Method for treating non-ferrous metal wastewater containing nickel and cadmium

Abstract

The invention discloses a nickel and cadmium-containing nonferrous metal wastewater treatment method, and relates to the technical field of wastewater treatment. The preparation method comprises the following steps: by taking polyvinyl alcohol and gelatin as raw materials, carrying out amination modification through 3-amino-trimethoxysilane to prepare an aminated gelatin solution, and then adding a modified metal organic framework adsorption material and modified nitrogen-containing biochar to react to prepare an adsorbent with a good adsorption effect on metal nickel and cadmium. The modified metal organic framework adsorption material and the modified nitrogen-containing biochar have amino groups, so that the modified metal organic framework adsorption material and the modified nitrogen-containing biochar have good dispersibility in the aminated gelatin, and the adsorption effect of the adsorbent is improved.

Description

Technical Field

[0001] The invention relates to the technical field of wastewater treatment, in particular to a method for treating nonferrous metal wastewater containing nickel and cadmium. Background Art

[0002] With the rapid development of industrialization, the amount of wastewater discharged from various metal smelting and processing industries has increased year by year. The wastewater contains many heavy metals, such as nickel and cadmium. These heavy metal elements not only cause great pollution to the environment, but also have serious harm to the ecosystem and human health. Nickel and cadmium are two typical toxic metals. They are widely used in industrial fields such as battery manufacturing, electroplating, and smelting. However, if these metals in wastewater are directly discharged without effective treatment, it will cause water pollution, soil degradation and destruction of the food chain. Nickel and cadmium can enter the body through the food chain, endangering the growth and reproduction of aquatic organisms, and even affecting human health, causing damage to the nervous system, kidneys, liver and other organs.

[0003] Traditional heavy metal wastewater treatment methods include chemical precipitation, ion exchange, electrolysis, etc. Although the chemical precipitation method is simple to operate, it consumes a lot of precipitants and may cause secondary pollution; the ion exchange method requires expensive resins and has limited processing capacity; the electrolysis method has high energy consumption and high costs. Therefore, it is urgent to develop a more efficient, economical and environmentally friendly treatment method to deal with the pollution problem of nickel and cadmium wastewater.

[0004] In order to solve the above problems and better absorb the metal elements in the wastewater, the present invention provides a method for treating nonferrous metal wastewater containing nickel and cadmium. Summary of the invention

[0005] The object of the present invention is to provide a method for treating nonferrous metal wastewater containing nickel and cadmium to solve the problems raised in the prior art.

[0006] To achieve the above object, the present invention provides the following technical solutions: A method for treating nonferrous metal wastewater containing nickel and cadmium comprises the following steps: Step 1: Take amino-branched modified chitosan and acetic acid aqueous solution, stir for 10-15 minutes, add zinc nitrate hexahydrate, and ultrasonically disperse for 1-2 hours to obtain a mixed solution; drop the mixed solution into a sodium hydroxide solution, stir for 2-4 hours, wash until neutral, and then immerse in a 2-methylimidazole aqueous solution, age for 22-26 hours, wash, and freeze-dry to obtain a modified metal organic framework adsorption material; Step 2: Take the amino gelatin solution, the modified metal organic framework adsorption material, and the modified nitrogen-containing biochar, heat them to 65-70° C., stir for 2-3 hours, filter, wash, and dry to obtain an adsorbent; Step 3: Pour the adsorbent into the non-ferrous metal wastewater containing nickel and cadmium, perform adsorption treatment for 4-6 hours, and obtain treated wastewater.

[0007] More optimally, in step one, the preparation method of amino-branched modified chitosan is: take chitosan microspheres and methanol, stir evenly under nitrogen protection, add methyl acrylate, react for 58-62 hours, collect the microspheres, wash and dry, and obtain methyl acrylate-grafted chitosan microspheres; take methyl acrylate-grafted chitosan microspheres and methanol, stir evenly under nitrogen protection, add diethylenetriamine, react for 70-74 hours, collect the microspheres, wash and dry, and obtain amino-branched modified chitosan.

[0008] More optimally, in step 2, the preparation method of modified nitrogen-containing biochar is: take nitrogen-containing biochar and deionized water, stir evenly, add sodium hydroxide, stir evenly, add diethylenetriamine, stir evenly, add carbon disulfide dropwise, react at 25-30°C for 50-70min, add epichlorohydrin dropwise, stir for 20-30min, heat to 60-65°C, react for 4-5h, wash and dry to obtain modified nitrogen-containing biochar.

