Photoresponsive three-dimensional graphene material and preparation method and use thereof

Abstract

This invention relates to a photoresponsive three-dimensional graphene material, its preparation method, and its applications. The preparation method includes the following steps: First, graphene oxide is reduced by amination using a graphene oxide solution and a diamine reagent to obtain amino-functionalized reduced graphene oxide, denoted as GO-NH2; then, the amino-functionalized reduced graphene oxide is mixed with an organic solvent to obtain an organic dispersion of GO-NH2; subsequently, the organic dispersion of GO-NH2 and porphyrin are covalently assembled to obtain a photoresponsive three-dimensional graphene material with a porphyrin covalently intercalated graphene structure. This invention provides a photoresponsive three-dimensional graphene material capable of accurately recovering gold from solution in the presence of multiple interfering elements, with an adsorption capacity exceeding 100 times that of activated carbon, and the adsorption process is green and efficient.

Description

Technical Field

[0001] This invention relates to the field of gold resource recycling technology, specifically to a photoresponsive three-dimensional graphene material, its preparation method, and its applications. Background Technology

[0002] With the rapid development of electronic information technology, the market demand for gold is soaring, and prices remain high. However, the production and disposal of electronic devices release large amounts of gold-containing wastewater, sludge, and electronic waste, resulting in significant resource waste and threatening environmental safety. Compared to primary minerals, the gold content in these waste materials is often higher and accumulates more rapidly. Therefore, developing precise extraction and recycling technologies for gold from waste materials to promote the regeneration and recycling of gold is of significant economic and environmental importance.

[0003] Adsorption materials are crucial for gold extraction and recovery. Natural gold mining typically involves using activated carbon as the adsorbent, combined with a desorption agent washing-displacement / incineration process to obtain crude gold, which is then refined and purified by electrolysis. However, activated carbon is unsuitable for gold extraction from waste materials. Firstly, the metal composition in waste is more complex, and activated carbon lacks adsorption selectivity, making gold separation and purification impossible. Secondly, activated carbon has a low adsorption capacity, leading to significant consumption of activated carbon, desorption reagents, and reducing agents, or carbon emissions from incineration, increasing energy consumption and process complexity in the electrolytic refining process. Therefore, emerging nanomaterials such as metal-organic covalent frameworks, covalent organic frameworks, and porous organic polymers have attracted widespread attention in the field of gold adsorption and recovery due to their large specific surface area and the designability of their structure and adsorption sites.

[0004] However, compared to activated carbon, existing emerging nanomaterials face challenges such as complex preparation processes and higher costs, limiting their large-scale application. Graphene, as a special carbon-based material, possesses numerous advantages, including a unique two-dimensional structure, light absorption properties, high specific surface area, and high electron mobility, and can be produced on a large scale. Currently, how to utilize graphene to prepare novel, low-cost carbon-based adsorbent materials to achieve the green, efficient, and selective extraction of gold from waste remains a challenge for the industry.

[0005] For example, CN114887591A discloses a simple one-step method for recovering gold using MXene / GO / NbFeB hydrogel. The adsorbent used in this method is prepared by mixing graphene oxide with MXene, NbFeB and EDTA. However, the high price of MXene and NbFeB limits its application prospects.

[0006] CN114836622A discloses a method for continuous gold recovery. The adsorbent material used in this method is prepared by a wet film-forming process, in which graphene dispersion is deposited on a filter membrane. However, the adsorption of gold by this method requires pressure to drive it, and graphene stacking may occur during the film-forming process, reducing the effective adsorption area of ​​the material.

[0007] CN111500871A discloses a method for enriching and separating gold, platinum, and palladium using sunlight. This method enriches and separates gold, platinum, and palladium under light. However, the adsorption process of gold, platinum, and palladium requires the addition of methanol as a sacrificial agent, which not only increases costs but also poses a risk of environmental pollution.

[0008] Therefore, providing a carbon-based adsorption material with low cost, high specific surface area, gold adsorption selectivity, and green and efficient adsorption process is of great significance for separating and recycling secondary gold resources from waste. Summary of the Invention

[0009] To address the above problems, the present invention aims to provide a photoresponsive three-dimensional graphene material, its preparation method, and its applications. Compared with the prior art, the photoresponsive three-dimensional graphene material provided by the present invention introduces porphyrin to form a porphyrin covalently intercalated graphene structure, preventing graphene stacking to obtain more adsorption sites and forming an open three-dimensional adsorption space. At the same time, porphyrin, as a photosensitizer, can further enhance the material's ability to generate photoelectrons, and utilizes the interlayer covalent bonds to rapidly transfer electrons, synergistically improving the adsorption capacity of gold. It can accurately recover gold from solution under the presence of multiple interfering elements, without the need for additional sacrificial agents, and has a low preparation cost. The adsorption process is green and efficient.

[0010] To achieve this objective, the present invention adopts the following technical solution:

[0011] In a first aspect, the present invention provides a method for preparing a photoresponsive three-dimensional graphene material, the method comprising the following steps:

[0012] (1) Mix graphene oxide solution and diamine reagent to reduce graphene oxide by amination, and then perform solid-liquid separation, washing and drying in sequence to obtain amino-functionalized reduced graphene oxide, denoted as GO-NH2;

[0013] (2) Mix the amino-functionalized reduced graphene oxide obtained in step (1) with an organic solvent to obtain an organic dispersion of GO-NH2;

[0014] (3) The organic dispersion of GO-NH2 obtained in step (2) and porphyrin are covalently assembled, and then solid-liquid separation, washing and drying are performed in sequence to obtain a photoresponsive three-dimensional graphene material with a porphyrin covalently intercalated graphene structure.

