A composite aerogel for adsorbing Cu in water and its preparation method

Abstract

This invention provides a composite aerogel for adsorbing Cu in water and its preparation method, belonging to the fields of new materials and energy conservation and environmental protection. The specific method is as follows: First, graphene oxide (GO) is synthesized, then molybdenum disulfide is aminated in a mercaptoethylamine solution, and a methanol solution of polyetherimide at a specific mass concentration is added to obtain MoS2-PEI. Finally, the prepared MoS2-PEI and GO are ultrasonically mixed, and the resulting product is immersed in an aqueous solution of zinc acetate dihydrate, followed by multiple growth cycles in an aqueous solution of 2-methylimidazole. This yields a ZIF-8 / MoS2-PEI / GO aerogel. This composite aerogel uses GO as a carrier and can selectively adsorb Cu, achieving efficient purification of the heavy metal Cu. This invention features low energy consumption, high separation efficiency, one-step solidification separation, and no secondary pollution, effectively avoiding the drawbacks of redundant separation operations and large waste volumes in traditional methods.

Description

Technical Field

[0001] This invention relates to a composite aerogel that adsorbs Cu in water and its preparation method, belonging to the fields of new materials and energy conservation and environmental protection. Background Technology

[0002] Copper, as a trace element, exists in living organisms and has a positive impact on metabolic activities. With the development of human economic activities, copper originally stored in ores has flowed into the aquatic environment, causing serious exceedances of copper in plants and animals. Due to the high affinity between copper and certain human tissues, it inhibits the activity of proteases, producing toxic effects on humans, leading to necrosis of the liver, kidneys, blood vessels, and digestive system, and even cancer. When the copper content in water approaches 0.01 mg / L, the aerobic metabolism of organic pollutants by microorganisms in the water is restricted, hindering the degradation of organic pollutants. When the copper content in water reaches 0.1–0.2 mg / L, some mammals will die. When it exceeds 3.0 mg / L, the water will produce an unpleasant odor. When irrigation water is contaminated with copper, copper will be fixed in the roots of plants. Soil copper pollution will affect the absorption of nutrients by plants and damage crop growth. In recent years, the types and contents of heavy metals in vegetables have been increasing, with Cu, Cd, and Zn becoming the most abundant pollutants in vegetables.

[0003] Copper in my country's water bodies mainly originates from the metallurgical, power, electroplating, papermaking, herbicide, and tanneries industries. Electroplating wastewater contains 50–100 mg / L of copper; circuit board manufacturing wastewater contains 130–150 mg / L; and dye wastewater contains over 1000 mg / L. my country stipulates that the copper concentration in drinking water should be below 1.0 mg / L (GB5749—2022), and the copper concentration in wastewater should be below 2.0 mg / L (GB8978—1996). Industrial enterprises often discharge wastewater with high concentrations of heavy metals during actual production processes. Without pre-treatment of this wastewater, it will cause significant environmental damage. The discharge of industrial wastewater leads to the continuous accumulation of heavy metals in water bodies, creating a very serious situation. Heavy metals are difficult to degrade through natural purification. Therefore, the treatment of heavy metal-polluted wastewater is urgent, and treating wastewater with excessive heavy metal content and reducing its discharge is of great significance. Among the current treatment methods, chemical precipitation, ion exchange, osmosis separation, and adsorption are the most widely used.

[0004] Graphene, as a typical carbon-based adsorbent, has been widely used in the field of environmental pollution control. Graphene-based materials are used as adsorbents, electrodes, and photocatalysts, effectively removing toxic pollutants such as heavy metals, dyes, pharmaceuticals, antibiotics, phenols, and polycyclic aromatic hydrocarbons. Since Neto et al. obtained graphene by physically exfoliating graphite crystals in 2004, this material has been widely used in various fields. Compared with traditional materials, graphene has a large specific surface area, good thermal conductivity, high surface electron mobility, and stable chemical and mechanical properties. In recent years, the application of graphene derivatives as adsorbents in wastewater treatment has increased significantly. Different graphene-based materials can be synthesized by chemical vapor deposition, mechanical and electrochemical exfoliation of graphite. Among them, graphene oxide, graphene quantum dots, graphene nanosheets, and graphene nanowires exhibit excellent performance.

[0005] Molybdenum disulfide (MoS2) is a graphene-like two-dimensional transition metal sulfide with a unique three-layer stacked atomic layer (S-Mo-S) sandwich structure, excellent chemical stability, and structural designability. Furthermore, the abundant sulfide groups on the surface and edges of MoS2 endow it with good adsorption properties. Therefore, in recent years, MoS2 has become a popular adsorption and reduction agent for removing Cu from wastewater. 2+ Ideal material for improving Cu removal from MoS2. 2+ To address the issue of Cu volume, researchers both domestically and internationally have conducted extensive and fruitful studies using composite modification methods. However, these composite-modified nano-MoS2 treatments for Cu... 2+ It also has drawbacks such as low removal volume and slow removal rate. Therefore, how to improve the removal efficiency of Cu by MoS2 is a key issue. 2+ The removal volume and removal rate remain highly challenging research topics in the field of heavy metal wastewater pollution.

