Method for proportionally and selectively recovering gallium, indium and selenium from flexible copper-gallium-indium-selenium thin-film solar cell leachate

Abstract

The invention discloses a method for proportionally and selectively recovering gallium, indium and selenium from a flexible copper gallium indium selenium thin film solar cell leachate, which comprises the following steps: preparing a linear thermo-sensitive polymer poly N, N-diethylacrylamide (PDEA) by adopting reversible addition-fragmentation chain transfer polymerization (RAFT); synthesizing a temperature-sensitive block PDEA-b-P (DEA-co-AM) from the synthesized poly (N, N-diethylacrylamide) (PDEA) serving as an RAFT (reversible addition fragmentation chain transfer) reagent and acrylamide (AM); a temperature-sensitive block is introduced through a solution polymerization method to synthesize a multi-template intelligent imprinted polymer (GIS-SIIP); and then eluting template ions from the dried and crushed imprinted polymer (GIS-SIIP) to obtain the adsorbent. And finally, carrying out primary adsorption / desorption circulation on the gallium-indium-selenium thin-film solar cell leachate by using an adsorbent to obtain a desorption recovery solution in which the amount of substances of gallium, indium and selenium ions is in a certain proportion.

Description

Technical Field

[0001] This invention relates to the field of precious metal recycling, and more particularly to a method for recovering gallium, indium, and selenium in proportion from the leachate of copper gallium indium selenide thin-film solar cells. Background Technology

[0002] Copper gallium indium selenide (CIGS) thin-film solar cells contain four elements: copper, indium, gallium, and selenium in their absorber layer. Global selenium resources are scarce and often associated with sulfide minerals. Industrially, selenium enrichment primarily originates from copper anode mud. High-purity selenium is considered a key material in metallurgy and semiconductors. Indium and gallium, as rare and dispersed metals, are globally recognized strategic elements. Indium and gallium do not have their own independent deposits but are produced as byproducts of the metallurgical industry. They mainly come from hydrometallurgical zinc and aluminum extraction industries. The abundance of indium and gallium in these minerals is low, ranging from tens to hundreds of parts per million, meaning that extraction and enrichment processes are cumbersome. Therefore, global primary indium and gallium production is influenced by their primary minerals. Furthermore, in terms of environmental impact, studies show that CIGS ranks second only to cadmium telluride in terms of global warming potential and other impact categories. Overall, CIGS exhibits relatively positive environmental impact outcomes. However, because CIGS is in the early stages of commercialization, currently commercially available CIGS systems have not yet reached their decommissioning date, resulting in less environmental assessment of CIGS recycling processes. The environmental impact of recycling CIGS after decommissioning is worrying, so it is essential to consider the recycling and reuse of valuable metal elements in waste CIGS.

[0003] Furthermore, existing ion imprinting techniques are mostly designed for single ions (such as "linear thermosensitive polymer block-modulated ReO4"). - Design, preparation and adsorption separation performance of intelligent ion-imprinted polymers (Xu Wan et al.), which are difficult to apply directly to complex systems with multiple ions coexisting (such as Ga in CIGS leachate). 3+ In 3+ SeO3 2- Simply replacing the template ions not only fails to achieve multi-ion synergistic imprinting and proportional recovery, but also leads to disordered imprinted holes and decreased selectivity due to ion competition. Therefore, developing a smart imprinting material and method capable of simultaneously and proportionally recovering multiple target ions has become a pressing technical challenge in this field. Summary of the Invention

[0004] The purpose of this invention is to provide a short-process, high-efficiency method for the proportional and selective recovery of gallium, indium, and selenium from the leachate of flexible copper gallium indium selenide (CGS) thin-film solar cells, in order to solve the following technical problems: 1. The challenge of multi-template collaborative imprinting: Through precise design of Ga 3+ In3+ SeO3 2- A mixed template system with a molar ratio of 1:4:6 overcomes the problem of disordered imprinting holes caused by multiple ions competing for binding sites, and realizes simultaneous imprinting and proportional recovery of three ions. 2. Innovative temperature-sensitive block structure: The PDEA-bP(DEA-co-AM) temperature-sensitive block is constructed by two-step RAFT polymerization. Compared with direct mixing polymerization, its chain segment movement is more flexible and its temperature-sensitive response is more significant. When adsorbed at 35℃, the imprinted pores are intact and the adsorption capacity is high. When desorbed at 25℃, the pores expand and the desorption rate is high. It can also be reused more than 8 times. 3. Targeted design of the desorption system: A mixed desorbent of 0.1 mol / L HCl and 0.3 mol / L thiourea is used to replace the traditional ammonia system, which is more suitable for the charge characteristics and binding strength of Ga, In and Se, and avoids the interference of ammonia on subsequent processes. The proportion of interfering elements in the desorption solution is less than 10%.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: First, a linear thermosensitive polymer, poly(N,N-diethylacrylamide) (PDEA), was prepared using reversible addition-fragmentation chain transfer polymerization (RAFT). The synthesized PDEA was then used as a RAFT reagent to synthesize a thermosensitive block polymer, PDEA-bP (DEA-co-AM), with acrylamide (AM). A multi-template smart imprinted polymer (GIS-SIIP) was synthesized by introducing the thermosensitive block polymer through solution polymerization. The template ions were then eluted from the dried and pulverized GIS-SIIP to obtain the adsorbent. Finally, the adsorbent was used to perform an adsorption / desorption cycle on the leaching solution of gallium indium selenide (CIGS) thin-film solar cells to obtain a desorbed recovery solution with gallium, indium, and selenium ions in a specific ratio.