[0015] In this invention, a diamine reagent is first used to amination and reduce graphene oxide. During the amination and reduction process, various functional groups on the surface of graphene oxide, including oxygen-containing functional groups (hydroxyl, epoxy, carboxyl, etc.), react with the diamine reagent to generate amino groups. On the one hand, by removing the oxygen-containing functional groups, the adsorption effect on various metal ions is avoided, so that the adsorption effect on gold ions comes only from the electrostatic adsorption capacity of graphene, while other metal ions are hardly adsorbed, thereby achieving precise recovery of gold. On the other hand, an amino functional group that can bond with porphyrin is constructed, providing conditions for porphyrin covalent intercalation into graphene. Then, in this invention, a photoresponsive three-dimensional graphene material with a porphyrin covalently intercalated graphene structure is obtained through the covalent assembly of GO-NH2 and porphyrin. On the one hand, the intercalation structure enables the graphene material to form an open adsorption three-dimensional space. The graphene surface adsorbs gold ions through electrostatic attraction and reduces the gold ions to metallic gold. The open adsorption three-dimensional space adopted in this invention can provide more gold ion adsorption sites and sufficient growth space for metallic gold particles, thereby improving the adsorption capacity for gold. On the other hand, graphene itself has a weak ability to generate electrons under light conditions. The introduction of the photosensitizer porphyrin can improve the ability to generate photoelectrons. At the same time, the electrons generated by porphyrin are transferred to the graphene sheets through covalent bonds, thereby further transferring electrons to the adsorbed gold ions, providing a continuous electron source for the adsorption and reduction of gold, thereby further improving the adsorption capacity for gold. The photoresponsive three-dimensional graphene material provided by this invention does not require additional sacrificial agents, and the cost of raw materials is low. The adsorption process is more green and efficient, enabling precise separation and recovery of gold even in the presence of multiple interfering elements. The adsorption capacity can reach more than 100 times that of ordinary activated carbon.

[0016] Preferably, the graphene oxide solution in step (1) is obtained by mixing graphene oxide and water.

[0017] In this invention, there is no special limitation on the sheet diameter of the graphene oxide.

[0018] Preferably, the concentration of the graphene oxide solution is 0.1-5 mg / mL, for example, it can be 0.1 mg / mL, 0.2 mg / mL, 0.4 mg / mL, 0.6 mg / mL, 0.8 mg / mL, 1 mg / mL, 1.2 mg / mL, 1.5 mg / mL, 1.8 mg / mL, 2 mg / mL, 2.2 mg / mL, 2.5 mg / mL, 2.8 mg / mL, 3 mg / mL, 3.2 mg / mL, 3.5 mg / mL, 3.8 mg / mL, 4 mg / mL, 4.2 mg / mL, 4.5 mg / mL, 4.8 mg / mL or 5 mg / mL, but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0019] Preferably, the diamine reagent includes any one or a combination of at least two of ethylenediamine, propylenediamine, p-aniline, or benzidine.

[0020] The large π bonds in graphene can promote efficient electron migration. This invention optimizes the type of diamine reagent so that porphyrin can be covalently linked with graphene while avoiding affecting the hexagonal honeycomb structure of graphene itself. Furthermore, the preferred method of introducing a benzene ring structure through a diamine reagent can further enhance the electron conduction capability.

[0021] Preferably, the mass ratio of graphene oxide to diamine reagent in the graphene oxide solution is 1:(1-10), for example, it can be 1:1, 1:1.5, 1:2, 1:2.5, 1:3, 1:3.5, 1:4, 1:4.5, 1:5, 1:5.5, 1:6, 1:6.5, 1:7, 1:7.5, 1:8, 1:8.5, 1:9, 1:9.5 or 1:10, but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0022] Preferably, the amination reduction temperature is 80-120℃, for example, it can be 80℃, 82℃, 85℃, 88℃, 90℃, 92℃, 95℃, 98℃, 100℃, 102℃, 105℃, 108℃, 110℃, 112℃, 115℃, 118℃ or 120℃, but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0023] Preferably, the amination reduction time is 6-24h, for example, it can be 6h, 8h, 10h, 12h, 14h, 16h, 18h, 20h, 22h or 24h, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0024] Preferably, the organic solvent in step (2) includes N,N-dimethylformamide and / or N,N-dimethylacetamide.

[0025] Preferably, the concentration of GO-NH2 in the organic dispersion is 0.1-10 mg / mL, for example, it can be 0.1 mg / mL, 0.2 mg / mL, 0.4 mg / mL, 0.6 mg / mL, 0.8 mg / mL, 1 mg / mL, 1.5 mg / mL, 2 mg / mL, 2.5 mg / mL, 3 mg / mL, 3.5 mg / mL, 4 mg / mL, 4.5 mg / mL, 5 mg / mL, 5.5 mg / mL, 6 mg / mL, 6.5 mg / mL, 7 mg / mL, 7.5 mg / mL, 8 mg / mL, 8.5 mg / mL, 9 mg / mL, 9.5 mg / mL or 10 mg / mL, but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0026] Preferably, the porphyrin in step (3) includes any one or a combination of at least two of dicarboxyphenylporphyrin, tetracarboxyphenylporphyrin, dinitrophenylporphyrin, or tetranitrophenylporphyrin, wherein typical but non-limiting combinations include a combination of dicarboxyphenylporphyrin and tetracarboxyphenylporphyrin or a combination of dinitrophenylporphyrin and tetranitrophenylporphyrin.

