Preparation method and application of a magnetic light nano-microsphere rapid high-selectivity gold adsorbent

Abstract

The application belongs to the technical field of adsorption separation function preparation, and discloses a preparation method and application of a magnetic light nanometer microsphere rapid high-selectivity gold extraction adsorbent. Polystyrene is used as a template, a silica layer is coated under hydrolysis and condensation of a silicon precursor, light magnetic nanometer balls are prepared through in-situ growth, and the balls are coated on the surface of the magnetic nanometer balls through radical reaction of hydrochloric acid dopamine and allyl thiourea, and in the later stage, the balls are etched by N,N-dimethylformamide to prepare hollow magnetic nanometer light composite adsorbents, and the adsorbents are used for selective recovery of gold in electronic waste liquid. Meanwhile, based on the Pearson soft and hard acid-base theory and the influence of the light response effect on the oxidation and reduction potential of gold, hydrochloric acid dopamine is selected as a functional monomer, and rapid and selective enrichment of gold ions can be realized. The preparation process is simple, the adsorbent has the characteristics of ultra-lightness, the light response effect significantly improves the adsorption capacity of the adsorbent, the adsorbent is easy to recover, and the regeneration performance is good.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of preparation of adsorption separation functional materials, and relates to a preparation method and application of a rapid high-selectivity gold extraction adsorbent of magnetic light nanometer microspheres. BACKGROUND

[0002] Gold is a precious metal, one of the earliest metals discovered and developed by mankind, an important raw material for making jewelry and coins, and an important reserve material for the state, known as the "King of Metals", commonly used in jewelry and electronic products, and also used as a catalyst in medicine and various chemical processes. In recent years, with the development of science and technology and modern industry, gold has played an increasingly important role in medicine, electronics and other industrial sectors, and its use has become more and more extensive, and its consumption has also become larger and larger. With the rapid growth of gold demand, the scale of gold mining has been expanding, which inevitably leads to a large amount of waste of resources and an extreme expansion of waste, and also causes serious environmental pollution and harm to human health. Therefore, "gold reuse" has gradually become a focus of keen attention.

[0003] Waste electrical and electronic equipment (WEEE) is a rapidly growing waste stream. Recently, the United Nations released the "2020 Global Electronic Waste Monitoring" report, which showed that the total amount of global electronic waste reached a record 53.6 million tons last year, a 21% increase in just five years. And it is estimated that the data will reach 74 million tons by 2030. At the same time, the total value of recyclable metals in the circuit boards of discarded computers and mobile phones will reach 160 billion yuan. China is the distribution center of 70% of the world's electronic waste, and also a big producer and consumer of electronic products. With the needs of enterprise development and the rapid integration of "Internet+", all kinds of innovative recycling modes of waste electrical and electronic products have sprung up like mushrooms after rain. Electronic waste contains bulk metals, which should be recycled within the framework of circular economy. Therefore, a more environmentally friendly and more economically competitive route is necessary for extracting metals and achieving a sustainable process.

[0004] The recovery of precious metals from electronic waste usually involves disassembly, shredding and separation, chemical pretreatment to dissolve base metals, followed by pyrometallurgical and or hydrometallurgical processes. Although there are challenges in using strong acids in the leaching process and the need to minimize the loss of chemicals, hydrometallurgical processes are considered a cleaner option that can be integrated into the back end of the recycling plan to recover and produce high-purity metals. Among them, the adsorption method has always been the main technology, which is considered a very promising adsorption method due to its low capital cost, easy operation, cost-effectiveness, environmental friendliness, and strong capacity, and has received widespread attention in recent years.

[0005] Polydopamine (PDA) has attracted widespread attention as an adsorbent material. Its main advantage is the simple and mild operation of forming a thin film on a substrate through spontaneous oxidative polymerization of dopamine under mild conditions. Due to the abundance of functional groups in its structure, including catechol, amine groups, and aromatic moieties, PDA is considered a novel potential adsorbent. It can provide numerous active sites for adsorbing metal ions and toxic organic pollutants through chelation and π-π stacking interactions. Furthermore, PDA has a lower redox potential than gold ions and exhibits strong reducing ability towards gold during redox reactions. Under photoexcitation, AuCl... 4- Ions can also become unstable through charge transfer from ligands to metals and dissociate into unstable AuCl. 3- And the free radical form of chlorine atoms, which readily reacts with AuCl. 4- Recombining. The free radical form of chlorine atoms can also be reduced to Cl. - Subsequently, AuCl was added in the presence of PDA as a proton donor. 4- It is reduced to metallic gold. Therefore, based on the fact that polydopamine adsorbents can be synthesized under mild conditions and exhibit excellent properties in adsorbing metal ions, this invention selects polydopamine as the main material for separation and adsorption.

