A MOF composite membrane for selectively adsorbing rhenium and a preparation method and application thereof

Abstract

The present application relates to copper smelting technical field, especially to a kind of selective adsorption MOF composite membrane of rhenium and its preparation method and application.The preparation method of selective adsorption MOF composite membrane of rhenium provided by the present application includes the following steps: sulfonic acid functionalized UiO-66 type metal organic framework material is dispersed in polyvinylidene fluoride solution, and metal organic framework material dispersion is obtained;The metal organic framework material dispersion is mixed with crosslinking agent, and crosslinking reaction is carried out, then the obtained reaction liquid is mixed with acid-resistant ionic liquid, and spinning solution is obtained;The spinning solution is electrospun, and silk film is obtained;After the silk film is immersed in aminosilane coupling agent solution, it is solidified, and the selective adsorption MOF composite membrane of rhenium is obtained.The selective adsorption MOF composite membrane of rhenium provided by the present application can selectively adsorb rhenium in the treatment of waste acid, so as to realize the selective separation of rhenium, and the membrane has excellent acid resistance.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of copper smelting, in particular to a MOF composite membrane for selectively adsorbing rhenium and a preparation method and application thereof. BACKGROUND

[0002] Rhenium, a rare metal, mainly exists in copper-molybdenum ore and will enter copper smelting waste acid along with flue gas in the copper smelting process. At present, the treatment of copper smelting waste acid in the industry mainly focuses on the harmless disposal of arsenic, and the rhenium resource is not paid attention to. Rhenium finally enters the hazardous waste landfill together with arsenic sulfide slag. This disposal mode not only causes the loss of strategic resources, but also increases the output of hazardous waste.

[0003] In recent years, researchers have carried out a lot of research in the field of rhenium extraction from waste acid. For example, an amine-based membrane is used to filter rhenium-containing acidic waste liquid, and high-efficiency adsorption of rhenium is realized through affinity groups (CN105803208A). However, amine groups are prone to protonation to form ammonium salt under acidic conditions, and sulfate radicals will also attack amine group carbon bonds. Extraction process is a common rhenium extraction technology, which uses specific binding of organic extractant and rhenium acid radical, and then realizes the recovery of rhenium through backwashing (CN119956131A, CN102502855A). However, the extractant is easy to emulsify to produce a third phase under low concentration background, which destroys the stability of the phase interface. The resin adsorption method has good recovery effect on rhenium (CN119464782A), but the selectivity is insufficient in a complex environment background, and the ion competition is large. Under the background of high acidity and interference of impurities, the existing methods are difficult to balance the selective separation and material resistance. SUMMARY

[0004] The present application provides a MOF composite membrane for selectively adsorbing rhenium and a preparation method and application thereof. The MOF composite membrane for selectively adsorbing rhenium provided by the present application can selectively adsorb rhenium in the treatment of waste acid, so as to realize the selective separation of rhenium, and the membrane has excellent acid resistance.

[0005] The present application provides a preparation method of a MOF composite membrane for selectively adsorbing rhenium, comprising the following steps:

[0006] Disperse a sulfonic acid functionalized UiO-66 type metal organic framework material in a polyvinylidene fluoride solution to obtain a metal organic framework material dispersion liquid,

[0007] Mix the metal organic framework material dispersion liquid with a crosslinking agent to perform a crosslinking reaction, and then mix the obtained reaction liquid with an acid-resistant ionic liquid to obtain a spinning solution,

[0008] Perform electrospinning on the spinning solution to obtain a silk membrane,

[0009] After the silk membrane is immersed in the amino silane coupling agent solution, and is cured, a MOF composite membrane which selectively adsorbs rhenium is obtained.

[0010] Optionally, the sulfonic acid functionalized UiO-66 type metal organic framework material is prepared by a method comprising the following steps:

[0011] A zirconium source, a sulfonic acid functional ligand and terephthalic acid are added into a mixed solvent of N,N-dimethylformamide and acid, ultrasonic treatment is performed for 15-20 min, and then a solvothermal reaction is performed, and the obtained reaction liquid is subjected to solid-liquid separation, to obtain a sulfonic acid functionalized UiO-66 precursor,

[0012] The sulfonic acid functionalized UiO-66 precursor is sequentially subjected to N,N-dimethylformamide aqueous solution washing, ethanol solvent replacement and acidification, and then is subjected to drying and activation, to obtain the sulfonic acid functionalized UiO-66 type metal organic framework material.

[0013] Optionally, the zirconium source is at least one of ZrCl4, ZrOCl4 and Zr(NO3)4, the sulfonic acid functional ligand is at least one of 2-sulfonic acid terephthalic acid and 2-sulfonic acid sodium terephthalate, and the acid is at least one of glacial acetic acid, formic acid, hydrochloric acid and benzoic acid,

[0014] The molar ratio of the zirconium source to the sulfonic acid functional ligand is 1:0.2-0.8, and the molar ratio of the zirconium source to terephthalic acid is 1:0.5-0.8,

[0015] The volume ratio of the N,N-dimethylformamide to the acid is 9-11:1, and the ratio of the zirconium source to the mixed solvent is 1 mmol:26-29 mL,

[0016] The solvothermal reaction is performed at 115-125℃ for 22-26 h.

[0017] Optionally, the volume ratio of N,N-dimethylformamide to water in the N,N-dimethylformamide aqueous solution is (3-4):1,

[0018] The acidification is washing the ethanol solvent-replaced sulfonic acid functionalized UiO-66 precursor with a 0.1 M hydrochloric acid / ethanol solution,

[0019] The drying is vacuum drying, the temperature of the drying is 140-160℃, and the time of the drying is 4-8 h,

[0020] The activation is performed in a protective atmosphere, the temperature of the activation is 180-220℃, and the time of the activation is 5-7 h.

[0021] Optionally, the solvent of the polyvinylidene fluoride solution is N,N-dimethylformamide, and the concentration of the polyvinylidene fluoride solution is 12-15 wt%,

[0022] The amount of the sulfonic acid functionalized UiO-66 type metal organic framework material is 30-40 wt% of the amount of polyvinylidene fluoride in the polyvinylidene fluoride solution,

[0023] The crosslinking agent is at least one of divinylbenzene and ethylene glycol dimethacrylate, and the amount of the crosslinking agent is 1.3-1.7 wt% of the amount of polyvinylidene fluoride in the polyvinylidene fluoride solution,

[0024] The crosslinking reaction is carried out at room temperature, and the time of the crosslinking reaction is 25-40 min,

[0025] The acid-resistant ionic liquid is [P 66614 ][OTf], and the amount of the acid-resistant ionic liquid is 18-22 wt% of the sulfonic acid functionalized UiO-66 type metal organic framework material.

[0026] Optionally, the diameter of the electrospinning nozzle is 0.4-0.6 mm, the spinning voltage is 18-22 kV, the receiving distance is 15-18 cm, the flow rate of the spinning solution is 0.8-1.2 mL / h, and the thickness of the silk membrane is 140-160 μm,

[0027] The amino silane coupling agent in the amino silane coupling agent solution includes at least one of 3-aminopropyl triethoxysilane and N-(β-aminoethyl)-γ-aminopropyl trimethoxysilane, the concentration of the amino silane coupling agent solution is 1.8-2.5 wt%, and the solvent of the 3-aminopropyl triethoxysilane solution is at least one of ethanol and isopropanol,

[0028] The time of the impregnation is 25-40 min, and the temperature of the curing is 60-80℃, and the time is 0.8-1.2 h.