[0027] Preferably, when the porphyrin in step (3) includes dicarboxyphenylporphyrin and / or tetracarboxyphenylporphyrin, covalent assembly is completed by condensation reaction of the amino group of GO-NH2 with the carboxyl group of the porphyrin.

[0028] Preferably, when the porphyrin includes dicarboxyphenylporphyrin and / or tetracarboxyphenylporphyrin, the covalent assembly process includes: covalently assembling a mixture of carboxyactivated porphyrin, an organic dispersion of GO-NH2, and triethylamine.

[0029] Preferably, the preparation method of the carboxyl-activated porphyrin includes: activating a mixture of porphyrin and an activation solution to obtain a carboxyl-activated porphyrin solution, and then sequentially performing solid-liquid separation, washing, and drying to obtain the carboxyl-activated porphyrin.

[0030] Preferably, the activating solution comprises a thionyl chloride solution.

[0031] Preferably, the concentration of porphyrin in the carboxyl-activated porphyrin solution is 1.5-10 mg / mL, for example, it can be 1.5 mg / mL, 2 mg / mL, 2.5 mg / mL, 3 mg / mL, 3.5 mg / mL, 4 mg / mL, 4.5 mg / mL, 5 mg / mL, 5.5 mg / mL, 6 mg / mL, 6.5 mg / mL, 7 mg / mL, 7.5 mg / mL, 8 mg / mL, 8.5 mg / mL, 9 mg / mL, 9.5 mg / mL or 10 mg / mL, but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0032] Preferably, the activation temperature is 50-100℃, for example, it can be 50℃, 55℃, 60℃, 65℃, 70℃, 75℃, 80℃, 85℃, 90℃, 95℃ or 100℃, but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0033] Preferably, the activation time is 6-48h, for example, it can be 6h, 8h, 10h, 12h, 14h, 16h, 18h, 20h, 22h, 24h, 26h, 28h, 30h, 32h, 34h, 36h, 38h, 40h, 42h, 44h, 46h or 48h, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0034] Preferably, the mass ratio of the carboxyl-activated porphyrin to GO-NH2 in the organic dispersion is (0.1-1):1, for example, it can be 0.1:1, 0.2:1, 0.3:1, 0.4:1, 0.5:1, 0.6:1, 0.7:1, 0.8:1, 0.9:1 or 1:1, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0035] Preferably, the amount of triethylamine added is 5-20 times the equivalent of carboxyl-activated porphyrin, for example, it can be 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19 or 20 times, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0036] Preferably, when the porphyrin in step (3) includes dinitrophenylporphyrin and / or tetranitrophenylporphyrin, covalent assembly is completed by condensation reaction of the amino group of GO-NH2 with the nitro group of the porphyrin.

[0037] Preferably, when the dinitrophenylporphyrin and / or tetranitrophenylporphyrin are used, the covalent assembly process includes: covalent assembly of mixed porphyrins, an organic dispersion of GO-NH2, and a base.

[0038] Preferably, the mass ratio of the porphyrin to the GO-NH2 in the organic dispersion is (0.1-1):1, for example, it can be 0.1:1, 0.2:1, 0.3:1, 0.4:1, 0.5:1, 0.6:1, 0.7:1, 0.8:1, 0.9:1 or 1:1, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0039] Preferably, the alkali includes KOH and / or NaOH.

[0040] Preferably, the amount of alkali added is 5-20 times the equivalent of porphyrin, for example, it can be 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19 or 20 times, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0041] Preferably, the temperature for covalent assembly in step (3) is 100-150℃, for example, it can be 100℃, 105℃, 120℃, 125℃, 130℃, 135℃, 140℃, 145℃ or 150℃, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0042] Preferably, the covalent assembly time is 6-72 hours, for example, it can be 6 hours, 8 hours, 10 hours, 15 hours, 20 hours, 25 hours, 30 hours, 35 hours, 40 hours, 45 hours, 50 hours, 55 hours, 60 hours, 65 hours, 70 hours or 72 hours, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0043] In this invention, the method of solid-liquid separation is not particularly limited and can be any solid-liquid separation method commonly used in the art, such as filtration or centrifugation.

[0044] The washing solution used in the washing process described in this invention can be a commonly used washing solution in the art, such as any one or a combination of at least two of water, methanol, ethanol or acetone. For example, the washing process in step (3) can be first washed with water, and then washed with an organic solvent such as ethanol, until the organic solvent and residue are removed.

[0045] As a preferred embodiment of the first aspect of the present invention, the preparation method includes the following steps:

[0046] (1) A graphene oxide solution with a concentration of 0.1-5 mg / mL and a diamine reagent are mixed, wherein the mass ratio of graphene oxide to diamine reagent in the graphene oxide solution is 1:(1-10). The graphene oxide is reduced by amination at a temperature of 80-120℃ for 6-24 h. Then, solid-liquid separation, washing and drying are performed sequentially to obtain amino-functionalized reduced graphene oxide, denoted as GO-NH2.

[0047] (2) Mix the amino-functionalized reduced graphene oxide obtained in step (1) with an organic solvent to obtain an organic dispersion of GO-NH2, wherein the concentration of GO-NH2 in the organic dispersion is 0.1-10 mg / mL.

[0048] (3) The organic dispersion of GO-NH2 obtained in step (2) and porphyrin are covalently assembled, and then solid-liquid separation, washing and drying are performed in sequence to obtain a photoresponsive three-dimensional graphene material with a porphyrin covalently intercalated graphene structure.