[0006] With the development of science and technology, the performance requirements for materials are becoming increasingly stringent, and low-density materials are receiving more and more attention, especially the emergence of lightweight materials, which has brought low-density materials to a new level. The performance of lightweight materials mainly depends on their structure and the properties of the solid components that make them up. These lightweight materials possess excellent specific strength and specific stiffness, representing a unity of superior physicochemical properties and structural performance. Here, we constructed a lightweight magnetic material. Compared to traditional magnetic materials, we endowed the material with magnetism through an in-situ growth strategy, but we overcame the problem of the traditional core-shell structure having a relatively heavy magnetic core, thus solving the problem of the small effective adsorption area per unit mass in traditional magnetic materials. Summary of the Invention

[0007] To address the problems of difficulty in collecting gold adsorbents and slow adsorption rates in existing technologies, this invention proposes a method for preparing a rapid and highly selective gold adsorbent from a light-enhanced ultralight magnetic material, which is then used for the rapid and selective enrichment of gold in electronic waste liquid.

[0008] The present application firstly polymerizes styrene to form PS nanoparticles with a particle size of about 250 nm, then uses ethanol as a solvent, and uses ammonia to catalyze the hydrolysis and condensation of tetraethyl orthosilicate (TEOS) to form a dense SiO2 layer, and in-situ growth of magnetic Fe3O4 nanoparticles on the surface. Then, through the adhesion of DA, a dense PDA polymer layer is coated on the surface, and allyl thiourea is used for functionalization. Finally, N,N'-dimethylformamide is used to react with the PS nanoparticles in the inner layer to form an internal hollow structure. Through the design of the hollow core-shell structure, the obtained lightweight nanosorbent has a large specific surface area and high adsorption capacity.

[0009] To achieve the above technical purpose, the technical scheme adopted by the present application is:

[0010] A preparation method of a magnetic lightweight nanomicrosphere rapid high-selectivity gold adsorbent, comprising the following steps:

[0011] (1) Preparation of polystyrene nanoparticles PS

[0012] Dissolve polyvinylpyrrolidone PVP and styrene ST into deionized water, uniformly mix and ultrasonically disperse, then transfer the mixture to an oil bath, then add potassium persulfate KPS, react at a certain temperature for a period of time, naturally cool to room temperature, separate by centrifugation, and wash with deionized water and ethanol for several times to remove residual reagents, and dry the obtained solid PS in a vacuum oven for standby use;

[0013] (2) Preparation of magnetic lightweight nanomicrosphere structure (PS-Fe3O4-PA)

[0014] a. Put the PS prepared in step (1) into anhydrous ethanol EtOH, ultrasonically disperse, then heat in an oil bath, then add ammonia water NH3·H2O, and add tetraethyl orthosilicate TEOS under continuous mechanical stirring, separate the product after reaction by centrifugation, and wash with deionized water and ethanol for several times to remove residual reagents, and dry the obtained solid PS-SiO2 in a vacuum oven for standby use.

[0015] b. Put the PS-SiO2 prepared in step a into deionized water, ultrasonically disperse to obtain solution A;

[0016] Weigh ferric chloride hexahydrate and ferrous sulfate heptahydrate, dissolve them in deionized water, and ultrasonically disperse to obtain solution B;

[0017] Pour solution B into solution A, ultrasonically mix again to make them completely uniform, heat in an oil bath, then add ammonia water, react at a certain speed for a period of time, collect the product after reaction by a magnet, wash with deionized water and anhydrous ethanol for several times to remove residual reagents, and dry the obtained solid PS-SiO2-Fe3O4 in a vacuum oven for standby use.

[0018] c. ultrasonic dispersion of the PS-SiO2-Fe3O4 prepared in step b in Tris solution, adding dopamine hydrochloride DA, uniformly dispersing, then adding an appropriate amount of allyl thiourea ATU ultrasonic, and finally adding azobisisobutyl AIBN, ultrasonic dispersion; after a period of reaction, the product after reaction is separated by magnet and washed with deionized water and anhydrous ethanol several times to remove residual reagents, and the obtained solid PS-Fe3O4-PA is placed in a vacuum oven for drying for standby use.

