Metal complex anion extraction membranes based on polymeric extractants, preparation and use

Abstract

The application discloses a metal complex anion extraction membrane based on a polymer extractant, preparation and application, and comprises the following steps: preparing a quaternary ammonium salt type ionic liquid polymer extractant, mixing a polymer, a tertiary amine organic matter and a solvent, refluxing, sedimentation, cleaning, suction filtration and vacuum drying to obtain the quaternary ammonium salt type ionic liquid polymer extractant; preparing a metal complex anion extraction membrane, mixing the polymer extractant, a plasticizer and an organic solvent, pouring the solution into a flat-bottomed container, removing the solvent by volatilization to form a film, and acidifying the film in a hydrochloric acid solution to obtain the metal complex anion extraction membrane. The metal complex anion in a solution is extracted and selectively separated by the extraction membrane under an operating voltage or without an electric condition. The method has the advantages of small environmental pollution, high transmission rate, high removal rate and high membrane extraction efficiency, and the membrane phase is not leaked, and is a high-stability membrane product with high mass transfer performance for the metal complex anion and a separation method.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of material chemical industry, hydrometallurgy and wastewater treatment, and relates to a kind of synthesis of quaternary ammonium salt type polymer extractant, preparation of metal complex anion extraction membrane and application of metal complex anion membrane extraction. BACKGROUND

[0002] Membrane extraction technology with simultaneous extraction and stripping has attracted much attention in the field of separation due to its high selectivity, greenness and energy saving. Compared with supported liquid membranes, polymer inclusion membranes (PIMs) have advantages of less carrier dosage and reusability, and thus become the most promising membrane extraction material. Traditional PIMs are prepared from a homogeneous solution of base polymer, extractant and plasticizer by phase inversion. The carrier is only fixed by non-bonding interactions such as van der Waals forces or hydrogen bonds between the carrier and the base polymer. Mechanical disturbance and water phase erosion can accelerate the loss of membrane phase carrier and lead to the decrease of membrane efficiency. Therefore, high-stability membrane extraction materials have been a bottleneck restricting the industrial application of membrane extraction technology.

[0003] Polymer blending, matrix modification or introduction of new components to regulate membrane structure are the research hotspots in recent years to improve the stability of PIMs. Copolymers such as PVDF-HFP and SBS, and polymers with high polarity such as PVDF and PSF have been tried to replace weakly polar polymers such as PVC and CTA. PIMs with polymer semi-interpenetrating crosslinked network structure and inorganic nanoparticle doping have also shown some beneficial effects. Due to the non-bonding interactions between the carrier and the base polymer in traditional PIMs, some modification techniques of existing PIMs are difficult to simultaneously consider mass transfer rate and stability, and even lead to the decrease of selectivity. However, there is no report on membrane extraction materials with fixed carrier so far. SUMMARY

[0004] To solve the problems of instability of existing membrane extraction materials, slow mass transfer rate of membrane extraction system and easy leakage of carrier, the present application provides a preparation method of high-stability membrane extraction material and a corresponding metal complex anion extraction membrane system, which provides an efficient and highly selective extraction process for heavy metal wastewater treatment.

[0005] The present application is realized by the following technical solutions.

[0006] According to one aspect of the present application, a method for preparing a metal complex anion extraction membrane based on a polymer extractant is provided, comprising the following steps:

[0007] Step 1: Preparation of quaternary ammonium salt type ionic liquid polymer extractant:

[0008] Mixing 8%~12% polymer, 20%~46% tertiary amine organic matter and 46%~70% solvent according to mass ratio; homogenous reflux reaction, reducing to normal temperature, adding anhydrous ethanol to precipitate, precipitate is washed with anhydrous ethanol for several times, suction filtration, and drying under reduced pressure to obtain quaternary ammonium salt type ionic liquid polymer extractant;

[0009] Step 2, preparation of metal complex anion extraction membrane:

[0010] Mixing 1~3% polymer extractant, 0.5~1% plasticizer and 96~98.5% organic solvent according to mass ratio, stirring to form a homogeneous solution, pouring the solution into a flat container to volatilize the solvent and form a film; acidifying the film in hydrochloric acid solution to obtain a metal complex anion extraction membrane.

