Aerogel-type MoS2 composite adsorbent, its preparation method and application in wastewater treatment

Abstract

The present invention belongs to the technical field of wastewater treatment, and particularly relates to an aerogel-type MoS2 composite adsorbent, its preparation method and application in wastewater treatment. The adsorbent is obtained by loading flake-shaped MoS2 nanoparticles on a carrier. The carrier is a hydrolyzed polyacrylonitrile porous aerogel crosslinked by heat treatment, and the flake-shaped MoS2 nanoparticles are uniformly dispersed inside and on the surface of the carrier pores. In the present invention, using hydrolyzed polyacrylonitrile as the carrier, a composite fiber membrane of hydrolyzed polyacrylonitrile / molybdenum salt is prepared by electrospinning technology. At 200 °C, molybdenum disulfide nanoparticles are uniformly dispersed in the hydrolyzed polyacrylonitrile porous aerogel by in-situ hydrothermal synthesis and freeze-drying methods to obtain an aerogel-type MoS2 composite adsorbent. The preparation process of the present invention is simple and easy to operate, solves the process problems of difficult dispersion and easy aggregation of nanoscale molybdenum disulfide in practical applications, and has broad application prospects in the field of wastewater treatment.

Description

Technical Field

[0001] The present invention relates to the technical field of wastewater treatment, and specifically to an aerogel-type MoS2 composite adsorbent, its preparation method, and its application in wastewater treatment. Background Art

[0002] With the continuous improvement of the world's industrialization level, a large amount of industrial wastewater is generated every year, which brings serious harm to the ecological environment and human health. Industrial wastewater containing heavy metals, antibiotics, and organic dyes is the key and focus in wastewater treatment.

[0003] Currently, the treatment methods for pollutants in wastewater mainly include chemical precipitation, adsorption, photocatalytic degradation, membrane separation, etc. Adsorption is considered one of the effective methods for sewage treatment due to its low cost, high efficiency, and easy control. Common adsorbents include zeolites, biochars, inorganic and organic polymer materials with adsorption properties, etc. The adsorbents studied so far can only efficiently remove specific pollutants or single types of pollutants, and it is difficult to achieve the simultaneous removal of multiple pollutants, and the operating conditions (such as temperature and pH range) are limited.

[0004] Molybdenum disulfide (MoS2) contains a large amount of sulfur elements, which endows it with high adsorption sites. Its controllable microstructure gives it excellent chemical stability and rapid adsorption ability, and it has great application potential in the fields of environmental protection and wastewater treatment. However, nanoscale molybdenum disulfide is prone to aggregation and has strong hydrophobicity. And MoS2 dispersed in water is prone to deposition due to its high density, increasing the difficulty of recovery. At the same time, there are few oxygen-containing functional groups on the surface of molybdenum disulfide. In the prior art, it is impossible to achieve the simultaneous removal of multiple pollutants using such single-functional materials. The invention patent CN112675805B discloses a method for preparing hydroxyapatite nanowire composite molybdenum disulfide adsorbent with simple process and low cost, but the adsorbent prepared by this method only shows high adsorption performance for Pb 2+ Therefore, there is an urgent need to develop a new type of MoS2 composite adsorbent, endow it with various functional groups on the surface, and achieve the multifunctionality of removing pollutants such as heavy metal ions, antibiotics, and organic dyes to solve the current water pollution problem. At the same time, increasing the specific surface area and porosity of the MoS2 composite adsorbent can not only reduce its density, facilitate repeated recycling; but also greatly improve the efficiency of wastewater treatment and save costs. Summary of the Invention

[0005] (1) Technical Problems to be Solved

[0006] In view of the deficiencies of the prior art, the present invention provides an aerogel-type MoS2 composite adsorbent, its preparation method, and its application in wastewater treatment, and solves the problems raised in the above background art.

[0007] (2) Technical Solution

[0008] The present invention specifically adopts the following technical solutions to achieve the above purposes:

[0009] Aerogel-type MoS2 composite adsorbent, wherein the adsorbent is a carrier loaded with flake-shaped MoS2 nanoparticles; the carrier is a hydrolyzed polyacrylonitrile porous aerogel crosslinked by heat treatment, and flake-shaped MoS2 nanoparticles are uniformly dispersed inside and on the surface of the carrier pores.

[0010] Furthermore, the size of the flake-shaped MoS2 nanoparticles is 20 - 200 nm.

[0011] Furthermore, the density of the adsorbent is 0.001 - 0.03 g / cm 3 , the specific surface area is 40 - 500 m 2 / g, and the internal pore size is 20 - 500 nm.

