1. A method for separating metals in electronic waste based on a nano carbon material is characterized in that; the method comprises the following steps:

preparing an adsorbing material:

s1, washing silkworm excrement by deionized water, removing surface dust, filtering, putting into a muffle furnace, and roasting to obtain carbonized silkworm excrement; mixing the carbonized silkworm excrement and solid potassium hydroxide according to the mass ratio of 4-5:1, and heating and activating to obtain activated carbonized silkworm excrement; washing the activated carbonized silkworm excrement with deionized water and a hydrochloric acid solution, and drying to constant weight to obtain microporous silkworm excrement;

s2, dispersing the carbon nano tube in absolute ethyl alcohol, adding a silane coupling agent for reaction, evaporating to remove an ethanol solution, and drying to constant weight to obtain a pretreated carbon nano tube;

dispersing the pretreated carbon nanotube in N, N-dimethylformamide, adding dimethyl azodiisobutyrate, dropwise adding an acrylonitrile solution in a nitrogen atmosphere, keeping the temperature at 70-80 ℃ for reaction, heating to 85-90 ℃, preserving heat, aging, performing vacuum dehydration, adding ethylenediamine and a catalyst concentrated sulfuric acid, heating to 85-90 ℃ for reaction, performing centrifugal separation to obtain a solid phase, and drying the solid phase to constant weight to obtain the imidazolidinone-carbon nanotube;

(2) crushing and sieving the electronic waste to obtain electronic waste particles, and performing electrostatic separation on the electronic waste particles to obtain nonmetal and metal mixed particles;

(3) taking the metal mixed particles prepared in the step (2), and carrying out magnetic separation to obtain iron powder and non-magnetic metal particles;

(4) adding a metal chloride aqueous solution into the nonmagnetic metal particles obtained in the step (3), standing for reaction to obtain a white silver chloride precipitate, filtering, and separating to obtain silver chloride and a mixed solution A;

dissolving the silver chloride precipitate, and reducing the silver chloride precipitate into metallic silver;

(5) adding the imidazolidinone-carbon nano tube into the mixed solution A obtained in the step (4), standing for reaction, filtering, and separating to obtain the imidazolidinone-carbon nano tube adsorbing palladium and the mixed solution A;

adding the palladium-adsorbed imidazolidinone-carbon nano tube into a thiourea solution, and desorbing for 30-40min to obtain metal palladium and the imidazolidinone-carbon nano tube;

(6) adding microporous silkworm excrement into the mixed solution B, adsorbing and filtering to obtain microporous silkworm excrement adsorbing gold and platinum and mixed solution C;

adding the microporous silkworm excrement adsorbed with gold and platinum into the thiourea-hydrochloric acid mixed solution, and desorbing for 30-40min to obtain metal gold, platinum and microporous silkworm excrement;

(7) and (3) adding the microporous silkworm excrement desorbed in the step (5) into the mixed solution C, adsorbing, filtering to obtain microporous silkworm excrement adsorbing gold and platinum, adding a thiourea-hydrochloric acid mixed solution, and desorbing for 30-40min to obtain metal gold, platinum and microporous silkworm excrement.

2. The method for separating metals in electronic waste based on nano carbon material as claimed in claim 1, wherein: comprises the following steps;

(1) preparing an adsorbing material:

s1, washing silkworm excrement by deionized water, removing surface dust, filtering, drying for 1-2h at the temperature of 110 ℃ in a 105-plus-material atmosphere, placing in a muffle furnace, heating to 800 ℃ in a nitrogen atmosphere, roasting for 4-6h, and cooling to 90-100 ℃ to obtain carbonized silkworm excrement; mixing the carbonized silkworm excrement and solid potassium hydroxide according to the mass ratio of 4-5:1, heating to 500-600 ℃ in a nitrogen atmosphere, activating for 40-60min, and cooling to 90-100 ℃ to obtain activated carbonized silkworm excrement; soaking the activated carbonized silkworm excrement in deionized water for 1-2h, adding 1mol/l hydrochloric acid solution for washing for 2-3 times, washing for 2-3 times by using deionized water, and drying to constant weight to obtain microporous silkworm excrement;

s2, dispersing the carbon nano tube in absolute ethyl alcohol, adding a silane coupling agent, heating to 70-75 ℃, reacting for 18-20h, evaporating to remove an ethanol solution, and drying to constant weight to obtain a pretreated carbon nano tube;

