An electroactive cyclic flow membrane electrically controlled ion selective separation system and method

Abstract

The application discloses an electrically activated cyclic flow membrane electrically controlled ion selective separation system and method. A water solution containing target ions and a hydrophobic ion extractant with ion selective separation function are simultaneously flowed through a tilted tube type extraction separator in a double-layer parallel flow mode, a directional electric field between upper and lower inner wall electrode plates of the extraction separator is used to drive the target ions in the water solution to selectively diffuse to the side of the hydrophobic ion extractant, separation of the target ions is realized, then the extractant extracting the target ions and a regenerated water solution are flowed through another tilted tube type extraction separator in a double-layer parallel flow mode, and under the action of a reverse electric field, the target ions are driven to diffuse into the regenerated water solution, regeneration of the ion extractant is realized, and the above-mentioned cyclic flow membrane system is used to realize selective continuous separation of the target ions in the water solution. The application has the advantages of small ion diffusion resistance, fast separation rate, high selectivity and low cost.

Description

TECHNICAL FIELD

[0001] The present application relates to an electroactive cyclic flow membrane electrically controlled ion selective separation system and method, and belongs to the technical field of electrically controlled ion selective separation. BACKGROUND

[0002] The selective separation of target ions in an aqueous phase system is a very important separation process in industrial production, involving the development of high-value-added resources such as lithium and bromine in salt lakes, the treatment of heavy metal ions such as lead and chromium in industrial wastewater, rare earth resource separation, cooling water softening and many other fields. Therefore, effective separation and recovery of target ions from a solution has broad market demand and application prospects in resource efficient utilization and environmental protection and management.

[0003] Currently, methods that can simultaneously separate and recover ions mainly include adsorption, ion exchange, membrane separation and solvent extraction. Among them, the adsorption and ion exchange methods have low cost and simple operation, but the adsorption and ion exchange processes mainly rely on the physical and chemical diffusion of ions, which is slow and time-consuming, and the regeneration of the adsorbent and ion exchange resin requires repeated acid washing, which increases the cost and causes secondary pollution; the membrane separation method has high selectivity, good separation effect, no need for additives, simple process and easy automation, but the cost is relatively high; the solvent extraction method has simple equipment, convenient operation and continuous operation, and has high concentration multiple and high purity when using multi-stage extraction, but has the problems of slow extraction rate, long time consumption and difficulty in back extraction, and the conventional extractants are mostly organic solvents, which are volatile, flammable and toxic. As a new type of extractant, ionic liquids have the advantages of non-volatility, non-flammability, thermal stability, low toxicity or no toxicity compared with conventional extractants, and have significant advantages in heavy metal ion extraction, but due to the high ionic viscosity, the same problems of slow extraction rate and difficulty in back extraction exist.

[0004] Chinese patent CN102718292A discloses an electrically controlled ion selective membrane separation process, which utilizes the electrically controlled ion exchange performance and selective permeability of the membrane electrode in a diaphragm electrode reactor, controls the simultaneous introduction and release of target anions and cations by alternately applying oxidation-reduction potential to the double diaphragm electrode, and realizes the separation and recovery of anions and cations in a dilute solution under the action of an external electric field applied by an auxiliary electrode. However, since the ion separation needs to pass through the solid membrane electrode, it needs to overcome the large resistance generated in the liquid-solid interface and the solid phase transfer process, so in the amplification process, the ion diffusion resistance will increase and the energy consumption will increase. SUMMARY

[0005] In order to solve the problem that ion transfer needs to overcome the large resistance generated in the solid phase interface and the solid phase transfer process in the conventional membrane separation method, the application provides an electroactive circulating flow membrane electric control ion selective separation system and method by using a circulating flow membrane system and an electric field strengthening process.

[0006] The application provides an electroactive circulating flow membrane electric control ion selective separation system, which comprises two groups of insulated rectangular tubular extraction separators, each group of the insulated rectangular tubular extraction separators is composed of a pair of electrode plates and a collection tank, the insulated rectangular tubular extraction separator is arranged at an inclination angle of 0.5°-80°, an electrode plate is embedded in the inner wall of each of the upper and lower sides of the insulated rectangular tubular extraction separator, and a constant voltage is applied to the two electrode plates through an external circuit, so that a directional electric field along the vertical direction of the electrode plate is generated between the electrode plates; the collection tank is arranged at the bottom of the electrode plate, the hydrophobic ion extractant containing the target ion separated by the first collection tank at the bottom of the first group of insulated rectangular tubular extraction separators is connected to the inlet of the second group of insulated rectangular tubular extraction separators, and the hydrophobic ion extractant from which the target ion is removed and separated by the second collection tank at the bottom of the second group of insulated rectangular tubular extraction separators is connected to the inlet of the first group of insulated rectangular tubular extraction separators; the two groups of insulated rectangular tubular extraction separators form a circulating system.

[0007] The application is implemented by the following technical scheme: the aqueous solution containing the target ion and the hydrophobic ion extractant flow through the inclined insulated rectangular tubular extraction separator in a double-layer parallel flow manner, forming two adjacent liquid films, an electrode plate is embedded in the inner wall of each of the upper and lower sides of the rectangular tubular extraction separator, and a constant voltage is applied to the two electrode plates through an external circuit, so that a directional electric field along the vertical direction of the electrode plate is generated between the electrode plates; when the aqueous solution containing the target ion and the hydrophobic ion extractant flow through the electrode plate in the insulated rectangular tubular extraction separator at the same time, the target ion diffuses from the aqueous solution side to the hydrophobic ion extractant side under the pushing action of the directional electric field, the selective extraction ability of the hydrophobic ion extractant to different heavy metal ions is controlled, and the extraction and separation of the target ion in the aqueous solution are realized; then, the regenerated aqueous solution and the hydrophobic ion extractant after extracting the target ion flow through another inclined insulated rectangular tubular extraction separator with the same structure in a double-layer liquid film parallel flow manner, and a reverse constant voltage is applied to the two electrode plates through an external circuit, so that when the regenerated aqueous solution and the hydrophobic ion extractant containing the target ion flow through the electrode plate in the insulated rectangular tubular extraction separator at the same time, the target ion diffuses from the hydrophobic ion extractant side to the regenerated aqueous solution side under the pushing action of the reverse electric field, and the recovery of the target ion and the regeneration of the hydrophobic ion extractant are realized.