[0012] A preparation method of an aerogel-type MoS2 composite adsorbent, comprising the following steps:

[0013] S1. First, add a certain amount of polyacrylonitrile powder to a sodium hydroxide solution, place it in an oven and heat for a period of time. After the reaction is completed, centrifuge, wash and dry to obtain partially hydrolyzed polyacrylonitrile powder;

[0014] S2. Then, dissolve the partially hydrolyzed polyacrylonitrile powder and molybdenum salts (including but not limited to sodium molybdate dihydrate, ammonium molybdate tetrahydrate, molybdenum oxide) in N,N-dimethylformamide solution to prepare a homogeneous pale yellow spinning solution, and obtain a hydrolyzed polyacrylonitrile / molybdenum salt blended fiber membrane through electrospinning technology;

[0015] S3. Finally, use a mixed solution obtained by dissolving a sulfur-containing compound (including but not limited to thioacetamide, thiourea, L-cysteine, sodium thiosulfate, sodium dithiocarbonate) in deionized water to soak the hydrolyzed polyacrylonitrile / molybdenum salt blended fiber membrane, then put it into a reaction kettle, react for a period of time by in-situ hydrothermal synthesis method to obtain a sol-like substance, and obtain an aerogel-type MoS2 composite adsorbent after freeze-drying.

[0016] Furthermore, in step S1, the concentration of the sodium hydroxide solution is 1 - 3 mol / L; the mass ratio of polyacrylonitrile added to the volume of the sodium hydroxide solution is 10 - 100 mg / mL; the hydrolysis reaction time is 20 - 40 min, and the hydrolysis reaction temperature is 20 - 50 °C; after the reaction is completed, wash with deionized water until neutral.

[0017] Further, in step S2, the mass ratio of hydrolyzed polyacrylonitrile to molybdenum salt is 1:1; the technical parameters of electrospinning are as follows: the voltage is 12 - 14 KV, the pushing speed is 0.5 - 1.5 ml / h, the distance is 10 - 15 cm, and the electrospinning time is 6 - 10 h.

[0018] Further, in step S3, the mass ratio of the sulfur-containing compound to the molybdenum salt in step S2 is 1.3:1 - 2.3:1; in the in-situ hydrothermal synthesis method, the reaction time is 22 - 26 h, and the reaction temperature is 180 - 220 °C; in the freeze-drying method, the pre-freezing time is 10 - 24 h, and the pre-freezing temperature is -20 - -18 °C; the freeze-drying time is 24 - 48 h, and the freeze-drying temperature is -60 - -40 °C.

[0019] An application of an aerogel-type MoS₂ composite adsorbent in one or several of the fields of wastewater treatment containing heavy metals (such as Cr(VI), Cu 2+ , Pb 2+ , Cd 2+ , Hg 2+ etc.), antibiotics (such as amoxicillin, tetracycline, oxytetracycline, erythromycin, ciprofloxacin, sulfamethoxazole, etc.) and organic dyes (such as rhodamine B, methyl orange, methyl blue, congo red, malachite green, etc.).

[0020] Further, batch adsorption experiments are carried out on the aerogel-type MoS₂ composite adsorbent, and the effects of pH value, contact time, temperature and pollutant concentration (the heavy metal concentration is 20 - 200 mg / L, the antibiotic concentration is 10 - 100 mg / L, and the organic dye concentration is 10 - 80 mg / L) on the adsorption capacity are investigated respectively. The adsorption kinetic model and the isotherm model are used to analyze the experimental data, and further explore the effects of contact time, temperature and pollutant concentration on the adsorption performance of the aerogel-type MoS₂ composite adsorbent.

[0021] Further, each gram of the composite adsorbent can adsorb 360 - 660 mg of heavy metals, 250 - 550 mg of antibiotics and 60 - 260 mg of organic dyes on average.

[0022] Further, after the composite adsorbent is saturated in adsorption, it can be desorbed and regenerated by EDTANa₂ solution.

[0023] (III) Beneficial effects

[0024] Compared with the prior art, the present invention provides an aerogel-type MoS₂ composite adsorbent, its preparation method and its application in wastewater treatment, and has the following beneficial effects:

[0025] The present invention: 1. uses hydrolyzed polyacrylonitrile as a carrier, and by means of hydrothermal synthesis technology, makes the hydrolyzed polyacrylonitrile generate a crosslinked porous structure. At the same time, molybdate dispersed in the carrier grows into flake-like MoS2 nanoparticles in the porous crosslinked framework structure and is stably and uniformly dispersed, avoiding the serious aggregation problem generated in the traditional MoS2 loading and dispersion process; 2. The technical solution of the present invention is that the carrier is a hydrolyzed and crosslinked polyacrylonitrile molecule, which contains various functional groups in its structure. The obtained aerogel-type MoS2 composite adsorbent after loading MoS2 has an ultra-low density and an ultra-high specific surface area, and has high-efficiency removal performance for various pollutants such as heavy metal ions, antibiotics and organic dyes in wastewater, and can rapidly adsorb pollutants in water within 5 to 30 minutes; 3. The crosslinked framework structure generated during the hydrothermal synthesis of the aerogel-type MoS2 composite adsorbent combined with the MoS2 nanoparticles dispersed in the porous framework greatly improves the stability of the composite adsorbent in different wastewater environments (pH value and temperature); through the desorption and regeneration of the adsorbent, the practical application problem of repeated recycling is solved. Description of the Drawings

