A transition metal sulfide adsorbent, its preparation method and application

Abstract

The present invention relates to the technical field of adsorbent materials, and particularly relates to a transition metal sulfide adsorbent, a preparation method thereof, and an application thereof. The transition metal sulfide adsorbent uses Mo-MOF as a template, and thiourea and Mo-MOF are calcined at a mass ratio of 3-4:1. The transition metal sulfide adsorbent is prepared by using a high-temperature template pyrolysis method. The present invention uses the MOF template high-temperature pyrolysis method to create active centers with both adsorption and reduction at the reaction interface of the adsorption material. The prepared MOF template-derived transition metal sulfide adsorption material can achieve efficient selective removal and resource recovery of Ag + in water bodies, which is of great significance for ensuring water environment safety and maintaining the development of the green and low-carbon circular economy of silver resources. It provides a prototype new technology that integrates selective adsorption and heavy metal elementalization for the low-carbonization technology of wastewater heavy metals.

Description

Technical Field

[0001] The present invention relates to the technical field of adsorbent materials, and particularly relates to a transition metal sulfide adsorbent, a preparation method thereof, and an application thereof. Background Art

[0002] As an important precious metal, silver has a wide range of applications in the fields of medicine, electronics, chemical engineering, etc. The latest data from the World Silver Association shows that the global silver demand has increased by 16% year-on-year, and the silver gap is as high as 194 million ounces. However, limited mines lead to a shortage in the supply of silver resources, and annually about 10% of the raw materials of silver-containing wastewater inevitably enters the water environment. If this silver-containing wastewater is not treated, on the one hand, it will cause environmental pollution, and on the other hand, it will also lead to a huge waste of silver resources. Therefore, the recovery of silver resources is crucial for maintaining the integrity of the future supply chain and reducing environmental pollution.

[0003] Methods for the removal and recovery of silver in water bodies include cyanide solution or nitric acid extraction, ion exchange, reverse osmosis, and adsorption. However, these methods will cause further environmental problems, such as the use of a large number of chemical reagents, the generation of waste acid solutions and toxic fumes. Some studies have considered the conversion of Ag + into insoluble precipitates, such as AgCl or Ag2SO4, but the process of reducing AgCl or Ag2SO4 to silver metal is complex, involving high carbon emissions and high energy consumption. In contrast, the adsorption method is considered a competitive technical means for Ag + removal due to its low cost, simple operation, high efficiency, and environmental friendliness.

[0004] Currently reported adsorbents such as activated carbon, fly ash, expanded perlite, biosorbents, electrospinning, etc. have been used for the removal of Ag + in water bodies. However, these traditional adsorbents often have the disadvantages of low adsorption capacity, poor reusability and stability. In addition, the adsorption materials prepared by existing methods usually need to be eluted and regenerated and then reduced after the adsorption of Ag + is completed, and the whole process is cumbersome and complex and generates a large amount of toxic acid-base waste liquid. Summary of the Invention

[0005] Aiming at the above deficiencies of the existing technology, the purpose of the present invention is to provide a transition metal sulfide adsorbent, a preparation method thereof, and an application thereof. The transition metal sulfide adsorbent of the present invention uses Mo-MOF as a template, and a transition metal sulfide adsorbent is prepared by mixing thiourea and Mo-MOF and using a high-temperature template cracking method.

[0006] To solve the above technical problems, the present invention adopts the following technical solutions:

[0007] A preparation method of a transition metal sulfide adsorbent, comprising the following steps:

[0008] Synthesize the Mo-MOF template using the hydrothermal method.

[0009] Under a protective atmosphere, place thiourea and the Mo-MOF template on one side and the center of the heat source of a tubular furnace respectively according to a mass ratio of 3 - 4:1, heat, and obtain a transition metal sulfide adsorbent through high-temperature template pyrolysis.

[0010] The present invention uses a molybdenum-based metal-organic framework as a template, calcines it with thiourea, and creates active centers with both adsorption and reduction functions at the reaction interface of the adsorption material by means of high-temperature pyrolysis. The prepared transition metal sulfide adsorption material derived from the molybdenum-based metal-organic framework template can achieve efficient and selective removal of Ag + in water. The present invention can inherit the large specific surface area and rich pores of the original molybdenum-based metal-organic framework through the template method, which is beneficial for providing sufficient sites and transport channels; through high-temperature calcination, unstable coordination structures can be calcined away to form a stable framework, and the H2S decomposed from thiourea at high temperature can react with Mo 4+ on the molybdenum-based metal-organic framework to form molybdenum sulfide, and the S atoms can react with Ag + to form Ag2S, and S can reduce Ag + , and at the same time, the potential of Ag + is higher than that of Mo 4+ , and Ag + can oxidize Mo 4+ as a weak oxidant, reducing Ag + to elemental Ag 0 . Therefore, the transition metal sulfide adsorbent of the present invention has excellent adsorption selectivity for Ag + .

[0011] In a preferred embodiment of the present invention, the heating temperature is 1000 °C - 1200 °C, and the calcination time is 1 hour - 1.2 hours.

[0012] In a preferred embodiment of the present invention, the preparation method of the Mo-MOF template includes the following steps:

[0013] Dissolve the molybdenum source in water to form a uniformly dispersed solution.

[0014] Add imidazole to the uniformly dispersed solution, heat and react, and obtain the Mo-MOF template through post-treatment.

[0015] In a preferred embodiment of the present invention, the mass ratio of the molybdenum source to the volume of water is 4 g:0.1 L - 0.3 L.

[0016] In a preferred embodiment of the present invention, the mass ratio of imidazole to the molybdenum source is 4:1 - 2.