dispersing the pretreated carbon nanotube in N, N-dimethylformamide, cooling to 0-10 ℃, adding dimethyl azodiisobutyrate, dropwise adding an acrylonitrile solution under the nitrogen atmosphere, keeping the temperature at 70-80 ℃, reacting for 6-8h, heating to 85-90 ℃, preserving heat and aging for 2-3h, carrying out vacuum dehydration, cooling to 30-35 ℃, adding ethylenediamine and a catalyst concentrated sulfuric acid, heating to 85-90 ℃, reacting for 6-8h, carrying out centrifugal separation to obtain a solid phase, and drying the solid phase to constant weight to obtain the imidazolidinone-carbon nanotube;

(2) crushing and sieving the electronic waste to obtain electronic waste particles with the average particle size of 0.05-5mm, and performing electrostatic separation on the electronic waste particles to obtain nonmetal and metal mixed particles;

(3) taking the metal mixed particles prepared in the step (2), and carrying out magnetic separation to obtain iron powder and non-magnetic metal particles;

(4) adding a metal chloride aqueous solution into the nonmagnetic metal particles obtained in the step (3), uniformly stirring, standing for reaction for 30-40min to obtain a white silver chloride precipitate, filtering, and separating to obtain silver chloride and a mixed solution A;

dissolving the silver chloride precipitate, and reducing the silver chloride precipitate into metallic silver;

(5) adding the imidazolidinone-carbon nano tube into the mixed solution A obtained in the step (4), uniformly stirring, standing for reaction for 30-40min, filtering, and separating to obtain the imidazolidinone-carbon nano tube adsorbing palladium and the mixed solution A;

adding thiourea solution into the palladium-adsorbed imidazolidinone-carbon nanotube, adjusting the pH to 1.5-2.0 by using phosphoric acid solution, and desorbing for 30-40min to obtain metal palladium and the imidazolidinone-carbon nanotube;

(6) adding phosphoric acid solution into the mixed solution B, adjusting pH to 4.0-5.0, adding microporous faeces Bombycis, stirring, adsorbing for 1-2 hr, and filtering to obtain microporous faeces Bombycis adsorbing gold and platinum and mixed solution C;

adding the microporous silkworm excrement adsorbed with gold and platinum into the thiourea-hydrochloric acid mixed solution, and desorbing for 30-40min to obtain metal gold, platinum and microporous silkworm excrement;

(7) and (3) adding the microporous silkworm excrement desorbed in the step (5) into the mixed solution C, heating to 40-50 ℃, adsorbing for 2-3h, filtering to obtain microporous silkworm excrement adsorbing gold and platinum, adding a thiourea-hydrochloric acid mixed solution, and desorbing for 30-40min to obtain metal gold, platinum and microporous silkworm excrement.

3. The method for separating metals in electronic waste based on nano carbon material as claimed in claim 2, wherein: and (3) in the step (4), the metal chloride salt is any one or more of sodium chloride, potassium chloride, magnesium chloride, calcium chloride, zinc chloride and copper chloride.

4. The method for separating metals in electronic waste based on nano carbon material as claimed in claim 2, wherein: and (3) in the step (6), the concentration of thiourea in the thiourea-hydrochloric acid mixed solution is 1.0-1.5 mol/L.

5. The method for separating metals in electronic waste based on nano carbon material as claimed in claim 2, wherein: the mass concentration of the phosphoric acid solution in the step (5) is 75 wt.%; the mass concentration of the phosphoric acid solution in the step (6) is 75 wt.%.

6. The method for separating metals in electronic waste based on nano carbon material as claimed in claim 2, wherein: and (3) the mass ratio of the mixed solution A to the imidazolidinone-carbon nano tube in the step (5) is 8-10: 1.

7. The method for separating metals in electronic waste based on nano carbon material as claimed in claim 2, wherein: the mass ratio of the mixed solution B to the microporous silkworm excrement in the step (6) is 10-12: 1.

Background

The electronic waste mainly refers to rejected or scrapped household appliances and electronic products such as televisions, refrigerators, washing machines, air conditioners, computers, mobile phones, radio recorders and the like. The electronic waste contains various metal components, resin and other non-metal components, and if the electronic waste is directly discarded, buried or combusted, the electronic waste not only wastes resources, but also brings more environmental pollution.