[0006] The specific steps are as follows: 1) PDEA synthesis Azobisisobutyronitrile, 2-(dodecyltrithiocarbonate)-2-methylpropionic acid and N,N-diethylacrylamide were dissolved in ethyl acetate, mixed thoroughly, and sealed after purging with nitrogen for 15-20 minutes. The mixture was then stirred in an oil bath at 60-80°C for 30-40 hours. After the reaction was completed, poly(N,N-diethylacrylamide), PDEA, was obtained by three dissolutions and three precipitations using ethyl acetate as the solvent and n-hexane as the precipitant. The molar ratio of azobisisobutyronitrile, 2-(dodecyltrithiocarbonate)-2-methylpropionic acid, and N,N-diethylacrylamide is 1:(15~25):(950~1050). A preferred molar ratio is 1:20:1000.

[0007] 2) Thermosensitive block synthesis of PDEA-bP(DEA-co-AM) Azobisisobutyronitrile (AIB), PDEA, acrylamide, and N,N-diethylacrylamide were co-dissolved in N,N-dimethylformamide and mixed thoroughly. After purging with nitrogen for 15-20 minutes, the mixture was sealed and stirred in an oil bath at 60-80°C for 30-40 hours. Using ethyl acetate as solvent and n-hexane as precipitant, the mixture underwent three dissolutions and three precipitations. The mixture was then removed and dried in a vacuum drying oven to constant weight to obtain the thermosensitive block [poly(N,N-diethylacrylamide-g-poly(N,N-diethylacrylamide-g-acrylamide)], denoted as PDEA-bP(DEA-co-AM). The molar ratio of azobisisobutyronitrile, PDEA and acrylamide is 1:(15~20):(950~1050), preferably 1:20:1000; the molar ratio of N,N-diethylacrylamide to acrylamide is 1:1.5~1:2.5, preferably 1:2.

[0008] 3) GIS-SIIP synthesis PDEA-bP(DEA-co-AM), acrylamide, acrylic acid, and template ions were co-dissolved in a mixed solution of methanol and water. After self-assembly in a water bath at 30-35°C for 1-2 hours, N,N-methylenebisacrylamide, a crosslinking agent, was added. After purging with nitrogen for 15-20 minutes, the mixture was sealed. The redox initiation system AP-TEMED was injected into the system using a syringe and then sealed. After initiating polymerization at 30-40°C for 20-25 hours, the mixture was removed and placed in a vacuum drying oven to constant weight to obtain GIS-SIIP. The mass ratio of PDEA-bP to acrylic acid is 1:5 to 1:20, the molar ratio of acrylamide to acrylic acid is 1:2 to 2:1, and the molar ratio of acrylic acid to N,N-methylenebisacrylamide is 1:5 to 1:7.

[0009] The template ions are a mixed ion system composed of gallium, indium, and selenium ions in a molar ratio of 1:4:6, and the amount of template ions added accounts for 30% to 40% of the molar amount of acrylic acid. Specifically, the template ion solution is obtained by mixing equal volumes of 0.0246 mmol / mL selenite solution, 0.0124 mmol / mL indium trichloride solution, and 0.0030 mmol / mL gallium trichloride solution.

[0010] The AP-TEMED redox initiation system is composed of equal volumes of ammonium persulfate solution and N,N,N,N-tetramethylethylenediamine solution in a molar ratio of 1:2.

[0011] 4) Adsorbent preparation The dried GIS-SIIP was crushed, and particles of 30-100 mesh were sieved and stored. The particles were placed in a 200-mesh filter bag and placed in a Soxhlet extractor. The template ions were eluted with analytical grade anhydrous ethanol as the eluent. The concentration of the corresponding template ions in the etching solution was determined by ICP-AES. Elution was stopped when the test value was lower than 0.02 μg / mL. The filter bag was then rinsed alternately with methanol and water until the solution was neutral. The solution was dried in a vacuum drying oven to constant weight to obtain the adsorbent.

[0012] 5) Ion adsorption / desorption The adsorbent was placed in the leaching solution of flexible copper gallium indium selenide (CGS) thin-film solar cells for adsorption at a temperature of 35°C for 120 min. After adsorption, the adsorbent was placed in a mixed solution containing 0.1 mol / L HCl and 0.3 mol / L thiourea for desorption at a temperature of 25°C for 300 min. This yielded a desorbed solution containing gallium, indium, and selenium elements recovered in proportion.