[0009] More optimally, the method for preparing the nitrogen-containing biochar is: taking shrimp shells, washing, drying, crushing, and sieving to obtain processed shrimp shells, heating to 600-620° C., using acetic acid solution for pickling and drying to obtain nitrogen-containing biochar.

[0010] More optimally, the preparation method of the chitosan microspheres is: take chitosan and acetic acid aqueous solution, stir evenly to obtain chitosan acetic acid aqueous solution; spray dry the chitosan acetic acid aqueous solution under the conditions of an inlet temperature of 200-210°C and an outlet temperature of 90-100°C to obtain chitosan microspheres.

[0011] More optimally, in step 2, the preparation method of the amination gelatin solution is: take polyvinyl alcohol and deionized water, stir evenly to obtain a polyvinyl alcohol aqueous solution, take gelatin and deionized water, stir evenly to obtain a gelatin aqueous solution, mix the polyvinyl alcohol aqueous solution and the gelatin aqueous solution evenly, add polyvinyl pyrrolidone, stir evenly, add hydrochloric acid, adjust the pH value of the solution to 3-4, add glutaraldehyde dropwise, stir evenly, add Span-80 and liquid paraffin, stir evenly, heat to 65-70°C, stir for 4-6h, filter, wash, and dry to obtain solid A; take solid A, triethylamine, and toluene, add 3-amino-trimethoxysilane under nitrogen protection, reflux and stir at 105-110°C, react for 2-3h to obtain an amination gelatin solution.

[0012] More optimally, the mass ratio of the amino gelatin solution, the modified metal organic framework adsorption material, and the modified nitrogen-containing biochar is (90-100): (2-2.5):3.

[0013] More optimally, the mass ratio of the amino gelatin solution, the modified metal organic framework adsorption material, and the modified nitrogen-containing biochar is 100:2:3.

[0014] Compared with the prior art, the present invention has the following beneficial effects: 1. The present invention uses polyvinyl alcohol and gelatin as raw materials, performs amino modification through 3-amino-trimethoxysilane, prepares an amino gelatin solution, and then adds modified metal organic framework adsorption material and modified nitrogen-containing biochar to react, and prepares an adsorbent with good adsorption effect on metal nickel and cadmium. The modified metal organic framework adsorption material and the modified nitrogen-containing biochar both have amino groups, so that the modified metal organic framework adsorption material and the modified nitrogen-containing biochar have good dispersibility in the amino gelatin, thereby improving the adsorption effect of the adsorbent.

[0015] 2. Shrimp shells are a nitrogen-rich substance. When using shrimp shells to prepare biochar, the biochar will contain a large amount of nitrogen. Nitrogen doping of biochar will change the overall electronic structure of the biochar, which is conducive to the interaction between biochar and metal substances and improves the wastewater treatment effect. The use of diethylenetriamine, carbon disulfide, and epichlorohydrin to modify nitrogen-containing biochar increases the specific surface area of ​​nitrogen-containing biochar, optimizes its pore structure, and can swell in water, further improving the adsorption of metal nickel and cadmium. At the same time, the synthesized modified nitrogen-containing biochar has amino groups.

[0016] 3. Metal organic framework materials have large specific surface area and porosity, and have good adsorption effect on metal nickel and cadmium. Amino branched modified chitosan can chelate metal substances, thereby better adsorbing metal substances, and at the same time make the surface of the modified metal organic framework adsorption material have a large number of amino groups. At this time, the modified metal organic framework adsorption material and modified nitrogen-containing biochar have good dispersion in the amino gelatin, which enhances the wastewater treatment capacity and improves the adsorption effect of the adsorbent. DETAILED DESCRIPTION

[0017] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0018] The sources of the substances involved in the present invention are not particularly limited, and exemplary include: Polyvinyl alcohol: Model: BP0442, which can be purchased from Beijing Biolabo Technology Co., Ltd.; Polyvinyl pyrrolidone: Model: B8290, which can be purchased from Beijing Solable Technology Co., Ltd.