[0049] When the porphyrin includes dicarboxyphenylporphyrin and / or tetracarboxyphenylporphyrin, covalent assembly is completed through a condensation reaction between the amino group of GO-NH2 and the carboxyl group of the porphyrin. The covalent assembly process includes: first, mixing the porphyrin and thionyl chloride solution and activating it at a temperature of 50-100℃ for 6-48 hours to obtain a carboxyl-activated porphyrin solution. The concentration of porphyrin in the carboxyl-activated porphyrin solution is 1.5-10 mg / mL. Then, solid-liquid separation and washing are performed sequentially. The mixture is dried to obtain carboxyl-activated porphyrin; then, the carboxyl-activated porphyrin, an organic dispersion of GO-NH2, and triethylamine are mixed, wherein the mass ratio of the carboxyl-activated porphyrin to the GO-NH2 in the organic dispersion is (0.1-1):1, and the amount of triethylamine added is 5-20 times the equivalent of the carboxyl-activated porphyrin. Covalent assembly is carried out at a temperature of 100-150℃ for 6-72 hours, followed by solid-liquid separation, washing, and drying to obtain photoresponsive three-dimensional graphene material.

[0050] When the porphyrin includes dinitrophenylporphyrin and / or tetranitrophenylporphyrin, covalent assembly is completed through a condensation reaction between the amino group of GO-NH2 and the nitro group of the porphyrin. The covalent assembly process includes: mixing porphyrin, an organic dispersion of GO-NH2, and an alkali. The mass ratio of the porphyrin to the GO-NH2 in the organic dispersion is (0.1-1):1. The alkali includes KOH and / or NaOH. The amount of alkali added is 5-20 times the equivalent of the porphyrin. Covalent assembly is carried out at a temperature of 100-150℃ for 6-72 hours. Then, solid-liquid separation, washing, and drying are performed sequentially to obtain photoresponsive three-dimensional graphene material.

[0051] In a second aspect, the present invention provides a photoresponsive three-dimensional graphene material, wherein the photoresponsive three-dimensional graphene material is obtained by the preparation method of the photoresponsive three-dimensional graphene material described in the first aspect of the present invention.

[0052] The photoresponsive three-dimensional graphene material provided by this invention has a porphyrin covalently intercalated graphene structure, forming an open three-dimensional adsorption space. Combined with the excellent specific surface area of ​​graphene, it can provide more adsorption sites and growth space for gold. At the same time, porphyrin and graphene synergistically adsorb and reduce gold ions. Graphene electrostatically adsorbs gold ions, while porphyrin enhances the photogenerated electron capability of the material and transfers electrons to the graphene sheets through covalent bonds, providing a continuous source of electrons for the adsorption and reduction of gold ions, thereby significantly improving the adsorption capacity of gold. Moreover, it can achieve precise adsorption and separation of gold under the interference of various impurity ions.

[0053] Thirdly, the present invention provides an application of the photoresponsive three-dimensional graphene material as described in the second aspect of the present invention, wherein the photoresponsive three-dimensional graphene material is used to selectively adsorb and extract gold from a gold-containing solution under illumination.

[0054] The photoresponsive three-dimensional graphene material provided by this invention is used to selectively adsorb and extract gold from gold-containing solutions under light irradiation, exhibiting high adsorption capacity and excellent adsorption selectivity.

[0055] Preferably, the gold-containing solution is acidic.

[0056] Preferably, the pH value of the gold-containing solution is 0-2, for example, it can be 0, 0.2, 0.4, 0.6, 0.8, 1, 1.2, 1.4, 1.6, 1.8 or 2, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0057] Preferably, the gold-containing solution includes any one or a combination of at least two of the following: natural ore leachate, gold-containing wastewater, or gold-containing waste leachate.

[0058] Preferably, the acid contained in the gold-containing solution includes any one or a combination of at least two of HCl, HNO3, H2SO4, HBr, or HI.

[0059] Compared with the prior art, the present invention has the following beneficial effects:

[0060] (1) The preparation method provided by the present invention uses a diamine reagent to aminate and reduce graphene oxide, which not only provides amino functional groups that are bonded to porphyrin, providing conditions for porphyrin covalently intercalated graphene, but also removes oxygen-containing functional groups, avoiding the adsorption effect of oxygen-containing functional groups on various metal ions, so that the adsorption of gold by graphene comes only from electrostatic adsorption, and hardly adsorbs other metal ions, thereby achieving precise recovery of gold.

[0061] (2) The preparation method provided by the present invention uses porphyrin covalently intercalated graphene to simultaneously disperse graphene sheets and porphyrin molecules, forming an open adsorption three-dimensional space. Combined with the excellent specific surface area of ​​graphene, it can provide more adsorption sites for gold ion adsorption and provide sufficient growth space for gold ion reduction and growth into gold particles, thereby improving the adsorption capacity for gold. At the same time, the photosensitizer porphyrin is introduced into the interlayer through covalent bonds, which enables the electrons generated by porphyrin to be transferred to the graphene sheets through covalent bonds, further providing a continuous source of electrons for the adsorption and reduction of gold ions, and further improving the adsorption capacity for gold.

[0062] (3) The photoresponsive three-dimensional graphene material provided by the present invention can achieve an adsorption capacity of more than 1023.52 mg / g for Au under light irradiation conditions, more than 2136.28 mg / g under better conditions, and an ultra-high gold adsorption capacity of nearly 3000 mg / g under even better conditions, which is more than 100 times the adsorption capacity of activated carbon for Au, and the purity of the recovered Au can reach more than 99%.