[0026] Figure 1 XRD diagram of the aerogel-type MoS2 composite adsorbent of Example 1 of the present invention;

[0027] Figure 2 Infrared spectrum curve of the aerogel-type MoS2 composite adsorbent of Example 1 of the present invention;

[0028] Figure 3 SEM and TEM morphology diagrams of the aerogel-type MoS2 composite adsorbent of Example 1 of the present invention;

[0029] Figure 4 Dispersion state of the aerogel-type MoS2 composite adsorbent of Example 1 of the present invention on the water surface and test results of specific surface area and pore size distribution of the aerogel-type MoS2 composite adsorbent;

[0030] Figure 5 Effect of solution pH on the aerogel-type MoS2 composite adsorbent in Examples 5, 8, and 11 of the present invention;

[0031] Figure 6 Kinetic model fitting curves of the aerogel-type MoS2 composite adsorbent for Cr(VI), tetracycline and rhodamine B in Examples 6, 9, and 12 of the present invention;

[0032] Figure 7 Isothermal model fitting curves of the aerogel-type MoS2 composite adsorbent for Cr(VI), tetracycline and rhodamine B in Examples 7, 10, and 13 of the present invention;

[0033] Figure 8Adsorption rates of the aerogel-type MoS₂ composite adsorbent in Example 14 of the present invention for simultaneous adsorption of Cr(VI), tetracycline, and rhodamine B;

[0034] Figure 9 Adsorption rate changes during 20 cycles of the aerogel-type MoS₂ composite adsorbent in Example 15 of the present invention. Specific embodiments

[0035] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0036] Embodiment

[0037] As Figures 1-9 shown, an aerogel-type MoS₂ composite adsorbent and its preparation method and application in wastewater treatment proposed in an embodiment of the present invention, where the adsorbent is a flake-shaped MoS₂ nanoparticle loaded on a carrier; the carrier is a hydrolyzed polyacrylonitrile porous aerogel crosslinked by heat treatment, and flake-shaped MoS₂ nanoparticles are uniformly dispersed inside and on the surface of the carrier pores.

[0038] As Figure 3 shown, in some embodiments, the size of the flake-shaped MoS₂ nanoparticles is 20 - 200 nm.

[0039] As Figure 4 shown, in some embodiments, the density of the adsorbent is 0.001 - 0.03 g / cm 3 , the specific surface area is 40 - 500 m 2 / g, and the internal pore size is 20 - 500 nm.

[0040] A preparation method of an aerogel-type MoS₂ composite adsorbent includes the following steps:

[0041] S1. First, in a sodium hydroxide solution with a concentration of 1 - 3 mol / L, a certain amount of polyacrylonitrile powder is added, and the mass ratio of polyacrylonitrile added to the volume of the sodium hydroxide solution is 10 - 100 mg / mL; it is placed in an oven and heated for a period of time, and after the reaction is completed, it is centrifuged, washed, and dried to obtain partially hydrolyzed polyacrylonitrile powder;

[0042] S2. Then, the partially hydrolyzed polyacrylonitrile powder and molybdate (the mass ratio of hydrolyzed polyacrylonitrile to molybdate is 1:1) are dissolved in N,N-dimethylformamide solution to prepare a uniform light yellow spinning solution, and a hydrolyzed polyacrylonitrile / molybdate blend fiber membrane is obtained through electrospinning technology;

[0043] S3. Finally, a mixed solution obtained by dissolving a sulfur-containing compound (the mass ratio of the sulfur-containing compound to the molybdenum salt in step S2 is 1.3:1 to 2.3:1) in deionized water is used to soak the hydrolyzed polyacrylonitrile / molybdenum salt blend fiber membrane, and then it is placed in a reaction kettle. After reacting for a period of time by the in-situ hydrothermal synthesis method, a sol-like substance is obtained, and an aerogel-type MoS₂ composite adsorbent is obtained after freeze-drying.

[0044] In step S1, the concentration of the sodium hydroxide solution is 1 to 3 mol / L; the mass ratio of the polyacrylonitrile added to the volume of the sodium hydroxide solution is 10 to 100 mg / mL; the hydrolysis reaction time is 20 to 40 min, and the hydrolysis reaction temperature is 20 to 50 °C; after the reaction is completed, it is washed with deionized water until neutral.

[0045] In step S2, the mass ratio of the hydrolyzed polyacrylonitrile to the molybdenum salt is 1:1; the electrospinning technical parameters: the voltage is 12 to 14 KV, the pushing speed is 0.5 to 1.5 ml / h, the distance is 10 to 15 cm, and the electrospinning time is 6 to 10 h.