[0017] In a preferred embodiment of the present invention, the heating reaction temperature is 100°C to 200°C, and the heating reaction time is 12 h to 72 h.

[0018] The second object of the present invention is to provide a transition metal sulfide adsorbent prepared by the preparation method described in any one of the above.

[0019] In a preferred embodiment of the present invention, the transition metal sulfide adsorbent has a nanorod structure, with a length of 10 μm to 20 μm and a diameter of 1 μm to 2 μm.

[0020] The third object of the present invention is to provide an application of the above-mentioned transition metal sulfide adsorbent in the targeted adsorption of silver in silver-containing wastewater.

[0021] In a preferred embodiment of the present invention, the concentration of the silver-containing wastewater is 50 mg / L to 2000 mg / L, and the dosage ratio of the transition metal molybdenum sulfide adsorbent to the silver-containing wastewater is 1 mg: 2 mL to 4 mL.

[0022] Compared with the prior art, the beneficial effects of the present invention are:

[0023] 1. The present invention uses a molybdenum-based metal-organic framework as a template and calcines it with thiourea. By using the high-temperature pyrolysis method, active centers with both adsorption and reduction properties are created at the reaction interface of the adsorption material. The prepared transition metal sulfide adsorption material derived from the molybdenum-based metal-organic framework template can achieve efficient and selective removal of Ag + in water. Through the template method, the present invention can inherit the large specific surface area and rich pores of the original molybdenum-based metal-organic framework, which is beneficial to providing sufficient sites and transport channels; through high-temperature calcination, unstable coordination structures can be calcined away to form a stable framework. The H2S decomposed from thiourea at high temperature can react with Mo 4+ on the molybdenum-based metal-organic framework to form molybdenum sulfide. The S atom can react with Ag + to form Ag2S, and S can reduce Ag + . At the same time, the potential of Ag + is higher than that of Mo 4+ . As a weak oxidant, Ag + can oxidize Mo 4+ , and reduce Ag + to elemental Ag 0 . Therefore, the transition metal sulfide adsorbent of the present invention has excellent adsorption selectivity for Ag + .

[0024] 2. The present invention uses Mo-MOF as a template to construct a derived transition metal sulfide adsorption material, thereby providing a construction of a porous adsorption material with both selective and reductive adsorption sites integrated for Ag +The resource utilization of [substance] is of great significance for ensuring the safety of water environment and maintaining the development of the green and low-carbon circular economy of silver resources, and provides a new prototype technology integrating selective adsorption and heavy metal elementalization for low-carbon wastewater heavy metal technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a process diagram for the preparation of the present invention.

[0026] Figure 2 It is a morphology diagram of the transition metal sulfide adsorbent materials prepared in Example 1 - Example 2 and Comparative Example 1 - Comparative Example 3 of the present invention.

[0027] Figure 3 It is a diagram of the adsorption capacity results of the transition metal sulfide adsorbent materials prepared in Example 1 and Example 3 of the present invention and Comparative Example 4 and Comparative Example 5 at different ratios of thiourea to Mo-MOF.

[0028] Figure 4 It is a diagram of the adsorption capacity results of the transition metal sulfide adsorbent materials prepared in Example 1 and Example 2 and Comparative Example 1 - Comparative Example 3 of the present invention at different calcination temperatures.

[0029] Figure 5 It is the affinity diagram of the transition metal sulfide adsorbent prepared in Example 1 of the present invention for Ag in the presence of coexisting ions + DETAILED DESCRIPTION OF THE INVENTION

[0030] The following combines the embodiments of the present invention, and uses preferred embodiments and accompanying drawings for detailed description. The technical solutions in the embodiments of the present invention are clearly and completely described. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the scope of protection of the present invention.

[0031] It should be noted that all the professional terms used in the present invention are only for the purpose of describing specific embodiments, and are not intended to limit the protection scope of the present invention. Unless otherwise specifically stated, various raw materials, reagents, instruments and equipment used in the following embodiments of the present invention can be obtained through market purchase or prepared by existing methods.

[0032] Metal-organic frameworks and transition metal sulfides, as representatives of porous materials, for Ag in water + ​It shows outstanding application prospects in removal. Metal-organic frameworks are an emerging class of porous crystalline solids, in which metal ions or metal clusters are combined with organic ligands through organic linkers, and have high porosity and open nodes. However, the coordination bonds between metal active centers and organic ligands in metal-organic framework adsorbents are often fragile, which makes the metal-organic framework unstable in water, resulting in structural collapse and thus site failure, reducing its adsorption performance. Transition metal sulfides are endowed with high interfacial reaction activity due to the size homogenization effect. However, transition metal sulfides are easy to agglomerate in water, resulting in limited exposed sites or insufficient site utilization. Therefore, the present invention provides a transition metal sulfide adsorbent, wherein the transition metal sulfide uses Mo-MOF as a template, calcines thiourea and Mo-MOF in a mass ratio of 3 to 4:1, and prepares the transition metal sulfide adsorbent by a high-temperature template pyrolysis method. The preparation process is as follows: Figure 1 As shown in the figure, active centers with both adsorption and reduction properties are created at the reaction interface of the adsorbent material. The prepared MOF template-derived transition metal sulfide adsorbent material can achieve the adsorption of Ag in water. + The present invention can inherit the large specific area and abundant pores of the original Mo-MOF through the template method, which is conducive to providing sufficient sites and transmission channels; high-temperature calcination can calcine the unstable coordination structure to form a stable framework, and the H2S decomposed by thiourea at high temperature can react with the Mo on the Mo-MOF. 4+ To form molybdenum sulfide, S atoms can react with Ag + The formation of Ag2S, and S can reduce Ag + ; At the same time Ag + The potential is higher than Mo 4+ , Ag + As a weak oxidant, it can oxidize Mo 4+ , Ag + Reduction to elemental Ag 0 Therefore, the transition metal sulfide adsorbent of the present invention has a great influence on Ag + It has excellent adsorption selectivity.