[0013] The leaching solution for the flexible copper gallium indium selenide (CGS) thin-film solar cell is obtained by first mechanically peeling off the outer protective film and substrate of the CGS thin-film solar cell, then cleaning the photovoltaic module after peeling off the protective layer with dimethyl sulfoxide (DMSO), and finally washing away the residual DMSO with ethanol and water.

[0014] The pretreatment process is as follows: hydrochloric acid (HCl) is used as the medium in the leaching process, and an HCl solution with a concentration of 5 mol / L containing 5 vol% hydrogen peroxide (H2O2) is used as the leaching solution. The solid-liquid ratio is 5 g / L, the leaching temperature is 35~45℃, and the leaching time is 1~2 h.

[0015] The term "proportional recovery" refers to the fact that, apart from gallium, indium, and selenium, the content of other interfering elements in the eluent is less than 10%.

[0016] Compared with the prior art, the present invention has the following beneficial effects: 1. This invention fully utilizes the safety, greenness and easy desorption characteristics of physical adsorption, combined with the selectivity of ion imprinting technology, to achieve specific and selective recovery of gallium, indium and selenium elements in the leachate of flexible copper gallium indium selenide thin film solar cells. 2. The leaching, adsorption and recovery processes used in this invention are all carried out at temperatures close to room temperature, giving the entire process the advantages of being green, low-energy, and low-cost. 3. This invention introduces a temperature-sensitive block [poly(N,N-diethylacrylamide-g-poly(N,N-diethylacrylamide-g-acrylamide)], denoted as PDEA-bP(DEA-co-AM). This achieves intelligent temperature-controlled adsorption / desorption of the ion-imprinted polymer, ensuring the integrity of the imprinted holes during adsorption while improving desorption efficiency and increasing recovery benefits. 4. This invention verifies that the amount of template ions is related to the ratio of adsorbed / desorbed target ions, making the recovery process more potentially applicable. 5. This invention not only achieves the separation and enrichment of valuable elements gallium, indium, and selenium in the leachate of waste flexible copper gallium indium selenide (CoGS) thin-film solar cells, but also ensures that the proportions of gallium, indium, and selenium ions in the desorption solution are similar to the proportions of the corresponding template ions added, thus achieving a proportional and selective recovery effect. Furthermore, because the synthesized multi-template smart imprinted polymer can be reused multiple times and its adsorption and desorption can be controlled by temperature, it reduces costs and improves efficiency, facilitating industrial production. Attached Figure Description

[0017] Figure 1 This is a flowchart illustrating the preparation process of the temperature-sensitive multi-template smart imprinted polymer GIS-SIIP in this invention.

[0018] Figure 2 The FTIR spectra of PDEA, P(DEA-co-AM), and PDEA-bP(DEA-co-AM) obtained in Example 1 of this invention are shown.

[0019] Figure 3 The PDEA-bP(DEA-co-AM) prepared in Example 1 of this invention 1 H NMR spectrum.

[0020] Figure 4 The images show SEM images of the temperature-sensitive multi-template smart imprinted polymer (left image) and the non-imprinted polymer (right image) prepared in Example 1 of this invention.

[0021] Figure 5 shows the adsorption kinetics curves of adsorbent 1 prepared in Example 1 of the present invention for a) gallium ions, b) indium ions, and c) selenite ions at 25℃, 35℃, and 45℃.

[0022] Figure 6 shows the desorption kinetics curves of adsorbent 1 prepared in Example 1 of the present invention for a) gallium ions, b) indium ions, and c) selenite ions at 25℃, 35℃, and 45℃.

[0023] Figure 7 This is a graph showing the reusability of adsorbent 1 prepared in Example 1 of the present invention. Detailed Implementation

[0024] The present invention will be further explained and described below with reference to specific embodiments.

[0025] according to Figure 1 The process shown is used to synthesize the temperature-sensitive multi-template smart imprint polymer GIS-SIIP in the following three embodiments.

[0026] Example 1 Weigh 0.006 g of azobisisobutyronitrile (AIB), 0.258 g of 2-(dodecyltrithiocarbonyl)-2-methylpropionic acid (RAFT reagent), and 4.54 g of N,N-diethylacrylamide (DEA). Dissolve all three in 9.423 g of ethyl acetate in a 25 mL test tube. Mix thoroughly, purge with 99.999% pure nitrogen gas for 15 min at room temperature, seal, and react in a 70°C oil bath with stirring for 36 h. After the reaction is complete, use ethyl acetate as solvent and n-hexane as precipitant to perform a three-stage dissolution and precipitation process on the initial product to obtain poly(N,N-diethylacrylamide) (PDEA).