[0006] 2-Methylimidazolium zinc salt ZIF-8 is self-assembled from metal ions (zinc ions) and organic ligands (2-methylimidazolium). It was first designed, synthesized, and reported by Academician Chen Xiaoming's research group at Sun Yat-sen University. ZIF-8 is currently the most thoroughly studied ZIF material and also the most widely used ZIF material. In its crystal structure, polyhedra represent Zn, spheres represent N, and lines represent C. It has a sod-type topology, consisting of 1.16 nm nanocages formed by six-membered windows with a size of 0.34 nm. ZIF-8 possesses many characteristics such as high thermal stability, high chemical stability, high tunability, high porosity, and high hydrophobicity, and has wide applications in many fields.

[0007] The information disclosed in this background section is intended only to enhance the understanding of the overall background of the present invention and should not be construed as an admission or in any way implying that the information constitutes prior art known to those skilled in the art. Summary of the Invention

[0008] This invention utilizes the Hummers oxidation method and hydrothermal synthesis to successively synthesize graphene oxide and amino-modified MoS2-PEI, and through three cycles of growth, obtains a ZIF-8 / MoS2-PEI / GO aerogel, successfully designing and developing a composite aerogel for adsorbing Cu in water. Applying this composite aerogel to the purification of wastewater contaminated with heavy metals can efficiently and rapidly remove Cu, while also solving the problems of easy dispersion and difficulty in recovery of adsorbents in water, demonstrating broad application potential.

[0009] This invention provides a composite aerogel for adsorbing Cu in water and a method for preparing the same, comprising:

[0010] S01: Concentrated sulfuric acid, graphite powder, sodium nitrate, potassium permanganate, hydrogen peroxide and water are added to an ice bath in a set ratio and mechanically stirred to prepare a graphene oxide dispersion.

[0011] S02: Ammonium molybdate and thiourea were vigorously stirred in water and placed in a reaction vessel. The temperature and time were set for high-temperature reaction. After naturally cooling to room temperature, the black product was washed three times each with deionized water and ethanol and then freeze-dried to obtain MoS2 nanosheets.

[0012] S03: Take the MoS2 nanosheets obtained in step S02, add a specific mass of them to deionized water to prepare a dispersion, add an equal mass of the MoS2 dispersion to a mercaptoethylamine solution, sonicate, then add water to disperse, and freeze-dry to obtain MoS2-NH2. Add MoS2-NH2 to a methanol solution containing a specific mass concentration of polyetherimide (PEI), sonicate to disperse, and while mechanically stirring, add glutaraldehyde solution, centrifuge to obtain MoS2-PEI, and freeze-dry to obtain powder;

[0013] S04: The MoS2-PEI obtained in step S03 is mixed with graphene oxide, ultrasonicated, and then H2O2 solution is added. Then, an aqueous solution of polyacrylic acid is added and transferred to a high-temperature hydrothermal reactor. The product is removed and soaked in water until zinc acetate dihydrate is dissolved in the aqueous solution, then soaked until 2-methylimidazole is dissolved in the aqueous solution. One growth cycle is performed, followed by freeze-drying. The ZIF-8 hydrogel grown once is removed, and the above growth steps are repeated. After multiple growth cycles, ZIF-8 / MoS2-PEI / GO aerogel is obtained.

[0014] Preferably, in step S01, concentrated sulfuric acid (98% by mass), graphite powder, sodium nitrate, and potassium permanganate are mixed in a ratio of 42.32:0.5:0.5:3 and mechanically stirred in an ice-water bath for 1-3 hours. The mixture is then transferred to an oil bath at 30-40°C and mechanically stirred for another 1-3 hours. Next, 40-50 mL of deionized water is added, and the oil bath is rapidly heated to 80-95°C. After stirring for 25-35 minutes, 90-105 mL of deionized water and 2-5 mL of hydrogen peroxide are added. The reaction is terminated after thorough stirring, and the reaction solution is bright yellow. The metal ions are then washed with HCl solution, followed by repeated washing with deionized water until neutral. Finally, the obtained product is dispersed in 40-60 mL of deionized water and sonicated for 1-3 hours to obtain a graphene oxide dispersion.

[0015] Preferably, in step S01, the mass concentration of H2O2 in the hydrogen peroxide is 25-35 wt%, the mass concentration of the HCl solution is 1-10 wt%, the concentration of the prepared graphene oxide solution is 3-10 mg / mL, and the concentration of the graphene oxide solution prepared by the selected components of the above materials is 5 mg / mL, which meets the concentration requirements of the graphene oxide solution of the present invention. The selected components enable the prepared graphene oxide dispersion to have advantages such as high oxygen content, high purity, and good dispersibility.

[0016] Preferably, in step S02, ammonium molybdate and thiourea are added to 60-70 mL of water at a molar ratio of 0.013:0.077, stirred vigorously for 25-35 min, and then placed in a reaction vessel. The mixture is reacted at 200-240°C for 22-26 h. After natural cooling to room temperature, it is washed three times each with deionized water and ethanol (ethanol concentration 80-95 wt%), and then freeze-dried to obtain MoS2 nanosheets. The mass control of the selected materials ensures that ammonium molybdate and thiourea react fully at 220°C and that the composite material contains C, S, Mo, and O elements. In the S2p spectrum of XPS testing, the binding energies are 161.9 and 163.0 eV, respectively. Centrifugation and vacuum drying of the reaction solution yield MoS2 nanosheets, ensuring that the Mo-S mixture does not break down and exhibiting excellent adsorption properties and good chemical stability. In the subsequent composite steps, these nanosheets will demonstrate their ability to adsorb Cu. 2+ The selection of adsorption properties.