[0033] Example 1

[0034] A method for preparing a transition metal sulfide adsorbent comprises the following steps:

[0035] (1) Weigh 0.8 g of molybdenum trioxide and dissolve it in a single-necked flask containing 60 mL of deionized water and 100 mL of solvent, and stir it ultrasonically for 10 min to form a uniformly dispersed solution.

[0036] (2) Add 0.2 g of imidazole to the uniformly dispersed solution until fully mixed, and then continue ultrasonic stirring for 10 minutes.

[0037] (3) Put a polytetrafluoroethylene magnetic stir bar on the three-necked flask, transfer the single-necked flask containing the mixture to a constant-temperature oil bath for heating reaction. The oil bath temperature is kept constant at 120 °C, condensing water is introduced for condensation reflux, the reaction time is 24 h, and the mechanical stirring speed is controlled at 300 rmp / min.

[0038] (4) After the reaction is completed, cool the single-necked flask at room temperature, filter the white precipitate in the single-necked flask, wash the precipitate three times with deionized water and three times with ethanol, and finally dry the white solid in a vacuum drying oven at 80 °C for 24 h. The white powder obtained by grinding is Mo-MOF.

[0039] (5) Transfer thiourea to the porcelain boat labeled No. 1 and weigh the Mo-MOF and thiourea in the porcelain boats labeled No. 1 and No. 2 according to a mass ratio of 3:1. At the same time, the two raw materials need to be evenly spread out in their respective magnetic boats.

[0040] (6) Place the porcelain boat labeled No. 1 on the upstream side of the tubular furnace hearth, that is, the side of the argon inlet, and place the porcelain boat labeled No. 2 at the heat source center of the tubular furnace. The two porcelain boats are adjacent to each other. Before heating the tubular furnace, first introduce argon for 1 h to remove the oxygen in the tubular furnace. After removing the oxygen in the tubular furnace, set the temperature of the tubular furnace to 1000 °C and perform programmed heating at a rate of 5 °C / min. Heat the tubular furnace under Ar gas protection and keep high-temperature calcination for 1 h. -1

[0041] (7) Stop the reaction. After natural cooling to room temperature, grind and collect the black product after the reaction to obtain a transition metal sulfide adsorbent, named MS-1000.

[0042] Example 2

[0043] A preparation method of a transition metal sulfide adsorbent, comprising the following steps:

[0044] (1) Weigh 0.8 g of molybdenum trioxide and dissolve it in a 100 mL solvent single-necked flask containing 60 mL of deionized water, and perform ultrasonic stirring for 10 min to form a uniformly dispersed solution.

[0045] (2) Add 0.2 g of imidazole to the uniformly dispersed solution, and continuously perform ultrasonic stirring for 10 min after sufficient mixing.

[0046] (3) Put a polytetrafluoroethylene magnetic stir bar on the three-necked flask, transfer the single-necked flask containing the mixture to a constant-temperature oil bath for heating reaction. The oil bath temperature is kept constant at 120 °C, condensing water is introduced for condensation reflux, the reaction time is 24 h, and the mechanical stirring speed is controlled at 300 rmp / min.

[0047] (4) After the reaction is completed, the single-necked flask is cooled at room temperature, the white precipitate in the single-necked flask is filtered, and the precipitate is washed three times with deionized water and three times with ethanol. Finally, the white solid is dried in a vacuum drying oven at 80° C. for 24 h. The white powder obtained by grinding is Mo-MOF.

[0048] (5) The thiourea is transferred to the porcelain boat marked as No. 1 and the Mo-MOF is weighed in the porcelain boats marked as No. 1 and No. 2 respectively in a mass ratio of 3:1. At the same time, the two raw materials need to be evenly spread in their respective magnetic boats.

[0049] (6) Place the porcelain boat marked as No. 1 on the upstream side of the tube furnace, that is, on the side of the argon inlet, and place the porcelain boat marked as No. 2 at the heat source center of the tube furnace. The two porcelain boats are adjacent to each other. Before heating the tube furnace, first pass argon gas for 1 hour to remove the oxygen in the tube furnace. After removing the oxygen in the tube furnace, set the temperature of the tube furnace to 1200℃ and heat it at 5℃min. -1 The temperature was programmed to rise at a rate of , and the tube furnace was heated under Ar gas protection, and the high temperature calcination was continued for 1 h.

[0050] (7) Stop the reaction, wait for the mixture to cool naturally to room temperature, grind and collect the black product after the reaction to obtain a transition metal sulfide adsorbent, named MS-1200.

[0051] Example 3

[0052] A method for preparing a transition metal sulfide adsorbent comprises the following steps:

[0053] (1) Weigh 0.89 g of molybdenum trioxide and dissolve it in a single-necked flask containing 60 mL of deionized water and 100 mL of solvent, and stir ultrasonically for 10 min to form a uniformly dispersed solution.

[0054] (2) Add 0.2 g of imidazole to the uniformly dispersed solution until fully mixed, and then continue ultrasonic stirring for 10 minutes.