[0019] Embodiment 1: A method for treating nonferrous metal wastewater containing nickel and cadmium, comprising the following steps: Pour the adsorbent into the non-ferrous metal wastewater containing nickel and cadmium, and perform adsorption treatment for 5 hours to obtain the treated wastewater; The preparation of the adsorbent comprises the following steps: Step 1: Preparation of amino-branched modified chitosan: Take 2g of chitosan and 100mL of 1.5% acetic acid aqueous solution, stir evenly to obtain chitosan acetic acid aqueous solution; spray dry the chitosan acetic acid aqueous solution under the conditions of an inlet temperature of 205°C and an outlet temperature of 95°C to obtain chitosan microspheres; take 6g of chitosan microspheres and 100mL of methanol, stir evenly under the conditions of nitrogen protection and constant temperature of 40°C, add 22mL of methyl acrylate, react for 60h, collect the microspheres, wash and dry to obtain methyl acrylate grafted chitosan microspheres; take 2g of methyl acrylate grafted chitosan microspheres and 100mL of methanol, stir evenly under the conditions of nitrogen protection and constant temperature of 40°C, add 25mL of diethylenetriamine, react for 72h, collect the microspheres, wash and dry to obtain amino-branched modified chitosan; Step 2: Preparation of modified metal organic framework adsorption materials: Take 0.5g amino-branched modified chitosan and 20mL acetic acid aqueous solution with a concentration of 2%, stir for 12min, add 0.8g zinc nitrate hexahydrate, and ultrasonically disperse for 1.5h to obtain a mixed solution; drop the mixed solution into 100mL 1mol / L sodium hydroxide solution, stir for 3h, wash until neutral, and then immerse in 40mL 2% 2-methylimidazole aqueous solution, age for 24h, wash, and freeze-dry to obtain a modified metal organic framework adsorption material; Step 3: Preparation of nitrogen-containing biochar: The shrimp shells were washed, dried, crushed, and sieved to obtain the treated shrimp shells, which were heated to 610°C, pickled with 15% acetic acid solution, and dried to obtain nitrogen-containing biochar; Step 4: Preparation of modified nitrogen-containing biochar: Take 5g of nitrogen-containing biochar and 100mL of deionized water, stir evenly, add 10g of sodium hydroxide, stir evenly, add 13mL of diethylenetriamine, stir evenly, drop 15mL of carbon disulfide, react at 28°C for 60min, drop 12mL of epichlorohydrin, stir for 25min, heat to 62°C, react for 4.5h, wash and dry to obtain modified nitrogen-containing biochar; Step 5: Preparation of amino gelatin solution: Take 10g of polyvinyl alcohol and 100mL of deionized water, stir evenly to obtain a polyvinyl alcohol aqueous solution, take 12g of gelatin and 100mL of deionized water, stir evenly to obtain a gelatin aqueous solution, mix the polyvinyl alcohol aqueous solution and the gelatin aqueous solution evenly, add 10g of polyvinyl pyrrolidone, stir evenly, add 5% hydrochloric acid, adjust the pH value of the solution to 3.5, drop 5g of glutaraldehyde, stir evenly, add 0.6g of Span-80 and 600mL of liquid paraffin, stir evenly, heat to 68°C, stir for 5h, filter, wash, and dry to obtain solid A; take 5g of solid A, 2mL of triethylamine, and 200mL of toluene, under nitrogen protection, add 6mL of 3-amino-trimethoxysilane, reflux and stir at 108°C, react for 2.5h to obtain an amino gelatin solution; Step 6: Preparation of adsorbent: Take 100 g of amino gelatin solution, 2 g of modified metal organic framework adsorption material, and 3 g of modified nitrogen-containing biochar, heat to 68° C., stir for 2.5 h, filter, wash, and dry to obtain an adsorbent. Example

