Aquaculture wastewater treatment agent and application thereof

Abstract

The invention discloses an aquaculture wastewater treatment agent and application thereof, and belongs to the technical field of wastewater treatment. The treatment agent is prepared by the following steps: treating crab shells of cultured aquatic products to obtain chitin, taking the chitin as a base material, and reacting with 4-methoxy-N-methyl-1-butylamine and 2-methyl-1-(methylthio) propan-2-amine in the presence of a cross-linking agent epichlorohydrin. The wastewater treatment agent prepared by the method has efficient flocculation turbidity removal and metal ion adsorption properties, is suitable for large-scale treatment of aquaculture wastewater, solves the problems of low efficiency and high cost of a traditional treatment agent, and has remarkable economic benefits and environmental benefits.

Description

Technical Field

[0001] The present invention belongs to the technical field of aquaculture wastewater treatment, and specifically relates to an aquaculture wastewater treatment agent and its application. Background Art

[0002] With the large-scale development of the aquaculture industry, aquaculture wastewater has become an important source of water pollution due to its rich pollutants such as suspended solids, organic matter, nitrogen and phosphorus nutrients, and metal ions.

[0003] Currently, common inorganic flocculants, such as polyaluminum chloride, can remove suspended solids, but are prone to aluminum ion residues and have limited removal effects on organic matter and metal ions; organic polymer flocculants, such as polyacrylamide, have problems such as poor biodegradability and high costs. As a natural polymer material, chitin has biocompatibility and degradability, but the hydroxyl groups on its molecular chain have strong hydrophilicity, resulting in low flocculation efficiency during direct application and requiring chemical modification to improve the charge density and adsorption performance.

[0004] Meanwhile, metal ions such as copper ions in aquaculture wastewater need to rely on specific adsorption of functional groups on the material surface. Although traditional adsorbents such as activated carbon and resin have certain effects, they have problems such as low adsorption capacity, difficult regeneration, or high costs.

[0005] The complexity of aquaculture wastewater requires the treatment agent to have both flocculation and turbidity removal and pollutant adsorption functions. However, in the existing technology, the flocculation and adsorption processes are usually carried out step by step, with a cumbersome process and high costs. Therefore, developing an "flocculation-adsorption" integrated treatment agent to achieve the synergistic effect of rapid turbidity removal and efficient metal ion adsorption through reasonable design of modified groups and structures is an urgent technical problem to be solved currently. Summary of the Invention

[0006] The purpose of the present invention is to provide a wastewater treatment agent with high efficiency in flocculation and adsorption, simple process, and environmental friendliness.

[0007] The technical solution adopted by the present invention to achieve the above purpose is as follows: A wastewater treatment agent, which is a chitin-based polymer compound, and amine derivatives are grafted onto the chitin crosslinking. The amine derivatives include 4-methoxy-N-methyl-1-butylamine and 2-methyl-1-(methylthio)propan-2-amine.

[0008] Preferably, the mass ratio of 4-methoxy-N-methyl-1-butylamine to chitin is 1-10:2-20.

[0009] Preferably, the mass ratio of 2-methyl-1-(methylthio)propan-2-amine to chitin is 1-10:2-20.

[0010] Under the action of the cross-linking agent epichlorohydrin, 4-methoxy-N-methyl-1-butanamine and 2-methyl-1-(methylthio)propan-2-amine are grafted onto the chitin backbone. Through the synergistic effect of electrostatic neutralization and hydrogen bond adsorption, it can endow the wastewater treatment agent with dual functions of flocculation and turbidity removal and metal ion adsorption, reduce the repulsive force between particles while promoting the bridging aggregation of flocs and accelerating sedimentation, effectively improving the flocculation efficiency and adsorption effect; during the process of participating in the reaction to construct the hydrogel structure, it can change the spatial configuration and porosity of the product, form a richer pore structure, increase the specific surface area, provide more space for adsorbing pollutants, and improve the adsorption efficiency.

[0011] A preparation method of a wastewater treatment agent includes the following preparation steps: The crab shells in aquaculture are decomposed and purified by biomass to obtain chitin; Dissolve chitin in an aqueous solution of sodium hydroxide / urea, add an amino derivative and a cross-linking agent for grafting reaction to obtain a wastewater treatment agent.

[0012] Preferably, the cross-linking agent is epichlorohydrin.