[0055] (3) A polytetrafluoroethylene magnetic stirring bar was placed on the three-necked flask, and the single-necked flask containing the mixture was transferred to a constant temperature oil bath for heating reaction. The oil bath temperature was controlled at 120°C, and condensed water was introduced for condensation reflux. The reaction time was 24 h, and the mechanical stirring speed was controlled at 300 rpm.

[0056] (4) After the reaction is completed, the single-necked flask is cooled at room temperature, the white precipitate in the single-necked flask is filtered, and the precipitate is washed three times with deionized water and three times with ethanol. Finally, the white solid is dried in a vacuum drying oven at 80° C. for 24 h. The white powder obtained by grinding is Mo-MOF.

[0057] (5) The thiourea is transferred to the porcelain boat marked as No. 1 and the Mo-MOF is weighed in the porcelain boats marked as No. 1 and No. 2 respectively in a mass ratio of 4:1. At the same time, the two raw materials need to be evenly spread in their respective magnetic boats.

[0058] (6) Place the porcelain boat marked as No. 1 on the upstream side of the tube furnace, that is, on the side of the argon inlet, and place the porcelain boat marked as No. 2 at the heat source center of the tube furnace. The two porcelain boats are adjacent to each other. Before heating the tube furnace, first pass argon gas for 1 hour to remove the oxygen in the tube furnace. After removing the oxygen in the tube furnace, set the temperature of the tube furnace to 1000℃ and heat it at 5℃min. -1 The temperature was programmed to rise at a rate of , and the tube furnace was heated under Ar gas protection, and the high temperature calcination was continued for 1 h.

[0059] (7) Stop the reaction, wait for the mixture to cool naturally to room temperature, and grind and collect the black product after the reaction to obtain a transition metal sulfide adsorbent.

[0060] Example 4

[0061] A method for preparing a transition metal sulfide adsorbent comprises the following steps:

[0062] (1) Weigh 0.8 g of molybdenum trioxide and dissolve it in a single-necked flask containing 20 mL of deionized water and 100 mL of solvent, and stir it ultrasonically for 10 min to form a uniformly dispersed solution.

[0063] (2) Add 0.4 g of imidazole to the uniformly dispersed solution until fully mixed, and then continue ultrasonic stirring for 10 minutes.

[0064] (3) A polytetrafluoroethylene magnetic stirring bar was placed on the three-necked flask, and the single-necked flask containing the mixture was transferred to a constant temperature oil bath for heating reaction. The oil bath temperature was controlled at 100°C, and condensed water was introduced for condensation reflux. The reaction time was 72 h, and the mechanical stirring speed was controlled at 300 rpm.

[0065] (4) After the reaction is completed, the single-necked flask is cooled at room temperature, the white precipitate in the single-necked flask is filtered, and the precipitate is washed three times with deionized water and three times with ethanol. Finally, the white solid is dried in a vacuum drying oven at 80° C. for 24 h. The white powder obtained by grinding is Mo-MOF.

[0066] (5) The thiourea is transferred to a porcelain boat labeled No. 1 and the Mo-MOF is weighed in porcelain boats labeled No. 1 and No. 2, respectively, at a mass ratio of 3:1. The two raw materials need to be evenly spread in their respective magnetic boats.

[0067] (6) Place the porcelain boat marked as No. 1 on the upstream side of the tubular furnace, that is, the side of the argon inlet, and place the porcelain boat marked as No. 2 at the heat source center of the tubular furnace. The two porcelain boats are adjacent to each other. Before heating the tubular furnace, first introduce argon for 1 h to remove the oxygen in the tubular furnace. After removing the oxygen in the tubular furnace, set the temperature of the tubular furnace to 1000 °C and perform programmed heating at a rate of 5 °C / min -1 and heat the tubular furnace under the protection of Ar gas, and keep high-temperature calcination for 1 h.

[0068] (7) Stop the reaction. After natural cooling to room temperature, grind and collect the black product after the reaction to obtain the transition metal sulfide adsorbent.

[0069] Example 5

[0070] A preparation method of a transition metal sulfide adsorbent, comprising the following steps:

[0071] (1) Weigh 0.8 g of molybdenum trioxide and dissolve it in a 100 mL single-necked flask containing 40 mL of deionized water, and perform ultrasonic stirring for 10 min to form a uniformly dispersed solution.

[0072] (2) Add 0.3 g of imidazole to the uniformly dispersed solution, and continuously perform ultrasonic stirring for 10 min after sufficient mixing.

[0073] (3) Put a polytetrafluoroethylene magnetic stir bar on the three-necked flask, transfer the single-necked flask containing the mixture to a constant-temperature oil bath for heating reaction, keep the oil bath temperature constant at 200 °C, introduce condensed water for condensation reflux, the reaction time is 12 h, and control the mechanical stirring speed at 300 rmp / min.

[0074] (4) After the reaction is completed, cool the single-necked flask at room temperature, filter the white precipitate in the single-necked flask, wash the precipitate three times with deionized water and three times with ethanol, and finally dry the white solid in a vacuum drying oven at 80 °C for 24 h, and grind the obtained white powder to obtain Mo-MOF.

[0075] (5) Transfer thiourea to the porcelain boat marked as No. 1 and weigh the Mo-MOF and thiourea in the porcelain boats marked as No. 1 and No. 2 respectively according to a mass ratio of 3:1. At the same time, it is necessary to spread the two raw materials evenly in their respective magnetic boats.