[0029] The application further provides a MOF composite membrane for selectively adsorbing rhenium, which is prepared by the preparation method in any one of the above technical solutions.

[0030] The application further provides an application of the MOF composite membrane for selectively adsorbing rhenium in the above technical solution in recovering rhenium from waste acid.

[0031] Optionally, the application includes the following steps:

[0032] The waste acid after removal of the suspended solids is subjected to arsenic removal to obtain a solidified arsenic residue and waste acid after arsenic removal,

[0033] The MOF composite membrane for selectively adsorbing rhenium is backwashed with an acidic washing solution, water and an alkaline washing solution in sequence to obtain a rhenium-rich solution.

[0034] The MOF composite membrane for selectively adsorbing rhenium is backwashed with an acidic washing solution, water and an alkaline washing solution in sequence to obtain a rhenium-rich solution.

[0035] Optionally, the arsenic removal comprises the following steps: adjusting the pH of the waste acid to 3.5-4.5, then adding sodium phosphate to a concentration of 0.02-0.1 M, then adding a ferric chloride solution dropwise until the arsenic concentration is less than 80 mg / L, and then filtering; wherein the concentration of the ferric chloride solution is 0.5-1.0 M.

[0036] The acidic washing solution is an acidic mixed aqueous solution of ethylenediaminetetraacetic acid and sodium chloride, the concentration of the ethylenediaminetetraacetic acid is 0.09-0.11 M, the concentration of the sodium chloride is 0.09-0.11 M, and the pH of the acidic mixed aqueous solution is 2-4.

[0037] When water is used for backwashing, the backwashing is performed until the washing solution is neutral.

[0038] The alkaline washing solution is an alkaline mixed aqueous solution of ammonium chloride and ammonia water, the concentration of the ammonium chloride is 0.09-0.11 M, the concentration of the ammonia water is 0.09-0.11 M, and the pH of the alkaline mixed aqueous solution is 8.8-9.2.

[0039] Compared with the prior art, the present application has the following beneficial effects:

[0040] The MOF composite membrane for selectively adsorbing rhenium prepared by the preparation method of the present application introduces a sulfonic acid functionalized UiO-66 type metal organic framework material, so that the MOF composite membrane is negatively charged, and high-charge arsenate and molybdate are prevented from being outside the pore channel of the composite membrane due to electrostatic repulsion, and rhenate is combined with H +The rhenium acid is formed, enters the pore of the MOF composite membrane, and forms a strong hydrogen bond with the sulfonic acid group, so as to be adsorbed, so as to realize selective adsorption of rhenium. In addition, the introduction of the sulfonic acid group can stabilize the Zr-O bond and enhance the stability of the MOF skeleton; the crosslinking agent can improve the acid swelling resistance and mechanical strength of the polymer matrix itself; the addition of the acid-resistant ionic liquid in the spinning solution can improve the acid resistance of the MOF composite membrane; and after the obtained silk membrane is immersed in the amino silane coupling agent solution and solidified, the amine group is introduced into the MOF composite membrane, the amine group is protonated to become a positively charged ammonium ion, which can form a bipolar charge synergistic repulsion together with the sulfonic acid group (that is, there are positive and negative charge groups on the membrane, the positive charge repels metal ions such as copper, lead and zinc, and the negative charge repels anions), and the amino silane coupling agent is solidified to form a silicone polymer network, wherein the silicon-oxygen covalent bond is relatively stable, so as to make the MOF composite membrane more resistant to acid, and the silicone polymer network on the surface can play an additional crosslinking and supporting role, thereby improving the mechanical strength of the MOF composite membrane. According to the description of the embodiments of the present application, the MOF composite membrane for selectively adsorbing rhenium provided by the present application can selectively adsorb rhenium in the treatment of waste acid, so as to realize selective separation of rhenium, and at the same time, the membrane has excellent acid resistance, and can still stably remove rhenium during long-term operation; in addition, the filtered purified liquid can be used for sulfuric acid regeneration and copper and lead recovery. DETAILED DESCRIPTION

[0041] The present application will be described in detail through specific embodiments, and those skilled in the art can understand that the specific embodiments below are only for illustrative purposes, and do not limit the scope of the present application in any way. In addition, in the following embodiments, unless otherwise specified, the reagents and equipment used are commercially available. If the specific treatment conditions and methods are not explicitly described in the following embodiments, the conditions and methods known in the art can be used for treatment.

[0042] The present application provides a preparation method of a MOF (metal organic framework material) composite membrane for selectively adsorbing rhenium, comprising the following steps:

[0043] The sulfonic acid functionalized UiO-66 type metal organic framework material is dispersed in a polyvinylidene fluoride solution to obtain a metal organic framework material dispersion liquid,

[0044] The metal organic framework material dispersion liquid is mixed with a crosslinking agent to perform a crosslinking reaction, and then the obtained reaction liquid is mixed with an acid-resistant ionic liquid to obtain a spinning solution,

[0045] The spinning solution is electrospun to obtain a silk membrane,

[0046] The silk membrane is immersed in an amino silane coupling agent solution and then solidified to obtain a MOF composite membrane for selectively adsorbing rhenium.

[0047] This invention introduces a sulfonic acid-functionalized UiO-66 type metal-organic framework material into a MOF composite membrane for selective adsorption of rhenium. This makes the MOF composite membrane negatively charged. Highly negatively charged arsenate and molybdate ions are prevented from entering the pores of the composite membrane due to electrostatic repulsion, while rhenium ions react with H+. + Rhenium acid is formed and enters the pores of the MOF composite membrane, forming strong hydrogen bonds with sulfonic acid groups, thereby being adsorbed to achieve selective adsorption of rhenium. In addition, the introduction of sulfonic acid groups can stabilize Zr-O bonds and enhance the stability of the MOF skeleton. Crosslinking agents can improve the acid swelling resistance and mechanical strength of the polymer matrix itself. Adding acid-resistant ionic liquids to the spinning solution can improve the acid resistance of the MOF composite membrane. After the resulting silk membrane is impregnated in an aminosilane coupling agent solution and cured, amino groups are introduced into the MOF composite membrane. The amino groups are protonated and transformed into positively charged ammonium ions, which can form bipolar charge synergistic repulsion with sulfonic acid groups. The aminosilane coupling agent cures to form an organosilicon polymer network, in which the silicon-oxygen covalent bonds are relatively stable, making the MOF composite membrane more acid-resistant. At the same time, the organosilicon polymer network on the surface can play an additional crosslinking and supporting role, improving the mechanical strength of the MOF composite membrane. When filtering acidic wastewater using the MOF composite membrane for selective rhenium adsorption provided by this invention, some hydrated metal cations have large ionic radii, making it difficult for them to enter the pores; simultaneously, under an acidic background, H... + It will preferentially occupy the negatively charged groups on the membrane surface to form a proton protective layer, reducing the binding of cations to the membrane surface; even if the metal cations and the negative charges of the MOF composite membrane attract each other, due to the large size of the metal cations, they will also adsorb on the surface of the MOF composite membrane, forming reversible surface adsorption, which is easy to wash off.

[0048] The present invention first disperses sulfonic acid-functionalized UiO-66 type metal-organic framework material in polyvinylidene fluoride solution to obtain metal-organic framework material dispersion.

[0049] The present invention does not have a specific limitation on the dispersion method, as long as a uniformly mixed dispersion can be obtained. In the embodiments of the present invention, ultrasonic dispersion is used, and the ultrasonic time is 20-30 min.