[0008] Further, the anode and the cathode are both stainless steel sheets, and the two electrode plates are arranged in parallel and fixed in the electrolytic tank.

[0009] The present application provides a kind of electroactive cyclic flow membrane electrically controlled ion selective separation method, comprising the following steps:

[0010] (1) the aqueous solution containing target ion and hydrophobic ion extractant are flowed through the inclined placement insulation rectangular tube type extraction separator in the way of upper and lower bilayer liquid membrane parallel flow;

[0011] (2) constant voltage 0-100V is applied on the electrode plate embedded in the upper and lower sides of rectangular tube type extraction separator, so that target ion diffuses from aqueous solution side to hydrophobic ion extractant side under the driving action of directional electric field, and selective extraction separation is realized;

[0012] (3) the aqueous solution removing target ion and the hydrophobic ion extractant extracting target ion flowed from rectangular tube type extraction separator are guided into collection tank and stratified;

[0013] (4) the upper layer aqueous solution removing target ion in collection tank enters next process to selectively separate remaining target ion, and the regenerated aqueous solution and the lower layer hydrophobic ion extractant extracting target ion in collection tank are flowed through another inclined placement insulation rectangular tube type extraction separator in the way of upper and lower bilayer liquid membrane parallel flow;

[0014] (5) reverse constant voltage is applied on the electrode plate embedded in the upper and lower sides of rectangular tube type extraction separator, so that target ion diffuses from hydrophobic ion extractant side to regenerated aqueous solution side under the driving action of directional electric field, and the stripping recovery of target ion and the regeneration of hydrophobic ion extractant are realized;

[0015] (6) the hydrophobic ion extractant removing target ion and the regenerated aqueous solution stripping target ion flowed from rectangular tube type extraction separator are guided into second collection tank and stratified;

[0016] (7) the upper layer regenerated aqueous solution stripping target ion in collection tank enters next process to further purify target ion by concentration method, and the lower layer hydrophobic ion extractant removing target ion in collection tank returns to step (1) for recycling.

[0017] Further, in the above method, the target ion is lithium Li + , rubidium Rb + , cesium Cs + , lead Pd 2+ , zinc Zn 2+ , cadmium Cd 2 + , arsenic As 3+ , lanthanum La 3+ , cerium Ce 4+ , neodymium Nd3+ Eu 3+ one of Eu, Yb, Sm, Gd, Tb, Dy, Ho, Er, Tm, Y, Lu, Ce, Pr, Nd, Pm.

[0018] Further, in the above method, the hydrophobic ion extractant is one of trioctylmethylammonium bis(2-ethylhexyl) diglycolate ([A336][DGA]), 1-hexyl-1-methylpyrrolinium bis(2-ethylhexyl) phosphate ([C6mpyr][DEHP]), N, N, N', N'-tetraoctyldiglycolamide (TODGA), 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl) imide ([C4mim][TFSI]), 1-butyl-3-methylimidazolium hexafluorophosphate ([BMIM][PF6]), 1-butyl-3-methylimidazolium octyl sulfate ([BMIM][OCTSO4]), methyltrioctyl-dio(2-ethylhexyl) phosphonium ester ammonium ([A336][DEHP]), [trioctylmethylammonium] [di-(2-ethylhexyl) orthophosphate] ([A336][P507]), trihexyl(tetradecyl) phosphonium chloride (Cyphos IL 101), 1-vinyl-3-butylimidazolium tetrafluoroborate ([BVIM][BF4]), 1-butyl-3-acetylbenzo 21 crown 7 imidazolium bis-trifluoromethanesulfonimide ([C4(benzo21C7)AIm]NTf2).

[0019] Advantages of the present application:

[0020] (1) The device of the present application realizes continuous separation through a circulating flow membrane system, has simple structure, is easy to operate, and has low running cost.

[0021] (2) Compared with the ion direct extraction method, the present application utilizes electric field to drive and strengthen the ion transfer process, and breaks the concentration diffusion balance, so that the extraction rate is fast and the separation efficiency is high.

[0022] (3) Compared with the electrically controlled ion-selective membrane separation method, the ion transfer eliminates the large resistance generated in the liquid-solid phase interface and the solid phase transfer process, and only needs to pass through the liquid-liquid phase interface to realize separation, so that the diffusion resistance is small. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 is a schematic diagram of an electrically controlled ion membrane extraction device based on a flowing liquid membrane;

[0024] Figure 2 is an extraction mechanism diagram of the target cation under the action of electric field force;

[0025] Figure 3 is an extraction mechanism diagram of the target anion under the action of electric field force.

[0026] In the diagram: 1 is an insulated rectangular tube extraction separator; 2 is an electrode plate; 3 is the first collection tank; 4 is the second collection tank; A1—an aqueous solution containing the target ion; A2—an aqueous solution from which the target ion has been removed; B1—a regenerated aqueous solution; B2—a regenerated aqueous solution from which the target ion has been back-extracted; C1—a hydrophobic ion extractant from which the target ion has been removed; C2—a hydrophobic ion extractant containing the target ion. Detailed Implementation

[0027] The present invention will be further illustrated by the following embodiments, but is not limited to the following embodiments.

[0028] like Figure 1 As shown, an electroactive circulating flow membrane electro-controlled ion selective separation system includes two sets of insulated rectangular tube extraction separators 1. Each set of insulated rectangular tube extraction separators consists of a pair of electrode plates 2 and a collection cell. The insulated rectangular tube extraction separators 1 are inclined at an angle of 45°. An electrode plate 2 is embedded in the inner wall of the upper and lower sides of the insulated rectangular tube extraction separator 1, and a constant voltage is applied to the two electrode plates 2 through an external circuit to generate a directional electric field between the electrode plates 2 along the vertical direction of the electrode plates.