[0020] A method for treating nonferrous metal wastewater containing nickel and cadmium comprises the following steps: Pour the adsorbent into the non-ferrous metal wastewater containing nickel and cadmium, and perform adsorption treatment for 5 hours to obtain the treated wastewater; The preparation of the adsorbent comprises the following steps: Step 1: Preparation of amino-branched modified chitosan: Take 2g of chitosan and 100mL of 1.5% acetic acid aqueous solution, stir evenly to obtain chitosan acetic acid aqueous solution; spray dry the chitosan acetic acid aqueous solution at an inlet temperature of 200°C and an outlet temperature of 90°C to obtain chitosan microspheres; take 6g of chitosan microspheres and 100mL of methanol, stir evenly under nitrogen protection and a constant temperature of 40°C, add 22mL of methyl acrylate, react for 58h, collect the microspheres, wash and dry to obtain methyl acrylate grafted chitosan microspheres; take 2g of methyl acrylate grafted chitosan microspheres and 100mL of methanol, stir evenly under nitrogen protection and a constant temperature of 40°C, add 25mL of diethylenetriamine, react for 70h, collect the microspheres, wash and dry to obtain amino-branched modified chitosan; Step 2: Preparation of modified metal organic framework adsorption materials: Take 0.5g amino-branched modified chitosan and 20mL acetic acid aqueous solution with a concentration of 2%, stir for 10min, add 0.8g zinc nitrate hexahydrate, and ultrasonically disperse for 1h to obtain a mixed solution; drop the mixed solution into 100mL 1mol / L sodium hydroxide solution, stir for 2h, wash until neutral, and then immerse in 40mL 2% 2-methylimidazole aqueous solution, age for 22h, wash, and freeze-dry to obtain a modified metal organic framework adsorption material; Step 3: Preparation of nitrogen-containing biochar: The shrimp shells were washed, dried, crushed, and sieved to obtain the treated shrimp shells, which were heated to 600°C, pickled with 15% acetic acid solution, and dried to obtain nitrogen-containing biochar; Step 4: Preparation of modified nitrogen-containing biochar: Take 5g of nitrogen-containing biochar and 100mL of deionized water, stir evenly, add 10g of sodium hydroxide, stir evenly, add 13mL of diethylenetriamine, stir evenly, drop 15mL of carbon disulfide, react at 25°C for 50min, drop 12mL of epichlorohydrin, stir for 20min, heat to 60°C, react for 4h, wash and dry to obtain modified nitrogen-containing biochar; Step 5: Preparation of amino gelatin solution: Take 10g of polyvinyl alcohol and 100mL of deionized water, stir evenly to obtain a polyvinyl alcohol aqueous solution, take 12g of gelatin and 100mL of deionized water, stir evenly to obtain a gelatin aqueous solution, mix the polyvinyl alcohol aqueous solution and the gelatin aqueous solution evenly, add 10g of polyvinyl pyrrolidone, stir evenly, add 5% hydrochloric acid, adjust the pH value of the solution to 3, drop 5g of glutaraldehyde, stir evenly, add 0.6g of Span-80 and 600mL of liquid paraffin, stir evenly, heat to 65°C, stir for 4h, filter, wash, and dry to obtain solid A; take 5g of solid A, 2mL of triethylamine, and 200mL of toluene, under nitrogen protection, add 6mL of 3-amino-trimethoxysilane, reflux and stir at 105°C, react for 2h to obtain an amino gelatin solution; Step 6: Preparation of adsorbent: Take 100 g of amino gelatin solution, 2 g of modified metal organic framework adsorption material, and 3 g of modified nitrogen-containing biochar, heat to 65° C., stir for 2 h, filter, wash, and dry to obtain an adsorbent. Example

[0021] A method for treating nonferrous metal wastewater containing nickel and cadmium comprises the following steps: Pour the adsorbent into the non-ferrous metal wastewater containing nickel and cadmium, and perform adsorption treatment for 5 hours to obtain the treated wastewater; The preparation of the adsorbent comprises the following steps: Step 1: Preparation of amino-branched modified chitosan: Take 2g of chitosan and 100mL of 1.5% acetic acid aqueous solution, stir evenly to obtain chitosan acetic acid aqueous solution; spray dry the chitosan acetic acid aqueous solution at an inlet temperature of 210°C and an outlet temperature of 100°C to obtain chitosan microspheres; take 6g of chitosan microspheres and 100mL of methanol, stir evenly under nitrogen protection and a constant temperature of 40°C, add 22mL of methyl acrylate, react for 62h, collect the microspheres, wash and dry to obtain methyl acrylate grafted chitosan microspheres; take 2g of methyl acrylate grafted chitosan microspheres and 100mL of methanol, stir evenly under nitrogen protection and a constant temperature of 40°C, add 25mL of diethylenetriamine, react for 74h, collect the microspheres, wash and dry to obtain amino-branched modified chitosan; Step 2: Preparation of modified metal organic framework adsorption materials: Take 0.5g amino-branched modified chitosan and 20mL acetic acid aqueous solution with a concentration of 2%, stir for 15min, add 0.8g zinc nitrate hexahydrate, and disperse by ultrasound for 2h to obtain a mixed solution; drop the mixed solution into 100mL 1mol / L sodium hydroxide solution, stir for 4h, wash until neutral, and then immerse in 40mL 2% 2-methylimidazole aqueous solution, age for 26h, wash, and freeze-dry to obtain a modified metal organic framework adsorption material; Step 3: Preparation of nitrogen-containing biochar: The shrimp shells were washed, dried, crushed, and sieved to obtain the treated shrimp shells, which were heated to 620°C, pickled with 15% acetic acid solution, and dried to obtain nitrogen-containing biochar; Step 4: Preparation of modified nitrogen-containing biochar: Take 5g of nitrogen-containing biochar and 100mL of deionized water, stir evenly, add 10g of sodium hydroxide, stir evenly, add 13mL of diethylenetriamine, stir evenly, drop 15mL of carbon disulfide, react at 30°C for 70min, drop 12mL of epichlorohydrin, stir for 30min, heat to 65°C, react for 5h, wash and dry to obtain modified nitrogen-containing biochar; Step 5: Preparation of amino gelatin solution: Take 10g of polyvinyl alcohol and 100mL of deionized water, stir evenly to obtain a polyvinyl alcohol aqueous solution, take 12g of gelatin and 100mL of deionized water, stir evenly to obtain a gelatin aqueous solution, mix the polyvinyl alcohol aqueous solution and the gelatin aqueous solution evenly, add 10g of polyvinyl pyrrolidone, stir evenly, add 5% hydrochloric acid, adjust the pH value of the solution to 4, drop 5g of glutaraldehyde, stir evenly, add 0.6g of Span-80 and 600mL of liquid paraffin, stir evenly, heat to 70°C, stir for 6h, filter, wash, and dry to obtain solid A; take 5g of solid A, 2mL of triethylamine, and 200mL of toluene, under nitrogen protection, add 6mL of 3-amino-trimethoxysilane, reflux and stir at 110°C, react for 3h to obtain an amino gelatin solution; Step 6: Preparation of adsorbent: Take 100 g of amino gelatin solution, 2 g of modified metal organic framework adsorption material, and 3 g of modified nitrogen-containing biochar, heat to 70° C., stir for 3 h, filter, wash, and dry to obtain an adsorbent.