[0027] 0.003 g of azobisisobutyronitrile, 1.3104 g of poly(N,N-diethylacrylamide) (PDEA), and 0.6486 g of acrylamide were weighed and completely dissolved in 2.6804 g of N,N-dimethylformamide in a 25 mL test tube. Then, 0.4972 g of N,N-diethylacrylamide (DEA) was added, and the mixture was thoroughly mixed. The mixture was then sealed after passing 99.999% pure nitrogen gas through the tube for 15 min at room temperature, and stirred in a 70°C oil bath for 36 h. A mixture of ethyl acetate and n-hexane (1:4 volume ratio) was used as a precipitant, and the mixture underwent a triple dissolution and triple precipitation process. Subsequently, the mixture was placed in a vacuum oven at 40°C until constant weight was achieved, yielding the thermosensitive block [poly(N,N-diethylacrylamide-g-poly(N,N-diethylacrylamide-g-acrylamide)], denoted as PDEA-bP(DEA-co-AM).

[0028] For comparison, the synthesis steps of P(DEA-co-AM) are given as follows: 0.003 g of azobisisobutyronitrile and 0.6486 g of acrylamide were weighed and completely dissolved in 2.6804 g of N,N-dimethylformamide in a 25 mL test tube. Then, 0.4972 g of N,N-diethylacrylamide (DEA) was added, and the mixture was thoroughly mixed. Nitrogen gas of 99.999% purity was passed through the tube at room temperature for 15 min, and the tube was sealed. The mixture was stirred in an oil bath at 70 °C for 36 h. A mixture of ethyl acetate and n-hexane (volume ratio 1:4) was used as a precipitant, and the mixture underwent three dissolutions and three precipitations. Subsequently, the mixture was placed in a vacuum oven at 40 °C until constant weight was achieved, yielding the random copolymer [poly(N,N-diethylacrylamide-g-acrylamide)], denoted as P(DEA-co-AM).

[0029] Weigh out 0.1 g of thermosensitive block copolymer, 0.56 g of acrylamide, 0.5 g of acrylic acid, and 0.2 mmol of template ion (0.123 mmol of SeO3). 2- 0.062 mmol In 3+ and 0.015 mmol of Ga 3+ The N,N-methylenebisacrylamide was dissolved in a 1:2 volume ratio of water and methanol and self-assembled for 1 hour in a constant temperature water bath at 33°C with magnetic stirring at 150 r / min. 6 g of N,N-methylenebisacrylamide was added and stirred until completely dissolved. Nitrogen gas of 99.999% purity was introduced at room temperature for 15 minutes, and the solution was then sealed to form a solution system. Equal volumes of ammonium persulfate solution with a molar volume concentration of 4.483 mmol / L and N,N,N,N-tetramethylethylenediamine solution with a molar volume concentration of 8.964 mmol / L were mixed to prepare the AP-TEMED redox initiation system solution. The AP-TEMED redox initiation system was injected into the solution system using a syringe and then sealed. After polymerization was initiated at 35°C, the polymer was removed and dried in a vacuum drying oven to constant weight, yielding the thermosensitive multi-template smart imprinted polymer GIS-SIIP. The preparation of the nonionic imprinted polymer (GIS-NSIIP) is the same as above, except that no template ions are added.

[0030] The dried polymer was pulverized using a pulverizer, and particles of 30-100 mesh were sieved and stored. The particles were then placed in a 200-mesh filter bag (7.6×50mm) and eluted with anhydrous ethanol in a Soxhlet extractor. The concentration of the corresponding template ions in the etching solution was determined by inductively coupled plasma atomic emission spectrometry (ICP-AES). Elution was stopped when the measured value was below 0.02μg / mL. The filter bag was then rinsed alternately with methanol and water until the solution was neutral and dried under vacuum at 45℃ to constant weight. After drying, adsorbent 1 was obtained.

[0031] Example 2 Weigh 0.002 g of azobisisobutyronitrile (AIB), 0.086 g of 2-(dodecyltrithiocarbonyl)-2-methylpropionic acid (RAFT reagent), and 1.513 g of N,N-diethylacrylamide (DEA). Dissolve all of these in 3.141 g of ethyl acetate in a 25 mL test tube. Mix thoroughly, purge with 99.999% pure nitrogen gas for 15 min at room temperature, then seal the tube and stir in a 70°C oil bath for 36 h. After the reaction is complete, use ethyl acetate as solvent and n-hexane as precipitant to perform a three-stage dissolution and precipitation process on the initial product to obtain poly(N,N-diethylacrylamide) (PDEA).