[0029] An aqueous solution A1 containing the target ion enters from the top of the first set of insulated rectangular tube extraction separators. A collection cell is located at the bottom of the electrode plate. The hydrophobic ion extractant C2 containing the target ion separated from the first collection cell 3 at the bottom of the first set of insulated rectangular tube extraction separators is connected to the inlet of the second set of insulated rectangular tube extraction separators. The aqueous solution A2 with the target ion removed separated from the first collection cell 3 is collected. The hydrophobic ion extractant C1 with the target ion removed separated from the second collection cell 4 at the bottom of the second set of insulated rectangular tube extraction separators is connected to the inlet of the first set of insulated rectangular tube extraction separators. The regenerated aqueous solution B2 with the target ion back-extracted separated from the second collection cell 4 is collected. The two sets of insulated rectangular tube extraction separators form a circulation system.

[0030] Extraction mechanism of target cations under the action of electric field:

[0031] (1) An aqueous solution containing the target cation and a hydrophobic ion extractant are simultaneously flowed through an inclined insulated rectangular tube extraction separator in a manner with upper and lower double liquid films flowing in parallel.

[0032] (2) Apply a constant voltage of 10 V to a pair of electrode plates embedded on the upper and lower sides of the rectangular tube extraction separator, as shown in the attached figure. Figure 2 As shown, the target cation diffuses from the aqueous solution side to the hydrophobic ion extractant side under the driving force of a directional electric field, thereby achieving selective extraction and separation.

[0033] (3) The water solution of removing target cation and hydrophobic ion extractant of extracting target cation are guided into the first collection pool and stratified;

[0034] (4) The water solution of removing target cation in the collection pool is guided into the next process to selectively separate the remaining target ions, and the regenerated water solution and the lower layer of the hydrophobic ion extractant of extracting target cation in the collection pool are guided through another inclined insulated rectangular tube extractor in a double-layer liquid film and concurrent manner;

[0035] (5) A pair of electrode plates embedded in the upper and lower sides of the rectangular tube extractor are applied with 10 V reverse constant voltage, as shown in the attached Figure 2 , so that the target cation diffuses from the hydrophobic ion extractant side to the regenerated water solution side under the driving action of the directional electric field, realizing the stripping recovery of target cation and the regeneration of hydrophobic ion extractant;

[0036] (6) The hydrophobic ion extractant of removing target cation and the regenerated water solution of stripping target cation are guided into the second collection pool and stratified;

[0037] (7) The upper layer of the regenerated water solution of stripping target cation in the collection pool is guided into the next process to further purify the target ions by concentration method, and the lower layer of the hydrophobic ion extractant of removing target cation in the collection pool is returned to step (1) for recycling.

[0038] Extraction mechanism of target anion under the action of electric field force:

[0039] (1) The water solution containing target anion and hydrophobic ion extractant are guided through the inclined insulated rectangular tube extractor in a double-layer liquid film and concurrent manner;

[0040] (2) A pair of electrode plates embedded in the upper and lower sides of the rectangular tube extractor are applied with 10 V constant voltage, as shown in the attached Figure 3 , so that the target anion diffuses from the water solution side to the hydrophobic ion extractant side under the driving action of the directional electric field, realizing selective extraction separation;

[0041] (3) The water solution of removing target anion and hydrophobic ion extractant of extracting target anion are guided into the first collection pool and stratified;

[0042] (4) The water solution in the upper layer of the collection tank, which has removed the target anion, is introduced into the next process to selectively separate the remaining target ions, while the regenerated water solution and the hydrophobic ionic extractant in the lower layer of the collection tank, which extracts the target anion, are simultaneously flowed through another inclined and insulated rectangular tube type extraction separator in a cocurrent manner through the upper and lower double liquid membranes;

[0043] (5) A pair of electrode plates embedded in the upper and lower sides of the rectangular tube type extraction separator are applied with a 10 V reverse constant voltage, as shown in FIG. 2, so that the target anion diffuses from the side of the hydrophobic ionic extractant to the side of the regenerated water solution under the driving action of the directional electric field, thereby realizing the stripping recovery of the target anion and the regeneration of the hydrophobic ionic extractant; Figure 3

[0044] (6) The hydrophobic ionic extractant, which has removed the target anion, and the regenerated water solution, which has stripped the target anion, flowed out of the rectangular tube type extraction separator are introduced into a second collection tank to be layered;

[0045] (7) The regenerated water solution in the upper layer of the collection tank, which has stripped the target anion, is introduced into the next process to further purify the target ion by concentration method, while the hydrophobic ionic extractant in the lower layer of the collection tank, which has removed the target anion, is returned to step (1) for recycling.

[0046] The process of ion selective separation by extraction according to the present application is described below through specific examples: Example 1

[0047] A water solution containing target ions Eu 3+ (including competitive ions Am 3+ ) and a hydrophobic ionic liquid extractant bis (2-ethylhexyl) diglycolate trioctylmethylammonium ([A336] [DGA]) organic phase are simultaneously flowed through an inclined and insulated rectangular tube type extraction separator in a cocurrent manner through the upper and lower double liquid membranes at a water phase / organic phase (volume ratio) of 1:1; a pair of electrode plates embedded in the upper and lower sides of the rectangular tube type extraction separator are applied with a constant voltage of -2.5 V, so that Eu 3+ diffuses from the side of the water solution to the side of the organic phase containing [A336] [DGA] under the driving action of the directional electric field; the water solution, which has removed Eu 3+ , and the [A336] [DGA] organic phase, which has extracted Eu 3+ , are introduced into a collection tank to be layered, the extraction rate of Eu 3+ is about 95.2%, the separation factor β Eu3+ / Am3+ = 10; a 0.5 mol / L HNO3 solution is introduced into the lower layer of the collection tank to extract Eu 3+ ​and the Eu 3+ was recovered by back extraction with 0.5 mol / L HNO3 solution, and the total recovery of Eu 3+ was about 94.1%, and the Eu 3+ ion was successfully recovered, and the back extraction of target ions and the regeneration of hydrophobic ion extractant were realized; the [A336][DGA] organic phase from which the Eu 3+ ion was removed and the HNO3 solution in which the target ions were back extracted were introduced into a second collection tank and allowed to separate into two layers; the HNO3 solution in which the target ions were back extracted was introduced into the next process to further purify Eu 3+ , while the [A336][DGA] organic phase from which the Eu 3+ ion was removed was returned to the first step for recycling; the total time required for the back extraction of the extractant was only 10 minutes, and the total recovery of Eu 3+ was 89.6%, and the separation factor of Eu 3+ / Am Example 2