[0022] Comparative Example 1: Chitosan was not subjected to amino branching modification, and the rest was the same as Example 1: Pour the adsorbent into the non-ferrous metal wastewater containing nickel and cadmium, and perform adsorption treatment for 5 hours to obtain the treated wastewater; The preparation of the adsorbent comprises the following steps: Step 1: Preparation of modified metal organic framework adsorption materials: Take 0.5g chitosan and 20mL acetic acid aqueous solution with a concentration of 2%, stir for 12min, add 0.8g zinc nitrate hexahydrate, and ultrasonically disperse for 1.5h to obtain a mixed solution; drop the mixed solution into 100mL sodium hydroxide solution with a concentration of 1mol / L, stir for 3h, wash until neutral, and then immerse in 40mL 2% 2-methylimidazole aqueous solution, age for 24h, wash, and freeze-dry to obtain a modified metal organic framework adsorption material; Step 2: Preparation of nitrogen-containing biochar: The shrimp shells were washed, dried, crushed, and sieved to obtain the treated shrimp shells, which were heated to 610°C, pickled with 15% acetic acid solution, and dried to obtain nitrogen-containing biochar; Step 3: Preparation of modified nitrogen-containing biochar: Take 5g of nitrogen-containing biochar and 100mL of deionized water, stir evenly, add 10g of sodium hydroxide, stir evenly, add 13mL of diethylenetriamine, stir evenly, drop 15mL of carbon disulfide, react at 28°C for 60min, drop 12mL of epichlorohydrin, stir for 25min, heat to 62°C, react for 4.5h, wash and dry to obtain modified nitrogen-containing biochar; Step 4: Preparation of amination gelatin solution: Take 10g of polyvinyl alcohol and 100mL of deionized water, stir evenly to obtain a polyvinyl alcohol aqueous solution, take 12g of gelatin and 100mL of deionized water, stir evenly to obtain a gelatin aqueous solution, mix the polyvinyl alcohol aqueous solution and the gelatin aqueous solution evenly, add 10g of polyvinyl pyrrolidone, stir evenly, add 5% hydrochloric acid, adjust the pH value of the solution to 3.5, drop 5g of glutaraldehyde, stir evenly, add 0.6g of Span-80 and 600mL of liquid paraffin, stir evenly, heat to 68°C, stir for 5h, filter, wash, and dry to obtain solid A; take 5g of solid A, 2mL of triethylamine, and 200mL of toluene, under nitrogen protection, add 6mL of 3-amino-trimethoxysilane, reflux and stir at 108°C, react for 2.5h to obtain an amino gelatin solution; Step 5: Preparation of adsorbent: Take 100 g of amino gelatin solution, 2 g of modified metal organic framework adsorption material, and 3 g of modified nitrogen-containing biochar, heat to 68° C., stir for 2.5 h, filter, wash, and dry to obtain an adsorbent.