In order to respond to the call for recycling waste resources and protecting the environment, the industry is constantly dedicated to research a method for recycling metal components in high-efficiency, high-quality and light-pollution electronic wastes, and the research can not only recycle and obtain a large amount of metals and create economic benefits, but also eliminate the serious harm of the electronic wastes to the environment and human beings.

The invention provides a method for separating metals from electronic waste based on a nano carbon material, which separates iron, silver, gold, platinum and palladium from the electronic waste by adopting a mode of combining a physical method and a chemical method and has high recovery rate and purity.

Disclosure of Invention

The present invention aims to provide a method for separating metals from electronic waste based on nano carbon material, so as to solve the problems in the background art.

In order to solve the technical problems, the invention provides the following technical scheme: a method for separating metals in electronic waste based on a nano carbon material comprises the following steps:

(1) preparing an adsorbing material:

s1, washing silkworm excrement by deionized water, removing surface dust, filtering, putting into a muffle furnace, and roasting to obtain carbonized silkworm excrement; mixing the carbonized silkworm excrement and solid potassium hydroxide according to the mass ratio of 4-5:1, and heating and activating to obtain activated carbonized silkworm excrement; washing the activated carbonized silkworm excrement with deionized water and a hydrochloric acid solution, and drying to constant weight to obtain microporous silkworm excrement;

s2, dispersing the carbon nano tube in absolute ethyl alcohol, adding a silane coupling agent for reaction, evaporating to remove an ethanol solution, and drying to constant weight to obtain a pretreated carbon nano tube;

dispersing the pretreated carbon nanotube in N, N-dimethylformamide, adding dimethyl azodiisobutyrate, dropwise adding an acrylonitrile solution in a nitrogen atmosphere, keeping the temperature at 70-80 ℃ for reaction, heating to 85-90 ℃, preserving heat, aging, performing vacuum dehydration, adding ethylenediamine and a catalyst concentrated sulfuric acid, heating to 85-90 ℃ for reaction, performing centrifugal separation to obtain a solid phase, and drying the solid phase to constant weight to obtain the imidazolidinone-carbon nanotube;

(2) crushing and sieving the electronic waste to obtain electronic waste particles, and performing electrostatic separation on the electronic waste particles to obtain nonmetal and metal mixed particles;

(3) taking the metal mixed particles prepared in the step (2), and carrying out magnetic separation to obtain iron powder and non-magnetic metal particles;

(4) adding a metal chloride aqueous solution into the nonmagnetic metal particles obtained in the step (3), standing for reaction to obtain a white silver chloride precipitate, filtering, and separating to obtain silver chloride and a mixed solution A;

dissolving the silver chloride precipitate, and reducing the silver chloride precipitate into metallic silver;

(5) adding the imidazolidinone-carbon nano tube into the mixed solution A obtained in the step (4), standing for reaction, filtering, and separating to obtain the imidazolidinone-carbon nano tube adsorbing palladium and the mixed solution A;

adding the palladium-adsorbed imidazolidinone-carbon nano tube into a thiourea solution, and desorbing for 30-40min to obtain metal palladium and the imidazolidinone-carbon nano tube;

(6) adding microporous silkworm excrement into the mixed solution B, adsorbing and filtering to obtain microporous silkworm excrement adsorbing gold and platinum and mixed solution C;

adding the microporous silkworm excrement adsorbed with gold and platinum into the thiourea-hydrochloric acid mixed solution, and desorbing for 30-40min to obtain metal gold, platinum and microporous silkworm excrement;

(7) and (3) adding the microporous silkworm excrement desorbed in the step (5) into the mixed solution C, adsorbing, filtering to obtain microporous silkworm excrement adsorbing gold and platinum, adding a thiourea-hydrochloric acid mixed solution, and desorbing for 30-40min to obtain metal gold, platinum and microporous silkworm excrement.

