in wastewater to the adsorption resin, thereby improving the adsorption effect and adsorption rate. Furthermore, the present invention simultaneously grafts sulfonic acid groups and phosphoric acid groups onto the resin spheres. These two groups can exert a gradient adsorption effect, further increasing the adsorption capacity and adsorption rate of ammonia nitrogen in wastewater.

Claims

1. An ammonia nitrogen treatment process, characterized in that: The following steps are involved: Ammonia nitrogen in wastewater is adsorbed by an adsorption resin, and after reaching adsorption equilibrium, 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 subjected to a polymerization reaction in a dispersion to obtain resin balls; the resin balls and a grafted monomer are then mixed and reacted in a mixed solvent consisting of water and an organic solvent to obtain an ion exchange resin, and the ion exchange resin is then mixed with an acid solution to obtain an adsorption resin; the monomer mixture is composed of divinylbenzene, 1,2-divinylcyclohexane, glycidyl methacrylate and an initiator, the dispersion is composed of water, gelatin and cellulose, the grafted monomer is composed of sodium aminosulfonate and sodium aminoethyl phosphate, and the organic solvent is dioxane.

2. The ammonia nitrogen treatment process according to claim 1, wherein 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 according to claim 1, wherein: The mass fraction of gelatin in the dispersion is 1-3%, and the mass fraction of cellulose is 0.5-1%.

4. The ammonia nitrogen treatment process according to claim 1, wherein: 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 to 4, characterized in that: The polymerization reaction temperature is 85-90° C. and the reaction time is 4-6 hours.

6. The ammonia nitrogen treatment process according to 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 according to claim 1, wherein: The method for mixing the resin balls and the grafting monomer is as follows: the grafting monomer, water, sodium hydroxide and an organic solvent are evenly mixed to obtain a grafting liquid, and then the resin balls and the grafting liquid are mixed and reacted at a temperature of 80-95° C. for 18-24 hours.

8. The ammonia nitrogen treatment process according to claim 7, wherein: The mass fraction of sodium hydroxide in the grafting solution is 4-6%, and the mass fraction of the grafting monomer is 20-25%.

9. The ammonia nitrogen treatment process according to claim 7, wherein: The mass ratio of water to organic solvent in the grafting liquid is 6-7:3-4.

10. The ammonia nitrogen treatment process according to claim 7, characterized in that: The ratio of the molar amount of the amino group in the grafting monomer to the molar amount of the epoxy group on the surface of the resin ball is 1.3-1.5:1.

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