[0050] In some embodiments of the present invention, the sulfonic acid-functionalized UiO-66 type metal-organic framework material is prepared by a method comprising the following steps:

[0051] Zirconium source, sulfonic acid functional ligand, and terephthalic acid were added to a mixed solvent of N,N-dimethylformamide and acid, and the mixture was sonicated for 15-20 min, followed by a solvothermal reaction. The resulting reaction solution was then subjected to solid-liquid separation to obtain the sulfonic acid-functionalized UiO-66 precursor.

[0052] The sulfonic acid functionalized UiO-66 precursor is sequentially subjected to N,N-dimethylformamide aqueous solution washing, ethanol solvent replacement and acidification, and then subjected to drying and activation to obtain the sulfonic acid functionalized UiO-66 type metal organic framework material.

[0053] In some embodiments of the present application, the zirconium source is at least one of ZrCl4, ZrOCl4 and Zr(NO3)4, the sulfonic acid functional ligand is at least one of 2-sulfonic acid terephthalic acid and 2-sulfonic acid sodium terephthalate, the acid is at least one of glacial acetic acid, formic acid, hydrochloric acid and benzoic acid, and when the acid is hydrochloric acid, the concentration of the hydrochloric acid is 1.0-1.5 M. In the present application, the zirconium source provides a metal center for the metal organic framework material, the sulfonic acid functional ligand provides a sulfonic acid functional group for the sulfometal organic framework material, the terephthalic acid can form a stable framework structure with zirconium ions, and the acid provides protons to maintain an acidic environment in the initial stage of the reaction, which can inhibit excessive hydrolysis of the zirconium source and avoid the generation of disordered zirconium-oxygen clusters.

[0054] In some embodiments of the present application, the molar ratio of the zirconium source and the sulfonic acid functional ligand is 1:0.2-0.8, preferably 1:0.2-0.4, and specifically can be 1:0.2, 1:0.3, 1:0.4, etc.; and the molar ratio of the zirconium source and the terephthalic acid is 1:0.5-0.8, preferably 1:0.6-0.8, and specifically can be 1:0.6, 1:0.7, 1:0.8, etc. In the present application, the above-mentioned ratio can further ensure that the sulfonic acid functionalized UiO-66 type metal organic framework material has sufficient sulfonic acid functional groups, so that the obtained MOF composite film has better adsorption performance. In addition, when the sulfonic acid group is modified in the internal pore of the MOF, steric hindrance is generated, which blocks the approach of water molecules to the active sites of the Zr-O bond and slows down the hydrolysis reaction rate. The sulfonic acid group itself is hydrophilic, but the hydrophobic part of the benzene ring connected thereto creates a local hydrophobic region, which can repel water molecules from entering the pore and reduce the possibility of water molecules and Zr-O bond contact, thereby stabilizing the Zr-O bond and enhancing the stability of the MOF framework.

[0055] In some embodiments of the present application, the volume ratio of the N,N-dimethylformamide and the acid is 9-11:1, and specifically can be 9:1, 10:1, 11:1, etc., and the ratio of the zirconium source to the mixed solvent is 1 mmol:26-29 mL, and specifically can be 1 mmol:26 mL, 1 mmol:27 mL, 1 mmol:27.5 mL, 1 mmol:29 mL, etc. In the present application, the above-mentioned ratio of the N,N-dimethylformamide and the acid is always, which can obtain large-size UiO-66 precursor with high yield, and lower than this ratio, the acid accounts for a high proportion, and the system is strongly acidic, which may excessively inhibit the deprotonation and coordination process of the ligand, resulting in a decrease in the yield of the product, and higher than this ratio, the acid accounts for a low proportion, and the concentration of the regulator (the anion of the acid and the ligand compete for the zirconium site, which can moderately slow down the crystal nucleation and growth rate) is insufficient, and the crystal grows too fast, which is easy to produce small-size and defect-rich crystals; the ratio of the zirconium source to the mixed solvent is moderate, which maintains a high reaction rate, and at the same time avoids agglomeration, and lower than this ratio, the solvent is excessive, the reaction concentration is low, and the reaction rate is low, and higher than this ratio, the solvent is insufficient, and the reaction may not be completely dissolved, the product uniformity is poor, and at the same time the crystal nucleation and growth are too fast, which is easy to agglomerate.

[0056] In the present application, ultrasonic is performed before the solvothermal reaction, which can make the raw material mixing and dispersion more uniform, and is beneficial to the solvothermal reaction.

[0057] In some embodiments of the present application, the solvothermal reaction is performed at 115-125℃ for 22-26 h, and specifically the temperature of the solvothermal reaction can be 115℃, 120℃, 125℃, etc., and the time of the solvothermal reaction can be 22 h, 24 h, 26 h, etc.

[0058] In some embodiments of the present application, the volume ratio of N,N-dimethylformamide to water in the N,N-dimethylformamide aqueous solution is (3-4):1. In the present application, the N,N-dimethylformamide aqueous solution washing can remove the unreacted ligand and metal salt, and the ethanol solvent replacement can replace the N,N-dimethylformamide in the channel of the precursor, which is beneficial to the later drying process. The present application does not have special limitation on the specific number of times of the N,N-dimethylformamide aqueous solution washing, which can be determined by the person skilled in the art according to the washing condition, and in the present application, the number of times of the washing is 3 times. The present application does not have special limitation on the replacement mode of the ethanol solvent, which can achieve the purpose of solvent replacement, and in the present application, the ethanol solvent replacement is performed by the ethanol washing mode, and the number of times of the washing is 3 times.

[0059] In some embodiments of the present application, the acidification is a sulfonic acid functionalized UiO-66 precursor after the ethanol solvent is replaced by washing with a 0.1 M hydrochloric acid / ethanol solution; the 0.1 M hydrochloric acid / ethanol solution is obtained by diluting 0.83 mL of concentrated hydrochloric acid (12 M) to 100 mL with ethanol. In the present application, the acidification can convert the sulfonic acid groups in the precursor from the salt form to the acid form to ensure that the sulfonic acid groups on the final UiO-66 type metal organic framework material are in the acid form, thereby selectively adsorbing rhenate.

[0060] In some embodiments of the present application, the drying is vacuum drying, the temperature of the drying is 140-160°C, and can be 140°C, 150°C, 160°C, etc., and the time of the drying is 4-8 h, and can be 4 h, 6 h, 8 h, etc. In the present application, vacuum drying can remove most of the free solvent in the surface and pores.

[0061] In some embodiments of the present application, the activation is carried out in a protective atmosphere, the temperature of the activation is 180-220°C, and can be 180°C, 200°C, 220°C, etc., and the time of the activation is 5-7 h, and can be 5 h, 6 h, 7 h, etc. In the present application, the protective atmosphere refers to a chemically inert gas such as nitrogen, argon, etc., unless otherwise specified, and in the embodiments of the present application, the protective atmosphere is a nitrogen atmosphere. In the present application, the activation in the protective atmosphere can overcome the interaction force between the solvent molecules and the pore walls, achieve complete opening of the pores, and completely remove the residual solvent.