[0048] An aqueous solution containing the target ion Nd 3+ (including the competitive ion La 3+ ) with a concentration of 7×10 -4 mol / L was simultaneously flowed through an insulating rectangular tube extractor placed at an angle in a co-current manner with the lower and upper double liquid membranes of an organic phase containing the hydrophobic ionic liquid extractant 1-hexyl-1-methylpyrrolinium bis(2-ethylhexyl) phosphate ([C6mpyr][DEHP]) and an aqueous phase in a volume ratio of 1:1; a constant voltage of -2.5 V was applied to a pair of electrode plates embedded on the upper and lower sides of the rectangular tube extractor, and Nd 3+ diffused from the aqueous solution side to the organic phase containing [C6mpyr][DEHP] side under the driving force of the directional electric field; the aqueous solution from which Nd 3+ was removed and the [C6mpyr][DEHP] organic phase in which Nd 3+ was extracted were introduced into a collection tank and allowed to separate into two layers, and the extraction rate of Nd 3+ was about 99%, and the separation factor β Nd3+ / La3+ = 2.8; 1.0 mol / L HNO3 solution was introduced into the lower layer of the collection tank in which Nd 3+[C6mpyr][DEHP] organic phase with double-layer liquid membrane in a countercurrent way through another inclined insulated rectangular tube extractor; a pair of electrode plates embedded in the upper and lower sides of the rectangular tube extractor were applied with a constant reverse voltage of 2.5 V, so that Nd 3+ was diffused from the side of [C6mpyr][DEHP] organic phase to the side of the regenerated aqueous solution under the driving force of the directional electric field, and about 93% of Nd 3+ was successfully recovered by back extraction with 1.0 mol / L HNO3 solution, realizing the back extraction and recovery of the target ion and the regeneration of the hydrophobic ionic extractant; the [C6mpyr][DEHP] organic phase from which Nd 3+ was removed and the HNO3 solution for back extraction of the target ion were introduced into a second collection tank and allowed to separate into layers; the HNO3 solution for back extraction of the target ion in the upper layer of the collection tank was introduced into the next process to further purify Nd 3+ , while the [C6mpyr][DEHP] organic phase in the lower layer of the collection tank from which Nd 3+ was removed was returned to the first step for recycling. The total time required for the back extraction of the extractant in this method was only 12 minutes, and the overall recovery rate of Nd 3+ was 92.1%, and the separation factor of Nd 3+ / La 3+ was 2.8. Example 3

[0049] An aqueous solution containing the target ion La 3+ (including the competitive ion Ce 3+ ) with a concentration of 0.003 mol / L and an organic phase containing the hydrophobic ionic liquid extractant N, N, N', N'-tetraoctyl diglycolamide (TODGA) in petroleum ether were simultaneously flowed through an inclined insulated rectangular tube extractor with double-layer liquid membrane in a countercurrent way; a pair of electrode plates embedded in the upper and lower sides of the rectangular tube extractor were applied with a constant voltage of -2.2 V, so that La 3+ was diffused from the side of the aqueous solution to the side of the organic phase containing (TODGA); the aqueous solution from which La 3+ was removed and the (TODGA) organic phase for extraction of La 3+ were introduced into a collection tank and allowed to separate into layers, and the extraction rate of La 3+ was about 92.6%, and the separation factor β La3+ / Ce3+ =1.9; 1.0 mol / L HCl solution was introduced into the lower layer of the collection tank containing the (TODGA) organic phase for extraction of La 3+(TODGA) organic phase with double-layer liquid film in parallel flow through another inclined insulated rectangular tube extractor; a pair of electrode plates embedded in the upper and lower sides of the rectangular tube extractor are applied with a constant reverse voltage of 2.2 V, so that La 3+ Under the driving of the directional electric field, about 93.8% of La 3+ is successfully recovered, realizing the back extraction and recovery of the target ion and the regeneration of the hydrophobic ion extractant; the (TODGA) organic phase from which La 3+ is removed and the HCl solution in which the target ion is back extracted are introduced into a second collection tank and allowed to separate; the HCl solution in which the target ion is back extracted is introduced into the next process to further purify La 3+ by concentration, while the (TODGA) organic phase in which La 3+ is removed is returned to the first step for recycling. The total recovery rate of La 3+ is 86.9%, and the separation factor of La 3+ / Ce 3+ is 1.9. Example 4

[0050] An aqueous solution containing the target ion Li + (including the competitive ion Mg 2+ ) with a Mg 2+ concentration of 7.5 mol / L and the rest of 0.15 mol / L is simultaneously flowed through an inclined insulated rectangular tube extractor with double-layer liquid film in parallel flow together with an organic phase containing the hydrophobic ion liquid extractant tri-n-butyl phosphate (TBP) and the ion liquid 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([C4mim][TFSI]) at a water phase / organic phase (volume ratio) of 3:1; a pair of electrode plates embedded in the upper and lower sides of the rectangular tube extractor are applied with a constant voltage of -1.5 V, so that Li + diffuses from the aqueous solution side to the organic phase containing [C4mim][TFSI] side under the driving of the directional electric field; the aqueous solution from which Li + is removed is introduced into a collection tank together with the [C4mim][TFSI] organic phase in which Li + is extracted, and allowed to separate; the extraction rate of Li + is about 81%, and the separation factor β Li+ / Mg2+ =1.9; 1.0 mol / L HCl solution is introduced into the lower layer of the collection tank in which Li +[C4mim][TFSI] organic phase with double liquid film in a countercurrent way through another inclined insulated rectangular tube extractor; a pair of electrode plates embedded in the upper and lower sides of the rectangular tube extractor were applied with a constant reverse voltage of 1.5 V, so that Li + Under the driving force of the directional electric field, La 3+ was successfully recovered from the [C4mim][TFSI] organic phase side to the aqueous solution side, and about 91.2% of La + was recovered after being back-extracted by 1.0 mol / L HCl solution, realizing the back-extraction recovery of the target ion and the regeneration of the hydrophobic ionic extractant; the [C4mim][TFSI] organic phase from which Li + was removed and the HCl solution in which the target ion was back-extracted were introduced into a second collection tank and separated into two layers; the HCl solution in which the target ion was back-extracted was introduced into the next process to further purify Li + from the upper layer of the collection tank, while the [C4mim][TFSI] organic phase from which Li + was removed was returned to the first step for recycling. The total recovery rate of Li + was 73.9%, and the separation factor of Li 2+ / Mg Example 5