[0017] Preferably, in step S03, the ultrasonic reaction is carried out at 20–35°C for 3–5 hours; MoS2-NH2 is added to a methanol solution of PEI with a mass concentration of 60–80 g / L, and the ultrasonic reaction time is 25–35 minutes. After uniform dispersion, glutaraldehyde solution is added dropwise while mechanically stirring at 290–320 r / min at room temperature, and the reaction time is continued for another 25–35 minutes. After centrifugation, MoS2-PEI is obtained and freeze-dried for 22–25 hours to obtain powder. The mass of the material is limited here to ensure the appearance of the characteristic peaks of PEI, and MoS2-PEI has been successfully reconstituted. The PEI-modified MoS2-PEI has excellent high-temperature resistance and unique strength, which makes it exhibit good thermal stability during the cyclic growth of ZIF-8.

[0018] Preferably, in step S03, the amount of MoS2-NH2 added to the methanol solution of PEI is 0.06-0.1 g / L, the volume ratio of glutaraldehyde solution to methanol solution is (0.1-1):(0.1-1), and the mass concentration of glutaraldehyde solution is 0.1-5 wt%.

[0019] Preferably, in step S04, the volume of the graphene oxide solution is 5-20 mL and the concentration is 1-10 mg / mL; the volume of the MoS2-PEI solution as a solvent is 5-20 mL and the concentration is 1-5 mg / mL; the mass concentration of the H2O2 solution is 0.01-10 wt% and the volume is 1-10 mL; the volume of the polyacrylic acid aqueous solution is 1-10 mL and the concentration is 1-10 mg / mL; the mass of zinc acetate dihydrate is 0.01-10 g; the mass of 2-methylimidazole is 0.01-10 g; and the volume of deionized water is 10-30 mL.

[0020] Preferably, in step S04, the MoS2-PEI obtained in step S03 is mixed with graphene oxide, ultrasonicated for 0.1 to 2 hours, and then added to H2O2 solution. Then, an aqueous solution of polyacrylic acid is added and transferred to a high-temperature hydrothermal reactor for reaction at 150 to 200°C for 5 to 10 hours.

[0021] Preferably, in step S04, the product is soaked in water in an aqueous solution of zinc acetate dihydrate for 1-5 hours, then soaked in an aqueous solution of 2-methylimidazole for 1-5 hours, and grown once. The freeze-drying time is 20-30 hours. The ZIF-8 hydrogel grown once is taken out and the above steps are repeated to obtain ZIF-8 / MoS2-PEI / GO aerogel. The growth steps are repeated three times, and the cycle time is 1-10 hours.

[0022] The present invention also provides a composite aerogel for adsorbing Cu in water prepared by the above method.

[0023] The composite aerogel has the structural formula ZIF-8 / MoS2-PEI / GO; ZIF-8 / MoS2-PEI / GO is obtained by repeatedly growing ZIF-8 with graphene oxide and MoS2-PEI.

[0024] The principle of this invention is as follows: Graphene oxide synthesized via the Hummers oxidation method is used as the carrier for the aerogel. MoS2 is synthesized via a hydrothermal method. MoS2 is then amino-modified to obtain MoS2-PEI, which is then ultrasonically composited with GO. XPS spectra of the MoS2-PEI / GO composite material show the presence of C, S, Mo, and O elements, with the appearance of CC, CO, and C=O. Furthermore, as the peak of MoS2-PEI gradually weakens, the GO peak appears. Under these conditions, ZIF-8 is continuously grown. With each growth cycle, SEM reveals the appearance of spherical particles on the carrier. These particles have smooth, full surfaces, and clear boundaries, until they completely cover the carrier, ultimately yielding the ZIF-8 / MoS2-PEI / GO aerogel. This selectively removes the heavy metal Cu from water, solving the problems of easy dispersion and difficult recovery of adsorbents in water, reducing secondary pollution, saving energy, and simplifying operation.

[0025] The specific application method of this invention is as follows: Take 10 mg of ZIF-8 / MoS2-PEI / GO aerogel and add it to a system of 20 mL Cu 2+ The Cu in the copper-containing wastewater was determined after adsorption in a 0.5 mg / mL solution at 220 rpm for 12 hours in a constant-temperature shaker. 2+ The removal rate can reach 96.5%. After adsorption by the composite aerogel, simple drying and separation are performed to purify Cu in the water. 2+ The purpose.

[0026] The beneficial effects of this invention are:

[0027] (1) The ZIF-8 / MoS2-PEI / GO aerogel prepared by this invention has a large specific surface area, high porosity, strong flexibility, stable chemical properties and easy surface modification. The experimental process is controllable. After multiple growths, the ZIF-8 / MoS2-PEI / GO aerogel can selectively adsorb Cu with GO as a carrier, achieving efficient purification of heavy metal Cu with an adsorption efficiency of up to 96.5%.

[0028] (2) This invention utilizes composite aerogel to adsorb Cu in water 2+ Afterwards, it can be effectively separated from the reaction system through simple drying and separation technology, without secondary pollution; effectively avoiding the disadvantages of redundant separation operations and large waste volume in traditional methods.