[0011] According to the exemplary embodiments of the present application, the polymer is high molecular weight polyvinyl chloride with a molecular weight greater than 72,000 and a polymerization degree less than 2,500;

[0012] The tertiary amine organic matter is one or a combination of two or more of tri-n-octylamine, tri-n-butylamine, triethylamine and tripropylamine;

[0013] The solvent is one or a mixture of two or more of N,N-dimethylacetamide, N,N-dimethylformamide, dimethyl sulfoxide, N-methyl pyrrolidone and dioxane;

[0014] The plasticizer is one or a mixture of two or more of dioctyl phthalate, carbon dodecanoic acid, 2-nitrophenyl ether and dibutyl phthalate;

[0015] The organic solvent is tetrahydrofuran or N,N-dimethylacetamide.

[0016] According to the exemplary embodiments of the present application, in step 1, the solvent is mixed and homogenous reflux reaction is carried out at 50~90℃ for 24~72h;

[0017] In step 2, the thickness of the film material is 45~250μm; and the concentration of the hydrochloric acid solution is 0.1mol / L.

[0018] According to another aspect of the present application, a metal complex anion extraction membrane prepared by the method is provided.

[0019] According to still another aspect of the present application, an application of the metal complex anion extraction membrane to separate and extract metal complex anions is provided, which comprises:

[0020] The metal complex anion extraction membrane is installed in a membrane extraction device to separate a feed liquid phase containing metal complex anions and an elution phase, and the material components in the two-phase solution remain homogeneous;

[0021] The metal complex anion in the feed solution phase is in the form of HCrO4 + or Cl - ion-containing metal complex anion solution;

[0022] The mass transfer reaction is carried out by placing the cathode platinum wire in the feed solution phase and the anode platinum wire in the resolving phase under an external electric field with an operating voltage of 10-40 V, or without applying electricity, and continuously stirring the feed solution phase and the resolving phase respectively.

[0023] According to the exemplary embodiments of the present application, the pH value and Cl - concentration of the feed solution phase are adjusted by using 1-4 M hydrochloric acid and NaCl solution, and the feed solution phase is in the form of HCrO4 - , CdCl3 - , CoCl4 2- , FeCl4 - , CuCl4 2 .

[0024] According to the exemplary embodiments of the present application, the hydrogen ion concentration in the Cr(Ⅵ)-containing solution is 0.05-0.1 mol / L;

[0025] The Cl ion concentration in the Cd(II)-containing solution is 0.4-0.5 mol / L;

[0026] The Cl ion concentration in the Co(II)-containing solution is 6-7 mol / L;

[0027] The Cl ion concentration in the Fe(III)-containing solution is 6-7 mol / L;

[0028] The Cl ion concentration in the Cu(II)-containing solution is 5-7 mol / L.

[0029] According to the exemplary embodiments of the present application, the resolving phase is in the form of sodium hydroxide solution, disodium ethylenediaminetetraacetate solution, hydrochloric acid solution and ammonium acetate solution.

[0030] According to the exemplary embodiments of the present application, the concentration of the sodium hydroxide solution is 0.05-0.2 mol / L;

[0031] The concentration of the disodium ethylenediaminetetraacetate solution is 5×10 -3 -0.01 mol / L;

[0032] The concentration of the hydrochloric acid solution is 0.05-1 mol / L;

[0033] The concentration of the ammonium acetate solution is 0.5-1 mol / L.

[0034] According to the example embodiment of the present application, the stirring speed in the two-phase solution is 300-500 rpm and is kept constant; the continuous stirring reaction time is 5-30 h.

[0035] The tertiary amine and the polyvinyl chloride are synthesized into trialkyl polyvinyl chloride ammonium through nucleophilic substitution reaction, and the trialkyl polyvinyl chloride ammonium is homogeneously formed into a film with or without a plasticizer, and after acidification, an extraction film for extracting and separating specific metal complex anions in a complex water body can be obtained.

[0036] The present application has the following beneficial effects due to the above technical scheme:

[0037] (1) The present application prepares a quaternary ammonium salt type ionic liquid polymer extractant (triallyl polyvinyl chloride ammonium), which is synthesized through a heating reflux homogeneous reaction, has low equipment requirement, simple operation and low cost.