[0051] An aqueous solution containing the target ion As 3+ (including the competitive ion As 5+ ) with a concentration of 0.5 mol / L and an organic phase containing the hydrophobic ionic liquid extractant 1-butyl-3-methylimidazolium hexafluorophosphate ([BMIM][PF6]) were simultaneously flowed through an inclined insulated rectangular tube extractor with double liquid film in a countercurrent way, with a water phase / organic phase (volume ratio) of 1:1; a pair of electrode plates embedded in the upper and lower sides of the rectangular tube extractor were applied with a constant voltage of -3 V, so that As 3+ diffused from the aqueous solution side to the organic phase containing [BMIM][PF6] side under the driving force of the directional electric field; the aqueous solution from which As 3+ was removed and the [BMIM][PF6] organic phase in which As 3+ was extracted were introduced into a collection tank and separated into two layers, and the extraction rate of As 3+ was about 87.5%, and the separation factor β As3+ / As5+ =3.2; 0.1 mol / L HCl solution was introduced into the lower layer of the collection tank in which As 3+and the [BMIM][PF6] organic phase with the double liquid film flows through another inclined insulation rectangular tube extractor in a parallel way; a pair of electrode plates embedded in the upper and lower sides of the rectangular tube extractor are applied with a constant reverse voltage of 3 V, so that As 3+ diffuses from the [BMIM][PF6] organic phase side to the regenerated aqueous solution side under the driving of the directional electric field, and about 89.6% of As 3+ is successfully recovered, realizing the back-extraction recovery of the target ion and the regeneration of the hydrophobic ionic extractant; the [BMIM][PF6] organic phase from which As 3+ is removed and the HCl solution for back-extracting the target ion are introduced into a second collection tank and allowed to separate; the HCl solution for back-extracting the target ion in the upper layer of the collection tank is introduced into the next process for further purifying As 3+ , while the [BMIM][PF6] organic phase in the lower layer of the collection tank from which As 3+ is removed is returned to the first step for recycling. The total time required for the back-extraction of the extractant is only 13 minutes, the total recovery rate of As 3+ is 78.4%, and the separation factor of As 3+ / As 5+ is 3.2. Example 6

[0052] An aqueous solution containing the target ion Pd 2+ (including the competitive ions Co 2+ , Cd 2+ , and Ni 2+ , all at a concentration of 0.003 mol / L) and the organic phase containing the hydrophobic ionic liquid extractant 1-butyl-3-methylimidazolium octyl sulfate [BMIM][OCTSO4] are simultaneously introduced into an inclined insulation rectangular tube extractor in a parallel way with a double liquid film in a volume ratio of water phase to organic phase of 1:1; a pair of electrode plates embedded in the upper and lower sides of the rectangular tube extractor are applied with a constant voltage of -3.2 V, so that Pd 2+ diffuses from the aqueous solution side to the organic phase containing [BMIM][OCTSO4] side under the driving of the directional electric field; the aqueous solution from which Pd 2+ is removed and the [BMIM][OCTSO4] organic phase for extracting Pd 2+ are introduced into a collection tank and allowed to separate, and the extraction rate of Pd 2+ is about 97.79%, the separation factors β Pd2+ / Co2+ = 29.8, β Pd2+ / Cd2+ = 38.4, and β Pd2+ / Ni2+ = 48.2.=10.6, 1.0 mol / L HNO3 solution was added to the lower layer Pd 2+ containing phase in the collection tank 2+ The [BMIM][OCTSO4] organic phase was flowed through another inclined insulation rectangular tube extractor with the upper and lower double liquid membranes in parallel way. A pair of electrode plates were embedded in the upper and lower sides of the rectangular tube extractor, and a constant reverse voltage of 3.2 V was applied to the electrode plates, so that Pd 2+ was diffused from the [BMIM][OCTSO4] organic phase side to the aqueous solution side under the driving of the directional electric field. After the back extraction, about 93.8% of Pd 2+ was successfully recovered, realizing the back extraction and recovery of the target ion and the regeneration of the hydrophobic ionic extractant. The [BMIM][OCTSO4] organic phase containing Pd 2+ was flowed into the second collection tank together with the HNO3 solution for back extraction of the target ion, and was separated into two layers. The upper layer HNO3 solution for back extraction of the target ion in the collection tank was used in the next process to further purify Pd 2+ by concentration method, while the lower layer [BMIM][OCTSO4] organic phase containing Pd 2+ was returned to the first step for recycling. The total recovery rate of Pd 2+ was 91.7%, and the separation factors of Pd 2+ / Co 2+ , Pd 2+ / Cd 2+ and Pd 2+ / Ni were 29.8, 38.4, 10.6, respectively. Example 7