[0032] 0.006 g of azobisisobutyronitrile, 2.621 g of poly(N,N-diethylacrylamide) (PDEA), and 1.2972 g of acrylamide were weighed and completely dissolved in 5.3608 g of N,N-dimethylformamide in a 25 mL test tube. Then, 0.9944 g of N,N-diethylacrylamide (DEA) was added, and the mixture was thoroughly mixed. The mixture was then sealed after passing 99.999% pure nitrogen gas through the tube for 15 min at room temperature, and stirred in a 70°C oil bath for 36 h. A precipitant mixture of ethyl acetate and n-hexane (1:4 volume ratio) was used, and the mixture underwent a triple dissolution and triple precipitation process. Subsequently, the mixture was placed in a vacuum oven at 40°C until constant weight was achieved, yielding the thermosensitive block [poly(N,N-diethylacrylamide-g-poly(N,N-diethylacrylamide-g-acrylamide)], denoted as PDEA-bP(DEA-co-AM).

[0033] Weigh out 0.05 g of thermosensitive block copolymer, 0.56 g of acrylamide, 1.0 g of acrylic acid, and 0.4 mmol of template ion (0.246 mmol of SeO3). 2- 0.124 mmol In 3+ and 0.030 mmol of Ga 3+ The N,N-methylenebisacrylamide was dissolved in a 1:2 volume ratio of water and methanol and self-assembled for 1 hour in a constant temperature water bath at 33°C with magnetic stirring at 150 r / min. 7 g of N,N-methylenebisacrylamide was added and stirred until completely dissolved. Nitrogen gas of 99.999% purity was then introduced at room temperature for 15 minutes, and the solution was sealed to form a solution system. Equal volumes of ammonium persulfate solution with a molar volume concentration of 4.483 mmol / L and N,N,N,N-tetramethylethylenediamine solution with a molar volume concentration of 8.964 mmol / L were mixed to prepare the AP-TEMED redox initiation system solution. The AP-TEMED redox initiation system was injected into the solution system using a syringe and then sealed. After polymerization was initiated at 35°C, the polymer was removed and dried in a vacuum drying oven to constant weight, yielding the temperature-sensitive multi-template smart imprinted polymer GIS-SIIP.

[0034] The dried polymer was pulverized using a multi-functional pulverizer, and particles of 30-100 mesh were sieved and stored. The particles were then placed in a 200-mesh filter bag (7.6×50 mm) and eluted with anhydrous ethanol in a Soxhlet extractor. The concentration of the corresponding template ions in the etching solution was determined by inductively coupled plasma atomic emission spectrometry (ICP-AES). Elution was stopped when the measured value was below 0.02 μg / mL. The filter bag was then rinsed alternately with methanol and water until the solution was neutral and dried under vacuum at 45°C to constant weight. After drying, adsorbent 2 was obtained.

[0035] Example 3 Weigh 0.004 g of azobisisobutyronitrile (AIB), 0.172 g of 2-(dodecyltrithiocarbonyl)-2-methylpropionic acid (RAFT reagent), and 3.027 g of N,N-diethylacrylamide (DEA). Dissolve all three in 6.282 g of ethyl acetate in a 25 mL test tube. Mix thoroughly, purge with 99.999% pure nitrogen gas for 15 min at room temperature, seal, and stir in a 70°C oil bath for 36 h. After the reaction is complete, use ethyl acetate as solvent and n-hexane as precipitant to perform a three-stage dissolution and precipitation process on the initial product to obtain poly(N,N-diethylacrylamide) (PDEA).

[0036] 0.005 g of azobisisobutyronitrile (AIB), 2.184 g of poly(N,N-diethylacrylamide) (PDEA), and 1.081 g of acrylamide were weighed and completely dissolved in a 25 mL test tube with 4.4673 g of N,N-dimethylformamide. Then, 0.8287 g of N,N-diethylacrylamide (DEA) was added, and the mixture was thoroughly mixed. The mixture was then sealed after passing 99.999% pure nitrogen gas through the tube for 15 min at room temperature and stirred in a 70 °C oil bath for 36 h. A mixture of ethyl acetate and n-hexane (1:4 volume ratio) was used as a precipitant, and the mixture underwent a triple dissolution and triple precipitation process. Subsequently, the mixture was placed in a vacuum oven at 40 °C until constant weight was achieved, yielding the thermosensitive block [poly(N,N-diethylacrylamide-g-poly(N,N-diethylacrylamide-g-acrylamide)], denoted as PDEA-bP(DEA-co-AM).

[0037] Weigh out 0.05 g of thermosensitive block copolymer, 1.12 g of acrylamide, 0.5 g of acrylic acid, and 0.1 mmol of template ion (0.0615 mmol of SeO3). 2- 0.031 mmol In 3+ and 0.0075 mmol of Ga 3+ The product was dissolved in a 1:2 mixture of water and methanol and self-assembled for 1 hour in a constant temperature water bath at 33°C with magnetic stirring at 150 r / min. 5.5 g of N,N-methylenebisacrylamide was added and stirred until completely dissolved. Nitrogen gas of 99.999% purity was then introduced at room temperature for 15 minutes, and the mixture was sealed to form a solution system. Equal volumes of ammonium persulfate solution (4.483 mmol / L) and N,N,N,N-tetramethylethylenediamine solution (8.964 mmol / L) were mixed to prepare the AP-TEMED redox initiation system solution. The AP-TEMED redox initiation system was injected into the solution system using a syringe and then sealed. After polymerization was initiated at 35°C, the polymer was removed and dried in a vacuum drying oven to constant weight, yielding the temperature-sensitive multi-template smart imprinted polymer GIS-SIIP.