[0063] (4) The preparation method provided by the present invention not only uses a low amount of raw materials, which can greatly reduce the carbon emissions of the subsequent incineration process and is more environmentally friendly, but also has a simple preparation method, mature raw material production technology and low price, making it easy to industrialize. Attached Figure Description

[0064] Figure 1 The graph shows the adsorption rates of various metal ions on the photoresponsive three-dimensional graphene material obtained in Example 1 of this invention under pH conditions of 1-4.

[0065] Figure 2 The graph shows the adsorption rate of various metal ions in a complex system by the photoresponsive three-dimensional graphene material obtained in Example 1 of this invention at a pH value of 1. Detailed Implementation

[0066] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention.

[0067] Example 1

[0068] This embodiment provides a method for preparing a photoresponsive three-dimensional graphene material, the method comprising the following steps:

[0069] (1) 0.05 g of graphene oxide (GO) was dispersed in 100 mL of water to obtain a graphene oxide solution with a concentration of 0.5 mg / mL. Then, 0.2 g of ethylenediamine was added to the solution. The mass ratio of graphene oxide to ethylenediamine in the graphene oxide solution was 1:4. The graphene oxide was amination-reduction at 90 °C for 12 h. Then, the solution was filtered, washed and dried to obtain amino-functionalized reduced graphene oxide, denoted as GO-NH2.

[0070] (2) Disperse 0.05g GO-NH2 in 50mL N,N-dimethylformamide to obtain an organic dispersion of GO-NH2, wherein the concentration of GO-NH2 in the organic dispersion is 1mg / mL;

[0071] (3) 0.05g of dicarboxyphenylporphyrin was dispersed in 10mL of SOCl2 solution and activated at 80℃ for 24h to obtain a carboxy-activated porphyrin solution with a porphyrin concentration of 5mg / mL. The solution was then filtered, washed and dried to obtain carboxy-activated porphyrin. Then, 0.05g of carboxy-activated porphyrin, the organic dispersion of GO-NH2 obtained in step (2) and triethylamine were mixed. The mass ratio of carboxy-activated porphyrin to GO-NH2 in the organic dispersion was 1:1 and the amount of triethylamine added was 0.5mL. The solution was covalently assembled at 120℃ for 15h, filtered, washed with water and ethanol, and then dried to obtain a photoresponsive three-dimensional graphene material.

[0072] Example 2

[0073] This embodiment provides a method for preparing a photoresponsive three-dimensional graphene material, the method comprising the following steps:

[0074] (1) 0.1 g of graphene oxide (GO) was dispersed in 100 mL of water to obtain a graphene oxide solution with a concentration of 1 mg / mL. Then, 0.4 g of p-aniline was added to the solution. The mass ratio of graphene oxide to p-aniline in the graphene oxide solution was 1:4. The graphene oxide was amination-reduction at 110 °C for 15 h. Then, the solution was filtered, washed and dried to obtain amino-functionalized reduced graphene oxide, denoted as GO-NH2.

[0075] (2) Disperse 0.1g GO-NH2 in 100mL N,N-dimethylformamide to obtain an organic dispersion of GO-NH2, wherein the concentration of GO-NH2 in the organic dispersion is 1mg / mL;

[0076] (3) 0.05g of tetracarboxyphenylporphyrin was dispersed in 20mL of SOCl2 solution and activated at 90℃ for 20h to obtain a carboxyactivated porphyrin solution with a porphyrin concentration of 2.5mg / mL. The solution was then filtered, washed and dried to obtain carboxyactivated porphyrin. Then, 0.05g of carboxyactivated porphyrin, the organic dispersion of GO-NH2 obtained in step (2) and triethylamine were mixed. The mass ratio of carboxyactivated porphyrin to GO-NH2 in the organic dispersion was 0.5:1 and the amount of triethylamine added was 1mL. The solution was covalently assembled at 120℃ for 15h, then filtered, washed with water and ethanol, and then dried to obtain photoresponsive three-dimensional graphene material.

[0077] Example 3

[0078] This embodiment provides a method for preparing a photoresponsive three-dimensional graphene material, the method comprising the following steps:

[0079] (1) 0.1 g of graphene oxide (GO) was dispersed in 50 mL of water to obtain a graphene oxide solution with a concentration of 2 mg / mL. Then, 0.5 g of propylenediamine was added to the solution. The mass ratio of graphene oxide to propylenediamine in the graphene oxide solution was 1:5. The graphene oxide was amination-reduction at 100 °C for 15 h. Then, the solution was filtered, washed and dried to obtain amino-functionalized reduced graphene oxide, denoted as GO-NH2.

[0080] (2) Disperse 0.1g GO-NH2 in 50mL N,N-dimethylformamide to obtain an organic dispersion of GO-NH2, wherein the concentration of GO-NH2 in the organic dispersion is 2mg / mL;

[0081] (3) Mix 0.1g of dinitrophenyl porphyrin, the organic dispersion of GO-NH2 obtained in step (2), and NaOH. The mass ratio of the carboxyl-activated porphyrin to GO-NH2 in the organic dispersion is 1:1. The amount of NaOH added is 0.2g. Covalent assembly is carried out at a temperature of 120℃ for 36h. Then, the mixture is filtered, washed with water and ethanol in sequence, and then dried to obtain photoresponsive three-dimensional graphene material.