[0053] An aqueous solution containing the target ion Nd 3+ (including the competitive ion Fe 2+ ) with a concentration of 0.001 mol / L was flowed through an inclined insulation rectangular tube extractor with the upper and lower double liquid membranes in parallel way, together with an organic phase containing the hydrophobic ionic liquid extractant methyltrioctyl-dio(2-ethylhexyl) phosphonium ester ammonium ([A336][DEHP]) and tri-n-octyl phosphine oxide (TOPO) at a volume ratio of water phase to organic phase of 1:1. A constant voltage of -2.5 V was applied to a pair of electrode plates embedded in the upper and lower sides of the rectangular tube extractor, so that Nd 3+ was diffused from the aqueous solution side to the organic phase containing [A336][DEHP] side under the driving of the directional electric field. The aqueous solution containing Nd 3+ was flowed out of the rectangular tube extractor, and was used to extract Nd 3+ organic phase of [A336][DEHP] into the collection tank and let it stand to stratify, Nd 3+ extraction rate of about 96.5%, separation factor β Nd3+ / Fe2+ = 8.2; 1.0 mol / L HCl solution and the lower layer of the extraction Nd 3+ organic phase of [A336][DEHP] through another inclined placed insulated rectangular tube type extractor in a co-current way; a pair of electrode plates embedded in the upper and lower sides of the rectangular tube type extractor were applied with a constant reverse voltage of 2.5 V, so that Nd 3+ diffused from the side of [A336][DEHP] organic phase to the side of the regenerated aqueous solution under the driving of the directional electric field, after back-extraction by 1.0 mol / L HCl solution, about 95% of Nd 3+ was successfully recovered, realizing the back-extraction recovery of the target ion and the regeneration of the hydrophobic ion extractant; the [A336][DEHP] organic phase removed Nd 3+ ion and the HCl solution back-extracting the target ion from the collection tank were introduced into the second collection tank and let it stand to stratify; the upper layer of the HCl solution back-extracting the target ion in the collection tank entered the next process to further purify Nd 3+ ion by concentration method, while the lower layer of the [A336][DEHP] organic phase removing Nd 3+ ion in the collection tank returned to the first step for recycling. The total time required for the back-extraction of the extractant in this method was only 13 minutes, the overall recovery rate of Nd 3+ was 91.6%, and the separation factor of Nd 3+ / Fe 2+ was 8.2. Example 8

[0054] An aqueous solution containing the target ion Ce 4+ (including the competitive ion CeF 3+ , Ce 3+ ) and the hydrophobic ionic liquid extractant [trisalkylmethylammonium][di-(2-ethylhexyl) orthophosphate] ([A336][P507]) n-heptane organic phase were simultaneously flowed through an inclined placed insulated rectangular tube type extractor in a co-current way with the upper and lower double liquid membrane with a water phase / organic phase (volume ratio) of 4:1; a pair of electrode plates embedded in the upper and lower sides of the rectangular tube type extractor were applied with a constant voltage of -2.3 V, so that Ce 4+ diffused from the side of the aqueous solution to the side of the organic phase containing [A336][P507] under the driving of the directional electric field; the aqueous solution removed Ce 4+ from the rectangular tube type extractor was flowed out and extracted Ce4 + The [A336][P507] organic phase is introduced into the collection tank together with the flow and is allowed to stand and separate into layers, and Ce 4+ The extraction rate of Ce Ce4+ / CeF3+ 3 = 3.32 × 10 Ce4+ / Ce3+ , β 3 = 2.58 × 10 4+ ; a 1.0 mol / L H2SO4 solution is passed through the other inclined insulation rectangular tube type extractor separator in a co-current manner with the double-layer liquid membrane of the [A336][P507] organic phase that extracts Ce 4+ Under the driving action of the directional electric field, Ce 4+ is diffused from the [A336][P507] organic phase side to the aqueous solution side, and after back extraction by the 1.0 mol / L H2SO4 solution, about 85% of Ce 4+ is successfully recovered, realizing the back extraction and recovery of the target ion and the regeneration of the hydrophobic ion extractant; the [A336][P507] organic phase from which Ce 4+ has been removed and the H2SO4 solution in which the target ion has been back extracted are introduced into the second collection tank and allowed to stand and separate into layers; the upper layer H2SO4 solution in which the target ion has been back extracted in the collection tank is introduced into the next process to further purify Ce 4+ by concentration, and the lower layer [A336][P507] organic phase from which Ce 4+ has been removed in the collection tank is returned to the first step for recycling. The total time required for the back extraction of the extractant in this method is only 18 minutes, the overall recovery rate of Ce 4+ is 83.9%, and the separation factors of Ce 3+ / CeF 4+ , Ce 3+ / Ce 3 are 3.32 × 10 3 , 2.58 × 10 2+ . Example 9

[0055] A solution containing the target ion Zn 2+ (including the competitive ions Cu 2+ , Ni 2+ , Cdaqueous solution (0.08 mol / L) and the organic phase containing hydrophobic ionic liquid extractant trishexyl (tetradecyl) phosphonium chloride (Cyphos IL 101) flow through the inclined insulation rectangular tube extractor in a co-current way with the double liquid membrane of the aqueous phase / organic phase (volume ratio) being 1:1; a constant voltage of -3 V is applied to the electrode plates embedded in the upper and lower sides of the rectangular tube extractor, so that Zn 2+ diffuses from the aqueous solution side to the organic phase containing (Cyphos IL 101) side under the driving of the directional electric field; the Zn 2+ free aqueous solution and the (Cyphos IL 101) organic phase containing extracted Zn 2+ flow into the collection tank and are layered, and the extraction rate of Zn 2+ is about 94.2%, the separation factor β Zn2+ / Cu2+ =1.1, β Zn2+ / Ni2+ =5.6, and β Zn2+ / Cd2+ =5.3; 1.0 mol / L H2SO4 solution and the lower layer (Cyphos IL 101) organic phase containing extracted Zn 2+ in the collection tank flow through another inclined insulation rectangular tube extractor in a co-current way with the double liquid membrane; a reverse constant voltage of 3 V is applied to the electrode plates embedded in the upper and lower sides of the rectangular tube extractor, so that Zn 2+ diffuses from the (Cyphos IL 101) organic phase side to the regenerated aqueous solution side under the driving of the directional electric field, and after the back extraction, about 90.7% of Zn 2+ is successfully recovered, realizing the back extraction and recovery of the target ion and the regeneration of the hydrophobic ionic extractant; the (Cyphos IL 101) organic phase containing Zn 2+ ions and the H2SO4 solution containing back-extracted target ions flow into the second collection tank and are layered; the upper layer H2SO4 solution containing back-extracted target ions in the collection tank is introduced into the next process to further purify Zn 2+ ions by the concentration method, and the lower layer (Cyphos IL 101) organic phase containing Zn 2+ ions in the collection tank is returned to the first step for recycling. The total time required for the back extraction of the extractant is only 20 minutes, the total recovery rate of Zn 2+ is 85.4%, and the separation factors are Zn 2+ / Cu 2+ , Zn 2+ / Ni 2+ , and Zn 2+ / Cd 2+1.1, 5.6, 5.3, respectively. Example 10