[0023] Comparative Example 2: The metal organic framework adsorption material is not modified, and the rest is the same as Example 1: Pour the adsorbent into the non-ferrous metal wastewater containing nickel and cadmium, and perform adsorption treatment for 5 hours to obtain the treated wastewater; The preparation of the adsorbent comprises the following steps: Step 1: Preparation of amino-branched modified chitosan: Take 2g of chitosan and 100mL of 1.5% acetic acid aqueous solution, stir evenly to obtain chitosan acetic acid aqueous solution; spray dry the chitosan acetic acid aqueous solution under the conditions of an inlet temperature of 205°C and an outlet temperature of 95°C to obtain chitosan microspheres; take 6g of chitosan microspheres and 100mL of methanol, stir evenly under the conditions of nitrogen protection and constant temperature of 40°C, add 22mL of methyl acrylate, react for 60h, collect the microspheres, wash and dry to obtain methyl acrylate grafted chitosan microspheres; take 2g of methyl acrylate grafted chitosan microspheres and 100mL of methanol, stir evenly under the conditions of nitrogen protection and constant temperature of 40°C, add 25mL of diethylenetriamine, react for 72h, collect the microspheres, wash and dry to obtain amino-branched modified chitosan; Step 2: Preparation of metal organic framework adsorption materials: Take 20mL of 2% acetic acid aqueous solution, add 0.8g of zinc nitrate hexahydrate, and disperse by ultrasonic for 1.5h to obtain a mixed solution; drop the mixed solution into 100mL of 1mol / L sodium hydroxide solution, stir for 3h, wash until neutral, and then immerse in 40mL of 2% 2-methylimidazole aqueous solution, age for 24h, wash, and freeze-dry to obtain a metal organic framework adsorption material; Step 3: Preparation of nitrogen-containing biochar: The shrimp shells were washed, dried, crushed, and sieved to obtain the treated shrimp shells, which were heated to 610°C, pickled with 15% acetic acid solution, and dried to obtain nitrogen-containing biochar; Step 4: Preparation of modified nitrogen-containing biochar: Take 5g of nitrogen-containing biochar and 100mL of deionized water, stir evenly, add 10g of sodium hydroxide, stir evenly, add 13mL of diethylenetriamine, stir evenly, drop 15mL of carbon disulfide, react at 28°C for 60min, drop 12mL of epichlorohydrin, stir for 25min, heat to 62°C, react for 4.5h, wash and dry to obtain modified nitrogen-containing biochar; Step 5: Preparation of amino gelatin solution: Take 10g of polyvinyl alcohol and 100mL of deionized water, stir evenly to obtain a polyvinyl alcohol aqueous solution, take 12g of gelatin and 100mL of deionized water, stir evenly to obtain a gelatin aqueous solution, mix the polyvinyl alcohol aqueous solution and the gelatin aqueous solution evenly, add 10g of polyvinyl pyrrolidone, stir evenly, add 5% hydrochloric acid, adjust the pH value of the solution to 3.5, drop 5g of glutaraldehyde, stir evenly, add 0.6g of Span-80 and 600mL of liquid paraffin, stir evenly, heat to 68°C, stir for 5h, filter, wash, and dry to obtain solid A; take 5g of solid A, 2mL of triethylamine, and 200mL of toluene, under nitrogen protection, add 6mL of 3-amino-trimethoxysilane, reflux and stir at 108°C, react for 2.5h to obtain an amino gelatin solution; Step 6: Preparation of adsorbent: Take 100 g of amino gelatin solution, 2 g of metal organic framework adsorption material, and 3 g of modified nitrogen-containing biochar, heat to 68° C., stir for 2.5 h, filter, wash, and dry to obtain an adsorbent.