[0013] Preferably, the volume-mass ratio of epichlorohydrin to chitin is 0.75 - 7.5 mL: 2 - 20 g.

[0014] Preferably, in the aqueous solution of sodium hydroxide / urea, the content of sodium hydroxide is 5 - 15 wt%.

[0015] Preferably, in the aqueous solution of sodium hydroxide / urea, the content of urea is 2 - 10 wt%.

[0016] Preferably, the mass ratio of chitin to the aqueous solution of sodium hydroxide / urea is 2 - 20: 50 - 500.

[0017] Preferably, the grafting reaction temperature is 0 - 5 °C, and the reaction duration is 1 - 3 h.

[0018] More preferably, the amino derivative may further include polyacrylamine hydrochloride, and the mass ratio of polyacrylamine hydrochloride to chitin is 1 - 10: 2 - 20. The introduction of polyacrylamine hydrochloride can further optimize the molecular chain structure, enhance the dispersibility and site contact efficiency of the treatment agent; increase its mechanical strength and stability, making it not easy to break or dissolve during the wastewater treatment process, which is beneficial for repeated use and long-term stable adsorption; through the synergistic effect of multiple amino groups, it realizes the efficient removal of suspended solids and metal ions in aquaculture wastewater, and has significant practical application value.

[0019] An application of a wastewater treatment agent in wastewater treatment, where the wastewater includes freshwater aquaculture wastewater or seawater aquaculture wastewater.

[0020] Preferably, the dosage of the wastewater treatment agent is 0.1 - 1.0 g / L, and the pH of the treatment system is 6.0 - 8.0.

[0021] The present invention also provides a preparation method of chitin, comprising: Preparation of chitin: Wash the cultured crab shells with deionized water, dry them to constant weight at 45 - 55 °C to obtain washed crab shells; at room temperature, soak the washed crab shells in a hydrochloric acid solution with a concentration of 0.5 - 1.5 mol / L for 3 - 5 h for decalcification treatment, filter and wash with deionized water until the filtrate is neutral, dry the filter residue to constant weight at 45 - 55 °C to obtain decalcified filter residue; at 85 - 95 °C, soak the decalcified filter residue in a sodium hydroxide solution with a concentration of 1.5 - 2.5 mol / L for 3 - 5 h for deproteinization treatment, filter and wash with deionized water until the filtrate is neutral, dry the filter residue to constant weight at 45 - 55 °C to obtain deproteinized filter residue; soak the deproteinized filter residue in a hydrogen peroxide solution with a concentration of 2.5 - 3.5 mol / L for 1 - 3 h for decolorization treatment, filter and wash with deionized water until the filtrate is neutral, dry the filter residue to constant weight at 45 - 55 °C to obtain decolorized filter residue; dissolve the decolorized filter residue in dimethylformamide, filter and add absolute ethanol to the filtrate for reprecipitation, dry to constant weight at 45 - 55 °C to obtain chitin.

[0022] Preferably, the mass - volume ratio of the washed crab shells to the hydrochloric acid solution is 5 - 50 g:50 - 500 mL.

[0023] Preferably, the mass - volume ratio of the decalcified filter residue to the sodium hydroxide solution is 5 - 50 g:50 - 500 mL.

[0024] Preferably, the mass - volume ratio of the deproteinized filter residue to the hydrogen peroxide solution is 5 - 50 g:50 - 500 mL.

[0025] Preferably, the mass - volume ratio of the decolorized filter residue to dimethylformamide is 5 - 50 g:50 - 500 mL.

[0026] Preferably, the mass - volume ratio of the decolorized filter residue to absolute ethanol is 5 - 50 g:50 - 500 mL.

[0027] The present invention also provides a preparation method of a wastewater treatment agent, comprising: Preparation of wastewater treatment agent: Dissolve sodium hydroxide and urea in deionized water to obtain a sodium hydroxide / urea aqueous solution. Add chitin, stir evenly, add 4-methoxy-N-methyl-1-butylamine and 2-methyl-1-(methylthio)propan-2-amine at 0 - 5 °C under stirring conditions, stir for 0.5 - 1.5 h, add epichlorohydrin, continue stirring and reacting for 1 - 3 h. Centrifuge the reaction solution at a rotation speed of 6000 - 10000 rpm for 1 - 5 min, let it stand at 55 - 65 °C to obtain a hydrogel, wash it and then put it into a dialysis bag for dialysis for 4 - 6 d to obtain the wastewater treatment agent.