[0029] (3) The overall processing structure of the present invention is relatively simple, lightweight, occupies a small area, and operates efficiently, conveniently and with low energy consumption. Attached Figure Description

[0030] Figure 1 SEM image of ZIF-8 / MoS2-PEI / GO aerogel;

[0031] Figure 2 XRD pattern of ZIF-8 grown by cyclic growth of composite aerogel;

[0032] Figure 3 The pore size distribution diagram is shown for ZIF-8 grown by cyclic growth of composite aerogel. Detailed Implementation

[0033] The present invention will be further described below with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and should not be used to limit the scope of protection of the present invention.

[0034] Components Commercially available Graphite powder Aladdin Reagent Co., Ltd. Sodium nitrate Sinopharm Chemical Reagent Co., Ltd. potassium permanganate Sinopharm Chemical Reagent Co., Ltd. 30% hydrogen peroxide Sinopharm Chemical Reagent Co., Ltd. concentrated sulfuric acid Sinopharm Chemical Reagent Co., Ltd. L-Ascorbic Acid Sinopharm Chemical Reagent Co., Ltd. Ammonium molybdate Sinopharm Chemical Reagent Co., Ltd. Thiourea Chengdu Xiya Chemical Co., Ltd. Anhydrous ethanol Sinopharm Chemical Reagent Co., Ltd. Polyacrylic acid Aladdin Reagent Co., Ltd. hydrochloric acid Sinopharm Chemical Reagent Co., Ltd. Sodium hydroxide Wuxi Huihuang Electronic Materials Co., Ltd. polyetherimide Aladdin Reagent Co., Ltd. glutaraldehyde Aladdin Reagent Co., Ltd. Zinc acetate dihydrate Sinopharm Chemical Reagent Co., Ltd. 2-Methylimidazole Aladdin Reagent Co., Ltd.

[0035] Figure 1 SEM image of ZIF-8 / MoS2-PEI / GO aerogel. The material was characterized using a Hitachi SU8020 scanning electron microscope.

[0036] Sample preparation: 5 mg of sample was weighed and dispersed in 10 mL of anhydrous ethanol, sonicated for 0.5 h, dried, and then adhered to a copper plate with conductive adhesive. After gold sputtering, measurements were taken, and the surface microstructure of the material was analyzed. It was observed that the MoS2-PEI / GO aerogel was almost entirely encapsulated by ZIF-8, with the entire aerogel surface covered by numerous well-defined and highly crystalline ZIF-8 lattice planes. Furthermore, the ZIF-8 exhibited a certain spherical morphology, both of which provide a basis for the aerogel's excellent adsorption properties.

[0037] Figure 2 XRD pattern of ZIF-8 grown from composite aerogel using a cyclic growth method. A DX-2700 X-ray diffractometer from Shanghai Precision Instruments Co., Ltd. was used.

[0038] Sample preparation: A suitable amount of sample was prepared into a slide. Measurements were performed under the conditions of Cu target, working voltage 35kV, current 25mA, and scanning step size of 0.02°. The scanning range was 5° to 80°, and data was collected every 0.5 seconds to analyze the crystal structure of the material. As shown in the figure, the ZIF-8 / MoS2-PEI / GO aerogel exhibits obvious characteristic peaks at 2θ = 7.32°, 10.08°, 12°, 14.6°, 16.3°, and 18.01°, indicating that ZIF-8 was successfully grown in the MoS2-PEI / GO aerogel after three growth cycles, and the peaks correspond to those of ZIF-8.

[0039] Figure 3 This image shows the pore size distribution of ZIF-8 composite aerogel grown in a cyclic manner. In this study, a BELSORP-miniII fully automated specific surface area analyzer from Macquarie Pharmaceuticals Co., Ltd. was used to determine the pore size, pore volume, and specific surface area of ​​the adsorbent material.

[0040] Sample preparation: 0.1 g of sample was placed in a sample tube and pretreated at 150 °C, followed by adsorption-desorption determination under a N2 atmosphere. As shown in the figure, the ZIF-8 / MoS2-PEI / GO aerogel with three ZIF-8 cycles has significantly more pore sites than the ZIF-8 / MoS2-PEI / GO aerogel with only one ZIF-8 growth, and the total pore volume of the ZIF-8 / MoS2-PEI / GO aerogel with three cycles is 0.4917 cm³. 3 / g, with an average pore size of 10.4655nm.

[0041] Example 1:

[0042] (1) GO was synthesized using the Hummers oxidation method. First, 23 mL of concentrated sulfuric acid was added to a 250 mL beaker under ice bath conditions. Then, 0.5 g of graphite powder and 0.5 g of sodium nitrate were slowly added with mechanical stirring, followed by 3.0 g of potassium permanganate, and mechanical stirring was continued for 1 h. Next, the beaker was transferred to an oil bath at 35 °C and stirred for 2 h. Then, 46 mL of deionized water was slowly added dropwise to a flask. The water bath was then rapidly heated to 90 °C and stirred for 30 min. Finally, 100 mL of ultrapure water and 3 mL of hydrogen peroxide (H2O2 concentration of 30 wt%) were added, and the reaction was terminated after stirring until homogeneous. The reaction solution was bright yellow. Subsequently, the metal ions were washed with 5 wt% HCl solution, followed by repeated washing with deionized water until neutral. Finally, the obtained product was dispersed in 50 mL of ultrapure water and sonicated for 2 h. A graphene oxide dispersion was obtained, and the concentration of the obtained graphene oxide solution was 5 mg / mL.