[0019] (3) Preparation of magnetic light-weight nanometer microsphere adsorbent (HS-Fe3O4-PA)

[0020] The PS-Fe3O4-PA prepared in step (2) is placed in a centrifuge tube, then N,N'-dimethyl formamide DMF is added, ultrasonic dispersion is performed, and then the centrifuge tube is placed on a shaking bed for reaction, the product after reaction is separated by magnet and washed with deionized water and ethanol several times to remove residual reagents, and the obtained solid HS-Fe3O4-PA is placed in a vacuum oven for drying for standby use.

[0021] Preferably, in step (1), the amount of PVP, ST, KPS and deionized water is (1.4-4.2) g: (40-120) mL: (0.54-1.62) g: (245-255) mL, the reaction temperature is 70-80℃, the reaction time is 22-24h, and the rotation speed of mechanical stirring is 500-600rpm.

[0022] Preferably, in step (2)a, the amount of PS, EtOH, NH3·H2O and TEOS is (500-1000) mg: (50-150) mL: (1-3) mL: (1-3) mL,

[0023] The oil bath reaction temperature is 50-60℃, and the reaction time is 10-12h.

[0024] The rotation speed of mechanical stirring is 600-900rpm.

[0025] Preferably, in step (2)b,

[0026] In solution A, the amount of PS-SiO2 and deionized water is (50-150) mg: (50-150) mL;

[0027] In solution B, the amount of ferric chloride hexahydrate, ferrous sulfate heptahydrate and deionized water is (0.05875-0.1762) g: (0.03027-0.09081) g: (50-150) mL;

[0028] Solution A: the volume ratio of solution B is 1:1; the ultrasonic time after mixing solution A and solution B is 30-40 min,

[0029] The ratio of the amount of ammonia and PS-SiO2 in solution A is (285-855) muL:(50-150) mg;

[0030] The oil bath reaction temperature is 35 DEG C, the stirring speed is 500-600 rpm, and the reaction time is 30 min.

[0031] Preferably, in step (2), the ratio of the amount of PS-SiO2-Fe3O4, Tris solution, DA, ATU and AIBN is (50-150) mg:(50-60) mL:(60-90) mg:(30-32) mg:(18-22) mg, the reaction temperature is 80-90 DEG C, and the reaction time is 4-6 h.

[0032] Preferably, in step (3), the ratio of the amount of PS-Fe3O4-PA and DMF is (50-150) mg:(10-25) mL, the reaction time on the shaking table is 30-40 min, and the temperature is room temperature.

[0033] The obtained magnetic light nano microsphere rapid high selectivity gold adsorbent is applied to the adsorption of gold ions in a solution.

[0034] The present application has the following beneficial effects:

[0035] The present application discloses a light magnetic nano adsorbent (HS-Fe3O4-PA) which can effectively separate and recover gold from electronic waste. The hard template technology is adopted, polystyrene (PS) nanoparticles are used as templates, the hydrolysis and condensation of silicon precursors are used to coat silica (SiO2) on the surface of the templates, Fe3O4 nanoparticles are in-situ grown on the surface of the silica under alkaline conditions, and then a layer of polydopamine (PDA) is coated on the surface of the Fe3O4 nanoparticles through the adhesion of dopamine hydrochloride (DA) and the modification of allyl thiourea (ATU). This not only can realize the specific adsorption of gold in the sample, but also can absolutely protect the magnetic core from the erosion of strong acid and strong base. In the recovery process, the adsorbent can be separated out efficiently and rapidly through the action of an external magnetic field, and the polydopamine and the allyl thiourea can be used to selectively adsorb gold. The present application has the advantages of simple preparation process, super light adsorbent, large gold adsorption capacity, light intensity adsorption performance, easy separation and recovery, and good regeneration performance. BRIEF DESCRIPTION OF DRAWINGS

[0036] Figure 1 The preparation process of the light magnetic adsorbent in Example 1 is shown in the schematic diagram.

[0037] Figure 2TEM images of materials at each stage in Example 1. Where PS (a), PS-Si02(b), PS-Si02-Fe304(c), PS-Fe304-PA adsorbent (d), HS-Fe304-PA (e, f).

[0038] Figure 3 are infrared spectrograms of the products at each stage in Example 1.

[0039] Figure 4 are hysteresis loop test analysis graphs of the final product HS-Fe304-PA in Example 1.

[0040] Figure 5 is the effect of different pH of the solution on the adsorption amount of gold ions.

[0041] Figure 6 is a display of the adsorption kinetics experimental results of the product HS-Fe304-PA in Example 1.

[0042] Figure 7 is a display of the equilibrium adsorption experimental results of the product HS-Fe304-PA in Example 1.