[0046] In step S3, the mass ratio of the sulfur-containing compound to the molybdenum salt in step S2 is 1.3:1 to 2.3:1; in the in-situ hydrothermal synthesis method, the reaction time is 22 to 26 h, and the reaction temperature is 180 to 220 °C; in the freeze-drying method, the pre-freezing time is 10 to 24 h, and the pre-freezing temperature is -20 to -18 °C; the freeze-drying time is 24 to 48 h, and the freeze-drying temperature is -60 to -40 °C.

[0047] An application of an aerogel-type MoS₂ composite adsorbent in one or more of the fields of wastewater treatment containing heavy metals (Cr(VI), Cu 2+ , Pb 2+ , Cd 2+ , Hg 2+ , etc.), antibiotics (amoxicillin, tetracycline, oxytetracycline, erythromycin, ciprofloxacin, sulfamethoxazole, etc.) and organic dyes (rhodamine B, methyl orange, methyl blue, congo red, malachite green, etc.).

[0048] Batch adsorption experiments are carried out on the aerogel-type MoS₂ composite adsorbent, and the effects of pH value, contact time, temperature and pollutant concentration (the heavy metal concentration is 20 to 200 mg / L, the antibiotic concentration is 10 to 100 mg / L, and the organic dye concentration is 10 to 80 mg / L) on the adsorption capacity are investigated respectively. The adsorption kinetic model and the isotherm model are used to analyze the experimental data, and further explore the effects of contact time, temperature and pollutant concentration on the adsorption performance of the aerogel-type MoS₂ composite adsorbent.

[0049] The composite adsorbent can adsorb 360 - 660 mg of heavy metals, 250 - 550 mg of antibiotics, and 60 - 260 mg of organic dyes per gram on average.

[0050] After the composite adsorbent is saturated with adsorption, it can be desorbed and regenerated with EDTANa2 solution.

[0051] Example 1

[0052] (1) Add polyacrylonitrile powder (10 g) to 2 mol / L sodium hydroxide solution (100 ml), react at 40 °C for 30 min, and after the reaction, centrifuge, wash, and dry to obtain hydrolyzed polyacrylonitrile powder.

[0053] (2) Dissolve 1.06 g of hydrolyzed polyacrylonitrile powder and 1.06 g of sodium molybdate dihydrate in 10 ml of N,N-dimethylformamide solution, stir evenly to prepare a spinning solution; carry out electrospinning on the spinning solution under the conditions of a spinning distance of 15 cm, a voltage of 13 kV, a feeding speed of 1.0 mL / h, and an electrospinning time of 10 h, using aluminum foil as the film receiving substrate to obtain a hydrolyzed polyacrylonitrile / sodium molybdate dihydrate blend fiber membrane.

[0054] (3) Dissolve 1.32 g of thioacetamide in 30 ml of deionized water, then put it into the reaction kettle together with the fiber membrane, react at 200 °C for 24 h; after in-situ hydrothermal synthesis, put the obtained sol into the refrigerator at -20 °C for pre-freezing for 20 h, and then freeze-dry at -60 °C in a freeze dryer for 48 h to obtain an aerogel-type MoS2 composite adsorbent.

[0055] The density of the prepared aerogel-type MoS2 composite adsorbent is 0.018 ± 0.005 g / cm 3 , the specific surface area is 168 ± 5 m 2 / g, the internal pore diameter is 20 ± 2 nm; the average size of the MoS2 particles dispersed in the porous structure is 20 ± 2 nm.

[0056] Example 2

[0057] (1) Add polyacrylonitrile powder (10 g) to 2 mol / L sodium hydroxide solution (100 ml), react at 50 °C for 30 min, and after the reaction, centrifuge, wash, and dry to obtain hydrolyzed polyacrylonitrile powder.

[0058] (2) Dissolve 1.2 g of hydrolyzed polyacrylonitrile powder and 1.2 g of sodium molybdate dihydrate in 10 ml of N,N-dimethylformamide solution, stir evenly to prepare a spinning solution; carry out electrospinning on the spinning solution under the conditions of a spinning distance of 15 cm, a voltage of 13 kV, a feeding speed of 1.0 mL / h, and an electrospinning time of 10 h, using aluminum foil as the film receiving substrate to obtain a hydrolyzed polyacrylonitrile / sodium molybdate dihydrate blend fiber membrane.

[0059] (3) Dissolve 1.56 g of thiourea in 30 ml of deionized water, then put it into a reaction kettle together with the fiber membrane, and react at 200 °C for 24 h; after in-situ hydrothermal synthesis, put the obtained sol into a refrigerator and pre-freeze it at -20 °C for 24 h, and then freeze-dry it at -60 °C in a freeze dryer for 48 h to obtain an aerogel-type MoS₂ composite adsorbent.

[0060] The density of the prepared aerogel-type MoS₂ composite adsorbent is 0.016 ± 0.005 g / cm 3 , and the specific surface area is 149 ± 5 m 2 / g, and the internal pore diameter is 30 ± 2 nm; the average size of the MoS₂ particles dispersed in the porous structure is 40 ± 2 nm.