[0043] (2) 1.249 g of ammonium molybdate ((NH4)6Mo7O2·4H2O) and 2.303 g of thiourea (CH4N2S) were dissolved in 35 mL of deionized water and stirred vigorously for 30 min. Then, the mixture was transferred to a 50 mL reactor and heated to 200 °C for 24 h. After naturally cooling to room temperature, the black product was washed several times with deionized water and ethanol, and then freeze-dried (-55 °C, 48 h) to obtain MoS2 nanosheets.

[0044] Take 200 mL of 0.4 mg / mL molybdenum disulfide dispersion, add an equal mass of 40 mL of 2 mg / mL mercaptoethylamine solution, sonicate at 30 °C for 4 h, disperse the product in water, centrifuge at 10000 rpm for 30 min to wash and collect the precipitate, continue to disperse and wash with water, repeat 3 times; finally centrifuge at 4000 rpm for 10 min, freeze dry for 24 h for later use.

[0045] 0.03 g of MoS2-NH2 was added to a methanol solution (50 mL) of PEI with a mass concentration of 70 g / L. After sonication for 30 min to disperse the mixture evenly, 50 mL of 2 wt% glutaraldehyde solution was added dropwise while mechanically stirring at 300 r / min at room temperature. The reaction was continued for 30 min, and then centrifuged to obtain MoS2-PEI. The mixture was then freeze-dried for 24 h to obtain powder.

[0046] (3) After mixing graphene oxide (10 mL, 5 mg / mL) and MoS2-PEI (12 mL, 2 mg / mL) and sonicating for 1 h, add H2O2 solution (wt%: 0.3; 3 mL), then add polyacrylic acid aqueous solution (1 mL, 1 mg / mL) and transfer to a high-temperature hydrothermal reactor (180℃, 8 h).

[0047] The product was removed and soaked in water for 3 hours in a solution of 0.216 g zinc acetate dihydrate dissolved in 10 mL of water, followed by soaking in a solution of 0.662 g 2-methylimidazole dissolved in 10 mL of water for 3 hours. This was repeated once for one growth cycle, followed by freeze-drying for 24 hours. The ZIF-8 hydrogel grown once was then removed and soaked again in a solution of 0.216 g zinc acetate dihydrate dissolved in 10 mL of water for 3 hours, followed by soaking in a solution of 0.662 g 2-methylimidazole dissolved in 10 mL of water for 3 hours. This was repeated twice for two growth cycles, followed by freeze-drying for 24 hours to obtain ZIF-8 / MoS2-PEI / GO aerogel. The above steps were repeated for three growth cycles, each lasting 6 hours.

[0048] 10 mg of the composite aerogel prepared in Example 1 was added to a 20 mL system containing Cu 2+ After adsorption in a 0.5 mg / mL solution at 190 rpm for 12 h in a constant temperature shaker, the Cu concentration in the wastewater was measured. 2+The removal rate can reach 96.5%. After adsorption by the composite aerogel, simple drying and separation are performed to achieve the adsorption of Cu in water. 2+ The purpose.

[0049] Example 2:

[0050] (1) GO was synthesized using the Hummers oxidation method. First, 23 mL of concentrated sulfuric acid was added to a 250 mL beaker under ice bath conditions. Then, 0.5 g of graphite powder and 0.5 g of sodium nitrate were slowly added while mechanically stirring, followed by the slow addition of 3.0 g of potassium permanganate and mechanical stirring for 3 h. Next, the beaker was transferred to an oil bath at 50 °C and stirred for 3 h. Then, 50 mL of deionized water was slowly added dropwise to a flask. The water bath was then rapidly heated to 80 °C and stirred for 30 min. Finally, 100 mL of ultrapure water and 3 mL of hydrogen peroxide (H2O2 concentration of 30 wt%) were added and stirred until homogeneous, at which point the reaction was terminated. The reaction solution was bright yellow. Subsequently, the metal ions were washed with 5 wt% HCl solution, followed by repeated washing with deionized water until neutral. Finally, the obtained product was dispersed in 50 mL of ultrapure water and sonicated for 2 h. A graphene oxide dispersion was obtained, with a concentration of 6 mg / mL.

[0051] (2) 2.498 g of ammonium molybdate ((NH4)6Mo7O2·4H2O) and 4.606 g of thiourea (CH4N2S) were dissolved in 35 mL of deionized water and stirred vigorously for 30 min. Then, the mixture was transferred to a 50 mL reactor and heated to 195 °C for 24 h. After naturally cooling to room temperature, the black product was washed several times with deionized water and ethanol, and then freeze-dried (-55 °C, 48 h) to obtain MoS2 nanosheets.

[0052] Take 200 mL of 0.4 mg / mL molybdenum disulfide dispersion, add an equal mass of 40 mL of 2 mg / mL mercaptoethylamine solution, sonicate at 30 °C for 4 h, disperse the resulting product in water, centrifuge at 10000 rpm for 25 min to wash and collect the precipitate, continue to disperse and wash with water, repeat 3 times; finally centrifuge at 4000 rpm for 10 min, freeze dry for 24 h for later use.

[0053] 0.03 g of MoS2-NH2 was added to a methanol solution (50 mL) of PEI with a mass concentration of 70 g / L. After sonication for 30 min to disperse the mixture evenly, 50 mL of 2 wt% glutaraldehyde solution was added dropwise while mechanically stirring at 300 r / min at room temperature. The reaction was continued for 30 min, and then centrifuged to obtain MoS2-PEI. The mixture was then freeze-dried for 24 h to obtain powder.