[0082] Example 4

[0083] This embodiment provides a method for preparing a photoresponsive three-dimensional graphene material, the method comprising the following steps:

[0084] (1) 0.1 g of graphene oxide (GO) was dispersed in 100 mL of water to obtain a graphene oxide solution with a concentration of 1 mg / mL. Then, 0.8 g of benzidine was added to the solution. The mass ratio of graphene oxide to benzidine in the graphene oxide solution was 1:8. The graphene oxide was amination-reduction at 120 °C for 24 h. Then, the solution was filtered, washed and dried to obtain amino-functionalized reduced graphene oxide, denoted as GO-NH2.

[0085] (2) Disperse 0.1g GO-NH2 in 50mL N,N-dimethylacetamide to obtain an organic dispersion of GO-NH2, wherein the concentration of GO-NH2 in the organic dispersion is 2mg / mL;

[0086] (3) Mix 0.05g of tetranitrophenylporphyrin, the organic dispersion of GO-NH2 obtained in step (2), and KOH. The mass ratio of the carboxyl-activated porphyrin to GO-NH2 in the organic dispersion is 0.5:1, and the amount of KOH added is 0.3g. Covalent assembly is performed at a temperature of 120℃ for 48h. Then, the mixture is filtered, washed with water and ethanol in sequence, and then dried to obtain photoresponsive three-dimensional graphene material.

[0087] Example 5

[0088] This embodiment provides a method for preparing a photoresponsive three-dimensional graphene material, the method comprising the following steps:

[0089] (1) 0.5g of graphene oxide (GO) was dispersed in 100mL of water to obtain a graphene oxide solution with a concentration of 5mg / mL. Then, 0.5g of ethylenediamine was added to the solution. The mass ratio of graphene oxide to ethylenediamine in the graphene oxide solution was 1:1. The graphene oxide was amination-reduction at 80℃ for 6h. Then, the solution was filtered, washed and dried to obtain amino-functionalized reduced graphene oxide, denoted as GO-NH2.

[0090] (2) Disperse 0.5g GO-NH2 in 50mL N,N-dimethylformamide to obtain an organic dispersion of GO-NH2, wherein the concentration of GO-NH2 in the organic dispersion is 10mg / mL;

[0091] (3) 0.5g of dicarboxyphenylporphyrin was dispersed in 50mL of SOCl2 solution and activated at 50℃ for 48h to obtain a carboxy-activated porphyrin solution with a porphyrin concentration of 10mg / mL. The solution was then filtered, washed and dried to obtain carboxy-activated porphyrin. Then, 0.05g of carboxy-activated porphyrin, the organic dispersion of GO-NH2 obtained in step (2) and triethylamine were mixed. The mass ratio of carboxy-activated porphyrin to GO-NH2 in the organic dispersion was 0.1:1 and the amount of triethylamine added was 0.5mL. The solution was covalently assembled at 100℃ for 72h, then filtered, washed with water and ethanol, and then dried to obtain a photoresponsive three-dimensional graphene material.

[0092] Example 6

[0093] This embodiment provides a method for preparing a photoresponsive three-dimensional graphene material, the method comprising the following steps:

[0094] (1) 0.01 g of graphene oxide (GO) was dispersed in 100 mL of water to obtain a graphene oxide solution with a concentration of 0.1 mg / mL. Then, 0.1 g of ethylenediamine was added to the solution. The mass ratio of graphene oxide to ethylenediamine in the graphene oxide solution was 1:10. The graphene oxide was amination-reduction at 120 °C for 18 h. Then, the solution was filtered, washed and dried to obtain amino-functionalized reduced graphene oxide, denoted as GO-NH2.

[0095] (2) Disperse 0.05g GO-NH2 in 10mL N,N-dimethylformamide to obtain an organic dispersion of GO-NH2, wherein the concentration of GO-NH2 in the organic dispersion is 5mg / mL;

[0096] (3) 0.05g of dicarboxyphenylporphyrin was dispersed in 25mL of SOCl2 solution and activated at 100℃ for 6h to obtain a carboxy-activated porphyrin solution with a porphyrin concentration of 2mg / mL. The solution was then filtered, washed and dried to obtain carboxy-activated porphyrin. Then, 0.05g of carboxy-activated porphyrin, the organic dispersion of GO-NH2 obtained in step (2) and triethylamine were mixed. The mass ratio of carboxy-activated porphyrin to GO-NH2 in the organic dispersion was 1:1 and the amount of triethylamine added was 0.5mL. The solution was covalently assembled at 150℃ for 6h, filtered, washed with water and ethanol, and then dried to obtain a photoresponsive three-dimensional graphene material.

[0097] Example 7

[0098] This embodiment provides a method for preparing a photoresponsive three-dimensional graphene material, which differs from Example 1 only in that ethylenediamine is replaced with hexamethylenediamine.

[0099] Example 8

[0100] This embodiment provides a method for preparing a photoresponsive three-dimensional graphene material. The only difference from Example 1 is that the mass ratio of graphene oxide to ethylenediamine in the graphene oxide solution is 1:0.5.

[0101] Example 9

[0102] This embodiment provides a method for preparing a photoresponsive three-dimensional graphene material. The only difference from Example 1 is that the porphyrin is not activated. Step (3) is replaced by mixing 0.05g of dicarboxyphenylporphyrin, the organic dispersion of GO-NH2 obtained in step (2), and triethylamine. The mixture is then covalently assembled at 120°C for 15h, filtered, washed with water and ethanol in sequence, and then dried to obtain the photoresponsive three-dimensional graphene material.

[0103] Example 10

[0104] This embodiment provides a method for preparing a photoresponsive three-dimensional graphene material. The only difference from Example 1 is that the mass ratio of carboxyl-activated porphyrin to GO-NH2 in the organic dispersion is 0.05:1.