Further, the method for separating the metals in the electronic waste based on the nano carbon material comprises the following steps;

(1) preparing an adsorbing material:

s1, washing silkworm excrement by deionized water, removing surface dust, filtering, drying for 1-2h at the temperature of 110 ℃ in a 105-plus-material atmosphere, placing in a muffle furnace, heating to 800 ℃ in a nitrogen atmosphere, roasting for 4-6h, and cooling to 90-100 ℃ to obtain carbonized silkworm excrement; mixing the carbonized silkworm excrement and solid potassium hydroxide according to the mass ratio of 4-5:1, heating to 500-600 ℃ in a nitrogen atmosphere, activating for 40-60min, and cooling to 90-100 ℃ to obtain activated carbonized silkworm excrement; soaking the activated carbonized silkworm excrement in deionized water for 1-2h, adding 1mol/l hydrochloric acid solution for washing for 2-3 times, washing for 2-3 times by using deionized water, and drying to constant weight to obtain microporous silkworm excrement;

s2, dispersing the carbon nano tube in absolute ethyl alcohol, adding a silane coupling agent, heating to 70-75 ℃, reacting for 18-20h, evaporating to remove an ethanol solution, and drying to constant weight to obtain a pretreated carbon nano tube;

dispersing the pretreated carbon nanotube in N, N-dimethylformamide, cooling to 0-10 ℃, adding dimethyl azodiisobutyrate, dropwise adding an acrylonitrile solution under the nitrogen atmosphere, keeping the temperature at 70-80 ℃, reacting for 6-8h, heating to 85-90 ℃, preserving heat and aging for 2-3h, carrying out vacuum dehydration, cooling to 30-35 ℃, adding ethylenediamine and a catalyst concentrated sulfuric acid, heating to 85-90 ℃, reacting for 6-8h, carrying out centrifugal separation to obtain a solid phase, and drying the solid phase to constant weight to obtain the imidazolidinone-carbon nanotube;

(2) crushing and sieving the electronic waste to obtain electronic waste particles with the average particle size of 0.05-5mm, and performing electrostatic separation on the electronic waste particles to obtain nonmetal and metal mixed particles;

(3) taking the metal mixed particles prepared in the step (2), and carrying out magnetic separation to obtain iron powder and non-magnetic metal particles;

(4) adding a metal chloride aqueous solution into the nonmagnetic metal particles obtained in the step (3), uniformly stirring, standing for reaction for 30-40min to obtain a white silver chloride precipitate, filtering, and separating to obtain silver chloride and a mixed solution A;

dissolving the silver chloride precipitate, and reducing the silver chloride precipitate into metallic silver;

(5) adding the imidazolidinone-carbon nano tube into the mixed solution A obtained in the step (4), uniformly stirring, standing for reaction for 30-40min, filtering, and separating to obtain the imidazolidinone-carbon nano tube adsorbing palladium and the mixed solution A;

adding thiourea solution into the palladium-adsorbed imidazolidinone-carbon nanotube, adjusting the pH to 1.5-2.0 by using phosphoric acid solution, and desorbing for 30-40min to obtain metal palladium and the imidazolidinone-carbon nanotube;

in the step, phosphoric acid solution is adopted to adjust the pH value to be strong acid, and amino on the surface of the imidazolidinone-carbon nano tube is easily substituted by H under the condition⁺Protonation, thereby promoting adsorption of metal ions; when the mixed solution A is strongly acidic, the concentration of chloride ions is higher, and palladium in the solution is PdCl₄ ^2-Form and exist when the imidazolidinone-carbon nano tube and PdCl₄ ^2-Ion exchange and metal chelation are carried out, and palladium is adsorbed on the surface of the molecule.

(6) Adding phosphoric acid solution into the mixed solution B, adjusting pH to 4.0-5.0, adding microporous faeces Bombycis, stirring, adsorbing for 1-2 hr, and filtering to obtain microporous faeces Bombycis adsorbing gold and platinum and mixed solution C;

adding the microporous silkworm excrement adsorbed with gold and platinum into the thiourea-hydrochloric acid mixed solution, and desorbing for 30-40min to obtain metal gold, platinum and microporous silkworm excrement;

(7) and (3) adding the microporous silkworm excrement desorbed in the step (5) into the mixed solution C, heating to 40-50 ℃, adsorbing for 2-3h, filtering to obtain microporous silkworm excrement adsorbing gold and platinum, adding a thiourea-hydrochloric acid mixed solution, and desorbing for 30-40min to obtain metal gold, platinum and microporous silkworm excrement.