[0038] (2) The metal complex anion extraction film provided by the present application has good mass transfer performance in removing, extracting or separating five kinds of metal anions Cr(Ⅵ), Cd(II), Co(II), Fe(Ⅲ) and Cu(II). The preparation of the film product and the film extraction operation process are simple and easy to operate, the reagent consumption is small, the environmental pollution is small, the transmission rate is fast, and the requirements of high efficiency, energy saving and environmental protection are met.

[0039] (3) The metal complex anion extraction film provided by the present application can be coupled with an external electric field for film extraction, which can accelerate extraction through an electric field. It has good application potential in the fields of environmental protection and hydrometallurgy.

[0040] (4) The present application first studies a carrier-bonding type film extraction system represented by trialkyl polyvinyl chloride ammonium, which provides a new way for industrial application of film extraction technology due to its excellent stability. BRIEF DESCRIPTION OF DRAWINGS

[0041] The drawings described herein are used to provide further understanding of the present application, constitute a part of the present application, and do not constitute an improper limitation on the present application, and in the drawings:

[0042] Figure 1 is a Co(II) anion film extraction diagram of the extraction film prepared in Example 1 of the present application;

[0043] Figure 2 is a Fe(Ⅲ) anion film extraction diagram of the extraction film prepared in Example 2 of the present application;

[0044] Figure 3 is a Cu(II) anion film extraction diagram of the extraction film prepared in Example 3 of the present application;

[0045] Figure 4is the membrane extraction and external electric field coupling membrane extraction diagram of the extraction membrane prepared from Example 4 of the present application to Cr(Ⅵ);

[0046] Figure 5 is the membrane extraction and external electric field coupling membrane extraction diagram of the extraction membrane prepared from Example 5 of the present application to Cd(II). DETAILED DESCRIPTION

[0047] The present application will be described in detail below with reference to the accompanying drawings and specific examples, which are used to explain the present application but not to limit the present application.

[0048] The present application provides a preparation method of metal complex anion extraction membrane based on polymer extractant, comprising the following steps:

[0049] Step 1, preparation of quaternary ammonium salt type ionic liquid polymer extractant:

[0050] According to the mass ratio, 8% to 12% of polyvinyl chloride, 20% to 46% of tertiary amine organic matter and 46% to 70% of solvent are mixed, and the total of the above raw materials is 100%; heated to reflux at 50 to 90℃, homogeneous phase reaction for 24 to 72h, then reduced to room temperature, the mixture is added with anhydrous ethanol for precipitation, the precipitate is repeatedly washed with anhydrous ethanol for several times to remove excess small molecule tertiary amine, and then filtered and dried to obtain the corresponding trialkyl polyvinyl ammonium polymer extractant.

[0051] The above polymer is polyvinyl chloride with an average molecular weight greater than 72,000 and a polymerization degree less than 2,500.

[0052] The above tertiary amine organic matter is one or a combination of two or more of tri-n-octylamine, tri-n-butylamine, triethylamine and tripropylamine.

[0053] The above synthesis solvent is one or a mixture of two or more of N,N-dimethylacetamide, N,N-dimethylformamide, dimethyl sulfoxide, N-methyl pyrrolidone and dioxane.

[0054] Step 2, preparation of metal complex anion extraction membrane:

[0055] 1) according to the mass ratio, 1 to 3% of polymer extractant, 0.5 to 1% of plasticizer and 96 to 98.5% of organic solvent are mixed to form a homogeneous solution, the solution is poured into a flat-bottomed container and the solvent is volatilized to form a film; the film is placed in a hydrochloric acid solution for acidification, and the metal complex anion extraction membrane is obtained.

[0056] The polymer extractant is trialkyl polyvinyl ammonium.

[0057] The plasticizer is one of dioctyl phthalate, carbon dodecanoic acid, 2-nitrophenyl ether and dibutyl phthalate or a mixture of two.

[0058] The organic solvent is tetrahydrofuran or N,N-dimethylacetamide.

[0059] 2) Dissolved into a homogeneous solution at room temperature, horizontally placed in a flat-bottomed vessel, and the solvent was completely volatilized at 30°C or 60°C under normal pressure, and solidified into a flat, homogeneous, transparent and uniform thickness, to obtain an extraction film of five metal anions of Cr(Ⅵ), Cd(II), Co(II), Fe(Ⅲ) and Cu(II), which was then acidified and transformed by 0.1M hydrochloric acid.