[0024] Comparative Example 3: No modification was performed on the nitrogen-containing biochar, and the rest was the same as in Example 1: Pour the adsorbent into the non-ferrous metal wastewater containing nickel and cadmium, and perform adsorption treatment for 5 hours to obtain the treated wastewater; The preparation of the adsorbent comprises the following steps: Step 1: Preparation of amino-branched modified chitosan: Take 2g of chitosan and 100mL of 1.5% acetic acid aqueous solution, stir evenly to obtain chitosan acetic acid aqueous solution; spray dry the chitosan acetic acid aqueous solution under the conditions of an inlet temperature of 205°C and an outlet temperature of 95°C to obtain chitosan microspheres; take 6g of chitosan microspheres and 100mL of methanol, stir evenly under the conditions of nitrogen protection and constant temperature of 40°C, add 22mL of methyl acrylate, react for 60h, collect the microspheres, wash and dry to obtain methyl acrylate grafted chitosan microspheres; take 2g of methyl acrylate grafted chitosan microspheres and 100mL of methanol, stir evenly under the conditions of nitrogen protection and constant temperature of 40°C, add 25mL of diethylenetriamine, react for 72h, collect the microspheres, wash and dry to obtain amino-branched modified chitosan; Step 2: Preparation of modified metal organic framework adsorption materials: Take 0.5g amino-branched modified chitosan and 20mL acetic acid aqueous solution with a concentration of 2%, stir for 12min, add 0.8g zinc nitrate hexahydrate, and ultrasonically disperse for 1.5h to obtain a mixed solution; drop the mixed solution into 100mL 1mol / L sodium hydroxide solution, stir for 3h, wash until neutral, and then immerse in 40mL 2% 2-methylimidazole aqueous solution, age for 24h, wash, and freeze-dry to obtain a modified metal organic framework adsorption material; Step 3: Preparation of nitrogen-containing biochar: The shrimp shells were washed, dried, crushed, and sieved to obtain the treated shrimp shells, which were heated to 610°C, pickled with 15% acetic acid solution, and dried to obtain nitrogen-containing biochar; Step 4: Preparation of amination gelatin solution: Take 10g of polyvinyl alcohol and 100mL of deionized water, stir evenly to obtain a polyvinyl alcohol aqueous solution, take 12g of gelatin and 100mL of deionized water, stir evenly to obtain a gelatin aqueous solution, mix the polyvinyl alcohol aqueous solution and the gelatin aqueous solution evenly, add 10g of polyvinyl pyrrolidone, stir evenly, add 5% hydrochloric acid, adjust the pH value of the solution to 3.5, drop 5g of glutaraldehyde, stir evenly, add 0.6g of Span-80 and 600mL of liquid paraffin, stir evenly, heat to 68°C, stir for 5h, filter, wash, and dry to obtain solid A; take 5g of solid A, 2mL of triethylamine, and 200mL of toluene, under nitrogen protection, add 6mL of 3-amino-trimethoxysilane, reflux and stir at 108°C, react for 2.5h to obtain an amino gelatin solution; Step 5: Preparation of adsorbent: Take 100 g of amino gelatin solution, 2 g of modified metal organic framework adsorption material, and 3 g of nitrogen-containing biochar, heat to 68° C., stir for 2.5 h, filter, wash, and dry to obtain an adsorbent.

[0025] experiment: Take the adsorbents prepared in Examples 1 to 3 and Comparative Examples 1 to 3, and measure the concentrations of heavy metal ions of nickel and cadmium in the wastewater before and after adsorption. Add 5 mg of adsorbent to deionized water containing 5 mL 100 mg / L Ni (II) and 5 mL 100 mg / L Cd (IV), respectively, and oscillate at a speed of 200 rpm for 4 hours. Calculate the removal rate, and the data obtained are as follows:

[0026] Conclusion: From the comparison of the data in the table, it can be seen that in Example 1, chitosan is not modified by amino branching, and the removal rate of heavy metal ions of nickel and cadmium decreases. In Example 2, the metal organic framework adsorption material is not modified, and the removal rate of heavy metal ions of nickel and cadmium decreases significantly. In Example 3, the nitrogen-containing biochar is not modified, the specific surface area of ​​the nitrogen-containing biochar is small, and the adsorption effect on metal nickel and cadmium becomes worse. In Examples 1-3 of the present invention, polyvinyl alcohol and gelatin are used as raw materials, and 3-amino-trimethoxysilane is used for amino modification to prepare an amino gelatin solution, and then modified metal organic framework adsorption materials and modified nitrogen-containing biochar are added to react, and an adsorbent with good adsorption effect on metal nickel and cadmium is prepared. The modified metal organic framework adsorption material and the modified nitrogen-containing biochar have amino groups, so that the modified metal organic framework adsorption material and the modified nitrogen-containing biochar have good dispersion in the amino gelatin, thereby improving the adsorption effect of the adsorbent.

[0027] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above and that the present invention can be implemented in other specific forms without departing from the spirit or essential features of the present invention. Therefore, the embodiments should be considered exemplary and non-restrictive in all respects, and the scope of the present invention is defined by the appended claims rather than the above description, and it is intended that all changes falling within the meaning and scope of the equivalent elements of the claims be included in the present invention.