In the step, biogenic silkworm excrement is used as a raw material, high-temperature carbonization and activation treatment are carried out to obtain porous microporous silkworm excrement, and the activated microporous silkworm excrement has excellent selective adsorption on metal gold and platinum in an acid environment with the pH value of 4.0-5.0; after the elution is carried out by thiourea-hydrochloric acid solution, high-purity gold and platinum can be obtained, and the eluted microporous silkworm excrement can be recycled; in the step, the eluted microporous silkworm excrement is used for adsorbing the mixed solution again to further adsorb residual trace gold and platinum, so that the recovery rate is further improved.

Further, in the step (4), the metal chloride salt is any one or more of sodium chloride, potassium chloride, magnesium chloride, calcium chloride, zinc chloride and copper chloride.

Further, the concentration of thiourea in the thiourea-hydrochloric acid mixed solution in the step (6) is 1.0-1.5 mol/L.

Further, the mass concentration of the phosphoric acid solution in the step (5) is 75 wt.%; the mass concentration of the phosphoric acid solution in the step (6) is 75 wt.%.

Further, the mass ratio of the mixed solution A to the imidazolidinone-carbon nanotubes in the step (5) is 8-10: 1.

Further, the mass ratio of the mixed solution B to the microporous silkworm excrement in the step (6) is 10-12: 1.

Compared with the prior art, the invention has the following beneficial effects: the invention provides a method for separating metal from electronic waste based on a nano carbon material, which adopts a physical separation method to separate resin plastic and magnetic metal iron powder with non-metal components through electrostatic separation and magnetic separation; separating the metal silver from the residual nonmagnetic metal particles by a chemical precipitation method, and respectively preparing adsorbents with stronger selectivity for the noble metals such as palladium, platinum and gold with smaller specific gravity in the electronic waste; the method comprises the steps of taking biomass resource silkworm excrement as a raw material, carrying out high-temperature carbonization and potassium hydroxide activation on the silkworm excrement to obtain high-purity gold and platinum, wherein the selective adsorption on noble metal gold and platinum is strong, the adsorption rate can reach more than 99.0%, and the adsorbed silkworm excrement is eluted by thiourea-hydrochloric acid solution; the eluted microporous silkworm excrement can be recycled. The invention also takes the carbon nano-tube of the nano-carbon material as the basic raw material, and the carbon nano-tube with the imidazolidinone structure on the surface is generated through the graft reaction with acrylonitrile and ethylenediamine, and the adsorption rate of the structure on noble metal palladium is extremely high and can reach 99.3 percent or more.

Detailed Description

The technical solutions in the embodiments of the present invention are clearly and completely described below, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Example 1

A method for separating metals in electronic waste based on a nano carbon material comprises the following steps;

(1) preparing an adsorbing material:

s1, washing silkworm excrement by deionized water, removing surface dust, filtering, drying for 1h at the temperature of 105 ℃, putting into a muffle furnace, heating to 700 ℃ under the nitrogen atmosphere, roasting for 4h, and cooling to 90 ℃ to obtain carbonized silkworm excrement; mixing the carbonized silkworm excrement and solid potassium hydroxide according to the mass ratio of 4:1, heating to 500 ℃ in a nitrogen atmosphere, activating for 40min, and cooling to 90 ℃ to obtain activated carbonized silkworm excrement; soaking the activated carbonized silkworm excrement in deionized water for 1h, adding 1mol/l hydrochloric acid solution to wash for 2 times, washing for 2 times by using the deionized water, and drying to constant weight to obtain microporous silkworm excrement;

s2, dispersing the carbon nano tube in absolute ethyl alcohol, adding a silane coupling agent, heating to 70 ℃, reacting for 18 hours, evaporating to remove an ethanol solution, and drying to constant weight to obtain a pretreated carbon nano tube;

dispersing the pretreated carbon nano tube in N, N-dimethylformamide, cooling to 0 ℃, adding dimethyl azodiisobutyrate, dropwise adding an acrylonitrile solution under the nitrogen atmosphere, keeping the temperature at 70 ℃, reacting for 6 hours, heating to 85 ℃, preserving heat and aging for 2 hours, performing vacuum dehydration, cooling to 30 ℃, adding ethylenediamine and a catalyst concentrated sulfuric acid, heating to 85 ℃, reacting for 6 hours, performing centrifugal separation to obtain a solid phase, and drying the solid phase to constant weight to obtain the imidazolidinone-carbon nano tube;