[0076] (6) Place the porcelain boat marked as No. 1 on the upstream side of the tubular furnace, that is, the side of the argon inlet, and place the porcelain boat marked as No. 2 at the heat source center of the tubular furnace. The two porcelain boats are adjacent to each other. Before heating the tubular furnace, first introduce argon for 1 h to remove the oxygen in the tubular furnace. After removing the oxygen in the tubular furnace, set the temperature of the tubular furnace to 1000 °C and perform programmed heating at a rate of 5 °C / min -1The temperature was programmed to rise at a rate of , and the tube furnace was heated under Ar gas protection, and the high temperature calcination was continued for 1 h.

[0077] (7) Stop the reaction, wait for the mixture to cool naturally to room temperature, and grind and collect the black product after the reaction to obtain a transition metal sulfide adsorbent.

[0078] Comparative Example 1

[0079] A method for preparing a transition metal sulfide adsorbent comprises the following steps:

[0080] (1) Weigh 0.8 g of molybdenum trioxide and dissolve it in a single-necked flask containing 60 mL of deionized water and 100 mL of solvent, and stir it ultrasonically for 10 min to form a uniformly dispersed solution.

[0081] (2) Add 0.2 g of imidazole to the uniformly dispersed solution until fully mixed, and then continue ultrasonic stirring for 10 minutes.

[0082] (3) A polytetrafluoroethylene magnetic stirring bar was placed on the three-necked flask, and the single-necked flask containing the mixture was transferred to a constant temperature oil bath for heating reaction. The oil bath temperature was controlled at 120°C, and condensed water was introduced for condensation reflux. The reaction time was 24 h, and the mechanical stirring speed was controlled at 300 rpm.

[0083] (4) After the reaction is completed, the single-necked flask is cooled at room temperature, the white precipitate in the single-necked flask is filtered, and the precipitate is washed three times with deionized water and three times with ethanol. Finally, the white solid is dried in a vacuum drying oven at 80° C. for 24 h. The white powder obtained by grinding is Mo-MOF.

[0084] (5) The thiourea is transferred to the porcelain boat marked as No. 1 and the Mo-MOF is weighed in the porcelain boats marked as No. 1 and No. 2 respectively in a mass ratio of 3:1. At the same time, the two raw materials need to be evenly spread in their respective magnetic boats.

[0085] (6) Place the porcelain boat marked as No. 1 on the upstream side of the tube furnace, that is, on the side of the argon inlet, and place the porcelain boat marked as No. 2 at the heat source center of the tube furnace. The two porcelain boats are adjacent to each other. Before heating the tube furnace, first pass argon gas for 1 hour to remove the oxygen in the tube furnace. After removing the oxygen in the tube furnace, set the temperature of the tube furnace to 400℃ and heat it at 5℃min. -1 The temperature was programmed to rise at a rate of , and the tube furnace was heated under Ar gas protection, and the high temperature calcination was continued for 1 h.

[0086] (7) Stop the reaction, wait for the mixture to cool naturally to room temperature, grind and collect the black product after the reaction to obtain a transition metal sulfide adsorbent, named MS-400.

[0087] Comparative Example 2

[0088] A preparation method of a transition metal sulfide adsorbent, comprising the following steps:

[0089] (1) Weigh 0.8 g of molybdenum trioxide and dissolve it in a 100 mL single-necked flask containing 60 mL of deionized water, and perform ultrasonic stirring for 10 min to form a uniformly dispersed solution.

[0090] (2) Add 0.2 g of imidazole to the uniformly dispersed solution, and continuously perform ultrasonic stirring for 10 min after sufficient mixing.

[0091] (3) Put a polytetrafluoroethylene magnetic stir bar on the three-necked flask, transfer the single-necked flask containing the mixture to a constant-temperature oil bath for heating reaction, keep the oil bath temperature constant at 120 °C, introduce condensed water for condensation reflux, the reaction time is 24 h, and control the mechanical stirring speed at 300 rmp / min.

[0092] (4) After the reaction is completed, cool the single-necked flask at room temperature, filter the white precipitate in the single-necked flask, wash the precipitate three times with deionized water and three times with ethanol, and finally dry the white solid in a vacuum drying oven at 80 °C for 24 h, and grind the obtained white powder to obtain Mo-MOF.

[0093] (5) Transfer thiourea to the porcelain boat labeled No. 1 and weigh the Mo-MOF and thiourea in the porcelain boats labeled No. 1 and No. 2 respectively according to a mass ratio of 3:1. At the same time, the two raw materials need to be evenly spread out in their respective magnetic boats.

[0094] (6) Place the porcelain boat labeled No. 1 on the upstream side of the tubular furnace hearth, that is, the argon inlet side, and place the porcelain boat labeled No. 2 at the heat source center of the tubular furnace. The two porcelain boats are adjacent to each other. Before heating the tubular furnace, first introduce argon for 1 h to remove the oxygen in the tubular furnace. After removing the oxygen in the tubular furnace, set the temperature of the tubular furnace to 600 °C, and perform programmed heating at a rate of 5 °C / min. Heat the tubular furnace under Ar gas protection and keep high-temperature calcination for 1 h. -1 The rate of temperature increase is carried out, and the tubular furnace is heated under Ar gas protection, and high-temperature calcination is continued for 1 h.

[0095] (7) Stop the reaction. After natural cooling to room temperature, grind and collect the reacted black product to obtain a transition metal sulfide adsorbent, named MS-600.

[0096] Comparative Example 3

[0097] A preparation method of a transition metal sulfide adsorbent, comprising the following steps:

[0098] (1) Weigh 0.8 g of molybdenum trioxide and dissolve it in a 100 mL single-necked flask containing 60 mL of deionized water, and perform ultrasonic stirring for 10 min to form a uniformly dispersed solution.

[0099] (2) Add 0.2 g of imidazole to the uniformly dispersed solution, and continuously perform ultrasonic stirring for 10 min after sufficient mixing.