[0062] In some embodiments of the present application, the solvent of the polyvinylidene fluoride (PVDF) solution is N,N-dimethylformamide (DMF), and the concentration of the polyvinylidene fluoride solution is 12-15 wt%. In the present application, polyvinylidene fluoride is the matrix of the composite membrane, and the MOF particles and the ionic liquid are both dispersed and embedded in the matrix. In the subsequent crosslinking process, the alkenyl functional groups in the crosslinking agent will abstract the hydrogen atoms of PVDF to form covalent bridges between the PVDF molecular chains, thereby achieving chemical crosslinking. At the above-mentioned concentration, the PVDF / DMF solution has suitable viscosity and surface tension. Below this range, the viscosity is low, the jet is easy to break, and it cannot be continuously fiberized, and the mechanical properties are poor. Above this range, the viscosity is high, the flowability is poor, and the spinning is difficult. The present application does not have special limitations on the method of obtaining the polyvinylidene fluoride solution, and any solution in which the polyvinylidene fluoride is completely dissolved can be used. In the embodiments of the present application, the polyvinylidene fluoride is dispersed in N,N-dimethylformamide, and stirring is carried out at 60°C for 6 h to obtain the solution.

[0063] In some embodiments of the present application, the amount of the sulfonic acid functionalized UiO-66 type metal organic framework material is 30-40 wt% of the amount of polyvinylidene fluoride in the polyvinylidene fluoride solution, and can be specifically 30 wt%, 35 wt%, 40 wt%, etc. In the present application, this amount range can ensure that the composite membrane has good adsorption capacity and mechanical properties at the same time. Below this range, there are insufficient adsorption sites in the membrane, and the adsorption capacity is low. Above this range, the MOF is unevenly dispersed, the fiber is prone to breakage, and the mechanical strength is low.

[0064] After obtaining the metal organic framework material dispersion, the present application mixes the metal organic framework material dispersion with a crosslinking agent to perform a crosslinking reaction, and then mixes the obtained reaction liquid with an acid-resistant ionic liquid to obtain a spinning solution. In the present application, through crosslinking, the crosslinking agent is polymerized to form a three-dimensional network structure, and is grafted with the PVDF molecular chain, further improving the acid swelling resistance and mechanical strength of the polymer matrix itself.

[0065] In some embodiments of the present application, the crosslinking agent is at least one of divinylbenzene and ethylene glycol dimethacrylate, and the amount of the crosslinking agent is 1.3-1.7 wt% of the amount of polyvinylidene fluoride in the polyvinylidene fluoride solution, and can be specifically 1.3 wt%, 1.5 wt%, 1.7 wt%, etc. In the present application, the above amount of the crosslinking agent can achieve effective crosslinking while avoiding embrittlement caused by excessive crosslinking. If the amount is too low, the crosslinking degree is insufficient, and the acid resistance improvement effect is not obvious. If the amount is too high, the membrane lacks flexibility.

[0066] In some embodiments of the present application, the crosslinking reaction is performed at room temperature, and the time of the crosslinking reaction is 25-40 min, and can be specifically 25 min, 30 min, 35 min, 40 min, etc.

[0067] In some embodiments of the present application, the acid-resistant ionic liquid is a [P 66614 66614 + ] (i.e., an ionic liquid composed of a cationic trihexyltetradecylphosphonium (P66614 - ) and an anionic triflate (OTf - )) and the amount of the acid-resistant ionic liquid is 18-22 wt% of the sulfonic acid functionalized UiO-66 type metal organic framework material, and can be specifically 18 wt%, 20 wt%, 22 wt%, etc. In the present application, the acid-resistant ionic liquid can improve the corrosion resistance of the MOF composite membrane.

[0068] After obtaining the spinning solution, the present application performs electrospinning on the spinning solution to obtain a silk membrane.

[0069] In some embodiments of the present application, the electrospinning nozzle diameter is 0.4-0.6 mm, specifically 0.4 mm, 0.5 mm, 0.6 mm, etc.; the spinning voltage is 18-22 kV, specifically 18 kV, 20 kV, 22 kV, etc.; the receiving distance is 15-18 cm, specifically 15 cm, 16 cm, 17 cm, 18 cm, etc.; the spinning solution flow rate is 0.8-1.2 mL / h, specifically 0.8 mL / h, 1.0 mL / h, 1.2 mL / h; and the thickness of the silk membrane is 140-160 μm, specifically 140 μm, 150 μm, 160 μm, etc. In the examples of the present application, the number of membrane filaments of the silk membrane is 140-160, specifically 140, 150, 160, etc.

[0070] After obtaining the silk membrane, the present application immerses the silk membrane in an amino silane coupling agent solution, and then solidifies to obtain a MOF composite membrane capable of selectively adsorbing rhenium.

[0071] In some embodiments of the present application, the amino silane coupling agent (i.e., a silane coupling agent containing an amino group) in the amino silane coupling agent solution includes at least one of 3-aminopropyl triethoxysilane and N-(β-aminoethyl)-γ-aminopropyl trimethoxysilane, and the concentration of the amino silane coupling agent solution is 1.8-2.5%, specifically 1.8%, 2.0%, 2.5%, etc.; and the solvent of the amino silane coupling agent solution is at least one of ethanol and isopropyl alcohol. The above-mentioned concentration of the amino silane coupling agent solution in the present application can ensure that the amino silane coupling agent is uniformly distributed on the silk membrane, forming sufficient amino functional groups while avoiding excessive intermolecular condensation due to high concentration.

[0072] In some embodiments of the present application, the immersion time is 25-40 min; after the immersion is completed, the immersed film is taken out for solidification; the solidification temperature is 60-80℃, specifically 60℃, 75℃, 80℃, etc.; and the solidification time is 0.8-1.2 h, specifically 0.8 h, 1.0 h, 1.2 h, etc. In the present application, 3-aminopropyl triethoxysilane is uniformly loaded on the silk membrane through immersion; during the solidification process, 3-aminopropyl triethoxysilane undergoes hydrolysis and condensation reaction, the ethoxyl group thereof reacts with water to form active silanol groups, the active silanol groups condense with the hydroxyl groups on the surface of the membrane (on the MOF metal clusters) to form silicon-oxygen surface covalent bonds, and the silanol groups also condense to form silicon-oxygen silicon structures, finally firmly grafting the amine groups on the membrane surface through covalent bonds to form an organic silicon polymer network with terminal amine groups, and the silicon-oxygen covalent bonds are relatively stable, making the membrane more resistant to acid, and the silane network on the surface of the membrane can play an additional crosslinking and supporting role to improve the mechanical strength of the membrane.

[0073] After the solidification is completed, the MOF film obtained after the solidification is preferably washed with water to remove impurities.

[0074] The application further provides the MOF composite film for selectively adsorbing rhenium prepared by the preparation method.

[0075] The application further provides the use of the MOF composite film for selectively adsorbing rhenium in the application of recovering rhenium from waste acid.

[0076] In some embodiments of the application, the use comprises the following steps:

[0077] The waste acid after the removal of the suspended substances is subjected to arsenic removal to obtain solidified arsenic residue and waste acid after arsenic removal,

[0078] The waste acid after the arsenic removal is adjusted to a pH of 1.3-1.7 and then filtered through the MOF composite film for selectively adsorbing rhenium to obtain purified acid liquid and the MOF composite film for adsorbing rhenium,

[0079] The MOF composite film for adsorbing rhenium is sequentially subjected to backwashing with acidic washing liquid, water and alkaline washing liquid to obtain rhenium-rich liquid.

[0080] In the application, the waste acid is first subjected to arsenic removal, and a small amount of residual arsenate is contained in the waste acid after the arsenic removal, while rhenium (in the form of rhenate) and most of molybdate remain in the waste acid after the arsenic removal; then the waste acid after the arsenic removal is filtered through the aforementioned MOF composite film for selectively adsorbing rhenium, so that rhenium is selectively adsorbed on the MOF composite film, the arsenate can also form neutral arsenic acid, but the molecule is too large to enter the pore channel due to the space group, the molybdate forms molybdic acid, which is easy to polymerize to form a polymer, and the size is also too large to enter the pore channel, and the hydrated ion radius of part of the metal ions is also too large to enter the pore channel, so the residual arsenate, rhenium and most of the molybdate are intercepted (among which the arsenate and the molybdate are in the concentrated liquid not filtered through the membrane (in the embodiment, a cross-flow filtration method is used)), while the sulfate and the metal cation pass through the MOF composite film with the fluid, and the purified acid liquid obtained can be used for sulfuric acid regeneration and copper and lead recovery.