[0061] Example 3

[0062] (1) Add polyacrylonitrile powder (10 g) to 2 mol / L sodium hydroxide solution (100 ml), react at 50 °C for 30 min, and after the reaction, centrifuge, wash and dry to obtain hydrolyzed polyacrylonitrile powder.

[0063] (2) Dissolve 1.14 g of hydrolyzed polyacrylonitrile powder and 1.14 g of ammonium molybdate tetrahydrate in 10 ml of N,N-dimethylformamide solution and stir evenly to prepare a spinning solution; carry out electrospinning on the spinning solution under the conditions of a spinning distance of 15 cm, a voltage of 13 kV, a propulsion speed of 1.0 mL / h, and an electrospinning time of 10 h, and use aluminum foil as the film receiving substrate to obtain a hydrolyzed polyacrylonitrile / sodium molybdate dihydrate blend fiber membrane.

[0064] (3) Dissolve 1.49 g of thioacetamide in 30 ml of deionized water, then put it into a reaction kettle together with the fiber membrane, and react at 200 °C for 24 h; after in-situ hydrothermal synthesis, put the obtained sol into a refrigerator and pre-freeze it at -20 °C for 24 h, and then freeze-dry it at -60 °C in a freeze dryer for 48 h to obtain an aerogel-type MoS₂ composite adsorbent.

[0065] The density of the prepared aerogel-type MoS₂ composite adsorbent is 0.034 ± 0.005 g / cm 3 , and the specific surface area is 140 ± 5 m 2 / g, and the internal pore diameter is 150 ± 5 nm. The average size of the MoS₂ particles dispersed in the porous structure is 100 ± 2 nm.

[0066] Example 4

[0067] (1) Add polyacrylonitrile powder (10 g) to 2 mol / L sodium hydroxide solution (100 ml), react at 50 °C for 30 min, and after the reaction, centrifuge, wash, and dry to obtain hydrolyzed polyacrylonitrile powder.

[0068] (2) Dissolve 1.2 g of hydrolyzed polyacrylonitrile powder and 1.2 g of sodium molybdate dihydrate in 10 ml of N,N-dimethylformamide solution, stir evenly to prepare a spinning solution; perform electrospinning on the spinning solution under the conditions of a spinning distance of 15 cm, a voltage of 13 kV, a propulsion speed of 1.0 mL / h, and an electrospinning time of 10 h, using aluminum foil as the film receiving substrate to obtain a hydrolyzed polyacrylonitrile / sodium molybdate dihydrate blend fiber membrane.

[0069] (3) Dissolve 1.56 g of thioacetamide in 30 ml of deionized water, then put it into a reaction kettle together with the fiber membrane, and react at 220 °C for 20 h; after in-situ hydrothermal synthesis, put the obtained sol into a refrigerator at -20 °C for pre-freezing for 24 h, and then freeze-dry at -60 °C in a freeze dryer for 48 h to obtain an aerogel-type MoS₂ composite adsorbent.

[0070] The density of the prepared aerogel-type MoS₂ composite adsorbent is 0.034 ± 0.005 g / cm 3 , and the specific surface area is 155 ± 5 m 2 / g, and the internal pore diameter is 100 ± 2 nm; the average size of MoS₂ particles dispersed in the porous structure is 80 ± 2 nm.

[0071] As Figure 1 shown, in the X-ray diffraction pattern of the prepared aerogel-type MoS₂ composite adsorbent, it can be observed that the positions of the crystal plane peaks of MoS₂ at (002), (100), (103), and (110) are unchanged compared with those of MoS₂ nanoparticles, indicating that the crystal structure of MoS₂ loaded in the cross-linked porous framework structure has not changed; at the same time Figure 2 the infrared spectrum curve of the aerogel-type MoS₂ composite adsorbent, at 603 cm -1 is the Mo-S bond of MoS₂, which all prove that MoS₂ is successfully loaded; at 1607 cm -1 and 1393 cm -1 the absorption peaks respectively belong to the amide group and carboxylic acid group of hydrolyzed polyacrylonitrile, which proves that the surface of the aerogel-type MoS₂ composite adsorbent contains rich active functional groups; as Figure 3 shown, the SEM and TEM images prove that flake-like MoS₂ is uniformly dispersed and loaded in the cross-linked porous structure; as Figure 4 shown, the prepared aerogel-type MoS₂ composite adsorbent floats on the water surface due to its low density, and the specific surface area of the aerogel-type MoS₂ composite adsorbent is 121 m 2 / g, and the pore size distribution is concentrated at 20 nm.