[0043] Figure 8 is a display of the regeneration performance experimental results of HS-Fe304-PA in Example 1.

[0044] Figure 9 is a display of the competitive adsorption performance of gold ions of HS-Fe304-PA in Example 1 in the presence of various ions.

[0045] Figure 10 is a display of the adsorption performance of gold ions of HS-Fe304-PA in Example 1 under different light conditions. DETAILED DESCRIPTION

[0046] As Figure 1 The preparation process schematic diagram of the light magnetic adsorbent is shown in the figure.

[0047] Example 1:

[0048] (1) Preparation of polystyrene nanoparticles (PS)

[0049] In a 500 mL round-bottom flask, 40 mL of styrene (ST), 250 mL of pure water, and 1.40 g of polystyrene pyrrolidone (PVP) were added and ultrasonically dissolved. Slowly heated to 75°C under the condition of 500 rpm, then 0.54 g of potassium persulfate (KPS) was added and reacted for 24 h, and the product was collected by centrifugation. Washed with deionized water and anhydrous ethanol (EtOH) three times respectively, and put into a 50°C vacuum oven to dry for 24 h, to obtain the product nano-PS particles.

[0050] (2) Preparation of light magnetic adsorbent (PS-Fe3O4-PA)

[0051] 1) 500 mg of PS prepared in step (1) was placed in a 100 mL three-necked flask, then 50 mL of anhydrous ethanol was added, after ultrasonic dispersion, it was placed in an oil bath at 50°C, 1 mL of ammonia water and 1 ml of tetraethyl orthosilicate were added, after mechanical stirring at 600 rpm for 12 h, the reaction was completed. Then separate by centrifugation, and wash with deionized water and ethanol several times to remove residual reagents, the obtained solid (PS-SiO2) was placed in a 50°C vacuum oven for drying.

[0052] 2) 50 mg of PS-SiO2 prepared in step 1) was weighed into a round-bottom flask, 50 mL of deionized water was added, and ultrasonic dispersion was performed. 0.05875 mg of iron trichloride hexahydrate, 0.0302 mg of ferrous sulfate heptahydrate were weighed into a beaker, 50 mL of deionized water was added, and ultrasonic dispersion was performed. Pour the solvent in the beaker into the round-bottom flask and ultrasonic for 30 min again, so that it is completely mixed and uniform. Then it was placed in an oil bath at 35°C, 285 uL of ammonia water was added, and mechanical stirring was carried out at 500 rpm for 30 min. The product after reaction was collected by magnetic separation. Wash with deionized water and anhydrous ethanol several times to remove residual reagents, the obtained solid (PS-SiO2-Fe3O4) was placed in a 50°C vacuum oven for drying. Naturally cool to room temperature by magnetic separation, and wash with deionized water and ethanol several times to remove residual reagents, the obtained solid (PS-SiO2-Fe3O4) was placed in a vacuum oven for drying.

[0053] 3) 50 mg of PS-SiO2-Fe3O4 prepared in step 2) was weighed into a round-bottom flask, ultrasonic dispersion was performed in a Tris solution, then 60 mg of DA, 30 mg of ATU, 20 mg of AIBN were added, and reaction was carried out at 80°C for 4 h. The product after reaction was collected by magnetic separation, and washed with deionized water and anhydrous ethanol several times to remove residual reagents, the obtained solid (PS-Fe3O4-PA) was placed in a 50°C vacuum oven for drying.

[0054] (3) Preparation of light magnetic adsorbent (HS-Fe3O4-PA)

[0055] 50 mg of (PS-Fe3O4-PA) prepared in step (2) was weighed into a centrifuge tube, then 10 mL of DMF was added, after ultrasonic dispersion, it was placed on a shaker for reaction for 30 min, the product after reaction was separated by magnet, and washed with deionized water and ethanol several times to remove residual reagents, the obtained final solid (HS-Fe3O4-PA) was placed in a vacuum oven for drying.

[0056] Figure 2TEM images of materials at each stage in Example 1. Wherein a is the TEM image of PS in (1), b is the TEM image of PS-SiO2 in (2), the thickness of the silicon layer and the change in roughness of the surface can be clearly seen; c is the TEM image of the ultra-light magnetic adsorbent PS-SiO2-Fe3O4 in (2) 2), it can be seen that the Fe3O4 nanoparticles are dispersed on the surface of the silicon layer, d is the PS-Fe3O4-PA adsorbent in (3), e, f are the adsorbents in (3) HS-Fe3O4-PA, it can be seen that through the action of DMF and PS, the adsorbent finally presents a hollow core-shell structure, with a large specific surface area and a light weight.