[0060] The application also provides an application of a metal complex anion extraction film based on a quaternary ammonium salt type ionic liquid polymer extractant. The metal complex anions that can be separated or extracted by the film extraction include but are not limited to Cr(Ⅵ), Cd(II), Co(II), Fe(Ⅲ) and Cu(II) metal complex anions.

[0061] The method for separating and extracting metal complex anions by film extraction is a method without electricity, including the following steps:

[0062] The obtained extraction film is installed in a film extraction device, and a feed liquid phase and a stripping phase of the metal ions to be separated are separated, so that the separated ions can only cross the membrane mass transfer in the two-phase solution through the membrane interface, and the stirring speed of the two-phase solution is kept consistent by an electric stirring device with a stirring speed of 300-500rmp during the separation process; the material composition in the two-phase solution is kept homogeneous to ensure the balance of the two-phase materials, and the continuous stirring reaction time is 9-30h, until the mass transfer is terminated when the ion concentration in the feed liquid phase has no obvious change. During the mass transfer process, 0.5mL of sample is taken from the feed liquid phase and the stripping phase solution every 1-3h, and 0.5mL of corresponding acid and alkali buffer solution is added to the two phases.

[0063] The ion concentrations in the two phases during the mass transfer process are detected by ultraviolet-visible spectrophotometry and inductively coupled plasma emission spectrometry.

[0064] The feed liquid phase is adjusted to a pH value and a Cl - concentration by 1-4M hydrochloric acid and NaCl solution to keep the metal complex anions in the form of HCrO4 - , CdCl3 - , CoCl4 2- , FeCl4 - , CuCl4 2-The feed phase includes a Cr(Ⅵ)-containing solution with a hydrogen ion concentration of 0.05-0.1 mol / L, a Cd(II)-containing solution with a chloride ion concentration of 0.4-0.5 mol / L, a Co(II)-containing solution with a chloride ion concentration of 6-7 mol / L, a Fe(III)-containing solution with a chloride ion concentration of 6-7 mol / L, and a Cu(II)-containing solution with a chloride ion concentration of 5-7 mol / L.

[0065] The resolving phase includes 0.05-0.2 mol / L sodium hydroxide solution, 5×10 -3 -0.01 mol / L disodium ethylenediaminetetraacetate solution, 0.05-1 mol / L hydrochloric acid solution, and 0.5-1 mol / L ammonium acetate solution.

[0066] Another method for extracting metal complex anions by membrane extraction is to couple the membrane extraction process with an external electric field:

[0067] In the membrane extraction process coupled with an external electric field, the cathode platinum wire is placed in the feed phase, and the anode platinum wire is placed in the resolving phase. The electric field is provided by a direct-current stabilized power supply. The voltage and the terminal current density I are obtained by a process-controlled adjustable stabilized power supply (HSPY-60-02, Beijing Han Sheng Pu Yuan Technology). The operating voltage in the membrane extraction process coupled with an external electric field is 10-40 V. The sampling and detection operations are the same as those in the method without an electric field.

[0068] The content of the quaternary ammonium functional group in the synthesized polymer extractant is between 10-25 wt.%.

[0069] The metal complex anions that can be separated or extracted by the membrane extraction include, but are not limited to, Cr(Ⅵ), Cd(II), Co(II), Fe(III), Cu(II), and the like.

[0070] The concentration of the metal complex anion to be separated in the feed phase is in the range of 12-150 mg / L, and the mass transfer permeability coefficient is in the range of 2.75 μm·s -1 -16.80 μm·s -1 .

[0071] The application will be further described below by different examples.

[0072] Example 1: Membrane extraction of Co(II) in an aqueous solution

[0073] Step 1: Preparation of a quaternary ammonium salt type ionic liquid polymer extractant:

[0074] Mix 8.14% of polyvinyl chloride, 46.09% of tri-n-octylamine and 45.77% of solvent N, N-dimethylacetamide according to the mass ratio, heat to reflux at 70°C, homogeneously react for 48 hours, then reduce to room temperature, add the mixture into anhydrous ethanol for precipitation, repeatedly wash the precipitate with anhydrous ethanol for several times to remove the excess tri-n-octylamine, then perform suction filtration and reduce pressure drying to obtain the product tri-octyl polyvinyl chloride ammonium.