[0072] Effect of solution pH value on the adsorption of heavy metal ion Cr(VI) by aerogel-type MoS2 composite adsorbent in Example 5

[0073] In a 60 ml Cr(VI) solution with a Cr(VI) concentration of 200 mg / L, 30 mg of aerogel-type MoS2 composite adsorbent, an oscillation rate of 200 r / min, a temperature of 25 °C, and an adsorption time of 12 h, the curve of the effect of solution pH value on the adsorption of Cr(VI) by aerogel-type MoS2 composite adsorbent is shown in Figure 5 . It can be seen from the figure that the aerogel-type MoS2 composite adsorbent can achieve a removal rate of higher than 95% for Cr(VI) within a wide pH value range (2 - 10) and an adsorption time of 5 - 30 min.

[0074] Effect of adsorption time on the adsorption of heavy metal ion Cr(VI) by aerogel-type MoS2 composite adsorbent in Example 6

[0075] In a 60 ml Cr(VI) solution with a Cr(VI) concentration of 400 mg / L, 30 mg of aerogel-type MoS2 composite adsorbent, an oscillation rate of 200 r / min, and a temperature of 25 °C, in order to better explore the effect of the aerogel-type MoS2 composite adsorbent on the adsorption of Cr(VI), the pseudo-first-order kinetic model and the pseudo-second-order kinetic model were used to analyze the experimental data. As Figure 6 shown, compared with the pseudo-first-order kinetic model, the adsorption of Cr(VI) by the aerogel-type MoS2 composite adsorbent is more in line with the pseudo-second-order kinetic model (R2 > 0.99), indicating that the adsorption process of Cr(VI) is controlled by chemical adsorption active sites; as Figure 4 can be seen, the aerogel-type MoS2 composite adsorbent has a relatively fast adsorption rate, and the adsorption amount of Cr(VI) is more than 90% of the equilibrium adsorption amount at 50 min.

[0076] Effect of initial concentration on the adsorption of heavy metal ion Cr(VI) by aerogel-type MoS2 composite adsorbent in Example 7

[0077] In a 60 ml Cr(VI) solution, 30 mg of aerogel-type MoS2 composite adsorbent, an oscillation rate of 200 r / min, and temperatures of 25 °C, 35 °C, and 45 °C respectively. In order to further explore the effect of pollutant concentration on the mass adsorption of Cr(VI) by the aerogel-type MoS2 composite adsorbent, three commonly used isotherm models, namely the Langmuir, Freundlich, and Temkin isotherm models, were studied. The fitting curves are shown in Figure 7 , the R of the Freundlich isotherm model 2R higher than the Langmuir and Temkin isotherm models 2 , indicating that the adsorption of the aerogel-type MoS₂ composite adsorbent is more suitable for the Freundlich isotherm model. As can be seen from the figure, when the initial concentration of Cr(VI) is 400 mg / L, the maximum adsorption capacity of the aerogel-type MoS₂ composite adsorbent for Cr(VI) is 655.31 mg / g.

[0078] Example 8 Effect of solution pH on the adsorption of tetracycline (antibiotic) by the aerogel-type MoS₂ composite adsorbent

[0079] In a 60 ml tetracycline solution with a tetracycline concentration of 100 mg / L, 30 mg of the aerogel-type MoS₂ composite adsorbent, an oscillation rate of 200 r / min, a temperature of 25 °C, and an adsorption time of 12 h, the curve of the effect of solution pH on the adsorption of tetracycline by the aerogel-type MoS₂ composite adsorbent is shown in Figure 5 . As can be seen from the figure, within a wide pH range (2 - 10) and an adsorption time within 5 - 30 min, the aerogel-type MoS₂ composite adsorbent achieves a removal rate of more than 90% for tetracycline.

[0080] Example 9 Effect of adsorption time on the adsorption of tetracycline (antibiotic) by the aerogel-type MoS₂ composite adsorbent

[0081] In a 60 ml tetracycline solution with a tetracycline concentration of 300 mg / L, 30 mg of the aerogel-type MoS₂ composite adsorbent, an oscillation rate of 200 r / min, and a temperature of 25 °C, to better explore the effect of the aerogel-type MoS₂ composite adsorbent on the adsorption of tetracycline, the pseudo-first-order kinetic model and the pseudo-second-order kinetic model were used to analyze the experimental data. As Figure 6 shown, compared with the pseudo-first-order kinetic model, the adsorption of tetracycline by the gel-type MoS₂ composite adsorbent is more in line with the pseudo-second-order kinetic model (R 2 > 0.99), indicating that the adsorption process of tetracycline is controlled by chemical adsorption active sites; as Figure 6 can be seen, the aerogel-type MoS₂ composite adsorbent has a relatively fast adsorption rate, and the adsorption amount of tetracycline reaches more than 90% of the equilibrium adsorption amount at 50 min.