[0081] The application does not have special limitations on the source and water quality of the waste acid to be treated, and conventional waste acid can be treated; in the embodiment of the application, the water quality of the waste acid to be treated is as follows: rhenium 19.4 mg / L, arsenic 3.9 g / L, sulfate 150 g / L, molybdenum 13.2 mg / L, and pH 2.1.

[0082] In some embodiments of the present application, the arsenic removal comprises the following steps: adjusting the pH of the spent acid to 3.5-4.5, then adding sodium phosphate to a concentration of 0.02-0.1 M, then adding ferric chloride solution dropwise until the arsenic concentration is less than 80 mg / L, and then filtering. In the traditional arsenic removal process without adding sodium phosphate, Fe 3+ After the addition, in addition to the generation of ferric arsenate, ferric hydroxide is also generated, and the ferric hydroxide colloid can adsorb rhenium acid radicals, resulting in the loss of rhenium. In the present application, the pH of the spent acid is first adjusted to 3.5-4.5, so that arsenic exists in the form of arsenic acid molecules, and then sodium phosphate is added first, and then ferric chloride is added, so that Fe 3+ PO4 3- Iron phosphate is generated, and iron phosphate acts as a crystal nucleus. When Fe 3+ is added again, it will gather around the iron phosphate. Fe 3+ reacts with arsenate to generate ferric arsenate and is wrapped outside the iron phosphate, forming a phosphoric acid / ferric arsenate composite precipitate, thereby avoiding the loss of rhenium.

[0083] The present application does not have special limitations on the adjustment method of the pH of the spent acid, and any desired pH can be obtained. In the embodiments of the present application, the pH of the spent acid is adjusted by adding calcium hydroxide.

[0084] In some embodiments of the present application, the concentration of the ferric chloride solution is 0.5-1.0 M, and can be 0.5 M, 0.8 M, 1.0 M, etc. In the embodiments of the present application, the ferric chloride solution is first added according to a molar ratio of iron in the ferric chloride solution to arsenic of 1.1-1.5:1 (which can be 1.1:1, 1.2:1, 1.5:1, etc.), the solution is stirred at room temperature for 30-60 min, then the arsenic content in the solution is detected, and the ferric chloride solution is added according to the arsenic content and stirred for 30-60 min. The operation is repeated (i.e., adding the ferric chloride solution-stirring for 30-60 min) until the arsenic concentration is less than 80 mg / L.

[0085] In some embodiments of the present application, the acidic washing solution is an acidic mixed aqueous solution of ethylenediaminetetraacetic acid and sodium chloride, the concentration of the ethylenediaminetetraacetic acid is 0.09-0.11 M, and can be 0.09 M, 0.1 M, 0.11 M, etc.; the concentration of the sodium chloride is 0.09-0.11 M, and can be 0.09 M, 0.1 M, 0.11 M, etc.; and the pH of the acidic mixed aqueous solution is 2-4. The present application does not have special limitations on the adjustment method of the pH of the acidic washing solution, and any conventional adjustment method can be used, such as adding sodium hydroxide, sulfuric acid, etc. In the present application, during the backwashing process of the acidic washing solution, the ethylenediaminetetraacetic acid can form a complex with a variety of metal cations, thereby stripping them from the membrane; and the sodium chloride can provide ionic strength to weaken the electrostatic interaction between the membrane and the pollutants,

[0086] In some embodiments of the present application, when backwashing is performed using water, the backwashing is to a neutral washing solution, thereby reducing damage to the membrane.

[0087] In some embodiments of the present application, the alkaline washing solution is an alkaline mixed aqueous solution of ammonium chloride and ammonia water, the concentration of the ammonium chloride is 0.09-0.11 M, specifically, 0.09 M, 0.1 M, 0.11 M, etc.; the concentration of the ammonia water is 0.09-0.11 M, specifically, 0.09 M, 0.1 M, 0.11 M, etc.; the pH of the alkaline mixed aqueous solution is 8.8-9.2, specifically, 8.8, 9.0, 9.2, etc. In the present application, backwashing of the alkaline washing solution can detach rhenate from the MOF composite membrane, thereby obtaining a rhenium-rich solution.

[0088] In the present application, backwashing is preferably performed after the MOF composite membrane selectively adsorbing rhenium is saturated with rhenium, specifically, by detecting the rhenium concentration and pH of the purified acid solution, when the rhenium concentration of the purified acid solution is greater than 5% of the rhenium concentration of the polluted acid to be filtered, it is considered that the MOF composite membrane selectively adsorbing rhenium is saturated with rhenium.

[0089] The technical solutions in the present application will be described clearly and completely below in conjunction with the embodiments. The embodiments of the present application are only examples, and all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0090] Example 1

[0091] (1) Preparation of MOF composite membrane selectively adsorbing rhenium:

[0092] ZrCl4, 2-sulfonic acid p-phthalic acid, and p-phthalic acid were added to a DMF / glacial acetic acid (10:1 v / v) mixed solvent (the ratio of ZrCl4 and the mixed solvent was 1 mmol:27.5 mL) at a molar ratio of 1:0.2:0.8, ultrasonic for 15 min until the solution was clear, then transferred to a reaction kettle, and subjected to solvothermal reaction at 120℃ for 24 h. After the reaction solution was cooled to room temperature, centrifugal separation was performed, and the obtained precipitate was the sulfonic acid functionalized UiO-66 precursor. The sulfonic acid functionalized UiO-66 type metal organic framework material was obtained by washing with DMF aqueous solution (the volume ratio of DMF and water was 3:1) and ethanol for 3 times respectively, washing with 0.1 M hydrochloric acid / ethanol solution for 2 times, and then vacuum drying at 150℃ for 6 hours, and then activating in a nitrogen atmosphere at 200℃ for 6 h.

[0093] Polyvinylidene fluoride particles were added to N,N-dimethylformamide, stirred at 60℃ for 6 h to dissolve polyvinylidene fluoride, and a polyvinylidene fluoride solution with a concentration of 12 wt% was obtained.

[0094] Sulfonic acid functionalized UiO-66 type metal organic framework material was added to the polyvinylidene fluoride solution, ultrasonically dispersed for 30 min, then divinylbenzene was added, stirred at room temperature for 30 min, then [P 66614 ][OTf] was added, stirred at room temperature for 1 h to obtain a spinning solution, wherein the amount of sulfonic acid functionalized UiO-66 type metal organic framework material was 30 wt% of the amount of polyvinylidene fluoride in the polyvinylidene fluoride solution, the amount of divinylbenzene was 1.5 wt% of the amount of polyvinylidene fluoride in the polyvinylidene fluoride solution, and the amount of [P 66614 ][OTf] was 20 wt% of the amount of sulfonic acid functionalized UiO-66 type metal organic framework material.

[0095] The spinning solution was injected into the feeding system (spinneret diameter 0.5 mm) of the electrospinning equipment, and spinning was carried out under the conditions of a spinning voltage of 18 kV, a receiving distance of 15 cm, and a spinning solution flow rate of 1 mL / h to obtain a silk film with a thickness of 150 μm and a number of 150 membrane filaments.