[0057] Figure 3 are infrared spectra of each stage in Example 1, and through the change of functional groups, it can be seen that the final product is successful.

[0058] Figure 4 is the hysteresis loop test analysis diagram of the final product HS-Fe3O4-PA in Example 1, it can be seen that the material has strong paramagnetism, and the magnetization is about 6emu g -1 , which confirms that it can be driven and magnetically separated by an external magnetic field.

[0059] Example 2:

[0060] (1) Preparation of polystyrene nanoparticles (PS)

[0061] In a 500ml round bottom flask, 80ml of styrene (ST), 250ml of pure water and 2.692g of polystyrene pyrrolidone (PVP) were added and ultrasonically dissolved. Slowly heated to 75°C under the condition of 500rpm, then 1.08g of potassium persulfate (KPS) was added and reacted for 24h, and the product was collected by centrifugation. Washed with deionized water and anhydrous ethanol (EtOH) three times respectively, and put into 50°C vacuum oven to dry for 24h, to obtain the product nano PS particles.

[0062] (2) Preparation of light magnetic adsorbent structure (PS-Fe3O4-PA)

[0063] 1) Put 750mg of PS prepared in step (1) into a 100ml three-necked flask, then add 50ml of anhydrous ethanol, ultrasonically disperse, then put it into a 50°C oil bath, add 2ml of ammonia water and react for 15min, then continue to add 2ml of tetraethyl orthosilicate, mechanically stir at 600rpm for 12h, then the reaction is completed. Then separate by centrifugation, and wash with deionized water and ethanol several times to remove residual reagents, and the obtained solid (PS-SiO2) is placed in a 50°C vacuum oven for drying.

[0064] 2) Take 100 mg of PS-SiO2 prepared in step 1) and place it in a round bottom flask, add 100 mL of deionized water and ultrasonically disperse. Take 0.1176 g of ferric chloride hexahydrate, 0.06054 g of ferrous sulfate heptahydrate in a beaker, add 100 mL of deionized water and ultrasonically disperse. Pour the solvent in the beaker into the round bottom flask and ultrasonically disperse for 30 min again, so that it is completely mixed and uniform. Then place it in an oil bath at 35°C, add 570 uL of ammonia water, mechanically stir at 500 rpm for 30 min, and collect the product after reaction by magnetic separation. Wash with deionized water and anhydrous ethanol several times to remove residual reagents, and dry the obtained solid (PS-SiO2-Fe3O4) in a vacuum oven at 50°C for standby. Cool to room temperature naturally, separate by magnet, and wash with deionized water and ethanol several times to remove residual reagents, and dry the obtained solid (PS-SiO2-Fe3O4) in a vacuum oven for standby.

[0065] 3) Take 50 mg of PS-SiO2-Fe3O4 prepared in step 2) and place it in a round bottom flask, ultrasonically disperse in 50 mL of Tris solution, then add 75 mg of DA, 30 mg of ATU, and 20 mg of AIBN, and react at 80°C for 4 h. The product after reaction is separated by magnet, and washed with deionized water and anhydrous ethanol several times to remove residual reagents, and the obtained solid (PS-Fe3O4-PA) is dried in a vacuum oven at 50°C for standby.

[0066] (3) Preparation of light magnetic adsorbent structure (HS-Fe3O4-PA)

[0067] Take 50 mg of (PS-SiO2-Fe3O4-PDA) prepared in step (2) and place it in a centrifuge tube, then add 10 mL of DMF, ultrasonically disperse, then place it in a shaking bed and react for 30 min. The product after reaction is separated by magnet, and washed with deionized water and ethanol several times to remove residual reagents, and the obtained solid (HS-Fe3O4-PA) is dried in a vacuum oven for standby.

[0068] Example 3:

[0069] (1) Preparation of polystyrene nanoparticles (PS)

[0070] Add 120 mL of styrene (ST), 250 mL of pure water, and 4.2 g of polystyrene pyrrolidone (PVP) to a 500 mL round bottom flask and ultrasonically dissolve. Slowly heat to 75°C under the condition of 500 rpm, then add 1.62 g of potassium persulfate (KPS) and react for 24 h. Centrifugally collect the product. Wash with deionized water and anhydrous ethanol (EtOH) three times, and place in a vacuum oven at 50°C for 24 h to obtain the product, nano-PS particles.