[0038] The dried polymer was pulverized using a multi-functional pulverizer, and particles of 30-100 mesh were sieved and stored. The particles were then placed in a 200-mesh filter bag (7.6×50 mm) and eluted with anhydrous ethanol in a Soxhlet extractor. The concentration of the corresponding template ions in the etching solution was determined by inductively coupled plasma atomic emission spectrometry (ICP-AES). Elution was stopped when the measured value was below 0.02 μg / mL. The filter bag was then rinsed alternately with methanol and water until the solution was neutral and dried under vacuum at 45°C to constant weight. After drying, adsorbent 3 was obtained.

[0039] The structural characterization and performance evaluation are as follows: The thermosensitive multi-template smart imprinted polymer (GIS-SIIP) prepared in Example 1 is used as an example.

[0040] Figure 2 The FTIR spectra of PDEA, P(DEA-co-AM), and PDEA-bP(DEA-co-AM) prepared in Example 1 of this invention are shown. PDEA-bP(DEA-co-AM) can be considered as a long-chain block of polymers PDEA and P(DEA-co-AM) linked by chemical bonds. However, in this application, after synthesizing PDEA, PDEA-bP(DEA-co-AM) is synthesized directly by random copolymerization, without involving the separate synthesis of P(DEA-co-AM). From the comparison of the spectra of the three substances, it can be seen that (1) in the random copolymer P(DEA-co-AM), the 3415 cm⁻¹... -1 and 3195 cm -1 The peak at 3415 cm⁻¹ represents the characteristic absorption peak of the stretching vibrations of OH⁻ and NH₄⁺ on AM in adsorbed water. However, in the block copolymer PDEA-bP(DEA-co-AM), the peak at 3415 cm⁻¹ is different. -1 The characteristic peak shifted at 3464 cm⁻¹ and appeared at 3464 cm⁻¹. -1 This is because the water retention capacity of PAM in the block copolymer is increased, resulting in a large number of water molecules, and the association between water molecules and amino groups is weakened. (2) 2972cm -1 The peak at 2927 cm⁻¹ represents the characteristic peak of the asymmetric stretching vibration of the CH group on the methyl group (-CH₃) in DEA. -1 The peak at 2875 cm⁻¹ is a characteristic peak of the CH stretching vibration on the methylene group (-CH₂-) in the polymer. -1 The peak at 1668 cm⁻¹ is a characteristic peak of the stretching vibration of CH on a tertiary carbon. The addition of DEA significantly strengthens the above characteristic peak, indicating that the DEA content in the copolymer increases. (3) 1668 cm⁻¹ -1 and 1635 cm -1 The peaks at 1616 cm⁻¹ are the stretching characteristic absorption peaks of the carbonyl group (C=O) on AM and DEA, respectively.-1 The peaks are characteristic of the bending vibrations of OH in water molecules and NH on primary amides. In random copolymers, the two peaks influence each other, masking the sharp peak of the carbonyl group in the original PDEA.

[0041] Figure 3 The PDEA-bP(DEA-co-AM) prepared in Example 1 of this invention 1 ¹H NMR spectrum. Based on the polymer's structural formula and by comparing the chemical shifts of characteristic hydrogens in the corresponding monomers, it can be found that... 1 H NMR (400 MHz, DMSO- d6) δ7.40 (s, J = 80.1 Hz, 0H), 6.99 (s, J = 61.0 Hz, 0H), 3.17 (s, 0H), 1 ¹H NMR (400MHz, DMSO) δ 7.50 (s, OH), 6.96 (s, J = 80.5 Hz, ¹H), 3.17 (s, ¹H). All of these values ​​are related to hydrogen atoms in DEA and AM in the polymer, confirming that the synthesized polymer is the target polymer PDEA-bP(DEA-co-AM).

[0042] Figure 4 The images show scanning electron microscope (SEM) images of the thermosensitive multi-template smart imprinted polymer (GIS-SIIP) (left) and the non-imprinted polymer (GIS-NSIIP) (right) prepared in Example 1. As can be seen from the images, the GIS-SIIP surface exhibits numerous pores, which are relatively sparsely distributed. In contrast, the GIS-NSIIP surface lacks obvious pores and shows a denser packing. This morphological difference stems from two main factors: firstly, the self-assembly between template ions and functional monomers leads to changes in the interfacial interactions between polymer microparticles; secondly, the hydrogen bonding between functional monomers and template ions in GIS-SIIP weakens the hydrogen bonds between polymer molecular chains, resulting in reduced forces between the polymer and the solvent, facilitating phase separation and thus leading to more pores and a more porous surface.