[0054] (3) After mixing graphene oxide (10 mL, 5 mg / mL) and MoS2-PEI (12 mL, 2 mg / mL) and sonicating for 1 h, add H2O2 solution (wt%: 0.3; 3 mL), then add polyacrylic acid aqueous solution (1 mL, 1 mg / mL) and transfer to a high-temperature hydrothermal reactor (180℃, 8 h).

[0055] The product was removed and soaked in water for 3 hours in a solution of 0.216 g zinc acetate dihydrate dissolved in 10 mL of water, followed by soaking in a solution of 0.662 g 2-methylimidazole dissolved in 10 mL of water for 3 hours. This was repeated once for one growth cycle, followed by freeze-drying for 24 hours. The ZIF-8 hydrogel grown once was then removed and soaked again in a solution of 0.216 g zinc acetate dihydrate dissolved in 10 mL of water for 3 hours, followed by soaking in a solution of 0.662 g 2-methylimidazole dissolved in 10 mL of water for 3 hours. This was repeated twice for two growth cycles, followed by freeze-drying for 24 hours to obtain ZIF-8 / MoS2-PEI / GO aerogel. The above steps were repeated for three growth cycles, each lasting 6 hours.

[0056] 15 mg of the composite aerogel prepared in Example 2 was added to a 20 mL system containing Cu 2+ Cu in a 0.75 mg / mL solution was placed in a constant-temperature shaker and shaken at 190 rpm for 12 h for adsorption. The Cu concentration in the wastewater was then measured. 2+ The removal rate can reach 94.1%. After adsorption by the composite aerogel, simple drying and separation are performed to achieve the adsorption of Cu in water. 2+ The purpose.

[0057] Example 3:

[0058] (1) GO was synthesized using the Hummers oxidation method. First, 23 mL of concentrated sulfuric acid was added to a 250 mL beaker under ice bath conditions. Then, 0.5 g of graphite powder and 0.5 g of sodium nitrate were slowly added while mechanically stirring, followed by the slow addition of 3.0 g of potassium permanganate and mechanical stirring for 2 h. Next, the beaker was transferred to an oil bath at 45 °C and stirred for 2 h. Then, 46 mL of deionized water was slowly added dropwise to a flask. The water bath was then rapidly heated to 85 °C and stirred for 30 min. Finally, 100 mL of ultrapure water and 3 mL of hydrogen peroxide (H2O2 concentration of 30 wt%) were added and stirred until homogeneous, at which point the reaction was terminated. The reaction solution was bright yellow. Subsequently, the metal ions were washed with 5 wt% HCl solution, followed by repeated washing with deionized water until neutral. Finally, the obtained product was dispersed in 50 mL of ultrapure water and sonicated for 2 h. A graphene oxide dispersion was obtained, with a concentration of 5 mg / mL.

[0059] (2) 2.498 g of ammonium molybdate ((NH4)6Mo7O2·4H2O) and 4.606 g of thiourea (CH4N2S) were dissolved in 40 mL of deionized water and stirred vigorously for 30 min. Then, the mixture was transferred to a 55 mL reactor and heated to 205 °C for 24 h. After naturally cooling to room temperature, the black product was washed several times with deionized water and ethanol, and then freeze-dried (-55 °C, 48 h) to obtain MoS2 nanosheets.

[0060] Take 200 mL of 0.4 mg / mL molybdenum disulfide dispersion, add an equal mass of 40 mL of 2 mg / mL mercaptoethylamine solution, sonicate at 30 °C for 4 h, disperse the product in water, centrifuge at 10000 rpm for 30 min to wash and collect the precipitate, continue to disperse and wash with water, repeat 3 times; finally centrifuge at 4000 rpm for 10 min, freeze dry for 25 h for later use.

[0061] 0.03 g of MoS2-NH2 was added to a methanol solution (50 mL) of PEI with a mass concentration of 70 g / L. After sonication for 30 min to disperse the mixture evenly, 50 mL of 2 wt% glutaraldehyde solution was added dropwise while mechanically stirring at 300 r / min at room temperature. The reaction was continued for 30 min, and then centrifuged to obtain MoS2-PEI. The mixture was then freeze-dried for 24 h to obtain powder.

[0062] (3) After mixing graphene oxide (10 mL, 5 mg / mL) and MoS2-PEI (12 mL, 2 mg / mL) and sonicating for 1 h, add H2O2 solution (wt%: 0.3; 3 mL), then add polyacrylic acid aqueous solution (1 mL, 1 mg / mL) and transfer to a high-temperature hydrothermal reactor (180℃, 8 h).

[0063] The product was removed and soaked in water for 3 hours in a solution of 0.216 g zinc acetate dihydrate dissolved in 10 mL of water, followed by soaking in a solution of 0.662 g 2-methylimidazole dissolved in 10 mL of water for 3 hours. This was repeated once for one growth cycle, followed by freeze-drying for 24 hours. The ZIF-8 hydrogel grown once was then removed and soaked again in a solution of 0.216 g zinc acetate dihydrate dissolved in 10 mL of water for 3 hours, followed by soaking in a solution of 0.662 g 2-methylimidazole dissolved in 10 mL of water for 3 hours. This was repeated twice for two growth cycles, followed by freeze-drying for 24 hours to obtain ZIF-8 / MoS2-PEI / GO aerogel. The above steps were repeated for three growth cycles, each lasting 6 hours.