[0056] aqueous solution containing target ions Cd 2+ (including competitive ions Pb 2+ , Co 2+ ) and organic phase containing hydrophobic ionic liquid extractant 1-vinyl-3-butyl imidazole tetrafluoroborate ([BVIM][BF4]) dithizone were simultaneously flowed through the lower bilayer liquid membrane of the insulating rectangular tube extractor placed obliquely in a parallel flow manner with the volume ratio of water phase to organic phase being 1:1; a constant voltage of -2.8 V was applied on the electrode plates embedded on the upper and lower sides of the rectangular tube extractor, so that Cd 2+ diffused from the aqueous solution side to the organic phase containing [BVIM][BF4] side under the driving of the directional electric field; the aqueous solution removed of Cd 2+ from the rectangular tube extractor and the [BVIM][BF4] organic phase extracting Cd 2+ were jointly flowed into the collection tank to stand for layering, and the extraction rate of Cd 2+ was about 83.8%, the separation factor β Cd2+ / Pb2+ = 2.4, and β Cd2+ / Co2+ = 2.2; 0.01 mol / L HNO3 solution and the lower [BVIM][BF4] organic phase extracting Cd 2+ in the collection tank were simultaneously flowed through another insulating rectangular tube extractor placed obliquely in a parallel flow manner with the lower bilayer liquid membrane; a reverse constant voltage of 2.8 V was applied on the electrode plates embedded on the upper and lower sides of the rectangular tube extractor, so that Cd 2+ diffused from the [BVIM][BF4] organic phase side to the regenerated aqueous solution side under the driving of the directional electric field, and after the reverse extraction of Cd 2+ , about 82.5% of Cd 2+ was successfully recovered, realizing the reverse extraction and recovery of target ions and the regeneration of hydrophobic ionic extractant; the [BVIM][BF4] organic phase removed of Cd 2+ ions and the HNO3 solution reverse-extracting target ions were jointly flowed into the second collection tank to stand for layering; the upper HNO3 solution reverse-extracting target ions in the collection tank was introduced into the next process to further purify Cd 2+ ions by concentration method, while the lower [BVIM][BF4] organic phase removed of Cd 2+ in the collection tank was returned to the first step for recycling. The total time required for the reverse extraction of the extractant was only 15 minutes, and the overall recovery rate of Cd 2+ was 69.1%. / Pb 2+ , Cd 2+ / Co 2+ The separation factors of Rb , K , Mg

[0057] are 2.4, 2.2, and 2.0, respectively. Example 11

[0057] The aqueous solution containing target ions Rb + (including competitive ions K + , Mg 2+ ) and the organic phase containing the hydrophobic ionic liquid extractant 1-butyl-3-acetylbenzo 21 crown 7 imidazolium bis-trifluoromethyl sulfonimide ([C4(benzo21C7)AIm]NTf2) were simultaneously flowed through the inclined insulating rectangular tube extractor in a countercurrent manner with the water phase / organic phase (volume ratio) being 1:1, and a constant voltage of -1.5 V was applied to the electrode plates embedded in the upper and lower sides of the rectangular tube extractor, so that Rb + diffused from the aqueous solution side to the organic phase containing [C4(benzo21C7)AIm]NTf2 side under the driving action of the directional electric field; the aqueous solution removed of Rb + and the [C4(benzo21C7)AIm]NTf2 organic phase extracted with Rb + were simultaneously flowed into the collection tank and were allowed to separate into layers, and the extraction rate of Rb + was about 99.8%, the separation factor β Rb+ / K+ = 1.5, and β Rb+ / Mg2+ = 6.6; 0.05 mol / L HNO3 solution and the lower layer [BVIM][BF4] organic phase extracted with Rb + in the collection tank were simultaneously flowed through another inclined insulating rectangular tube extractor in a countercurrent manner with the water phase / organic phase (volume ratio) being 1:1, and a constant voltage of 1.5 V was applied to the electrode plates embedded in the upper and lower sides of the rectangular tube extractor, so that Rb + diffused from the [C4(benzo21C7)AIm]NTf2 organic phase side to the aqueous solution side under the driving action of the directional electric field, and after the reverse extraction of Rb + by the 0.05 mol / L HNO3 solution, about 95.4% of Rb + was successfully recovered, achieving the reverse extraction and recovery of the target ions and the regeneration of the hydrophobic ionic liquid extractant; the [C4(benzo21C7)AIm]NTf2 organic phase removed of Rb + and the HNO3 solution reverse-extracted with the target ions were simultaneously flowed into the second collection tank and were allowed to separate into layers; the upper layer HNO3 solution reverse-extracted with the target ions in the collection tank was subjected to further purification of Rb + ions by the concentration method in the next process, and the lower layer Rb ++ The organic phase of the ion [C4(benzo21C7)AIm]NTf2 was recycled in the first step. The total time required for stripping of the extractant in this method was only 17 minutes, and the overall recovery of Rb + was 95.2%, and the separation factor of Rb + / K + was 1.5, and the separation factor of Rb + / Mg 2+ was 6.6. Example 12