[0043] Figure 5 shows the adsorption kinetics curves of the thermosensitive multi-template smart imprinted polymer adsorbent prepared in Example 1 of this invention for a) gallium ions, b) indium ions, and c) selenite ions at 25℃, 35℃, and 45℃. The figure shows that compared to 25℃ and 45℃, GIS-SIIP has a higher adsorption capacity at 35℃. This is because the introduction of the thermosensitive block ensures that the imprinted pores remain intact during self-assembly of GIS-SIIP at 35℃. When the external temperature changes, the thermosensitive block undergoes a sol / gel phase transition, causing the imprinted pores to expand and contract, thus reducing the adsorption capacity.

[0044] Figure 6 shows the adsorption kinetics curves of the thermosensitive multi-template smart imprinted polymer adsorbent prepared in Example 1 of this invention for a) gallium ions, b) indium ions, and c) selenite ions at 25°C, 35°C, and 45°C. The figure shows that compared to 35°C and 45°C, GIS-SIIP exhibits a higher desorption capacity at 25°C. This is because when the adsorption temperature T = 25 °C (below the low critical phase transition temperature of the thermosensitive block), the molecular chains are in a stretched state, causing the imprinted pores to expand. This results in poorer integrity of the imprinted pores, a poorer spatial fit between the imprinted pores and the target ions, and the imprinted sites become incomplete imprinted sites. Consequently, the affinity of the imprinted pores for the template ions weakens, making the adsorbed template ions easier to desorb.

[0045] Equal volumes of 0.615 mmol / L selenite solution, 0.31 mmol / L indium trichloride solution, and 0.075 mmol / L gallium trichloride solution were mixed, and the ion concentration in the solution before adsorption was determined using inductively coupled plasma mass spectrometry (ICP-MS). 0.1 g of the adsorbent prepared in Example 1 was adsorbed at 35 °C for 120 min, then placed in a mixed solution of 0.1 mol / L hydrochloric acid (HCl) and 0.3 mol / L thiourea (TU), and desorbed at 25 °C for 300 min. This adsorption-desorption cycle was repeated 10 times, and the ion concentrations after adsorption and desorption were determined using ICP-MS. The results are as follows: Figure 7 As shown in the figure, after 8 adsorption-desorption cycles, the adsorption amount did not change significantly from the original value, indicating that the temperature-sensitive multi-template smart imprinted polymer prepared by the method of this invention has good reusability.

[0046] 1.00 mL of leaching solution from flexible copper indium gallium selenide (CIGS) thin-film solar cells was diluted 20-fold, and then an adsorption / desorption cycle was performed in the above solution using the thermosensitive multi-template smart imprinted polymer GIS-SIIP. The procedure was as follows: 0.200 g of GIS-SIIP was placed in 20.00 mL of the diluted leaching solution from the flexible CIGS thin-film solar cells, and adsorption was carried out at 35 °C for 120 min. Then, a mixed solution of 0.1 mol / L hydrochloric acid (HCl) and 0.3 mol / L thiourea (TU) was used as the desorbent, and desorption was carried out at 25 °C for 300 min. The concentrations of each element in the solution before adsorption and in the desorption solution were determined by inductively coupled plasma mass spectrometry (ICP-MS), and the proportion of each element was calculated. The results are shown in Table 1.

[0047] Table 1. Proportion of each element in the original leachate and the proportion of each element in the desorbate after one adsorption / desorption. It can be seen that after one adsorption / desorption cycle, the purity of gallium increased from 4.38% to 12.77%; the purity of indium increased from 18.67% to 35.43%; and the purity of selenium increased from 34.08% to 45.8%. This indicates that the GIS-SIIP adsorbent has a good separation and purification capability for the target metal elements.