[0100] (3) Put a polytetrafluoroethylene magnetic stir bar on the three-necked flask, transfer the single-necked flask containing the mixture to a constant-temperature oil bath for heating reaction, keep the oil bath temperature constant at 120 °C, introduce condensed water for condensation reflux, the reaction time is 24 h, and control the mechanical stirring speed at 300 rmp / min.

[0101] (4) After the reaction is completed, cool the single-necked flask at room temperature, filter the white precipitate in the single-necked flask, wash the precipitate three times with deionized water and three times with ethanol, and finally dry the white solid in a vacuum drying oven at 80 °C for 24 h. The ground white powder is Mo-MOF.

[0102] (5) Transfer thiourea to the porcelain boat labeled No. 1 and weigh the Mo-MOF and thiourea in the porcelain boats labeled No. 1 and No. 2 respectively according to a mass ratio of 3:1. At the same time, the two raw materials need to be evenly spread out in their respective magnetic boats.

[0103] (6) Place the porcelain boat labeled No. 1 on the upstream side of the tube furnace, that is, the argon inlet side, and place the porcelain boat labeled No. 2 at the heat source center of the tube furnace. The two porcelain boats are adjacent to each other. Before heating the tube furnace, first introduce argon for 1 h to remove the oxygen in the tube furnace. After removing the oxygen in the tube furnace, set the temperature of the tube furnace to 800 °C, and perform programmed heating at a rate of 5 °C / min. Heat the tube furnace under Ar gas protection and keep high-temperature calcination for 1 h. -1 The rate is used for programmed temperature rise, and the tube furnace is heated under Ar gas protection, and high-temperature calcination is continued for 1 h.

[0104] (7) Stop the reaction. After natural cooling to room temperature, grind and collect the black product after the reaction to obtain a transition metal sulfide adsorbent, named MS-800.

[0105] Comparative Example 4

[0106] A preparation method of a transition metal sulfide adsorbent, comprising the following steps:

[0107] (1) Weigh 0.8 g of molybdenum trioxide and dissolve it in a 100 mL single-necked flask containing 60 mL of deionized water, and perform ultrasonic stirring for 10 min to form a uniformly dispersed solution.

[0108] (2) Add 0.2 g of imidazole to the uniformly dispersed solution, and continuously perform ultrasonic stirring for 10 min after sufficient mixing.

[0109] (3) Fit a PTFE magnetic stir bar onto the three-necked flask, transfer the single-necked flask containing the mixture to a thermostatic oil bath for heating reaction. The oil bath temperature is kept constant at 120 °C, condensing water is introduced for condensation reflux, the reaction time is 24 h, and the mechanical stirring speed is controlled at 300 rmp / min.

[0110] (4) After the reaction is completed, cool the single-necked flask at room temperature, filter the white precipitate in the single-necked flask, wash the precipitate three times with deionized water and three times with ethanol, and finally dry the white solid in a vacuum drying oven at 80 °C for 24 h. The white powder obtained by grinding is Mo-MOF.

[0111] (5) Transfer thiourea to the porcelain boat labeled No. 1 and weigh the Mo-MOF and thiourea in the porcelain boats labeled No. 1 and No. 2 respectively according to a mass ratio of 1:1. At the same time, the two raw materials need to be evenly spread out in their respective magnetic boats.

[0112] (6) Place the porcelain boat labeled No. 1 on the upstream side of the tube furnace, i.e., the side of the argon inlet, and place the porcelain boat labeled No. 2 at the heat source center of the tube furnace. The two porcelain boats are adjacent to each other. Before heating the tube furnace, first introduce argon for 1 h to remove the oxygen in the tube furnace. After removing the oxygen in the tube furnace, set the temperature of the tube furnace to 1000 °C and perform programmed heating at a rate of 5 °C / min. Heat the tube furnace under Ar gas protection and keep high-temperature calcination for 1 h. -1 and heat the tube furnace under Ar gas protection for 1 h at a high temperature.

[0113] (7) Stop the reaction. After natural cooling to room temperature, grind and collect the black product after the reaction to obtain the transition metal sulfide adsorbent.

[0114] Comparative Example 5

[0115] A preparation method of a transition metal sulfide adsorbent, comprising the following steps:

[0116] (1) Weigh 0.8 g of molybdenum trioxide and dissolve it in a 100 mL solvent single-necked flask containing 60 mL of deionized water, and perform ultrasonic stirring for 10 min to form a uniformly dispersed solution.

[0117] (2) Add 0.2 g of imidazole to the uniformly dispersed solution, and continuously perform ultrasonic stirring for 10 min after sufficient mixing.

[0118] (3) Fit a PTFE magnetic stir bar onto the three-necked flask, transfer the single-necked flask containing the mixture to a thermostatic oil bath for heating reaction. The oil bath temperature is kept constant at 120 °C, condensing water is introduced for condensation reflux, the reaction time is 24 h, and the mechanical stirring speed is controlled at 300 rmp / min.

[0119] (4) After the reaction is completed, cool the single-neck flask at room temperature, filter the white precipitate in the single-neck flask, wash the precipitate three times with deionized water and three times with ethanol, and finally dry the white solid in a vacuum drying oven at 80 °C for 24 h. The white powder obtained by grinding is Mo-MOF.

[0120] (5) Transfer thiourea to the porcelain boat labeled No. 1 and weigh the Mo-MOF and thiourea in the porcelain boats labeled No. 1 and No. 2 respectively according to a mass ratio of 2:1. At the same time, the two raw materials need to be evenly spread out in their respective magnetic boats.