[0071] (2) Preparation of light magnetic adsorbent structure (PS-Fe3O4-PA)

[0072] 1) 500 mg of PS prepared in step (1) was placed in a 100 mL three-necked flask, then 50 mL of anhydrous ethanol was added, after ultrasonic dispersion, it was placed in an oil bath at 50°C, 3 mL of ammonia water was added and reacted for 15 min, then 3 mL of tetraethyl orthosilicate was added, after mechanical stirring at 600 rpm for 12 h, the reaction was completed. Then it was separated by centrifugation and washed with deionized water and ethanol several times to remove residual reagents, and the obtained solid (PS-SiO2) was placed in a vacuum oven at 50°C for drying.

[0073] 2) 150 mg of PS-SiO2 prepared in step 1) was weighed into a round-bottom flask, 150 mL of deionized water was added, and ultrasonic dispersion was performed. 0.1762 g of iron trichloride hexahydrate and 0.09081 g of ferrous sulfate heptahydrate were weighed into a beaker, 150 ml of deionized water was added, and ultrasonic dispersion was performed. The solvent in the beaker was poured into the round-bottom flask and ultrasonic dispersion was performed for another 30 min to make it completely mixed and uniform. Then it was placed in an oil bath at 35°C, 855 uL of ammonia water was added, and mechanical stirring was performed at 500 rpm for 30 min. The product after reaction was collected by magnet separation. It was washed with deionized water and anhydrous ethanol several times to remove residual reagents, and the obtained solid (PS-SiO2-Fe3O4) was placed in a vacuum oven at 50°C for drying. It was naturally cooled to room temperature, separated by magnet, and washed with deionized water and ethanol several times to remove residual reagents, and the obtained solid (PS-SiO2-Fe3O4) was placed in a vacuum oven for drying.

[0074] 3) 50 mg of PS-SiO2-Fe3O4 prepared in step 2) was weighed into a round-bottom flask, ultrasonic dispersion was performed in a Tris solution, then 90 mg of DA, 30 mg of ATU, and 20 mg of AIBN were added, and the reaction was performed at 80°C for 4 h. The product after reaction was separated by magnet and washed with deionized water and anhydrous ethanol several times to remove residual reagents, and the obtained solid (PS-Fe3O4-PA) was placed in a vacuum oven at 50°C for drying.

[0075] (3) Preparation of light magnetic adsorbent structure (HS-Fe3O4-PA)

[0076] 50 mg of (HS-Fe3O4-PA) prepared in step (2) was placed in a centrifuge tube, then 20 mL of DMF was added, after ultrasonic dispersion, it was placed on a shaker for reaction for 30 min. The product after reaction was separated by magnet and washed with deionized water and ethanol several times to remove residual reagents, and the obtained solid (HS-Fe3O4-PA) was placed in a vacuum oven for drying.

[0077] Example 4: Effect of solution pH on gold ion adsorption amount

[0078] Accurately weigh 6 portions of 1 mg of HS-Fe3O4-PA prepared under the conditions described in Example 1, and add them to 5 mL of gold ion solution with pH values of 1, 2, 3, 4, 5, and 6, respectively, all with a concentration of 500 mg / L. Place the solution in a shaker at room temperature for adsorption for 12 h, then separate by magnet, collect the solution, and pass it through a membrane before detecting the concentration of the remaining gold ions by inductively coupled plasma emission spectrometer (ICP). Perform three sets of parallel experiments.

[0079] Figure 5 The pH results of Example 1 are shown in the figure. It can be seen that the adsorption amount of HS-Fe3O4-PA is the largest in an environment with a pH of 4, approximately 1750 mg g -1 The corresponding Zeta potential also reached a minimum at a pH of 4, and the change rule is consistent.

[0080] Example 5: Effect of adsorption time on gold ion adsorption amount

[0081] Accurately weigh 9 portions of 1 mg of HS-Fe3O4-PA prepared under the conditions described in Example 1, and add them to 5 mL of gold ion solution with a concentration of 500 mg / L and a pH of 4. Place the solution in a shaker at room temperature for adsorption for 5, 10, 15, 30, 60, 120, 240, 360, and 720 min, respectively, then separate by magnet, collect the solution, and pass it through a membrane before detecting the concentration of the remaining gold ions by inductively coupled plasma emission spectrometer (ICP). Perform three sets of parallel experiments.

[0082] Figure 6 The adsorption kinetics experiment results of Example 1 are shown in the figure. It can be seen that HS-Fe3O4-PA can achieve rapid enrichment of gold ions under the action of an external magnetic field, and the maximum adsorption amount of 1719.96 mg g -1 .