Claims

1. A method for the proportional selective recovery of gallium, indium, and selenium from the leachate of flexible copper gallium indium selenide (CGS) thin-film solar cells, characterized in that, Includes the following steps: 1) PDEA synthesis Azobisisobutyronitrile, 2-(dodecyltrithiocarbonate)-2-methylpropionic acid and N,N-diethylacrylamide were dissolved in ethyl acetate, mixed thoroughly, and sealed after purging with nitrogen for 15-20 minutes. The mixture was then stirred in an oil bath at 60-80°C for 30-40 hours. After the reaction was completed, poly(N,N-diethylacrylamide), PDEA, was obtained by three dissolutions and three precipitations using ethyl acetate as the solvent and n-hexane as the precipitant. 2) Thermosensitive block synthesis of PDEA-bP(DEA-co-AM) Azobisisobutyronitrile (AIB), PDEA, acrylamide, and N,N-diethylacrylamide were co-dissolved in N,N-dimethylformamide and mixed thoroughly. After purging with nitrogen for 15-20 minutes, the mixture was sealed and stirred in an oil bath at 60-80°C for 30-40 hours. Using ethyl acetate as solvent and n-hexane as precipitant, the mixture underwent three dissolutions and three precipitations. The mixture was then removed and dried in a vacuum drying oven to constant weight to obtain the thermosensitive block [poly(N,N-diethylacrylamide-g-poly(N,N-diethylacrylamide-g-acrylamide)], denoted as PDEA-bP(DEA-co-AM). 3) GIS-SIIP synthesis PDEA-bP (DEA-co-AM), acrylamide, acrylic acid, and template ions were co-dissolved in a mixed solution of methanol and water. After self-assembly in a water bath at 30-35°C for 1-2 hours, N,N-methylenebisacrylamide, a crosslinking agent, was added. After purging with nitrogen for 15-20 minutes, the mixture was sealed. The redox initiation system AP-TEMED was injected into the system using a syringe, and the mixture was sealed again. After initiating polymerization at 30-40°C for 20-25 hours, the mixture was removed and placed in a vacuum drying oven to constant weight to obtain GIS-SIIP. 4) Adsorbent preparation The dried GIS-SIIP was crushed, and particles of 30-100 mesh were sieved and stored. The particles were placed in a 200-mesh filter bag and placed in a Soxhlet extractor. The template ions were eluted with analytical grade anhydrous ethanol as the eluent. The concentration of the corresponding template ions in the etching solution was determined by ICP-AES. Elution was stopped when the test value was lower than 0.02 μg / mL. The filter bag was then rinsed alternately with methanol and water until the solution was neutral. The filter bag was dried in a vacuum drying oven to constant weight to obtain the adsorbent. 5) Ion adsorption / desorption The adsorbent was placed in the leaching solution of flexible copper gallium indium selenide (CGS) thin-film solar cells for adsorption at a temperature of 35°C for 120 min. After adsorption, the adsorbent was placed in a mixed solution containing 0.1 mol / L HCl and 0.3 mol / L thiourea for desorption at a temperature of 25°C for 300 min. This yielded a desorbed solution containing gallium, indium, and selenium elements recovered in proportion.

2. The method for selectively recovering gallium, indium, and selenium in proportion from the leachate of flexible copper gallium indium selenide thin-film solar cells as described in claim 1, characterized in that, In step 1), the molar ratio of azobisisobutyronitrile, 2-(dodecyltrithiocarbonate)-2-methylpropionic acid and N,N-diethylacrylamide is 1:(15~25):(950~1050).

3. The method for selectively recovering gallium, indium, and selenium in proportion from the leachate of flexible copper gallium indium selenide thin-film solar cells as described in claim 1, characterized in that... In step 2), the molar ratio of azobisisobutyronitrile, PDEA and acrylamide is 1:(15~25):(950~1050), and the molar ratio of N,N-diethylacrylamide to acrylamide is 1:1.5~1:2.

5.

4. The method for selectively recovering gallium, indium, and selenium in proportion from the leachate of flexible copper gallium indium selenide thin-film solar cells as described in claim 1, characterized in that, In step 3), the mass ratio of PDEA-bP(DEA-co-AM) to acrylic acid is 1:5 to 1:20, the molar ratio of acrylamide to acrylic acid is 1:2 to 2:1, and the molar ratio of acrylic acid to N,N-methylenebisacrylamide is 1:5 to 1:

7.

5. The method for selectively recovering gallium, indium, and selenium in proportion from the leachate of flexible copper gallium indium selenide thin-film solar cells as described in claim 1, characterized in that, In step 3), the template ions are a mixed ion system composed of gallium, indium and selenium ions in a molar ratio of 1:4:6, and the amount of template ions added accounts for 30% to 40% of the molar amount of acrylic acid.

6. The method for selectively recovering gallium, indium, and selenium in proportion from the leachate of flexible copper gallium indium selenide thin-film solar cells as described in claim 1, characterized in that, In step 3), the AP-TEMED redox initiation system is composed of equal volumes of ammonium persulfate solution and N,N,N,N-tetramethylethylenediamine solution with a molar concentration ratio of 1:

2.

7. The method for selectively recovering gallium, indium, and selenium in proportion from the leachate of flexible copper gallium indium selenide thin-film solar cells as described in claim 1, characterized in that, In step 5), the leaching solution for flexible copper gallium indium selenide (CGS) thin-film solar cells refers to the solution obtained by adding a 5 mol / L HCl solution containing 5 vol% hydrogen peroxide to a flexible CGS thin-film solar cell after removing the outer protective film and substrate at a solid-liquid ratio of 5 g / L, and leaching at 35-45°C for 1-2 hours.

8. The method for selectively recovering gallium, indium, and selenium in proportion from the leachate of flexible copper gallium indium selenide thin-film solar cells as described in claim 1, characterized in that, In step 5), proportional recovery means that the content of other interfering elements in the solution, other than gallium, indium, and selenium, is less than 10%.

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