[0075] Step 2, preparation of the extraction film for Co(II) metal anion:

[0076] Mix 1.97% of tri-octyl polyvinyl chloride ammonium, 0.87% of dodecanoic acid and 97.16% of organic solvent tetrahydrofuran according to the mass ratio, dissolve into a homogeneous solution at room temperature, horizontally place in a flat-bottomed vessel, volatilize the solvent completely at 30°C under normal pressure, solidify into a flat, homogeneous, transparent and uniform thickness, to obtain a Co(II) anion extraction film with a thickness of 150 μm, and then acidize and transform.

[0077] Membrane extraction separation method for extracting metal complex anion: extraction method without electricity.

[0078] The prepared Co(II) metal anion extraction film is sealed with hollow clamps and polytetrafluoroethylene gaskets, screws and the like, and then assembled with two 250 mL liquid pools, and the effective mass transfer area of the film is 26.4 cm 2 .

[0079] Put a 250 mL solution containing 25 mg / L of Co(II) and 7 mol / L of hydrochloric acid into the feed liquid phase, and at the same time, fill 250 mL of 0.05 M hydrochloric acid solution into the stripping pool, start the mass transfer by starting the magnetic stirring devices with a rotation speed of 300 rpm on both sides, and after 30 hours of continuous extraction, the removal rate of Co(II) in the feed liquid phase is 91.89%, and the recovery rate of Co(II) in the stripping phase reaches 88.74%. The anion membrane extraction is shown in Figure 1 .

[0080] Example 2: membrane extraction of Fe(III) in aqueous solution

[0081] Step 1, preparation of quaternary ammonium salt type ionic liquid polymer extractant:

[0082] Mix 11.97% of polyvinyl chloride, 20.14% of tri-n-butylamine and 67.89% of solvent N, N-dimethylformamide according to the mass ratio, heat to reflux at 60°C, homogeneously react for 24 hours, then reduce to room temperature, add the mixture into anhydrous ethanol for precipitation, repeatedly wash the precipitate with anhydrous ethanol for several times to remove the excess tri-n-butylamine, then perform suction filtration and reduce pressure drying to obtain the product tri-butyl polyvinyl chloride ammonium.

[0083] Step 2, preparation of the extraction film for Fe(III) metal anion:

[0084] Mix 1.02% of tributyl polyvinyl chloride ammonium, 0.98% of dioctyl phthalate, 98.00% of organic solvent N,N-dimethylacetamide according to the mass ratio, dissolve into a homogeneous solution at room temperature, horizontally stand in a flat-bottomed vessel, completely volatilize the solvent at 60°C under normal pressure, solidify into a flat, homogeneous, transparent and uniform thickness, obtain Fe(III) anion extraction film with a thickness of 50μm, and then acidize and transform.

[0085] Metal complex anion extraction film extraction method: extraction method without external electric field.

[0086] Put 250mL solution containing 25mg / L Fe(III) and 7mol / L hydrochloric acid in the feed solution phase, fill 250mL 0.05M hydrochloric acid solution in the stripping tank, start mass transfer by starting the magnetic stirring device with a rotating speed of 400rmp in both tanks, after 20h continuous extraction, the removal rate of Fe(III) in the feed solution phase is 98.72%, and the recovery rate of Fe(III) in the stripping phase reaches 95.52%. The anion film extraction is shown in Figure 2 .

[0087] Example 3: Cu(II) film extraction in aqueous solution

[0088] Step 1, preparation of quaternary ammonium salt type ionic liquid polymer extractant:

[0089] Mix 9.00% of polyvinyl chloride, 21.12% of triethylamine and 69.88% of solvent dimethyl sulfoxide + dioxane according to the mass ratio, heat under reflux at 50°C, after 72h homogeneous reaction, reduce to room temperature, add anhydrous ethanol to the mixture for precipitation, repeatedly wash the precipitate with anhydrous ethanol for several times to remove excess triethylamine, extract by suction, and dry under reduced pressure to obtain the product triethyl polyvinyl chloride ammonium.