[0082] Example 10 Effect of initial concentration on the adsorption of tetracycline (antibiotic) by the aerogel-type MoS₂ composite adsorbent

[0083] In a tetracycline solution with a volume of 60 ml, the mass of the aerogel-type MoS2 composite adsorbent is 30 mg, the oscillation rate is 200 r / min, and the temperatures are 25 °C, 35 °C, and 45 °C respectively. To further explore the effect of pollutant concentration on the mass adsorption of tetracycline by the aerogel-type MoS2 composite adsorbent, three commonly used isotherm models, namely the Langmuir, Freundlich, and Temkin isotherm models, were studied. The fitting curves are shown in Figure 7 , the R of the Freundlich isotherm model 2 is higher than the R of the Langmuir and Temkin isotherm models 2 , indicating that the adsorption of the aerogel-type MoS2 composite adsorbent is more suitable for the Freundlich isotherm model. As can be seen from the figure, when the initial concentration of tetracycline is 300 mg / L, the maximum adsorption capacity of the aerogel-type MoS2 composite adsorbent for tetracycline is 540.37 mg / g.

[0084] Example 11 Effect of solution pH on the adsorption of Rhodamine B (organic dye) by the aerogel-type MoS2 composite adsorbent

[0085] In a Rhodamine B solution with a volume of 60 ml, the concentration of Rhodamine B is 40 mg / L, the mass of the aerogel-type MoS2 composite adsorbent is 30 mg, the oscillation rate is 200 r / min, the temperature is 25 °C, and the adsorption time is 12 h. The influence curve of the solution pH value on the adsorption of Rhodamine B by the aerogel-type MoS2 composite adsorbent is shown in Figure 5 , as can be seen from the figure, the aerogel-type MoS2 composite adsorbent can achieve a removal rate of more than 97% for Rhodamine B within a wide pH range (2 - 10) and an adsorption time within 5 - 30 min.

[0086] Example 12 Effect of adsorption time on the adsorption of Rhodamine B (organic dye) by the aerogel-type MoS2 composite adsorbent

[0087] In a Rhodamine B solution with a volume of 60 ml, the concentration of Rhodamine B is 150 mg / L, the mass of the aerogel-type MoS2 composite adsorbent is 30 mg, the oscillation rate is 200 r / min, and the temperature is 25 °C. To better explore the effect of the aerogel-type MoS2 composite adsorbent on the adsorption of Rhodamine B, the pseudo-first-order kinetic model and the pseudo-second-order kinetic model were used to analyze the experimental data. As Figure 6 shown, compared with the pseudo-first-order kinetic model, the adsorption of Rhodamine B by the gel-type MoS2 composite adsorbent is more in line with the pseudo-second-order kinetic model (R 2 > 0.99), indicating that the adsorption process of Rhodamine B is controlled by chemical adsorption active sites. As Figure 6 can be seen, the adsorption rate of the aerogel-type MoS2 composite adsorbent is relatively fast, and the adsorption amount of Rhodamine B has reached more than 90% of the equilibrium adsorption amount at 20 min.

[0088] Example 13 Influence of Initial Concentration on the Adsorption of Rhodamine B (Organic Dye) by Aerogel-Type MoS2 Composite Adsorbent

[0089] With the volume of Rhodamine B solution being 60 ml, the mass of the aerogel-type MoS2 composite adsorbent being 30 mg, the oscillation rate being 200 r / min, and the temperatures being 25 °C, 35 °C, and 45 °C respectively, to further explore the influence of pollutant concentration on the mass adsorption of Rhodamine B by the aerogel-type MoS2 composite adsorbent, three commonly used isotherm models, namely the Langmuir, Freundlich, and Temkin isotherm models, were studied. The fitting curves are shown in Figure 7 , the R of the Freundlich isotherm model 2 is higher than the R of the Langmuir and Temkin isotherm models 2 , indicating that the adsorption of the aerogel-type MoS2 composite adsorbent is more suitable for the Freundlich isotherm model. As can be seen from the figure, when the initial concentration of Rhodamine B is 150 mg / L, the maximum adsorption capacity of the aerogel-type MoS2 composite adsorbent for Rhodamine B is 253.11 mg / g.

[0090] Example 14 Adsorption Performance of Aerogel-Type MoS2 Composite Adsorbent for Multiple Pollutants Coexisting in Wastewater

[0091] In a mixed solution with a volume of 60 ml (where the concentration of Cr(VI) is 200 mg / L, the concentration of tetracycline is 100 mg / L, and the concentration of Rhodamine B is 80 mg / L), the mass of the aerogel-type MoS2 composite adsorbent is 30 mg, the oscillation rate is 200 r / min, and the temperature is 25 °C. The influence curve of multiple pollutants coexisting on the aerogel-type MoS2 composite adsorbent is shown in Figure 8 , as can be seen from the figure, the removal efficiencies of the aerogel-type MoS2 composite adsorbent for Cr(VI), tetracycline, and Rhodamine B are 94.93%, 97.45%, and 99.46% respectively.