[0028] Preferably, the mass ratio of sodium hydroxide to deionized water is 5.5 - 55:42.5 - 425.

[0029] Preferably, the mass ratio of urea to deionized water is 2 - 20:42.5 - 425.

[0030] Preferably, the mass ratio of chitin to deionized water is 2 - 20:42.5 - 425.

[0031] Preferably, the mass ratio of 4-methoxy-N-methyl-1-butylamine to chitin is 1 - 10:2 - 20.

[0032] Preferably, the mass ratio of 2-methyl-1-(methylthio)propan-2-amine to chitin is 1 - 10:2 - 20.

[0033] Preferably, the volume-mass ratio of epichlorohydrin to chitin is 0.75 - 7.5 mL:2 - 20 g.

[0034] Preferably, the stirring speed is 600 - 800 rpm.

[0035] The present invention also provides a preparation method of a wastewater treatment agent, including: Preparation of wastewater treatment agent: Dissolve sodium hydroxide and urea in deionized water to obtain a sodium hydroxide / urea aqueous solution. Add chitin, stir evenly, add 4-methoxy-N-methyl-1-butylamine, 2-methyl-1-(methylthio)propan-2-amine and polyacrylamine hydrochloride at 0 - 5 °C under stirring conditions, stir for 0.5 - 1.5 h, add epichlorohydrin, continue stirring and reacting for 1 - 3 h. Centrifuge the reaction solution at a rotation speed of 6000 - 10000 rpm for 1 - 5 min, let it stand at 55 - 65 °C to obtain a hydrogel, wash it and then put it into a dialysis bag for dialysis for 4 - 6 d to obtain the wastewater treatment agent.

[0036] Preferably, the mass ratio of sodium hydroxide to deionized water is 5.5 - 55:42.5 - 425.

[0037] Preferably, the mass ratio of urea to deionized water is 2 - 20:42.5 - 425.

[0038] Preferably, the mass ratio of chitin to deionized water is 2-20:42.5-425.

[0039] Preferably, the mass ratio of 4-methoxy-N-methyl-1-butanamine to chitin is 1-10:2-20.

[0040] Preferably, the mass ratio of polyacrylamine hydrochloride to chitin is 1-10:2-20.

[0041] Preferably, the mass ratio of 2-methyl-1-(methylthio)propan-2-amine to chitin is 1-10:2-20.

[0042] Preferably, the volume-mass ratio of epichlorohydrin to chitin is 0.75-7.5 mL:2-20 g.

[0043] Preferably, the stirring speed is 600-800 rpm.

[0044] Since the present invention adopts the obtained wastewater treatment agent, it has the following beneficial effects: The wastewater treatment agent has excellent flocculation performance and adsorption performance, and can achieve rapid flocculation and sedimentation and long-term removal of metal ions in complex aquaculture wastewater. Therefore, the present invention is a wastewater treatment agent with high efficiency in flocculation and adsorption, simple process, and environmental protection. Description of the Drawings

[0045] Figure 1 It is a schematic diagram of the test result of the flocculation and turbidity removal performance of the wastewater treatment agent.

[0046] Figure 2 It is a schematic diagram of the test result of the copper ion adsorption performance of the wastewater treatment agent. Detailed Embodiments

[0047] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0048] The concepts involved in the present application will be described below with reference to the accompanying drawings. It should be noted here that the following descriptions of each concept are only for making the content of the present application easier to understand, and do not represent a limitation on the protection scope of the present application; at the same time, without conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present application will be described in detail below with reference to the drawings and in combination with the embodiments.