[0064] 20 mg of the composite aerogel prepared in Example 3 was added to a 20 mL system containing Cu 2+ After adsorption in a 1.0 mg / mL solution at 190 rpm for 12 h in a constant temperature shaker, the Cu concentration in the wastewater was measured. 2+The removal rate can reach 91.4%. After adsorption by the composite aerogel, simple drying and separation are performed to achieve the adsorption of Cu in water. 2+ The purpose.

[0065] Example 4:

[0066] (1) GO was synthesized using the Hummers oxidation method. First, 24 mL of concentrated sulfuric acid was added to a 250 mL beaker under ice bath conditions. Then, 0.6 g of graphite powder and 0.4 g of sodium nitrate were slowly added with mechanical stirring, followed by 2.9 g of potassium permanganate, and mechanical stirring was continued for 2 h. Next, the beaker was transferred to an oil bath at 40 °C and stirred for 2 h. Then, 47 mL of deionized water was slowly added dropwise to a flask. The water bath was then rapidly heated to 85 °C and stirred for 30 min. Finally, 100 mL of ultrapure water and 3 mL of hydrogen peroxide (H2O2 concentration of 30 wt%) were added, and the reaction was terminated after stirring until homogeneous. The reaction solution was bright yellow. Subsequently, the metal ions were washed with 4.9 wt% HCl solution, followed by repeated washing with deionized water until neutral. Finally, the obtained product was dispersed in 45 mL of ultrapure water and sonicated for 3 h. A graphene oxide dispersion was obtained, and the concentration of the obtained graphene oxide solution was 4.327 mg / mL.

[0067] (2) 2.498 g of ammonium molybdate ((NH4)6Mo7O2·4H2O) and 4.606 g of thiourea (CH4N2S) were dissolved in 35 mL of deionized water and stirred vigorously for 30 min. Then, the mixture was transferred to a 50 mL reactor and heated to 195 °C for 24 h. After naturally cooling to room temperature, the black product was washed several times with deionized water and ethanol, and then freeze-dried (-55 °C, 48 h) to obtain MoS2 nanosheets.

[0068] Take 200 mL of 0.4 mg / mL molybdenum disulfide dispersion, add an equal mass of 40 mL of 2 mg / mL mercaptoethylamine solution, sonicate at 30 °C for 4 h, disperse the product in water, centrifuge at 10000 rpm for 30 min to wash and collect the precipitate, continue to disperse and wash with water, repeat 3 times; finally centrifuge at 4000 rpm for 10 min, freeze dry for 24 h for later use.

[0069] 0.03 g of MoS2-NH2 was added to a methanol solution (50 mL) of PEI with a mass concentration of 70 g / L. After sonication for 30 min to disperse the mixture evenly, 50 mL of 2 wt% glutaraldehyde solution was added dropwise while mechanically stirring at 300 r / min at room temperature. The reaction was continued for 30 min, and then centrifuged to obtain MoS2-PEI. The mixture was then freeze-dried for 24 h to obtain powder.

[0070] (3) After mixing graphene oxide (10 mL, 4.901 mg / mL) and MoS2-PEI (6 mL, 2 mg / mL) and sonicating for 1 h, add H2O2 solution (wt%: 0.3; 3 mL), then add polyacrylic acid aqueous solution (1 mL, 1 mg / mL) and transfer to a high-temperature hydrothermal reactor (180℃, 8 h).

[0071] The product was removed and soaked in water for 3 hours in a solution of 0.216 g zinc acetate dihydrate dissolved in 10 mL of water, followed by soaking in a solution of 0.662 g 2-methylimidazole dissolved in 10 mL of water for 3 hours. This was repeated once for one growth cycle, followed by freeze-drying for 24 hours. The ZIF-8 hydrogel grown once was then removed and soaked again in a solution of 0.216 g zinc acetate dihydrate dissolved in 10 mL of water for 3 hours, followed by soaking in a solution of 0.662 g 2-methylimidazole dissolved in 10 mL of water for 3 hours. This was repeated twice for two growth cycles, followed by freeze-drying for 24 hours to obtain ZIF-8 / MoS2-PEI / GO aerogel. The above steps were repeated for three growth cycles, each lasting 6 hours.

[0072] Take 30 mg of the composite aerogel prepared in Example 4 and add it to a system of 30 mL Cu 2+ Cu was adsorbed in a 1 mg / mL solution in a constant temperature shaker at 190 rpm for 12 h, and then the concentration of Cu in the wastewater was measured. 2+ The removal rate was only 82.03%. The concentration of graphene oxide solution during the material composite process was 4.327 mg / mL, which is too different from the optimal solution. In addition, too little MoS2-PEI was added in step S04, which caused the composite aerogel to be poorly formed and too loose, resulting in the loss of many CC, CO and C=O key valence bonds. This led to a large gap between the final adsorption and removal rate of the composite aerogel and the optimal solution.