(2) crushing and sieving the electronic waste to obtain electronic waste particles with the average particle size of 0.05mm, and performing electrostatic separation on the electronic waste particles to obtain nonmetal and metal mixed particles;

(3) taking the metal mixed particles prepared in the step (2), and carrying out magnetic separation to obtain iron powder and non-magnetic metal particles;

(4) adding a metal chloride aqueous solution into the nonmagnetic metal particles obtained in the step (3), uniformly stirring, standing for 30min for reaction to obtain a white silver chloride precipitate, filtering, and separating to obtain silver chloride and a mixed solution A;

dissolving the silver chloride precipitate, and reducing the silver chloride precipitate into metallic silver;

(5) adding the imidazolidinone-carbon nano tube into the mixed solution A obtained in the step (4), uniformly stirring, standing for reaction for 30min, filtering, and separating to obtain the imidazolidinone-carbon nano tube adsorbing palladium and the mixed solution A;

adding a thiourea solution into the palladium-adsorbed imidazolidinone-carbon nanotube, adjusting the pH to 1.5 with 75wt.% phosphoric acid solution, and desorbing for 30min to obtain metal palladium and the imidazolidinone-carbon nanotube;

(6) adding 75wt.% phosphoric acid solution into the mixed solution B, adjusting the pH to 4.0, adding microporous silkworm excrement, uniformly stirring, adsorbing for 1h, and filtering to obtain microporous silkworm excrement adsorbing gold and platinum and a mixed solution C;

adding the microporous silkworm excrement adsorbed with gold and platinum into the thiourea-hydrochloric acid mixed solution, and desorbing for 30min to obtain metal gold, platinum and microporous silkworm excrement;

(7) and (3) adding the microporous silkworm excrement desorbed in the step (5) into the mixed solution C, heating to 40 ℃, adsorbing for 2h, filtering to obtain microporous silkworm excrement adsorbing gold and platinum, adding a thiourea-hydrochloric acid mixed solution, and desorbing for 30min to obtain metal gold, platinum and microporous silkworm excrement.

In this embodiment, the metal chloride salt in step (4) is sodium chloride; in the step (6), the concentration of thiourea in the thiourea-hydrochloric acid mixed solution is 1.0 mol/L; in the step (5), the mass ratio of the mixed solution A to the imidazolidinone-carbon nano tube is 8: 1; and (4) the mass ratio of the mixed solution B to the microporous silkworm excrement in the step (6) is 10: 1.

Example 2

A method for separating metals in electronic waste based on a nano carbon material comprises the following steps;

(1) preparing an adsorbing material:

s1, washing silkworm excrement by deionized water, removing surface dust, filtering, drying for 1-2h at the temperature of 107 ℃, putting into a muffle furnace, heating to 750 ℃ under the nitrogen atmosphere, roasting for 4.5h, and cooling to 95 ℃ to obtain carbonized silkworm excrement; mixing the carbonized silkworm excrement and solid potassium hydroxide according to the mass ratio of 4.5:1, heating to 540 ℃ in a nitrogen atmosphere, activating for 45min, and cooling to 96 ℃ to obtain activated carbonized silkworm excrement; soaking the activated carbonized silkworm excrement in deionized water for 1.5h, adding 1mol/l hydrochloric acid solution for washing for 2.5 times, washing for 2.5 times by using the deionized water, and drying to constant weight to obtain microporous silkworm excrement;

s2, dispersing the carbon nano tube in absolute ethyl alcohol, adding a silane coupling agent, heating to 73 ℃, reacting for 19 hours, evaporating to remove an ethanol solution, and drying to constant weight to obtain a pretreated carbon nano tube;

dispersing the pretreated carbon nanotube in N, N-dimethylformamide, cooling to 5 ℃, adding dimethyl azodiisobutyrate, dropwise adding an acrylonitrile solution under the nitrogen atmosphere, keeping the temperature at 77 ℃, reacting for 7 hours, heating to 88 ℃, preserving heat and aging for 2.5 hours, performing vacuum dehydration, cooling to 32 ℃, adding ethylenediamine and a catalyst concentrated sulfuric acid, heating to 87 ℃, reacting for 7 hours, performing centrifugal separation to obtain a solid phase, and drying the solid phase to constant weight to obtain the imidazolidinone-carbon nanotube;