[0096] The silk film was immersed in a 2% APTES / ethanol solution, taken out after soaking for 30 min, placed at 60℃ for curing for 1 h, then washed with pure water to obtain a MOF composite film capable of selectively adsorbing rhenium.

[0097] (2) Arsenic removal: The waste acid generated by a certain smelting enterprise was treated, and the water quality of the waste acid was as follows: rhenium 19.4 mg / L, arsenic 3.9 g / L, sulfate 150 g / L, molybdenum 13.2 mg / L, and pH 2.1. The filtered waste acid was adjusted to pH 3.5 with calcium hydroxide, sodium phosphate was added to a concentration of 0.02 M, and a 0.5 M ferric chloride solution (wherein the molar ratio of iron to arsenic was 1.1:1) was added dropwise, while stirring at room temperature for 30 min. According to the concentration of arsenic, the ferric chloride solution was continuously added and stirred for 30 min, and the operation was repeated until the arsenic concentration was less than 80 mg / L, and then filtration was performed to obtain solidified arsenic residue and waste acid after arsenic removal.

[0098] (3) The waste acid after arsenic removal was adjusted to pH 1.5, then filtered through the MOF composite film capable of selectively adsorbing rhenium (wherein the membrane flux was 75 L / (m 2 ·h), and the water flow rate was set to 318 mL / h) to obtain purified acid and the MOF composite film capable of selectively adsorbing rhenium.

[0099] (4) After adsorption saturation, the MOF composite membrane adsorbed with rhenium is back-flushed with an acidic mixed aqueous solution of ethylenediaminetetraacetic acid and sodium chloride (the concentration of ethylenediaminetetraacetic acid is 0.1 M, the concentration of sodium chloride is 0.1 M, and the pH is 3), then back-flushed with clean water until neutral, and finally back-flushed with an alkaline mixed aqueous solution of ammonium chloride and ammonia water (the concentration of ammonium chloride is 0.1 M, the concentration of ammonia water is 0.1 M, and the pH is 9.0), at which time the back-flushing liquid is collected to obtain a rhenium-rich liquid.

[0100] Example 2

[0101] (1) Preparation of a MOF composite membrane selectively adsorbing rhenium:

[0102] ZrCl4, 2-sulfonic acid p-phthalic acid and p-phthalic acid were added to a mixed solvent of DMF / glacial acetic acid (10:1 v / v) in a molar ratio of 1:0.3:0.7 (the ratio of ZrCl4 and the mixed solvent was 1 mmol:27.5 mL), and ultrasonic treatment was performed for 15 min until the solution was clear, and then the solution was transferred to a reaction kettle for solvothermal reaction at 120°C for 24 h. After the reaction liquid was cooled to room temperature, centrifugal separation was performed, and the obtained precipitate was a sulfonic acid functionalized UiO-66 precursor. The sulfonic acid functionalized UiO-66 precursor was washed with a DMF aqueous solution (the volume ratio of DMF and water was 4:1) and ethanol for 3 times respectively, and then washed with a 0.1 M hydrochloric acid / ethanol solution for 2 times. Then, the sulfonic acid functionalized UiO-66 precursor was vacuum dried at 150°C for 6 h, and then activated at 200°C for 6 h in a nitrogen atmosphere to obtain a sulfonic acid functionalized UiO-66 type metal organic framework material.

[0103] Polyvinylidene fluoride particles were added to N,N-dimethylformamide, and stirring was performed at 60°C for 6 h to dissolve the polyvinylidene fluoride and obtain a polyvinylidene fluoride solution with a concentration of 12 wt%.

[0104] The sulfonic acid functionalized UiO-66 type metal organic framework material was added to the polyvinylidene fluoride solution, and ultrasonic dispersion was performed for 30 min. Then, divinylbenzene was added, and stirring reaction was performed at room temperature for 30 min. Then, [P 66614 ][OTf] was added, and stirring was performed at room temperature for 1 h to obtain a spinning solution. In the spinning solution, the amount of the sulfonic acid functionalized UiO-66 type metal organic framework material was 30 wt% of the amount of polyvinylidene fluoride in the polyvinylidene fluoride solution, the amount of divinylbenzene was 1.5 wt% of the amount of polyvinylidene fluoride in the polyvinylidene fluoride solution, and the amount of [P 66614 ][OTf] was 20 wt% of the amount of the sulfonic acid functionalized UiO-66 type metal organic framework material.

[0105] The spinning solution was injected into the feeding system (spinneret diameter of 0.5 mm) of the electrostatic spinning device, and spinning was performed under the conditions of a spinning voltage of 18 kV, a receiving distance of 15 cm, and a spinning solution flow rate of 1 mL / h, to obtain a silk membrane with a thickness of 150 μm and a number of membrane filaments of 150.

[0106] The silk membrane was immersed in a 2% APTES / ethanol solution, taken out after soaking for 30 min, placed at 75°C for 1 h, and then washed with pure water to obtain the MOF composite membrane for selective adsorption of rhenium.

[0107] (2) Arsenic removal: The waste acid generated by a certain smelting enterprise was treated, and the water quality of the waste acid was as follows: rhenium 19.4 mg / L, arsenic 3.9 g / L, sulfate 150 g / L, molybdenum 13.2 mg / L, and pH 2.1. The filtered waste acid was adjusted to pH 4.0 with calcium hydroxide, and sodium phosphate was added to a concentration of 0.05 M, and then a 0.8 M ferric chloride solution (with a molar ratio of iron to arsenic of 1.2:1) was added dropwise, while stirring at room temperature for 40 min. According to the concentration of arsenic, the ferric chloride solution was continuously added and stirred for 40 min, and the operation was repeated until the arsenic concentration was less than 80 mg / L, and then filtration was performed to obtain solidified arsenic residue and waste acid after arsenic removal.

[0108] (3) The waste acid after arsenic removal was adjusted to pH 1.5, and then filtered through the MOF composite membrane for selective adsorption of rhenium (wherein the membrane flux was 75 L / (m 2 ·h), and the water flow rate was set to 318 mL / h), to obtain purified acid and the MOF composite membrane for adsorption of rhenium.

[0109] (4) After adsorption saturation, the MOF composite membrane for adsorption of rhenium was back-flushed with an acidic mixed aqueous solution of ethylenediaminetetraacetic acid and sodium chloride (the concentration of ethylenediaminetetraacetic acid was 0.1 M, the concentration of sodium chloride was 0.1 M, and the pH was 3), then back-flushed with clean water to neutral, and finally back-flushed with an alkaline mixed aqueous solution of ammonium chloride and ammonia water (the concentration of ammonium chloride was 0.1 M, the concentration of ammonia water was 0.1 M, and the pH was 9.0), at which time the back-flushing liquid was collected to obtain a rhenium-rich liquid.

[0110] Example 3

[0111] (1) Preparation of the MOF composite membrane for selective adsorption of rhenium:

[0112] ZrCl4, 2-sulfonic acid p-phthalic acid, p-phthalic acid were added into DMF / glacial acetic acid (10:1 v / v) mixed solvent (the ratio of ZrCl4 and mixed solvent was 1 mmol:27.5 mL) according to the molar ratio of 1:0.4:0.6, and ultrasonic for 15 min until the solution was clear, then transferred to the reaction kettle, and carried out solvothermal reaction at 120℃ for 24 h. After the reaction solution was cooled to room temperature, centrifugal separation was carried out, and the obtained precipitate was the sulfonic acid functionalized UiO-66 precursor. Then, the sulfonic acid functionalized UiO-66 precursor was washed with DMF aqueous solution (the volume ratio of DMF and water was 4:1) and ethanol for 3 times respectively, and then washed with 0.1 M hydrochloric acid / ethanol solution for 2 times. Then, the sulfonic acid functionalized UiO-66 precursor was vacuum dried at 150℃ for 6 h, and then activated at 200℃ for 6 h in nitrogen atmosphere, to obtain the sulfonic acid functionalized UiO-66 type metal organic framework material.