[0105] Comparative Example 1

[0106] This comparative example provides a method for preparing porphyrin / graphene materials. The difference between this method and Example 1 is that the amination reduction is not performed. The preparation method includes:

[0107] 0.05 g of GO was dispersed in 50 mL of N,N-dimethylformamide to obtain an organic dispersion of GO; carboxyl-activated porphyrin, the organic dispersion of GO and triethylamine were mixed and covalently assembled, and then filtered, washed and dried to obtain porphyrin / graphene material.

[0108] Taking the material obtained in Example 1 as an example, a mixed metal solution containing Al, Cd, Cu, Fe, Ni, Pb, Zn, and Au was prepared, with each ion concentration of 10 ppm. Under light irradiation, the adsorption rate of the material for each ion within a pH range of 1-4 was as follows: Figure 1 As shown, from Figure 1 It can be seen that the photoresponsive three-dimensional graphene material provided by this invention can achieve precise separation and recovery of gold under the interference of various impurity ions within a pH range of 1-2. Using the above-mentioned mixed metal solution, under a pH value of 1, the materials obtained in Examples 1-10 and Comparative Example 1 were used for adsorption. The adsorption capacity of Au and the purity of the recovered Au were determined by ICP-OES, and the results are shown in Table 1.

[0109] Based on the above investigation, using the material obtained in Example 1 and further expanding the types of impurity elements in the system, a mixed metal solution containing Al, As, Ba, Be, Bi, Cd, Co, Cr, Cu, Fe, Ga, Li, Mg, Mn, Ni, Pb, Sb, Sn, Sr, Ti, Tl, V, Zn, and Au was prepared, with each ion concentration of 10 ppm. Under illumination and at a pH of 1, the adsorption rates of the obtained photoresponsive three-dimensional graphene material for each element in the above complex system are as follows: Figure 2 As shown, from Figure 2 It can be seen that the photoresponsive three-dimensional graphene material provided by this invention can also achieve precise separation and recovery of gold under various complex impurity ion systems.

[0110] Table 1

[0111] Au adsorption capacity (mg / g) Purity of recovered Au / % Example 1 2136.28 >99％ Example 2 2931.18 >99％ Example 3 2293.93 >99％ Example 4 2862.75 >99％ Example 5 2238.46 >99％ Example 6 2315.25 >99％ Example 7 1625.26 >99％ Example 8 1256.32 >99％ Example 9 1568.21 >99％ Example 10 1023.52 >99％ Comparative Example 1 153.24 <10％

[0112] The following points can be observed from the data in Table 1:

[0113] (1) As can be seen from the data of Examples 1-10, the photoresponsive three-dimensional graphene material provided by the present invention can achieve an adsorption capacity of more than 1023.52 mg / g for Au, and under better conditions it can reach more than 2136.28 mg / g. The purity of the recovered Au can reach more than 99%, that is, it can achieve ultra-high adsorption capacity for gold and accurate recovery.

[0114] (2) As can be seen from the data of Example 1 and Example 7, the only difference between Example 7 and Example 1 is that ethylenediamine is replaced with hexamethylenediamine. The results show that the adsorption capacity in Example 1 is significantly higher than that in Example 7. It can be seen that by optimizing and controlling the type of diamine reagent, the present invention can further improve the electronic conduction ability of the material while avoiding affecting the electronic transport structure of graphene itself, thereby improving the adsorption capacity of Au.

[0115] (3) As can be seen from the data of Example 1 and Example 8, the only difference between Example 8 and Example 1 is that the ratio of the mass of graphene oxide to the mass of ethylenediamine in the graphene oxide solution is not within the preferred range of the present invention. The results show that the adsorption capacity in Example 1 is significantly higher than that in Example 8. It can be seen that the present invention can avoid reagent waste and promote the amination reduction of graphene oxide by preferably controlling the ratio of the mass of graphene oxide to the mass of ethylenediamine in the graphene oxide solution, thereby further improving the adsorption capacity of Au.

[0116] (4) As can be seen from the data of Examples 1 and 9-10, the only difference between Example 9 and Example 1 is that the porphyrin is not activated. The only difference between Example 10 and Example 1 is that the mass ratio of carboxyl-activated porphyrin to GO-NH2 in the organic dispersion is not within the preferred range of the present invention. The adsorption capacity in Example 1 is significantly higher than that in Examples 9-10. It can be seen that the present invention can avoid reagent waste and fully promote the covalent assembly of GO-NH2 and porphyrin by activating the carboxyl group of porphyrin and controlling the mass ratio of carboxyl-activated porphyrin to GO-NH2, thereby further improving the adsorption capacity of Au.

[0117] (5) As can be seen from the data of Example 1 and Comparative Example 1, the only difference between Comparative Example 1 and Example 1 is that the amination reduction is not performed. The adsorption capacity and Au purity in Example 1 are much higher than those in Comparative Example 1. It can be seen that the present invention can not only remove the various oxygen-containing functional groups on the surface of graphene oxide by amination reduction, thereby achieving accurate recovery of Au, but also construct amino functional groups that can bond with porphyrin, thereby effectively improving the adsorption capacity of Au.

[0118] In summary, the photoresponsive three-dimensional graphene material provided by this invention can achieve ultra-high capacity adsorption and precise recovery of Au under light conditions. Furthermore, the preparation method is simple, environmentally friendly, and the raw material production technology is mature and inexpensive, which is conducive to industrial application.