[0090] Step 2, preparation of extraction film for Cu(II) metal anion:

[0091] Mix 2.98% of trioctyl polyvinyl chloride ammonium, 0.52% of 2-nitrophenyl octyl ether, 96.5% of organic solvent N,N-dimethylacetamide according to the mass ratio, stir into a homogeneous solution, pour the solution into a flat-bottomed container, horizontally stand in a flat-bottomed vessel, completely volatilize the solvent at 60°C under normal pressure, solidify into a flat, homogeneous, transparent and uniform thickness, obtain Cu(II) anion extraction film with a thickness of 100μm, and then acidize and transform.

[0092] Extraction of metal complex anion by film extraction without external electric field:

[0093] A 250 mL solution containing Cu(II) 25 mg / L and 6 mol / L hydrochloric acid was placed in the feed solution phase, while 250 mL of 0.5 M ammonium acetate solution was filled in the stripping cell, and the magnetic stirring device with a rotating speed of 500 rpm on both sides of the cell was started to begin mass transfer. After 20 h of continuous extraction, the removal rate of Cu(II) in the feed solution phase was 100%, and the recovery rate of Cu(II) in the stripping phase reached 93.02%. The anion membrane extraction is shown in Figure 3 .

[0094] Example 4: Membrane extraction of Cr(Ⅵ) in aqueous solution and external electric field coupled membrane extraction

[0095] Step 1: Preparation of quaternary ammonium salt type ionic liquid polymer extractant:

[0096] According to the mass ratio, 10.35% of polyvinyl chloride, 37.00% of triethylamine + tripropylamine and 52.65% of solvent N-methylpyrrolidone were mixed and heated to reflux at 90°C. After 24 h of homogeneous reaction, the temperature was lowered to room temperature, the mixture was added with anhydrous ethanol for precipitation, and the precipitate was repeatedly washed with anhydrous ethanol to remove excess triethylamine + tripropylamine. After suction filtration and drying under reduced pressure, the product trialkyl polyvinyl ammonium chloride was obtained.

[0097] In step 2, the extraction membrane for Cr(Ⅵ) metal anion was prepared:

[0098] According to the mass ratio, 1.0% of triethylamine + tripropylamine, 0.5% of dibutyl phthalate and 98.5% of organic solvent tetrahydrofuran were mixed to form a homogeneous solution at room temperature. The solution was placed horizontally in a flat-bottomed vessel and the solvent was completely volatilized at 30°C and normal pressure to form a flat, homogeneous, transparent and uniform thickness of 250 μm. The Cr(Ⅵ) anion extraction membrane was obtained, and then acidification and transformation were carried out.

[0099] The metal complex anion was extracted by the external electric field coupled membrane extraction process:

[0100] A 250 mL solution containing Cr(Ⅵ) 12 mg / L and 0.05 mol / L hydrochloric acid was placed in the feed solution phase, while 250 mL of 0.2 M sodium hydroxide solution was filled in the stripping cell, and the magnetic stirring device with a rotating speed of 450 rpm on both sides of the cell was started to begin mass transfer. After 9 h of continuous extraction, the removal rate of Cr(Ⅵ) in the feed solution phase was 100%, and the recovery rate of Cr(Ⅵ) in the stripping phase reached 58.06%.

[0101] The newly added external electric field coupling membrane extraction voltage is 40V, and the operation steps are as follows: during the membrane extraction process, the cathode platinum wire is placed in the feed liquid phase, the anode platinum wire is placed in the stripping phase, and the electric field is provided by a direct current stabilized power supply. After 5 hours of continuous electrically driven membrane extraction, the removal rate of Cr (VI) in the feed liquid phase is 100%, and the recovery rate of Cr (VI) in the stripping phase is increased to 77.16%. It can be seen that the electric field accelerates the membrane extraction. The anion membrane extraction is shown in Figure 4 .

[0102] Example 5: Membrane extraction of Cd (II) in aqueous solution and external electric field coupling membrane extraction

[0103] Step 1, preparation of quaternary ammonium salt type ionic liquid polymer extractant:

[0104] According to the mass ratio, 11.42% of polyvinyl chloride, 32.32% of tri-n-octylamine and 56.26% of solvent N,N-dimethylformamide are mixed, heated and refluxed at 80°C, after 60 hours of homogeneous reaction, the temperature is reduced to room temperature, the mixture is added into anhydrous ethanol for precipitation, the excess tri-n-octylamine is washed repeatedly with anhydrous ethanol, and the product tri-octyl polyvinyl chloride ammonium is obtained by filtration and drying under reduced pressure.