Claims

1. A method for treating nonferrous metal wastewater containing nickel and cadmium, characterized in that: The following steps are involved: Step 1: Take amino-branched modified chitosan and acetic acid aqueous solution, stir for 10-15 minutes, add zinc nitrate hexahydrate, and ultrasonically disperse for 1-2 hours to obtain a mixed solution; drop the mixed solution into a sodium hydroxide solution, stir for 2-4 hours, wash until neutral, and then immerse in a 2-methylimidazole aqueous solution, age for 22-26 hours, wash, and freeze-dry to obtain a modified metal organic framework adsorption material; Step 2: Take the amino gelatin solution, the modified metal organic framework adsorption material, and the modified nitrogen-containing biochar, heat them to 65-70° C., stir for 2-3 hours, filter, wash, and dry to obtain an adsorbent; Step 3: Pour the adsorbent into the non-ferrous metal wastewater containing nickel and cadmium, perform adsorption treatment for 4-6 hours, and obtain treated wastewater.

2. The method for treating nonferrous metal wastewater containing nickel and cadmium according to claim 1, characterized in that: In step one, the preparation method of amino-branched modified chitosan is as follows: take chitosan microspheres and methanol, stir them evenly under nitrogen protection, add methyl acrylate, react for 58-62 hours, collect the microspheres, wash and dry them to obtain methyl acrylate-grafted chitosan microspheres; take methyl acrylate-grafted chitosan microspheres and methanol, stir them evenly under nitrogen protection, add diethylenetriamine, react for 70-74 hours, collect the microspheres, wash and dry them to obtain amino-branched modified chitosan.

3. The method for treating nonferrous metal wastewater containing nickel and cadmium according to claim 1, characterized in that: In step 2, the preparation method of modified nitrogen-containing biochar is as follows: take nitrogen-containing biochar and deionized water, stir evenly, add sodium hydroxide, stir evenly, add diethylenetriamine, stir evenly, drop carbon disulfide, react at 25-30°C for 50-70min, drop epichlorohydrin, stir for 20-30min, heat to 60-65°C, react for 4-5h, wash and dry to obtain modified nitrogen-containing biochar.

4. The method for treating nonferrous metal wastewater containing nickel and cadmium according to claim 3, characterized in that: The method for preparing the nitrogen-containing biochar comprises: taking shrimp shells, washing, drying, crushing and sieving to obtain treated shrimp shells, heating the shrimp shells to 600-620° C., washing with acetic acid solution and drying to obtain nitrogen-containing biochar.

5. The method for treating nonferrous metal wastewater containing nickel and cadmium according to claim 2, characterized in that: The preparation method of the chitosan microspheres comprises: taking chitosan and acetic acid aqueous solution, stirring evenly to obtain chitosan acetic acid aqueous solution; spray drying the chitosan acetic acid aqueous solution under the conditions of an inlet temperature of 200-210° C. and an outlet temperature of 90-100° C. to obtain chitosan microspheres.

6. The method for treating nonferrous metal wastewater containing nickel and cadmium according to claim 1, characterized in that: In step 2, the preparation method of the amino gelatin solution is as follows: take polyvinyl alcohol and deionized water, stir evenly to obtain a polyvinyl alcohol aqueous solution, take gelatin and deionized water, stir evenly to obtain a gelatin aqueous solution, mix the polyvinyl alcohol aqueous solution and the gelatin aqueous solution evenly, add polyvinyl pyrrolidone, stir evenly, add hydrochloric acid, adjust the pH value of the solution to 3-4, add glutaraldehyde dropwise, stir evenly, add Span-80 and liquid paraffin, stir evenly, heat to 65-70°C, stir for 4-6h, filter, wash, and dry to obtain solid A; take solid A, triethylamine, and toluene, add 3-amino-trimethoxysilane under nitrogen protection, reflux and stir at 105-110°C, react for 2-3h to obtain an amino gelatin solution.

7. The method for treating nonferrous metal wastewater containing nickel and cadmium according to claim 1, characterized in that: The mass ratio of the amino gelatin solution, the modified metal organic framework adsorption material, and the modified nitrogen-containing biochar is (90-100): (2-2.5):

3.

8. The method for treating nonferrous metal wastewater containing nickel and cadmium according to claim 7, characterized in that: The mass ratio of the amino gelatin solution, the modified metal organic framework adsorption material and the modified nitrogen-containing biochar is 100:2:3.

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