[0119] The applicant declares that the above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A method for preparing a photoresponsive three-dimensional graphene material, characterized in that, The preparation method includes the following steps: (1) Mix graphene oxide solution and diamine reagent to reduce graphene oxide by amination, and then perform solid-liquid separation, washing and drying in sequence to obtain amino-functionalized reduced graphene oxide, denoted as GO-NH2; (2) Mix the amino-functionalized reduced graphene oxide obtained in step (1) with an organic solvent to obtain an organic dispersion of GO-NH2; (3) The organic dispersion of GO-NH2 obtained in step (2) and porphyrin are covalently assembled, and then solid-liquid separation, washing and drying are performed in sequence to obtain a photoresponsive three-dimensional graphene material with a porphyrin covalently intercalated graphene structure. The porphyrin in step (3) includes any one or a combination of at least two of dicarboxyphenylporphyrin, tetracarboxyphenylporphyrin, dinitrophenylporphyrin, or tetranitrophenylporphyrin.

2. The preparation method according to claim 1, characterized in that, The graphene oxide solution in step (1) is obtained by mixing graphene oxide and water.

3. The preparation method according to claim 1, characterized in that, The concentration of the graphene oxide solution is 0.1-5 mg / mL.

4. The preparation method according to claim 1, characterized in that, The diamine reagent includes any one or a combination of at least two of ethylenediamine, propylenediamine, p-aniline, or benzidine.

5. The preparation method according to claim 1, characterized in that, The mass ratio of graphene oxide to diamine reagent in the graphene oxide solution is 1:(1-10).

6. The preparation method according to claim 1, characterized in that, The amination reduction temperature is 80-120℃.

7. The preparation method according to claim 1, characterized in that, The amination reduction time is 6-24 h.

8. The preparation method according to claim 1, characterized in that, The organic solvent in step (2) includes N,N-dimethylformamide and / or N,N-dimethylacetamide.

9. The preparation method according to claim 1, characterized in that, The concentration of GO-NH2 in the organic dispersion is 0.1-10 mg / mL.

10. The preparation method according to claim 1, characterized in that, When the porphyrin in step (3) includes dicarboxyphenylporphyrin and / or tetracarboxyphenylporphyrin, covalent assembly is completed by condensation reaction between the amino group of GO-NH2 and the carboxyl group of the porphyrin.

11. The preparation method according to claim 1, characterized in that, When the porphyrin includes dicarboxyphenyl porphyrin and / or tetracarboxyphenyl porphyrin, the covalent assembly process includes: covalently assembling a mixture of carboxyactivated porphyrin, an organic dispersion of GO-NH2, and triethylamine.

12. The preparation method according to claim 11, characterized in that, The method for preparing the carboxyl-activated porphyrin includes: activating a mixture of porphyrin and an activation solution to obtain a carboxyl-activated porphyrin solution, followed by solid-liquid separation, washing, and drying to obtain the carboxyl-activated porphyrin.

13. The preparation method according to claim 12, characterized in that, The activation solution includes a thionyl chloride solution.

14. The preparation method according to claim 12, characterized in that, The concentration of porphyrin in the carboxyl-activated porphyrin solution is 1.5-10 mg / mL.

15. The preparation method according to claim 12, characterized in that, The activation temperature is 50-100℃.

16. The preparation method according to claim 12, characterized in that, The activation time is 6-48 h.

17. The preparation method according to claim 11, characterized in that, The mass ratio of the carboxyl-activated porphyrin to GO-NH2 in the organic dispersion is (0.1-1):

1.

18. The preparation method according to claim 11, characterized in that, The amount of triethylamine added is 5-20 equivalents of carboxyl-activated porphyrin.

19. The preparation method according to claim 1, characterized in that, When the porphyrin in step (3) includes dinitrophenylporphyrin and / or tetranitrophenylporphyrin, covalent assembly is completed by reacting the amino group of GO-NH2 with the nitro group of the porphyrin.

20. The preparation method according to claim 1, characterized in that, When the porphyrin includes dinitrophenyl porphyrin and / or tetranitrophenyl porphyrin, the covalent assembly process includes: covalent assembly of mixed porphyrins, an organic dispersion of GO-NH2, and a base.

21. The preparation method according to claim 1, characterized in that, The mass ratio of the porphyrin to the GO-NH2 in the organic dispersion is (0.1-1):

1.

22. The preparation method according to claim 20, characterized in that, The base includes KOH and / or NaOH.

23. The preparation method according to claim 20, characterized in that, The amount of alkali added is 5-20 times the equivalent of porphyrin.

24. The preparation method according to claim 1, characterized in that, The temperature for covalent assembly in step (3) is 100-150℃.

25. The preparation method according to claim 1, characterized in that, The covalent assembly time is 6-72 h.

26. A photoresponsive three-dimensional graphene material, characterized in that, The photoresponsive three-dimensional graphene material is obtained by the preparation method of the photoresponsive three-dimensional graphene material according to any one of claims 1-25.

27. The use of the photoresponsive three-dimensional graphene material as described in claim 26, characterized in that, The photoresponsive three-dimensional graphene material is used to selectively adsorb and extract gold from gold-containing solutions under light conditions.

28. The use according to claim 27, characterized in that, The gold-containing solution is acidic.

29. The use according to claim 27, characterized in that, The pH value of the gold-containing solution is 0-2.

30. The use according to claim 27, characterized in that, The gold-containing solution includes any one or a combination of at least two of the following: natural ore leaching solution, gold-containing wastewater, or gold-containing waste leaching solution.

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