[0049] Example 1: Preparation of chitin: The cultured crab shells were cleaned with deionized water and dried to a constant weight at 50 °C to obtain the washed crab shells. Under room temperature conditions, the washed crab shells were soaked in a 1 mol / L hydrochloric acid solution for 4 h for decalcification treatment. After filtration, they were rinsed with deionized water until the filtrate was neutral, and the filter residue was dried to a constant weight at 50 °C to obtain the decalcified filter residue. Under the condition of 90 °C, the decalcified filter residue was soaked in a 2 mol / L sodium hydroxide solution for 4 h for deproteinization treatment. After filtration, it was rinsed with deionized water until the filtrate was neutral, and the filter residue was dried to a constant weight at 50 °C to obtain the deproteinized filter residue. The deproteinized filter residue was soaked in a 3 mol / L hydrogen peroxide solution for 2 h for decolorization treatment. After filtration, it was rinsed with deionized water until the filtrate was neutral, and the filter residue was dried to a constant weight at 50 °C to obtain the decolorized filter residue. The decolorized filter residue was dissolved in dimethylformamide, and after filtration, absolute ethanol was added to the filtrate for reprecipitation, and it was dried to a constant weight at 50 °C to obtain chitin. The mass-volume ratio of the washed crab shells to the hydrochloric acid solution was 10 g:100 mL, the mass-volume ratio of the decalcified filter residue to the sodium hydroxide solution was 10 g:100 mL, the mass-volume ratio of the deproteinized filter residue to the hydrogen peroxide solution was 10 g:100 mL, the mass-volume ratio of the decolorized filter residue to dimethylformamide was 10 g:100 mL, and the mass-volume ratio of the decolorized filter residue to absolute ethanol was 10 g:100 mL.

[0050] Preparation of wastewater treatment agent: Sodium hydroxide and urea were dissolved in deionized water to obtain a sodium hydroxide / urea aqueous solution. Chitin was added and stirred evenly. Under the conditions of 4 °C and stirring, 4-methoxy-N-methyl-1-butylamine and 2-methyl-1-(methylthio)propan-2-amine were added, and stirred for 1 h. Epichlorohydrin was added and the reaction was continued for 2 h. The reaction solution was centrifuged at 8000 rpm for 2 min, and left to stand at 60 °C to obtain a hydrogel. After washing, it was put into a dialysis bag for dialysis for 5 d to obtain the wastewater treatment agent. The mass ratio of sodium hydroxide to deionized water was 11:85, the mass ratio of urea to deionized water was 4:85, the mass ratio of chitin to deionized water was 4:85, the mass ratio of 4-methoxy-N-methyl-1-butylamine to chitin was 2:4, the mass ratio of 2-methyl-1-(methylthio)propan-2-amine to chitin was 2:4, and the volume-mass ratio of epichlorohydrin to chitin was 1.5 mL:4 g; the stirring speed was 700 rpm.

[0051] Example 2: Compared with Example 1, the only difference in this example lies in the preparation of the wastewater treatment agent.

[0052] Preparation of wastewater treatment agent: Dissolve sodium hydroxide and urea in deionized water to obtain an aqueous sodium hydroxide / urea solution. Add chitin, stir evenly, add 4-methoxy-N-methyl-1-butanamine and 2-methyl-1-(methylthio)propan-2-amine at 4 °C with stirring, stir for 1 h, add epichlorohydrin, and continue stirring and reacting for 2 h. Centrifuge the reaction solution at 8000 rpm for 2 min, let it stand at 60 °C to obtain a hydrogel, wash it and then put it into a dialysis bag for dialysis for 5 d to obtain the wastewater treatment agent. The mass ratio of sodium hydroxide to deionized water is 11:85, the mass ratio of urea to deionized water is 4:85, the mass ratio of chitin to deionized water is 4:85, the mass ratio of 4-methoxy-N-methyl-1-butanamine to chitin is 4:4, the mass ratio of 2-methyl-1-(methylthio)propan-2-amine to chitin is 2:4, and the volume-mass ratio of epichlorohydrin to chitin is 1.5 mL:4 g; the stirring speed is 700 rpm.

[0053] Example 3: This example is different from Example 1 only in the preparation of the wastewater treatment agent.

[0054] Preparation of wastewater treatment agent: Dissolve sodium hydroxide and urea in deionized water to obtain an aqueous sodium hydroxide / urea solution. Add chitin, stir evenly, add 4-methoxy-N-methyl-1-butanamine, 2-methyl-1-(methylthio)propan-2-amine and polyacrylamine hydrochloride at 4 °C with stirring, stir for 1 h, add epichlorohydrin, and continue stirring and reacting for 2 h. Centrifuge the reaction solution at 8000 rpm for 2 min, let it stand at 60 °C to obtain a hydrogel, wash it and then put it into a dialysis bag for dialysis for 5 d to obtain the wastewater treatment agent. The mass ratio of sodium hydroxide to deionized water is 11:85, the mass ratio of urea to deionized water is 4:85, the mass ratio of chitin to deionized water is 4:85, the mass ratio of 4-methoxy-N-methyl-1-butanamine to chitin is 2:4, the mass ratio of 2-methyl-1-(methylthio)propan-2-amine to chitin is 2:4, the mass ratio of polyacrylamine hydrochloride to chitin is 2:4, and the volume-mass ratio of epichlorohydrin to chitin is 1.5 mL:4 g; the stirring speed is 700 rpm.