[0121] (6) Place the porcelain boat labeled No. 1 on the upstream side of the tube furnace, that is, the side of the argon inlet, and place the porcelain boat labeled No. 2 at the heat source center of the tube furnace. The two porcelain boats are adjacent to each other. Before heating the tube furnace, first introduce argon for 1 h to remove the oxygen in the tube furnace. After removing the oxygen in the tube furnace, set the temperature of the tube furnace to 1000 °C and perform programmed heating at a rate of 5 °C / min. Heat the tube furnace under Ar gas protection and keep high-temperature calcination for 1 h. -1 at a rate of, and heat the tube furnace under Ar gas protection for 1 h of continuous high-temperature calcination.

[0122] (7) Stop the reaction. After natural cooling to room temperature, grind and collect the black product after the reaction to obtain the transition metal sulfide adsorbent.

[0123] Result analysis

[0124] Preparation of adsorption solution

[0125] Ag + solution is prepared by dissolving silver nitrate in ultrapure water. Preparation and determination of Ag + solution: ① Prepare a 2.0 g / L -1 Ag + stock solution: Dissolve 3.1496 g of AgNO3 in 1 L of ultrapure water and store it refrigerated. ② Prepare Ag + solutions with different concentrations: Dilute the 2.0 g / L -1 Ag + stock solution with deionized water to obtain Ag -1 solutions with an initial concentration range of 50 - 2000 mg·L + . ③ Prepare and determine the standard curve of the Ag + solution: Dilute the Ag + solution with 1% HNO3 solution to obtain 6 different concentrations of Ag + standard solutions with a concentration range of 0 - 6 mg / L -1 . Measure with a continuous light source atomic absorption spectrometer ContrAA 700, with absorbance as the ordinate and Ag +Using the solution concentration as the abscissa, a straight line is obtained, which is the Ag + solution standard curve. ④ The determination of the Ag + concentration in the solution: Use a continuous light source atomic absorption spectrometer to measure the Ag + concentration in the water sample to evaluate the removal effect of the adsorbent on Ag + . All experiments were carried out three times, and the final data is the average of the three experiments.

[0126] Figure 2 This is the SEM morphology diagram of the transition metal sulfide adsorbent materials prepared in Examples 1-2 and Comparative Examples 1-3 of the present invention. It can be seen that the morphology of the adsorbent material is a nanorod structure. As the reaction temperature increases, the generated nanorods become irregular, with a length of about 10 μm - 20 μm and a diameter of 1 μm - 2 μm. When the calcination temperature increases from 400 °C to 800 °C, sporadic fragments appear on the surface. When calcined at 1000 °C, a dense structure formed by a large number of fragments accumulates on the surface. And from the cross-section, a multi-layered "cabbage" structure is formed inside. This layered form is a typical MoS2 structure, and there are a large number of fragments and particles embedded in the nanorods inside. When calcined at 1200 °C, the nanorods become very thin, and a large amount of cracking appears on the surface at high temperature. In addition, the corresponding EDX-mapping shows the presence of the S element, which is the result of the reaction between H2S generated by the decomposition of thiourea at high temperature and MOF. The adsorbent synthesized using Mo-MOF as a template maintains part of the morphology and structure of the original MOFs. The nanorod substrate can not only disperse the MoS2 nanosheets well but also expose more edge active sites, thus greatly improving the removal performance of the material for Ag + .

[0127] Weigh 20 mg of four different proportions of the adsorbent material and add it to a solution containing 80 mL and a concentration of 2000 mg / L Ag + concentration. Oscillate in a constant temperature shaker at 298 K for 12 h, and set the rotation speed to 180 rpm. After the oscillation ends and equilibrium is reached, filter the sample with a 0.22 μm polyethersulfone membrane to obtain the supernatant, and use a ContrAA 700 high-resolution continuous light source atomic absorption spectrometer to measure the Ag + concentration before and after adsorption.

[0128] Figure 3This is the adsorption capacity result diagram of the transition metal sulfide adsorbent materials prepared in Example 1 and Example 3 of the present invention, and Comparative Example 4 and Comparative Example 5 at different ratios of thiourea to Mo-MOF. It can be seen from the figure that the adsorption performance is the best when the ratio of thiourea to Mo-MOF material is 3:1 and 4:1. This is mainly because excessive thiourea can cause thiourea to decompose at high temperature and fully contact with molybdenum atoms on Mo-MOF to form molybdenum sulfide. Due to the limited number of exposed molybdenum atoms, even if more thiourea decomposes, the formed molybdenum sulfide is certain, so the adsorption amount no longer increases.

[0129] Isothermal adsorption: 20 mg of adsorbent nanorods calcined at different temperatures were respectively added to 80 mL of Ag + solutions. The isothermal adsorption experiments of Sb(V) were carried out at different temperatures of 283 K, 298 K and 318 K respectively, and oscillated in a constant temperature shaker for 12 h, with the set rotation speed of 180 rpm. The initial concentration of the adsorption solution Ag + was in the range of 50 mg L -1 , 100 mg L -1 , 200 mg L -1 , 400 mg L -1 , 600 mg L -1 , 800 mg L -1 , 1000 mg L -1 , 1200 mg L -1 , 1400 mg L -1 , 1600 mg L -1 , 1800 mg L -1 , 2000 mg L -1 . After the adsorption equilibrium, the samples were filtered through a 0.22 μm polyethersulfone membrane to obtain the supernatant, and a ContrAA 700 high-resolution continuum source atomic absorption spectrometer was used to measure the Ag + concentration before and after adsorption.