[0113] The polyvinylidene fluoride particles were added into N,N-dimethylformamide, and stirred at 60℃ for 6 h to dissolve the polyvinylidene fluoride, to obtain a polyvinylidene fluoride solution with a concentration of 15 wt%.

[0114] The sulfonic acid functionalized UiO-66 type metal organic framework material was added into the polyvinylidene fluoride solution, and ultrasonic dispersed for 20 min, then di-vinyl benzene was added, and stirred at room temperature for 30 min. Then, [P 66614 ][OTf] was added, and slowly stirred at room temperature for 1 h, to obtain a spinning solution, wherein the amount of the sulfonic acid functionalized UiO-66 type metal organic framework material was 40 wt% of the amount of polyvinylidene fluoride in the polyvinylidene fluoride solution, the amount of di-vinyl benzene was 1.5 wt% of the amount of polyvinylidene fluoride in the polyvinylidene fluoride solution, and the amount of [P 66614 ][OTf] was 20 wt% of the sulfonic acid functionalized UiO-66 type metal organic framework material.

[0115] The spinning solution was injected into the feeding system (spinneret diameter was 0.5 mm) of the electrospinning equipment, and spinning was carried out under the conditions of a spinning voltage of 18 kV, a receiving distance of 15 cm, and a spinning solution flow rate of 1 mL / h, to obtain a silk film with a thickness of 150 μm and a number of 150 membrane silk.

[0116] The silk film was immersed into a 2% APTES / ethanol solution, and taken out after soaking for 30 min, and then solidified at 80℃ for 1 h. Then, the silk film was washed with pure water, to obtain a MOF composite film capable of selectively adsorbing rhenium.

[0117] (2) Arsenic removal: The waste acid produced by a smelting enterprise was treated in this example. The water quality of the waste acid was as follows: rhenium 19.4 mg / L, arsenic 3.9 g / L, sulfate 150 g / L, molybdenum 13.2 mg / L, pH 2.1. The filtered waste acid was adjusted to pH 4.5 with calcium hydroxide, and sodium phosphate was added to a concentration of 0.1 M, and then a 1.0 M ferric chloride solution (the molar ratio of iron to arsenic was 1.5:1) was added dropwise, while stirring slowly at room temperature for 60 min. According to the concentration of arsenic, the ferric chloride solution was continuously added and stirred for 60 min, and the operation was repeated until the arsenic concentration was less than 80 mg / L, and then filtration was performed to obtain solid arsenic residue and waste acid after arsenic removal.

[0118] (3) The waste acid after arsenic removal was adjusted to pH 1.5, and then filtered through the MOF composite membrane for selective adsorption of rhenium (wherein the membrane flux was 75 L / (m 2 ·h), and the water flow rate was set to 318 mL / h) to obtain purified acid and MOF composite membrane for adsorption of rhenium.

[0119] After adsorption saturation, the MOF composite membrane for adsorption of rhenium was backwashed with an acidic mixed aqueous solution of ethylenediaminetetraacetic acid and sodium chloride (the concentration of ethylenediaminetetraacetic acid was 0.1 M, the concentration of sodium chloride was 0.1 M, and the pH was 3), then backwashed with clean water to neutral, and finally backwashed with an alkaline mixed aqueous solution of ammonium chloride and ammonia water (the concentration of ammonium chloride was 0.1 M, the concentration of ammonia water was 0.1 M, and the pH was 9.0). At this time, the backwash liquid was collected to obtain a rhenium-rich liquid.

[0120] Comparative Example 1

[0121] The MOF composite membrane for selective adsorption of rhenium was prepared by the method of Example 1, and the membrane was used to treat the same waste acid, with the only difference being that no sodium phosphate was added in the arsenic removal stage.

[0122] Comparative Example 2

[0123] The MOF composite membrane for selective adsorption of rhenium was prepared by the method of Example 1, and the membrane was used to treat the same waste acid, with the only difference being that the molar ratio of ZrCl4, 2-sulfonic acid p-phthalic acid, and p-phthalic acid was 1:0.1:1.

[0124] Comparative Example 3

[0125] The MOF composite membrane for selective adsorption of rhenium was prepared by the method of Example 1, and the membrane was used to treat the same waste acid, with the only difference being that no ionic liquid was added when preparing the MOF composite membrane for selective adsorption of rhenium.

[0126] Comparative Example 4

[0127] The MOF composite membrane for selectively adsorbing rhenium was prepared by the method of Example 1, and the membrane was used to treat the same waste acid, with the only difference being that the arsenic removal step was not performed.

[0128] The concentrations of arsenic and rhenium in the waste acid before and after the arsenic removal step in Examples 1-3 and Comparative Examples 1-4 were tested by inductively coupled plasma optical emission spectrometry (ICP-OES), and the removal rates of arsenic and rhenium in the arsenic removal step were calculated, with the results shown in Table 1.

[0129] The concentrations of molybdenum, sulfate and rhenium in the waste acid before and after filtration by the MOF composite membrane for selectively adsorbing rhenium were tested by ICP-OES, and the membrane permeation rates of molybdenum, sulfate and rhenium were calculated, with the results shown in Table 1.

[0130] Table 1 Effects of the arsenic removal step and the MOF composite membrane filtration step in Examples 1-3 and Comparative Examples 1-4

[0131]

[0132] As can be seen from Table 1, the arsenic removal rates in the arsenic removal steps in Examples 1-4 were all higher than 98%, and the removal rate of rhenium in Comparative Example 1, in which no sodium phosphate was added in the arsenic removal step, was obviously improved, indicating that iron has an adsorption effect on rhenium. As can be seen from the membrane permeation rates of molybdenum, sulfate and rhenium in Table 1, the membrane permeation rate of rhenium in Examples 1-3 was 1.1-3.6%, indicating that rhenium remained in the membrane and thus was enriched. In Comparative Example 2, the amount of sulfonic acid functional ligand was small, and the membrane permeation rate of rhenium increased, indicating that the reduction of sulfonic acid groups reduced the adsorption of rhenium. In Comparative Example 3, no ionic liquid was added, and the membrane permeation rate of rhenium was high, because the protection of the acid-resistant ionic liquid on the pore channel was lacking, and the acid in the waste acid corroded the membrane. In Comparative Example 4, no arsenic removal step was performed, and the membrane permeation rate of rhenium was the highest, because the waste acid contained a high content of arsenic, and arsenic and rhenium had competitive adsorption.

[0133] The MOF composite membranes for selectively adsorbing rhenium obtained in Examples 1-3 were used to continuously filter the waste acid after the arsenic removal step (according to step (3)) for 500 h, and the membrane permeation rates of molybdenum, sulfate and rhenium were determined, with the results shown in Table 2.

[0134] Table 2 Ion membrane permeation rates of the MOF composite membranes for selectively adsorbing rhenium obtained in Examples 1-3 after continuous operation for 500 h

[0135]

[0136] As shown in Table 2, after the MOF composite membrane for selectively adsorbing rhenium is continuously operated for 500 h, the permeation rate of rhenium slightly increases by 1.6-2.9%, the permeation rate of sulfate is always higher than 95%, and the permeation rate of molybdenum increases by 2.3-3.1%. It is indicated that the MOF composite membrane for selectively adsorbing rhenium provided by the application has excellent stability.