[0083] Example 6: Effect of initial gold ion concentration on adsorption amount

[0084] Accurately weigh 9 portions of 1 mg of HS-Fe3O4-PA prepared under the conditions described in Example 1, and add them to 5 mL of gold ion solution with concentrations of 50, 100, 200, 300, 400, 500, 600, 700, and 800 mg / L, respectively (pH = 4). Place the solution in a shaker at room temperature for adsorption for 12 h, then separate by magnet, collect the adsorption solution, and pass it through a membrane before detecting the concentration of the remaining gold ions by inductively coupled plasma emission spectrometer (ICP). Perform three sets of parallel experiments.

[0085] Figure 7 The equilibrium adsorption experiment results of Example 1 show that the adsorption capacity of HS-Fe3O4-PA gradually increases with the increase of the initial concentration of gold ions, and gradually increases with the increase of temperature, and the maximum reaches 2577 mg g -1 around, and the fitting results of the adsorption data are more consistent with the Langmuir model.

[0086] Example 7: Effect of adsorbent regeneration on gold ion adsorption capacity

[0087] Accurately weigh 1 mg of HS-Fe3O4-PA prepared under the conditions described in Example 1, add 5 mL of gold ion solution with a concentration of 500 mg / L and a pH value of 4, and place the solution in a shaker at room temperature for 12 h. After separation by magnet, remove the solution and wash with deionized water. Then add 1 mL of eluent of 1 mol / L thiourea in 0.1 mol / L hydrochloric acid, continue to adsorb dynamically on the shaker, and then separate by magnet. After removing the solution, wash with deionized water. This is one cycle, and a total of five cycles are performed. After the adsorption solution and desorption solution are filtered, they are detected by inductively coupled plasma emission spectrometer (ICP), and three groups of parallel experiments are performed.

[0088] Figure 8 The regeneration performance experiment results of HS-Fe3O4-PA in Example 1 show that after 5 cycles, the adsorption performance of H-PDA-ATU still does not decrease significantly, and it has good stability and durability.

[0089] Example 8: Effect of coexistence of multiple ions on adsorption of gold ions

[0090] Accurately weigh 1 mg of HS-Fe3O4-PA prepared under the conditions described in Example 1, add 5 mL of actual electronic waste liquid containing Au(III), Al(III), Co(II), Cr(III), Cu(II), Mn(II), Na(I), Ni(II), Zn(II) (pH = 4), and place it in a magnetic stirrer at 25°C. After dynamic adsorption on the shaker for 12 h, separate by magnet, collect the adsorption solution, and filter it through inductively coupled plasma emission spectrometer (ICP) to detect the concentration of each ion remaining. Three groups of parallel experiments are performed.

[0091] Figure 9 The competitive adsorption performance of HS-Fe3O4-PA on gold ions in the presence of multiple ions in Example 1 is shown. The results show that the recovery rate of gold ions (recovery rate 86%) of HS-Fe3O4-PA is significantly higher than that of other ions, indicating that it has high selectivity for gold ions.

[0092] Example 9: Influence of different light conditions on adsorption of gold ions

[0093] Accurately weigh 3 portions of 1 mg of HS-Fe3O4-PA prepared under the conditions described in Example 1, add 5 mL of gold ion solution with a concentration of 500 mg / L and a pH value of 4, and keep other conditions unchanged. Then, place the solution under darkness, incandescent light, and ultraviolet light, respectively, for dynamic adsorption for 2 h. After that, separate the solution by a magnet, collect the adsorption solution, and pass it through a membrane. Then, detect the concentration of each ion remaining by inductively coupled plasma emission spectrometry (ICP). Perform three sets of parallel experiments.

[0094] Figure 10 is a display of the adsorption performance of HS-Fe3O4-PA in Example 1 under different light conditions for gold ions. The results show that the adsorption capacity of HS-Fe3O4-PA for gold ions under darkness is about 1750 mg g -1 , the adsorption capacity for gold ions under strong incandescent light is about 2577 mg g -1 , and the adsorption capacity for gold ions under ultraviolet light is about 2715 mg g -1 . The results show that the final adsorption effect under ultraviolet irradiation is the best.