[0073] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing a composite aerogel that adsorbs Cu in water, characterized in that, The preparation method includes: S01: Add concentrated sulfuric acid, graphite powder, sodium nitrate, potassium permanganate, hydrogen peroxide and water into a beaker according to a set ratio, and mechanically stir to prepare a graphene oxide dispersion; SO2: Ammonium molybdate and thiourea were stirred vigorously in water and placed in a reaction vessel for high-temperature reaction. After naturally cooling to room temperature, they were washed three times each with deionized water and ethanol, and then freeze-dried to obtain MoS2 nanosheets. S03: Take the MoS2 nanosheets obtained in step S02, add a specific mass to deionized water to prepare a dispersion, add an equal mass of mercaptoethylamine solution, sonicate and then add water to disperse, and freeze-dry to obtain MoS2-NH2; add MoS2-NH2 to a methanol solution containing polyetherimide, sonicate and disperse, and add glutaraldehyde solution while mechanically stirring, centrifuge to obtain MoS2-PEI, and freeze-dry to obtain powder; S04: The MoS2-PEI obtained in step S03 is mixed with graphene oxide and sonicated before being added to H2O2 solution. Then, an aqueous solution of polyacrylic acid is added and transferred to a high-temperature hydrothermal reactor. The product is taken out and immersed in a solution of zinc acetate dihydrate dissolved in water, and then immersed in a solution of 2-methylimidazole dissolved in water for one growth cycle. The product is then freeze-dried. The hydrogel grown once for ZIF-8 is taken out and the above growth steps are repeated. After multiple growth cycles, ZIF-8 / MoS2-PEI / GO aerogel is obtained.

2. The method for preparing a composite aerogel for adsorbing Cu in water according to claim 1, characterized in that: In step S01, concentrated sulfuric acid (98% by mass), graphite powder, sodium nitrate, and potassium permanganate were mixed in a ratio of 23 ml: 0.5 g: 0.5 g: 3 g and mechanically stirred in an ice-water bath for 1-3 h. The mixture was then transferred to an oil bath at 30-40°C and mechanically stirred for another 1-3 h. 40-50 mL of deionized water was added, and the oil bath was rapidly heated to 80-95°C. After stirring for 25-35 min, 90-105 mL of deionized water and 2-5 mL of hydrogen peroxide were added. The reaction was terminated after thorough stirring, and the reaction solution was bright yellow. The metal ions were then washed with HCl solution, followed by repeated washing with deionized water until neutral. Finally, the obtained product was dispersed in 40-60 mL of deionized water and sonicated for 1-3 h to obtain a graphene oxide dispersion.

3. The method for preparing a composite aerogel for adsorbing Cu in water according to claim 2, characterized in that: In step S01, the mass concentration of H2O2 in the hydrogen peroxide is 25~35 wt%, the mass concentration of the HCl solution is 1~10 wt%, and the concentration of the prepared graphene oxide dispersion is 3~10 mg / mL.

4. The method for preparing a composite aerogel for adsorbing Cu in water according to claim 1, characterized in that: In step S02, ammonium molybdate and thiourea were added to 60-70 mL of water at a molar ratio of 0.013:0.077 and stirred vigorously for 25-35 min. The mixture was then placed in a reaction vessel and reacted at 200-240℃ for 22-26 h. After naturally cooling to room temperature, the mixture was washed three times each with deionized water and ethanol (ethanol concentration 80-95 wt%). MoS2 nanosheets were obtained by freeze-drying.

5. The method for preparing a composite aerogel for adsorbing Cu in water according to claim 1, characterized in that: In step S03, MoS2-NH2 is added to a methanol solution of PEI with a mass concentration of 60-80 g / L. The ultrasonic reaction time is 25-35 min. After uniform dispersion, glutaraldehyde solution is added dropwise while mechanically stirring at 290-320 r / min at room temperature. The reaction is continued for 25-35 min. After centrifugation, MoS2-PEI is obtained and freeze-dried for 22-25 h to obtain powder.

6. The method for preparing a composite aerogel for adsorbing Cu in water according to claim 5, characterized in that: In step S03, the amount of MoS2-NH2 added to the methanol solution of PEI is 0.06~0.1 g / L, and the mass concentration of glutaraldehyde solution is 0.1~5 wt%.

7. The method for preparing a composite aerogel for adsorbing Cu in water according to claim 1, characterized in that: In step S04, the H2O2 solution has a mass concentration of 0.01~10 wt% and a volume of 1~10 mL; the polyacrylic acid aqueous solution has a volume of 1~10 mL and a concentration of 1~10 mg / mL; the zinc acetate dihydrate has a mass of 0.01~10 g and the 2-methylimidazole has a mass of 0.01~10 g.

8. The method for preparing a composite aerogel for adsorbing Cu in water according to claim 1, characterized in that: In step S04, the MoS2-PEI obtained in step S03 is mixed with graphene oxide and sonicated for 0.1-2 h, then added to H2O2 solution, followed by the addition of polyacrylic acid aqueous solution and transferred to a high-temperature hydrothermal reactor for reaction at 150-200°C for 5-10 h.

9. The method for preparing a composite aerogel for adsorbing Cu in water according to claim 1, characterized in that: In step S04, the product is taken out and soaked in a solution of zinc acetate dihydrate dissolved in water for 1-5 h, and then soaked in a solution of 2-methylimidazole dissolved in water for 1-5 h. One growth cycle is performed, and the freeze-drying time is 20-30 h. The ZIF-8 hydrogel grown once is taken out and the above steps are repeated to obtain ZIF-8 / MoS2-PEI / GO aerogel. The growth cycle is three times in total, and the time of one cycle is 1-10 h.

10. The composite aerogel prepared by the method according to any one of claims 1 to 9.

Images