[0105] In step 2, the extraction membrane for Cd (II) metal anion is prepared:

[0106] According to the mass ratio, 2.0% of tri-octyl polyvinyl chloride ammonium, 1% of dioctyl phthalate and 97% of organic solvent tetrahydrofuran are mixed to form a homogeneous solution at room temperature, and then the solution is horizontally placed in a flat-bottomed vessel. The solvent is completely volatilized at 30°C under normal pressure, and the solution is solidified into a flat, homogeneous, transparent and uniform thickness to obtain a Cd (II) anion extraction membrane with a thickness of 200μm. Then the acidification transformation is carried out.

[0107] The metal complex anion is extracted by the external electric field coupling membrane extraction process:

[0108] A 250mL solution containing 13mg / L of Cd (II) and 0.4mol / L of hydrochloric acid is placed in the feed liquid phase, and 250mL of 5×10 -3 M ethylenediaminetetraacetic acid disodium solution is filled in the stripping tank, and the magnetic stirring devices on both sides of the tank are started to begin mass transfer. After 16 hours of continuous extraction, the removal rate of Cd (II) in the feed liquid phase is 66.67%, and the recovery rate of Cd (II) in the stripping phase reaches 62.07%.

[0109] The newly added external electric field coupling membrane extraction voltage is 10V. After 14 hours of continuous electrically driven membrane extraction, the removal rate and recovery rate of Cd (II) are increased to 99.22% and 97.70% respectively. It can be seen that the electric field significantly accelerates the Cd (II) membrane extraction. The anion membrane extraction is shown inFigure 5 The results are shown in the table.

[0110] The better performance index of metal complex anion extraction membrane based on polymer extractant is compared by a comparative example.

[0111] The comparative example is a conventional polymer inclusion membrane, and details are shown in Table 1.

[0112] Table 1 Comparison of extraction effects of the present application and the comparative example

[0113]

[0114] As shown in Table 1, compared with the comparative example, the metal complex anion extraction membrane provided in the present application shortens the mass transfer time of HCrO4 - , increases the initial flux of CdCl3 - , significantly improves the recovery rate of FeCl4 - , and doubles the permeation coefficient of CoCl4 2- and CuCl4 2- .

[0115] In summary, the polymer extractant and the application of the membrane extraction and separation of metal complex anions provided in the present application achieve the reverse mass transfer time of Cr(Ⅵ), Cd(Ⅱ), Co(Ⅱ), Fe(Ⅲ) and Cu(Ⅱ) of 3h, 5h, 10h, 5h and 8h respectively without electricity, and the removal rate can reach more than 90% except for Cd(Ⅱ); after coupling an external electric field, the mass transfer time is shortened and the mass transfer rate is improved, and the membrane extraction efficiency of HCrO4 - reaches 710mg·m -2 ·h -1 in an electric field of 10V, and can operate stably.

[0116] The method for removing, extracting or separating metal anions has small environmental pollution, fast transmission rate, high removal rate and membrane extraction efficiency, and no leakage of the membrane phase, and is a high-stability membrane product with high mass transfer performance for metal complex anions and a separation method.

[0117] The metal complex anion extraction membrane is a novel membrane extraction material with good transmission capacity for metal complex anions, and also has good selectivity and applicability. In addition, it is simple to prepare and has low cost.

[0118] The present application is not limited to the above examples, and based on the technical solutions disclosed in the present application, those skilled in the art can make some substitutions and modifications to some technical features according to the disclosed technical content without creative labor, and these substitutions and modifications are within the protection scope of the present application.