[0055] Example 4: This example is different from Example 3 only in the preparation of modified chitin.

[0056] Preparation of modified chitin: Sodium hydroxide and urea were dissolved in deionized water to obtain an aqueous sodium hydroxide / urea solution. Chitin was added and stirred evenly. Under the conditions of 4 °C and stirring, 4-methoxy-N-methyl-1-butanamine, 2-methyl-1-(methylthio)propan-2-amine, and polyacrylamine hydrochloride were added, and stirred for 1 h. Epichlorohydrin was added and the reaction was continued with stirring for 2 h. The reaction solution was centrifuged at 8000 rpm for 2 min, and allowed to stand at 60 °C to obtain a hydrogel. After washing, it was placed in a dialysis bag and dialyzed for 5 d to obtain a wastewater treatment agent. The mass ratio of sodium hydroxide to deionized water was 11:85, the mass ratio of urea to deionized water was 4:85, the mass ratio of chitin to deionized water was 4:85, the mass ratio of 4-methoxy-N-methyl-1-butanamine to chitin was 2:4, the mass ratio of 2-methyl-1-(methylthio)propan-2-amine to chitin was 2:4, the volume-mass ratio of polyacrylamine hydrochloride to chitin was 4:4, and the volume-mass ratio of epichlorohydrin to chitin was 1.5 mL:4 g; the stirring speed was 700 rpm.

[0057] Comparative Example 1: This comparative example is different from Example 1 only in the preparation of the wastewater treatment agent.

[0058] Preparation of wastewater treatment agent: Sodium hydroxide and urea were dissolved in deionized water to obtain an aqueous sodium hydroxide / urea solution. Chitin was added and stirred evenly. Under the conditions of 4 °C and stirring, 4-methoxy-N-methyl-1-butanamine was added and stirred for 1 h. Epichlorohydrin was added and the reaction was continued with stirring for 2 h. The reaction solution was centrifuged at 8000 rpm for 2 min, and allowed to stand at 60 °C to obtain a hydrogel. After washing, it was placed in a dialysis bag and dialyzed for 5 d to obtain a wastewater treatment agent. The mass ratio of sodium hydroxide to deionized water was 11:85, the mass ratio of urea to deionized water was 4:85, the mass ratio of chitin to deionized water was 4:85, the mass ratio of 4-methoxy-N-methyl-1-butanamine to chitin was 2:4, the volume-mass ratio of epichlorohydrin to chitin was 1.5 mL:4 g; the stirring speed was 700 rpm.

[0059] Comparative Example 2: This comparative example is different from Example 1 only in the preparation of the wastewater treatment agent.

[0060] Preparation of wastewater treatment agent: Dissolve sodium hydroxide and urea in deionized water to obtain a sodium hydroxide / urea aqueous solution. Add chitin and stir evenly. Add 2-methyl-1-(methylthio)propan-2-amine at 0 °C under stirring conditions and stir for 1 h. Then add epichlorohydrin and continue stirring for 2 h. Centrifuge the reaction solution at 8000 rpm for 2 min, and let it stand at 60 °C to obtain a hydrogel. After washing, put it into a dialysis bag and dialyze for 5 d to obtain the wastewater treatment agent. The mass ratio of sodium hydroxide to deionized water is 11:85, the mass ratio of urea to deionized water is 4:85, the mass ratio of chitin to deionized water is 4:85, the mass ratio of 2-methyl-1-(methylthio)propan-2-amine to chitin is 2:4, and the volume-mass ratio of epichlorohydrin to chitin is 1.5 mL:4 g; the stirring speed is 700 rpm.

[0061] Comparative Example 3: This comparative example is the same as Example 1 except for the preparation of the wastewater treatment agent.