[0130] Figure 4 This is the adsorption capacity result diagram of the transition metal sulfide adsorbent materials prepared in Example 1 and Example 2 of the present invention, and Comparative Example 1 - Comparative Example 3 at different calcination temperatures. From Figure 4 it can be seen that the capacities of MS-400, MS-600, MS-800, MS-1000 and MS-1200 nanorods for Ag + removal are 172.1 mg g -1 , 250.2 mg g -1 , 484.8 mg g -1 , 2315.6 mg g -1 and 1860 mg g -1MS-1000 obtained an ultra-high adsorption capacity superior to the other four materials, which is almost 13 times that of MS-400, indicating that the nanorods generated at a calcination temperature of 1000°C have a high adsorption capacity for Ag. + The removal effect is the best. This is mainly because two different crystal phases of molybdenum sulfide 1T and 2H phases are formed at 1000℃. 1T phase molybdenum sulfide can reduce Ag + , the 2H phase of MoS provides a layered structure that is beneficial to Ag + transported to the adsorption site and formed coordination.

[0131] 20 mg of MS-1000 nanorod adsorbent was added to 20 mL of K + , Ca 2+ Mg 2+ 、Co 2+ 、Ni 2+ , Cu 2+ 、Cd 2+ 、Zn 2+ , Pb 2+ and Ag + The 10 ion concentrations were all 1 mmol / L in a mixed solution. The mixture was shaken in a 298K constant temperature shaker for 12 hours. After adsorption equilibrium, the supernatant was collected by pinhole filter membrane filtration, and the concentration of each component ion in the supernatant was determined using a ContrAA 700 high-resolution continuous light source atomic absorption spectrometer.

[0132] In Ag + and interfering ions K + Mg 2+ 、Ni 2+ 、Co 2+ 、Zn 2+ 、Cd 2+ , Cu 2+ and Pb 2+ In the mixture of + The removal of MS-1000 nanorods and Ag + The affinity of d Come and evaluate, K d It is an important indicator to measure the selectivity of the adsorbent. d Value 1.0×10 5 mL g -1 It can determine the selectivity of the adsorbent. Figure 5 In the presence of coexisting ions, the transition metal sulfide adsorbent prepared in Example 1 of the present invention is used to absorb Ag. + The affinity diagram shows that the MS-1000 nanorod adsorbent can completely separate silver ions from other metal ions in a mixed solution, indicating that the MS-1000 nanorod adsorbent still has good affinity for Ag in a complex silver-containing solution.+ It has excellent selectivity. This is mainly because as the calcination temperature increases, more Mo atoms are exposed, and more molybdenum sulfide is formed. When the temperature exceeds 1000 °C, the structure of the MOF is cracked, making it difficult to maintain the growth of more sites, resulting in a decrease in the adsorption capacity.

[0133] In summary, the present invention uses the high-temperature pyrolysis method of the MOF template to create active centers with both adsorption and reduction functions at the reaction interface of the adsorption material. The MOF template-derived transition metal sulfide adsorption material prepared can achieve the efficient selective removal and resource recovery of Ag in water + This has important significance for ensuring water environment safety and maintaining the development of the green and low-carbon circular economy of silver resources, and provides a new prototype technology that combines selective adsorption and heavy metal elementalization for wastewater heavy metal low-carbonization technology.

[0134] It should be noted that when the present invention involves a numerical range, it should be understood that both endpoints of each numerical range and any value between the two endpoints can be selected. Since the steps and methods used are the same as those in the embodiments, in order to prevent repetition, the present invention describes the preferred embodiments. Although the preferred embodiments of the present invention have been described, those skilled in the art can make additional changes and modifications to these embodiments once they know the basic creative concept. Therefore, the scope of protection is intended to cover the preferred embodiments and all changes and modifications that fall within the scope of the present invention.

[0135] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the present invention and its equivalent technologies, the present invention also intends to include these modifications and variations.

Claims

1. A preparation method of a transition metal sulfide adsorbent for targeted silver adsorption in silver-containing wastewater, characterized in that, It includes the following steps: Synthesize the Mo-MOF template by hydrothermal method; Under a protective atmosphere, calcine thiourea and the Mo-MOF template at a mass ratio of 3-4:1, and obtain a transition metal sulfide adsorbent through high-temperature template pyrolysis method; The calcination temperature is 1000 °C - 1200 °C, and the calcination time is 1 hour - 1.2 hours.

2. The preparation method according to claim 1, characterized in that, The preparation method of the Mo-MOF template includes the following steps: Dissolve the molybdenum source in water to form a uniformly dispersed solution; Add imidazole to the uniformly dispersed solution, heat and react, and obtain the Mo-MOF template through post-treatment.

3. The preparation method according to claim 2, characterized in that, The mass ratio of the molybdenum source to the volume of water is 4 g:0.1 L - 0.3 L.

4. The preparation method according to claim 2, characterized in that, The mass ratio of imidazole to the molybdenum source is 4:1 - 2.

5. The preparation method according to claim 2, characterized in that, The heating reaction temperature is 100 °C - 200 °C, and the heating reaction time is 12 h - 72 h.

6. A transition metal sulfide adsorbent prepared by the preparation method according to any one of claims 1-5.

7. The application of the transition metal sulfide adsorbent according to claim 6 in targeted adsorption of silver in silver-containing wastewater.

8. The application according to claim 7, wherein The concentration of the silver-containing wastewater is 50 mg / L - 2000 mg / L, and the dosage ratio of the transition metal sulfide adsorbent to the silver-containing wastewater is 1 mg:2 mL - 4 mL.

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