[0092] Example 15 Desorption and Reuse of Aerogel-Type MoS2 Composite Adsorbent:

[0093] Take three portions of 30 mg of the aerogel-type MoS2 composite adsorbent and add them to 60 ml of solutions containing 200 mg / L of Cr(VI), 100 mg / L of tetracycline, and 80 mg / L of Rhodamine B respectively. After adsorption equilibrium, desorption is carried out by oscillating with 0.5 mol / L EDTA Na2 solution for 5 hours. This process is one cycle, and a total of 20 cycles are carried out; the cycle results are shown in Figure 9 , as can be seen from the figure, after 20 cycles, the adsorption rate still remains above 80%, and no obvious decline is observed.

[0094] In summary, due to the presence of a large number of cross-linked porous framework structures and rich oxygen-containing and functional groups in the aerogel-type MoS2 composite adsorbent prepared by the present invention, it can efficiently adsorb and remove one or several of various pollutants such as heavy metal ions, antibiotics, and organic dyes in wastewater within a wide pH range; the proposed method will have broad application prospects in the treatment fields of industrial wastewater such as paint, ink, leather, and textile industries.

[0095] Finally, it should be noted that the above are only the preferred embodiments of the present invention and are not used to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, for those skilled in the art, they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements for some of the technical features. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. Aerogel-type MoS2 composite adsorbent, characterized in that: The adsorbent is obtained by loading flake-shaped MoS2 nanoparticles on a carrier; the carrier is a hydrolyzed polyacrylonitrile porous aerogel crosslinked by heat treatment, and the flake-shaped MoS2 nanoparticles are uniformly dispersed inside and on the surface of the carrier pores. The size of the flake-shaped MoS2 nanoparticles is 20-200 nm, and the density of the adsorbent is 0.001-0.03 g / cm 3 , and the specific surface area is 40-500 m 2 / g. The internal pore size is 20-500 nm. The preparation method of the aerogel-type MoS2 composite adsorbent includes the following steps: S1. First, add a certain amount of polyacrylonitrile powder to the sodium hydroxide solution, put it in an oven and heat for a period of time. After the reaction is completed, centrifuge, wash and dry to obtain partially hydrolyzed polyacrylonitrile powder; S2. Then, dissolve the partially hydrolyzed polyacrylonitrile powder and molybdenum salt in N, N-dimethylformamide solution to prepare a homogeneous pale yellow spinning solution, and obtain a fiber membrane of hydrolyzed polyacrylonitrile / molybdenum salt blend through electrospinning technology; S3. Finally, use the mixed solution obtained by dissolving the sulfur-containing compound in deionized water to soak the hydrolyzed polyacrylonitrile / molybdenum salt blend fiber membrane, then put it into a reaction kettle, and react for a period of time by in-situ hydrothermal synthesis method to obtain a sol-like substance, and obtain an aerogel-type MoS2 composite adsorbent after freeze-drying.

2. The aerogel-type MoS2 composite adsorbent according to claim 1, wherein: In step S1, the concentration of the sodium hydroxide solution is 1-3 mol / L; the mass ratio of the added polyacrylonitrile to the volume of the sodium hydroxide solution is 10-100 mg / mL; the hydrolysis reaction time is 20-40 min, and the hydrolysis reaction temperature is 20-50 °C; after the reaction is completed, wash with deionized water until neutral.

3. The aerogel-type MoS2 composite adsorbent according to claim 1, characterized in that: In step S2, the mass ratio of the hydrolyzed polyacrylonitrile to the molybdenum salt is 1:1; the electrospinning technology parameters: the voltage is 12-14 KV, the pushing speed is 0.5-1.5 mL / h, the distance is 10-15 cm, and the electrospinning time is 6-10 h.

4. The aerogel-type MoS2 composite adsorbent according to claim 1, characterized in that: In step S3, the mass ratio of the sulfur-containing compound to the molybdenum salt in step S2 is 1.3:1-2.3:1; the reaction time in the in-situ hydrothermal synthesis method is 22-26 h, and the reaction temperature is 180-220 °C; in the freeze-drying method, the pre-freezing time is 10-24 h, and the pre-freezing temperature is -20- -18 °C; the freeze-drying time is 24-48 h, and the freeze-drying temperature is -60- -40 °C.

5. Use of an aerogel-type MoS2 composite adsorbent according to claim 1 in one or more of the fields of wastewater treatment containing heavy metals, antibiotics and organic dyes; Perform a batch adsorption experiment on the aerogel-type MoS2 composite adsorbent, respectively investigate the effects of pH value, contact time, temperature and pollutant concentration on the adsorption capacity, analyze the experimental data using adsorption kinetic models and isotherm models, and further explore the effects of contact time, temperature and pollutant concentration on the adsorption performance of the aerogel-type MoS2 composite adsorbent. The composite adsorbent can adsorb 360-660 mg of heavy metals, 250-550 mg of antibiotics and 60-260 mg of organic dyes per gram on average. After the composite adsorbent is saturated with adsorption, it is desorbed and regenerated with EDTANa2 solution.

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