[0062] Preparation of wastewater treatment agent: Dissolve sodium hydroxide and urea in deionized water to obtain a sodium hydroxide / urea aqueous solution. Add chitin and stir evenly. Add epichlorohydrin at 4 °C under stirring conditions and continue stirring for 2 h. Centrifuge the reaction solution at 8000 rpm for 2 min, and let it stand at 60 °C to obtain a hydrogel. After washing, put it into a dialysis bag and dialyze for 5 d to obtain the wastewater treatment agent. The mass ratio of sodium hydroxide to deionized water is 11:85, the mass ratio of urea to deionized water is 4:85, the mass ratio of chitin to deionized water is 4:85, the volume-mass ratio of epichlorohydrin to chitin is 1.5 mL:4 g; the stirring speed is 700 rpm.

[0063] Test Example 1: Test on the flocculation and turbidity removal performance of the wastewater treatment agent.

[0064] Test samples: The wastewater treatment agents prepared in each example and comparative example.

[0065] Test method: Prepare a 500 mg / L kaolin suspension as simulated wastewater and adjust the pH to 7.0; take 500 mL of the simulated wastewater, measure the initial turbidity with a turbidimeter, add 0.5 g of the wastewater treatment agents prepared in each example and comparative example respectively, first stir rapidly at 200 rpm for 2 min on a coagulation mixer, then stir slowly at 60 rpm for 15 min, let it stand for 30 min, take the supernatant, and measure the turbidity after treatment with a turbidimeter to obtain the turbidity removal rate.

[0066] The turbidity removal rate is calculated as follows:

[0067] In the formula: C 0is the initial turbidity, C t is the turbidity after treatment.

[0068] The test results of the flocculation and turbidity removal performance of the wastewater treatment agent prepared in this invention are as Figure 1 shown. In Example 1, chitin is grafted with 4-methoxy-N-methyl-1-butanamine and 2-methyl-1-(methylthio)propan-2-amine, which can effectively neutralize the charged suspended substances in water through electrostatic attraction, reduce the repulsive force between particles, promote the destabilization and aggregation of colloids, and have a good flocculation effect; compared with Example 1, in Example 2, by adjusting the mass ratio of 4-methoxy-N-methyl-1-butanamine to 2-methyl-1-(methylthio)propan-2-amine, the turbidity removal rate is improved, indicating that appropriately increasing the proportion of hydrophobic long carbon chains is beneficial to optimizing the flocculation efficiency. In Examples 3 and 4, polyacrylamine hydrochloride is introduced to increase the cross-linking degree and hydrophilicity of the molecular chain, significantly optimizing the flocculation effect and further increasing the removal rate. Compared with Example 1, in Comparative Example 1, 2-methyl-1-(methylthio)propan-2-amine is not used, and only 4-methoxy-N-methyl-1-butanamine is introduced, which cannot effectively destabilize the colloidal particles, and the turbidity removal rate drops significantly; in Comparative Example 2, 4-methoxy-N-methyl-1-butanamine is not used, and the stability of the flocs decreases; in Comparative Example 3, neither 4-methoxy-N-methyl-1-butanamine nor 2-methyl-1-(methylthio)propan-2-amine is used, and the removal rate is the lowest, confirming the key role of 4-methoxy-N-methyl-1-butanamine and 2-methyl-1-(methylthio)propan-2-amine in enhancing the charge density and flocculation performance.

[0069] Test Example 3: Test on the copper ion adsorption performance of the wastewater treatment agent.

[0070] Test samples: The wastewater treatment agents prepared in each example and comparative example.

[0071] Test method: Prepare a 500 mg / L kaolin suspension, add copper sulfate pentahydrate to make the final concentration of copper ions 100 mg / L, and adjust the pH to 6 as the simulated wastewater; take 100 mL of the simulated wastewater, add 0.1 g of the wastewater treatment agents prepared in each example and comparative example respectively, oscillate and adsorb at 25 °C and 150 rpm for 12 h, take the supernatant after centrifugation, and measure the residual concentration of copper ions with an inductively coupled plasma optical emission spectrometer to calculate the copper ion adsorption capacity.

[0072] The adsorption capacity is calculated as follows:

[0073] In the formula: q is the copper ion adsorption capacity, C 0 is the initial copper ion concentration, C tis the concentration of copper ions after adsorption, V is the volume of the solution, m is the mass of the wastewater treatment agent.