[0058] An aqueous solution containing the target ion Cs + (including the competitive ions Na + and Ca 2+ ) with a concentration of 0.001 mol / L was flowed through an inclined insulated rectangular tube extractor in a cocurrent manner with the organic phase containing the hydrophobic ionic liquid extractant 1-butyl-3-acetylbenzo21C7 imidazolium bis-trifluoromethyl sulfonimide ([C4(benzo21C7)AIm]NTf2) in a water phase / organic phase (volume ratio) of 1:1. A constant voltage of -1.5 V was applied to a pair of electrode plates embedded on the upper and lower sides of the rectangular tube extractor, and the target ion Cs + diffused from the aqueous solution side to the organic phase containing [C4(benzo21C7)AIm]NTf2 under the driving force of the directional electric field. The aqueous solution removed of Cs + and the [C4(benzo21C7)AIm]NTf2 organic phase extracting Cs + were simultaneously flowed into a collection pool and allowed to separate into layers. The extraction efficiency of Cs + was about 99.9%, the separation factor β Cs+ / Na+ = 5.5, and β Cs+ / Ca2+ = 4.1. A 0.05 mol / L HNO3 solution was simultaneously flowed through another inclined insulated rectangular tube extractor in a cocurrent manner with the lower layer of the [C4(benzo21C7)AIm]NTf2 organic phase extracting Cs + in the collection pool. A reverse constant voltage of 1.5 V was applied to a pair of electrode plates embedded on the upper and lower sides of the rectangular tube extractor, and the target ion Cs + diffused from the [C4(benzo21C7)AIm]NTf2 organic phase side to the regenerated aqueous solution side under the driving force of the directional electric field. After the reverse extraction of the 0.05 mol / L HNO3 solution, about 90.8% of Cs + was successfully recovered, achieving the reverse extraction and recovery of the target ion and the regeneration of the hydrophobic ionic liquid extractant. The aqueous solution removed of Cs +The organic phase of the extracted ions, [C4(benzo2 1C7)Alm]NTf2, and the HNO3 solution of the back-extracted target ions are introduced into a second collection tank and left to separate into layers; the upper layer of the HNO3 solution of the back-extracted target ions in the collection tank is introduced into the next process for further purification of Cs by concentration + ions, while the lower layer of the collection tank is removed from Cs + ions. The organic phase of the extracted ions, [C4(benzo2 1C7)Alm]NTf2, is recycled to the first step. The total time required for the back-extraction of the extractant in this method is only 20 minutes, and the overall recovery of Cs + is 90.7%, and the separation factor of Cs + / Na + is 5.5, and the separation factor of Cs + / Ca 2+ is 4.1.

Claims

1. An electroactive cyclic flow membrane electrically controlled ion selective separation system characterized by: The application relates to a two-group insulating rectangular tube type extraction separator, each group of insulating rectangular tube type extraction separators is composed of a pair of electrode plates and a collection tank, the insulating rectangular tube type extraction separators are arranged obliquely, the inclination angle is 0.5-80 DEG, one electrode plate is embedded in the inner wall of the upper and lower sides of the insulating rectangular tube type extraction separators respectively, and a constant voltage is applied on the two electrode plates through an external circuit, so that a directional electric field along the vertical direction of the electrode plates is generated between the electrode plates; the collection tank is arranged at the bottom of the electrode plate, the hydrophobic ion extractant containing target ions separated from the first collection tank at the bottom of the first group of insulating rectangular tube type extraction separators is connected with the inlet of the second group of insulating rectangular tube type extraction separators, the hydrophobic ion extractant removing the target ions separated from the second collection tank at the bottom of the second group of insulating rectangular tube type extraction separators is connected with the inlet of the first group of insulating rectangular tube type extraction separators; the two groups of insulating rectangular tube type extraction separators form a circulation system.

2. The electroactive cyclic flow membrane electrically-controlled ion-selective separation system of claim 1, wherein: The anode and the cathode are both made of stainless steel sheets, and the two electrode plates are fixed in parallel in the electrolytic tank.

3. An electroactive cyclic flow membrane electrically controlled ion selective separation process using the electroactive cyclic flow membrane electrically controlled ion selective separation system of claim 1 or 2, characterized by The application comprises the following steps: (1) flowing the aqueous solution containing target ions and the hydrophobic ion extractant in the form of upper and lower double liquid films through the obliquely arranged insulating rectangular tube type extraction separator simultaneously; (2) applying a constant voltage of 0-100 V on the pair of electrode plates embedded in the upper and lower sides of the rectangular tube type extraction separator, so that the target ions diffuse from the aqueous solution side to the hydrophobic ion extractant side under the pushing action of the directional electric field, and selective extraction separation is realized; (3) flowing the aqueous solution removing the target ions and the hydrophobic ion extractant extracting the target ions out of the rectangular tube type extraction separator into the collection tank to stand and stratify; (4) flowing the regenerated aqueous solution and the lower layer hydrophobic ion extractant extracting the target ions in the collection tank through another obliquely arranged insulating rectangular tube type extraction separator in the form of upper and lower double liquid films simultaneously; (5) applying a reverse constant voltage on the pair of electrode plates embedded in the upper and lower sides of the rectangular tube type extraction separator, so that the target ions diffuse from the hydrophobic ion extractant side to the regenerated aqueous solution side under the pushing action of the directional electric field, and the reverse extraction recovery of the target ions and the regeneration of the hydrophobic ion extractant are realized; (6) flowing the hydrophobic ion extractant removing the target ions and the regenerated aqueous solution reverse-extracting the target ions out of the rectangular tube type extraction separator into the second collection tank to stand and stratify; (7) flowing the upper layer regenerated aqueous solution reverse-extracting the target ions in the collection tank into the next process to further purify the target ions by the concentration method, and flowing the lower layer hydrophobic ion extractant removing the target ions in the collection tank back to step (1) to be recycled.

4. The electrically active cyclic flow by membrane electro- controlled ion-selective separation process according to claim 3, characterized in that: The target ion is one of lithium Li + , rubidium Rb + , cesium Cs + , lead Pd 2+ , zinc Zn 2+ , cadmium Cd 2+ , arsenic As 3+ , lanthanum La 3+ , cerium Ce 4+ , neodymium Nd 3+ , europium Eu 3+ .

5. The electrically active cyclic flow by membrane electro- controlled ion-selective separation process according to claim 3, characterized by: The hydrophobic ionophore is one of N,N,N',N'-tetraoctyldiglycolamide, 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, 1-butyl-3-methylimidazolium hexafluorophosphate, 1-butyl-3-methylimidazolium octyl sulfate, trihexyl(tetradecyl)phosphonium chloride, 1-vinyl-3-butylimidazolium tetrafluoroborate, 1-butyl-3-acetylbenzo-21-crown-7 imidazolium bis(trifluoromethylsulfonyl)imide.

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