(2) crushing and sieving the electronic waste to obtain electronic waste particles with the average particle size of 2mm, and performing electrostatic separation on the electronic waste particles to obtain nonmetal and metal mixed particles;

(3) taking the metal mixed particles prepared in the step (2), and carrying out magnetic separation to obtain iron powder and non-magnetic metal particles;

(4) adding a metal chloride aqueous solution into the nonmagnetic metal particles obtained in the step (3), uniformly stirring, standing for reaction for 37min to obtain a white silver chloride precipitate, filtering, and separating to obtain silver chloride and a mixed solution A;

dissolving the silver chloride precipitate, and reducing the silver chloride precipitate into metallic silver;

(5) adding the imidazolidinone-carbon nano tube into the mixed solution A obtained in the step (4), uniformly stirring, standing for reacting for 35min, filtering, and separating to obtain the imidazolidinone-carbon nano tube adsorbing palladium and the mixed solution A;

adding a thiourea solution into the palladium-adsorbed imidazolidinone-carbon nanotube, adjusting the pH to 1.8 by using a 75wt.% phosphoric acid solution, and desorbing for 33min to obtain metal palladium and the imidazolidinone-carbon nanotube;

(6) adding 75wt.% phosphoric acid solution into the mixed solution B, adjusting the pH value to 4.3, adding microporous silkworm excrement, uniformly stirring, adsorbing for 1.5h, and filtering to obtain microporous silkworm excrement adsorbing gold and platinum and a mixed solution C;

adding the microporous silkworm excrement adsorbed with gold and platinum into the thiourea-hydrochloric acid mixed solution, and desorbing for 35min to obtain metal gold, platinum and microporous silkworm excrement;

(7) and (3) adding the microporous silkworm excrement desorbed in the step (5) into the mixed solution C, heating to 44 ℃, adsorbing for 2.5h, filtering to obtain microporous silkworm excrement adsorbing gold and platinum, adding a thiourea-hydrochloric acid mixed solution, and desorbing for 35min to obtain metal gold, platinum and microporous silkworm excrement.

In this embodiment, the metal chloride salt in step (4) is sodium chloride; in the step (6), the concentration of thiourea in the thiourea-hydrochloric acid mixed solution is 1.2 mol/L; the mass ratio of the mixed solution A to the imidazolidinone-carbon nano tube in the step (5) is 9: 1; and (4) the mass ratio of the mixed solution B to the microporous silkworm excrement in the step (6) is 11: 1.

Example 3

A method for separating metals in electronic waste based on a nano carbon material comprises the following steps;

(1) preparing an adsorbing material:

s1, washing silkworm excrement by deionized water, removing surface dust, filtering, drying for 2 hours at the temperature of 110 ℃, putting into a muffle furnace, heating to 800 ℃ in the nitrogen atmosphere, roasting for 6 hours, and cooling to 100 ℃ to obtain carbonized silkworm excrement; mixing the carbonized silkworm excrement and solid potassium hydroxide according to the mass ratio of 5:1, heating to 600 ℃ in a nitrogen atmosphere, activating for 60min, and cooling to 100 ℃ to obtain activated carbonized silkworm excrement; soaking the activated carbonized silkworm excrement in deionized water for 2h, adding 1mol/l hydrochloric acid solution to wash for 3 times, washing for 3 times by using the deionized water, and drying to constant weight to obtain microporous silkworm excrement;

s2, dispersing the carbon nano tube in absolute ethyl alcohol, adding a silane coupling agent, heating to 75 ℃, reacting for 20 hours, evaporating to remove an ethanol solution, and drying to constant weight to obtain a pretreated carbon nano tube;

dispersing the pretreated carbon nano tube in N, N-dimethylformamide, cooling to 10 ℃, adding dimethyl azodiisobutyrate, dropwise adding an acrylonitrile solution under the nitrogen atmosphere, keeping the temperature at 80 ℃, reacting for 8 hours, heating to 90 ℃, preserving heat and aging for 3 hours, performing vacuum dehydration, cooling to 35 ℃, adding ethylenediamine and a catalyst concentrated sulfuric acid, heating to 90 ℃, reacting for 8 hours, performing centrifugal separation to obtain a solid phase, and drying the solid phase to constant weight to obtain the imidazolidinone-carbon nano tube;