Claims

1. A method for the preparation of a metal complex anion extraction membrane based on a polymeric extractant, characterized in that, The method comprises the following steps: Step 1, preparation of a quaternary ammonium salt type ionic liquid polymer extractant: 8-12% polymer, 20-46% tertiary amine organic matter and 46-70% solvent are mixed according to the mass ratio; homogeneous reflux reaction, reduced to room temperature, added with anhydrous ethanol for precipitation, the precipitate is washed with anhydrous ethanol for several times, suction filtration and reduced pressure drying to obtain a quaternary ammonium salt type ionic liquid polymer extractant; Step 2, preparation of a metal complex anion extraction membrane: 1-3% polymer extractant, 0.5-1% plasticizer and 96-98.5% organic solvent are mixed according to the mass ratio, stirred into a homogeneous solution, the solution is poured into a flat container and the solvent is volatilized to form a membrane; the membrane is placed in a hydrochloric acid solution for acidification to obtain a metal complex anion extraction membrane; The polymer is a high molecular weight polyvinyl chloride with a molecular weight greater than 72,000 and a degree of polymerization less than 2,500; The tertiary amine organic matter is one or a combination of two or more of tri-n-octylamine, tri-n-butylamine, triethylamine and tripropylamine; The solvent is one or a mixture of two or more of N,N-dimethylacetamide, N,N-dimethylformamide, dimethyl sulfoxide, N-methyl pyrrolidone and dioxane; The plasticizer is one or a mixture of two of dioctyl phthalate, dodecanoic acid, 2-nitrophenyl ether and dibutyl phthalate; The organic solvent is tetrahydrofuran or N,N-dimethylacetamide.

2. The method for the preparation of a metal complex anion extraction membrane based on a polymeric extractant according to claim 1, characterized in that, In step 1, the solvent is mixed and homogeneous reflux reaction is carried out at 50-90℃ for 24-72 h; In step 2, the thickness of the extraction membrane is 50-250 μm; the concentration of the hydrochloric acid solution is 0.1 mol / L.

3. A metal complex anion extraction membrane prepared by the method of any one of claims 1-2.

4. Use of a metal complex anion extraction membrane for separating and extracting a metal complex anion as claimed in claim 3, characterized in that, The method comprises the following steps: The metal complex anion extraction membrane is installed in a membrane extraction device to separate the solution containing the metal complex anion and the stripping phase, and the components in the two-phase solution remain homogeneous; The metal complex anion is kept in the form of a solution of metal complex anions containing H + or Cl - ions in the feed solution phase; Under the action of an external electric field with an operating voltage of 10-40 V, the cathode platinum wire is placed in the solution containing the metal complex anion, and the anode platinum wire is placed in the stripping phase, or without applying electricity, the solution containing the metal complex anion and the stripping phase are continuously stirred respectively to carry out mass transfer reaction.

5. Use of a metal complex anion extraction membrane for separating and extracting a metal complex anion according to claim 4, characterized by pH value and Cl concentration of the feed solution phase were adjusted with 1-4 M hydrochloric acid and NaCl solution - The feed solution phase exists in the form of HCrO4 - , CdCl3 - , CoCl4 2- , FeCl4 - , CuCl4 2- .

6. Use of a metal complex anion extraction membrane for separating and extracting a metal complex anion according to claim 5, characterized by The concentration of hydrogen ions in the solution containing Cr(Ⅵ) is 0.05-0.1 mol / L; The concentration of chloride ions in the solution containing Cd(II) is 0.4-0.5 mol / L; The concentration of chloride ions in the solution containing Co(II) is 6-7 mol / L; The concentration of chloride ions in the solution containing Fe(Ⅲ) is 6-7 mol / L; The concentration of chloride ions in the solution containing Cu(II) is 5-7 mol / L.

7. Use of a metal complex anion extraction membrane for separating and extracting a metal complex anion according to claim 4, characterized by The stripping phase is a sodium hydroxide solution, a disodium ethylenediaminetetraacetate solution, a hydrochloric acid solution or an ammonium acetate solution.

8. Use of a metal complex anion extraction membrane for separating and extracting a metal complex anion according to claim 7, characterized by The concentration of the sodium hydroxide solution is 0.05-0.2 mol / L; The concentration of the ethylenediaminetetraacetic acid disodium salt solution is 5 x 10 -3 ~ 0.01 mol / L; The concentration of the hydrochloric acid solution is 0.05-1 mol / L; The concentration of the ammonium acetate solution is 0.5-1 mol / L.

9. Use of a metal complex anion extraction membrane for separating and extracting a metal complex anion according to claim 4, characterized by, The stirring speed of the two-phase solution is 300-500 rpm and remains consistent; the continuous stirring reaction time is 5-30 h.

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