Claims

1. A method for preparing a magnetic lightweight nanometer microsphere rapid high selectivity gold extraction adsorbent, characterized in that, Comprising the following steps: (1) Preparation of polystyrene nanoparticles PS: Dissolve polyvinylpyrrolidone PVP, styrene ST into deionized water, mix uniformly, then ultrasonic dispersion, then transfer the mixture to an oil bath, then add potassium persulfate KPS, react for a period of time at a certain temperature, cool to room temperature naturally, separate by centrifugation, and wash with deionized water and ethanol several times to remove residual reagents, and dry the obtained solid PS in a vacuum oven for standby; (2) Preparation of magnetic light nano microsphere structure PS-Fe3O4-PA: a. Put the PS prepared in step (1) into anhydrous ethanol EtOH, ultrasonic dispersion, then oil bath heating, then add ammonia water NH3·H2O, add tetraethyl orthosilicate TEOS under continuous mechanical stirring, separate the product after reaction by centrifugation, and wash with deionized water and ethanol several times to remove residual reagents, and dry the obtained solid PS-SiO2 in a vacuum oven for standby; b. Put the PS-SiO2 prepared in step a into deionized water, ultrasonic dispersion, to obtain solution A; Weigh iron trichloride hexahydrate and ferrous sulfate heptahydrate into deionized water, ultrasonic dispersion, to obtain solution B; Pour solution B into solution A, ultrasonic again, mix uniformly, oil bath heating, then add ammonia water, react for a period of time at a certain speed, separate the product after reaction by magnet, wash with deionized water and anhydrous ethanol several times to remove residual reagents, and dry the obtained solid PS-SiO2-Fe3O4 in a vacuum oven for standby; c. Ultrasonic dispersion of PS-SiO2-Fe3O4 prepared in step b in Tris solution, add dopamine hydrochloride DA, disperse uniformly, then add appropriate amount of allyl thiourea ATU, ultrasonic, finally add azobisisobutyl AIBN, ultrasonic dispersion; react for a period of time, separate the product after reaction by magnet, and wash with deionized water and anhydrous ethanol several times to remove residual reagents, and dry the obtained solid PS-Fe3O4-PA in a vacuum oven for standby; (3) Preparation of magnetic light nano microsphere adsorbent HS-Fe3O4-PA: Put PS-Fe3O4-PA prepared in step (2) into a centrifuge tube, then add N,N'-dimethylformamide DMF, ultrasonic dispersion, then put on a shaker for reaction, separate the product after reaction by magnet, and wash with deionized water and ethanol several times to remove residual reagents, and dry the obtained solid HS-Fe3O4-PA in a vacuum oven for standby.

2. The production method according to claim 1, wherein In step (1), the amount ratio of PVP, ST, KPS, deionized water is (1.4-4.2) g:(40-120) mL:(0.54-1.62) g:(245-255) mL; the reaction temperature is 70-80℃, the reaction time is 22-24h, and the reaction speed is 500-600rpm.

3. The production method according to claim 1, wherein In step (2)a, The amount ratio of PS, EtOH, NH3·H2O and TEOS is (500-1000) mg:(50-150) mL:(1-3) mL:(1-3) mL; The oil bath reaction temperature is 50-60℃, and the reaction time is 10-12h; The mechanical stirring speed is 600-900rpm.

4. The production method according to claim 1, wherein In step (2) b, In solution A, the ratio of the amount of PS-SiO2 to deionized water is (50-150) mg:(50-150) mL; In solution B, the ratio of the amount of ferric chloride hexahydrate, ferrous sulfate heptahydrate and deionized water is (0.05875-0.1762) g:(0.03027-0.09081) g:(50-150) mL; The volume ratio of solution A:solution B is 1:1; after mixing solution A and solution B, the ultrasonic time is 30-40min.

5. The production method according to claim 1, wherein In step (2) b, The ratio of the amount of ammonia to PS-SiO2 in solution A is (285-855) μL:(50-150) mg; The oil bath reaction temperature is 35℃, the stirring speed is 500-600rpm, and the reaction time is 30min.

6. The production method according to claim 1, wherein In step (2) c, the ratio of the amount of PS-SiO2-Fe3O4, Tris solution, DA, ATU and AIBN is (50-150) mg:(50-60) mL:(60-90) mg:(30-32) mg:(18-22) mg.

7. The production method according to claim 1, wherein In step (2) c, the reaction temperature is 80-90℃, and the reaction time is 4-6h.

8. The production method according to claim 1, wherein In step (3), the ratio of the amount of PS-Fe3O4-PA to DMF is (50-150) mg:(10-25) mL.

9. The production method according to claim 1, wherein In step (3), the reaction time on the shaking table is 30-40min, and the temperature is room temperature.

10. The use of the magnetic light nano-microsphere adsorbent HS-Fe3O4-PA prepared by the preparation method of any one of claims 1-9 for adsorbing gold ions in a solution.

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