(2) crushing and sieving the electronic waste to obtain electronic waste particles with the average particle size of 5mm, and performing electrostatic separation on the electronic waste particles to obtain nonmetal and metal mixed particles;

(3) taking the metal mixed particles prepared in the step (2), and carrying out magnetic separation to obtain iron powder and non-magnetic metal particles;

(4) adding a metal chloride aqueous solution into the nonmagnetic metal particles obtained in the step (3), uniformly stirring, standing for reacting for 40min to obtain a white silver chloride precipitate, filtering, and separating to obtain silver chloride and a mixed solution A;

dissolving the silver chloride precipitate, and reducing the silver chloride precipitate into metallic silver;

(5) adding the imidazolidinone-carbon nano tube into the mixed solution A obtained in the step (4), uniformly stirring, standing for reacting for 40min, filtering, and separating to obtain the imidazolidinone-carbon nano tube adsorbing palladium and the mixed solution A;

adding a thiourea solution into the palladium-adsorbed imidazolidinone-carbon nanotube, adjusting the pH to 2.0 by using a 75wt.% phosphoric acid solution, and desorbing for 40min to obtain metal palladium and the imidazolidinone-carbon nanotube;

(6) adding 75wt.% phosphoric acid solution into the mixed solution B, adjusting the pH to 5.0, adding microporous silkworm excrement, uniformly stirring, adsorbing for 2h, and filtering to obtain microporous silkworm excrement adsorbing gold and platinum and a mixed solution C;

adding the microporous silkworm excrement adsorbed with gold and platinum into the thiourea-hydrochloric acid mixed solution, and desorbing for 40min to obtain metal gold, platinum and microporous silkworm excrement;

(7) and (3) adding the microporous silkworm excrement desorbed in the step (5) into the mixed solution C, heating to 50 ℃, adsorbing for 3h, filtering to obtain microporous silkworm excrement adsorbing gold and platinum, adding a thiourea-hydrochloric acid mixed solution, and desorbing for 40min to obtain metal gold, platinum and microporous silkworm excrement.

In this embodiment, the metal chloride salt in step (4) is sodium chloride; in the step (6), the concentration of thiourea in the thiourea-hydrochloric acid mixed solution is 1.5 mol/L; in the step (5), the mass ratio of the mixed solution A to the imidazolidinone-carbon nano tube is 10: 1; and (4) in the step (6), the mass ratio of the mixed solution B to the microporous silkworm excrement is 12: 1.

Comparative example 1

Comparative example 1 is compared with example 2, and the carbon nanotubes are prepared without any treatment, and the rest is the same as example 2.

Comparative example 2

Comparative example 2 compared with example 2, when gold and platinum were adsorbed, gold and platinum ions were separated by polyaniline treatment without using microporous silkworm excrement, and then treated with aqua regia solution to recover metal gold and platinum.

Examples of effects

The recovery rates of the metals of iron, silver, palladium, gold and platinum obtained by the separation of the examples 1-3 and the comparative examples 1-2 are calculated and recorded in the following table 1, and the purities of the metals of palladium, gold and platinum obtained by the separation of the examples 1-3 and the comparative examples 1-2 are detected, and the detection results are shown in the following table 1;

TABLE 1

As can be seen from the data in Table 1, examples 1-3, which employ the separation method of the present invention, have high recovery and purity of each metal; compared with the embodiment 2, the carbon nano tube does not carry out any treatment when the comparative example 1 adsorbs the palladium, and the recovery rate and the purity of the final palladium are both reduced compared with the embodiment 2; comparative example 2 compared with example 2, polyaniline is used to replace microporous silkworm excrement to adsorb gold and platinum, and after adsorption, conventional aqua regia treatment is used to obtain metal gold and platinum, but the recovery rate and purity are lower than those of example 2. Therefore, the microporous silkworm excrement and imidazolidinone-carbon nanotube adsorbing material prepared by the method has stronger selective adsorption and better adsorption effect than the conventional technology.

Finally, it should be noted that: although the present invention has been described in detail with reference to the foregoing embodiments, it will be apparent to those skilled in the art that changes may be made in the embodiments and/or equivalents thereof without departing from the spirit and scope of the invention. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.