[0074] The test results of the copper ion adsorption performance of the wastewater treatment agent prepared by the present invention are as Figure 2 shown. The copper ion adsorption capacity of Example 1 benefits from the introduction of multiple amino groups by 4-methoxy-N-methyl-1-butanamine and 2-methyl-1-(methylthio)propan-2-amine, which increases the number of active sites and enhances the complexation and adsorption ability of the wastewater treatment agent for pollutants such as metal ions; in Example 2, by optimizing the modifier ratio, the adsorption capacity is improved, indicating that the increase in the hydrophobic long carbon chain helps to reduce the solvation effect and enhance the adsorption; in Examples 3 and 4, polyacrylamine hydrochloride is introduced, making the spatial network structure of the treatment agent more dense and rich, increasing its mechanical strength and stability, improving hydrophilicity, increasing the specific surface area, and making the binding of amino groups to copper ion polar groups more efficient, further improving the adsorption capacity. Compared with Example 1, in Comparative Example 1, the adsorption capacity decreased due to the lack of 2-methyl-1-(methylthio)propan-2-amine, and in Comparative Example 2, the adsorption capacity also decreased due to the lack of 4-methoxy-N-methyl-1-butanamine; in Comparative Example 3, 4-methoxy-N-methyl-1-butanamine and 2-methyl-1-(methylthio)propan-2-amine were not used, and the adsorption capacity was the lowest, indicating the efficient effect of 4-methoxy-N-methyl-1-butanamine and 2-methyl-1-(methylthio)propan-2-amine on adsorbing pollutants.

[0075] The above-described embodiments and / or implementation manners are only used to illustrate the preferred embodiments and / or implementation manners for implementing the technology of the present invention, and do not impose any formal restrictions on the implementation manners of the technology of the present invention. Any person skilled in the art, without departing from the scope of the technical means disclosed in the content of the present invention, may make some modifications or changes to other equivalent embodiments, but should still be regarded as the same technology or embodiment as the present invention in essence.

[0076] In this article, specific examples are used to elaborate on the principles and implementation manners of the present application. The description of the above embodiments is only used to help understand the method and its core idea of the present application. The above is only the preferred implementation manner of the present application. It should be noted that due to the limited nature of written expression and objectively existing infinite specific structures, for those of ordinary skill in the art in this technical field, without departing from the principle of the present application, several improvements, refinements or changes can be made, or the above technical features can be combined in an appropriate manner; these improvements, refinements, changes or combinations, or directly applying the concept and technical solution of the invention to other occasions without improvement, should all be regarded as the protection scope of the present application.

Claims

1. A wastewater treatment agent, which is a chitosan-based polymer compound, wherein the chitosan is cross-linked and grafted with an amino derivative, and the amino derivative includes 4-methoxy-N-methyl-1-butylamine and 2-methyl-1-(methylthio)propan-2-amine.

2. A wastewater treatment agent according to claim 1, characterized in that: The mass ratio of the 4-methoxy-N-methyl-1-butylamine to chitin is 1-10:2-20.

3. A wastewater treatment agent according to claim 1, characterized in that: The mass ratio of the 2-methyl-1-(methylthio)propan-2-amine to chitin is 1-10:2-20.

4. The method for preparing a wastewater treatment agent according to claim 1, comprising the following preparation steps: Chitosan is obtained by decomposing and purifying farmed crab shells through biomass; Chitosan is dissolved in a sodium hydroxide / urea aqueous solution, and an amino derivative and a cross-linking agent are added to carry out a grafting reaction to obtain a wastewater treatment agent.

5. The method for preparing a wastewater treatment agent according to claim 4, characterized in that: The cross-linking agent is epichlorohydrin, and the volume mass ratio of epichlorohydrin to chitosan is 0.75-7.5 mL:2-20 g.

6. The method for preparing a wastewater treatment agent according to claim 5, characterized in that: In the sodium hydroxide / urea aqueous solution, the content of sodium hydroxide is 5-15wt%.

7. The method for preparing a wastewater treatment agent according to claim 5, characterized in that: The content of urea in the sodium hydroxide / urea aqueous solution is 2-10wt%.

8. The method for preparing a wastewater treatment agent according to claim 5, characterized in that: The mass ratio of the chitosan to the sodium hydroxide / urea aqueous solution is 2-20:50-500.

9. Use of a wastewater treatment agent according to any one of claims 1 to 3 in wastewater treatment, wherein the wastewater comprises freshwater aquaculture wastewater or seawater aquaculture wastewater.

10. Use of a wastewater treatment agent according to claim 9 in wastewater treatment, characterized in that: The dosage of the wastewater treatment agent is 0.1-1.0 g / L, and the pH of the treatment system is 6.0-8.0.

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