[0137] In the examples, in order to observe the backwashing efficiency, the elution rate of rhenium is determined after backwashing once every 100 h, and the results are shown in Table 3.

[0138] Table 3 Elution rate of rhenium of the MOF composite membrane for selectively adsorbing rhenium obtained in Examples 1-3

[0139]

[0140] According to the data recorded in Table 3, it is known that the method of the application can sufficiently elute rhenate from the composite membrane, so as to be recovered.

[0141] According to the elution rate of rhenium and the total amount of addition, the recovery rate of rhenium is calculated, and the results are shown in Table 4.

[0142] Table 4 Recovery rate of rhenium of the MOF composite membrane for selectively adsorbing rhenium obtained in Examples 1-3

[0143]

[0144] As shown in Table 4, the MOF composite membrane for selectively adsorbing rhenium provided by the application can recover more than 91% of rhenium.

[0145] Although the preferred embodiments of the application have been shown and described, it is to be understood that various modifications can be made by those skilled in the art without departing from the spirit and scope of the application as defined in the appended claims.

Claims

1. A method for preparing a MOF composite membrane capable of selectively adsorbing rhenium, comprising the following steps: dispersing a sulfonic acid functionalized UiO-66 type metal organic framework material in a polyvinylidene fluoride solution to obtain a metal organic framework material dispersion, mixing the metal organic framework material dispersion with a crosslinking agent to perform a crosslinking reaction, and then mixing the obtained reaction solution with an acid-resistant ionic liquid to obtain a spinning solution, performing electrospinning on the spinning solution to obtain a silk membrane, immersing the silk membrane in an amino silane coupling agent solution, and then performing solidification to obtain the MOF composite membrane capable of selectively adsorbing rhenium, wherein, The crosslinking agent is at least one of divinylbenzene and ethylene glycol dimethacrylate; the acid-resistant ionic liquid is [P 66614 ][OTf].

2. The production method according to claim 1, characterized by, the sulfonic acid functionalized UiO-66 type metal organic framework material is prepared by a method comprising the following steps: adding a zirconium source, a sulfonic acid functional ligand and terephthalic acid into a mixed solvent of N,N-dimethylformamide and acid, performing ultrasonic for 15-20 min, and then performing a solvothermal reaction, and then performing solid-liquid separation on the obtained reaction solution to obtain a sulfonic acid functionalized UiO-66 precursor, sequentially performing N,N-dimethylformamide aqueous solution washing, ethanol solvent replacement and acidification on the sulfonic acid functionalized UiO-66 precursor, and then performing drying and activation to obtain the sulfonic acid functionalized UiO-66 type metal organic framework material.

3. The preparation method according to claim 2, characterized in that, the zirconium source is at least one of ZrCl4, ZrOCl4 and Zr(NO3)4, the sulfonic acid functional ligand is at least one of 2-sulfonic acid terephthalic acid and 2-sulfonic acid sodium terephthalate, and the acid is at least one of glacial acetic acid, formic acid, hydrochloric acid and benzoic acid, the molar ratio of the zirconium source and the sulfonic acid functional ligand is 1:0.2-0.8, and the molar ratio of the zirconium source and terephthalic acid is 1:0.5-0.8, the volume ratio of N,N-dimethylformamide and acid is 9-11:1, and the ratio of the zirconium source to the mixed solvent is 1 mmol:26-29 mL, the solvothermal reaction is performed at 115-125℃ for 22-26 h.

4. The preparation method according to claim 2, characterized in that, the volume ratio of N,N-dimethylformamide and water in the N,N-dimethylformamide aqueous solution is (3-4):1, the acidification is washing the sulfonic acid functionalized UiO-66 precursor after ethanol solvent replacement with a 0.1 M hydrochloric acid / ethanol solution, the drying is vacuum drying, the temperature of the drying is 140-160℃, and the time is 4-8 h, the activation is performed in a protective atmosphere, the temperature of the activation is 180-220℃, and the time is 5-7 h.

5. The production method according to claim 1, characterized by, the solvent of the polyvinylidene fluoride solution is N,N-dimethylformamide, and the concentration of the polyvinylidene fluoride solution is 12-15 wt%, the amount of the sulfonic acid functionalized UiO-66 type metal organic framework material is 30-40 wt% of the amount of polyvinylidene fluoride in the polyvinylidene fluoride solution, the amount of the crosslinking agent is 1.3-1.7 wt% of the amount of polyvinylidene fluoride in the polyvinylidene fluoride solution, the crosslinking reaction is performed at room temperature, and the time of the crosslinking reaction is 25-40 min, The amount of the acid-resistant ionic liquid is 18-22 wt% of the sulfonic acid functionalized UiO-66 type metal organic framework material.

6. The production method according to claim 1, characterized by, The electrospinning nozzle diameter is 0.4-0.6 mm, the spinning voltage is 18-22 kV, the receiving distance is 15-18 cm, the spinning liquid flow rate is 0.8-1.2 mL / h, and the thickness of the silk membrane is 140-160 μm, The amino silane coupling agent in the amino silane coupling agent solution includes at least one of 3-aminopropyl triethoxysilane and N-(β-aminoethyl)-γ-aminopropyl trimethoxysilane, the concentration of the amino silane coupling agent solution is 1.8-2.5 wt%, the solvent of the 3-aminopropyl triethoxysilane solution is at least one of ethanol and isopropyl alcohol, The impregnation time is 25-40 min, and the curing temperature is 60-80℃ for 0.8-1.2 h.

7. A MOF composite membrane capable of selectively adsorbing rhenium, prepared by the preparation method of any one of claims 1-6.

8. Use of the MOF composite membrane capable of selectively adsorbing rhenium of claim 7 in recovering rhenium from waste acid.

9. Use according to claim 8, characterized in that, The use comprises the following steps: The waste acid after removing the suspended solids is subjected to arsenic removal to obtain a solidified arsenic residue and waste acid after arsenic removal, The waste acid after arsenic removal is adjusted to a pH of 1.3-1.7 and then filtered through the MOF composite membrane capable of selectively adsorbing rhenium to obtain purified acid liquid and the MOF composite membrane adsorbed with rhenium, The MOF composite membrane adsorbed with rhenium is sequentially backwashed with an acidic washing solution, water and an alkaline washing solution to obtain a rhenium-rich liquid.

10. Use according to claim 9, characterized in that, The arsenic removal comprises the following steps: adjusting the pH of the waste acid to 3.5-4.5, then adding sodium phosphate to a concentration of 0.02-0.1 M, then adding a ferric chloride solution dropwise until the arsenic concentration is less than 80 mg / L, and then filtering; wherein the concentration of the ferric chloride solution is 0.5-1.0 M; The acidic washing solution is an acidic mixed aqueous solution of ethylenediaminetetraacetic acid and sodium chloride, the concentration of the ethylenediaminetetraacetic acid is 0.09-0.11 M, the concentration of the sodium chloride is 0.09-0.11 M, and the pH of the acidic mixed aqueous solution is 2-4, When water is used for backwashing, the backwashing is performed until the washing liquid is neutral, The alkaline washing solution is an alkaline mixed aqueous solution of ammonium chloride and ammonia water, the concentration of the ammonium chloride is 0.09-0.11 M, the concentration of the ammonia water is 0.09-0.11 M, and the pH of the alkaline mixed aqueous solution is 8.8-9.2.

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