阅读说明：本技术 双极膜-电控离子膜萃取法用于盐湖卤水产酸产碱的装置及工艺 (Device and process for producing acid and alkali from salt lake brine through bipolar membrane-electronic control ionic membrane extraction method ) 是由 高凤凤 王灿 车雨衡 郝晓刚 岳秀萍 郭继保 于 2021-09-30 设计创作，主要内容包括：本发明公开了一种双极膜-电控离子膜萃取法用于盐湖卤水产酸产碱的装置及工艺。该装置采用一腔多室板框结构,由膜堆、极区、压紧装置、脉冲电源和直流稳压电源组成；利用电活性膜材料对目标离子的电控萃取原理和双极膜水解离特性,将电活性阴、阳离子萃取膜与双极膜巧妙组合构成膜堆,在外加直流、脉冲电场与液路供给系统的协同作用下,原料室中的Li～(+)、I～(-)分别透过阳离子萃取膜与阴离子萃取膜到达碱室和酸室,与双极膜水解离出的H～(+)、OH～(-)结合生成酸和碱,达到盐湖卤水中金属离子的选择性分离并生成高附加值酸碱产品的目的。本发明电控离子萃取膜材料可重复利用；可连续运行,利于工业化生产。(The invention discloses a device and a process for producing acid and alkali from salt lake brine by using a bipolar membrane-electronic control ionic membrane extraction method. The device adopts a one-cavity multi-chamber plate frame structure and consists of a film stack, a polar region, a pressing device, a pulse power supply and a direct-current stabilized power supply; by using the electric control extraction principle of the active membrane material on target ions and the water dissociation characteristic of the bipolar membrane, the electroactive anion and cation extraction membrane and the bipolar membrane are skillfully combined to form a membrane stack, and under the synergistic action of an external direct current and pulse electric field and a liquid circuit supply system, Li in a raw material chamber + 、I ‑ Respectively penetrate through the cation extraction membrane and the anion extraction membrane to reach the alkali chamber and the acid chamber, and are separated from the bipolar membrane by water dissociation + 、OH ‑ The acid and alkali are generated in a combined manner, so that the aim of selectively separating metal ions in the salt lake brine and generating acid-base products with high added values is fulfilled. The electric control ion extraction membrane material can be repeatedly used; can continuously operate and is beneficial to industrial production.)

1. A bipolar membrane-electronic control ionic membrane extraction method is used for producing acid and alkali from salt lake brine, and is characterized in that: the device adopts a one-cavity multi-chamber plate frame structure and comprises a cathode/anode area at two ends, a film stack between the cathode and the anode, a pressing device, a pulse power supply, a direct-current stabilized power supply and auxiliary equipment;

the cathode/anode area consists of a supporting plate, a pole frame, a cathode/anode chamber electrode and a silica gel gasket; the center of the supporting plate is provided with a polar frame and a polar water connecting pipe, and is provided with a water distribution hole and a bolt hole; an electrode is arranged in the pole frame and is communicated with the pole water connecting pipe to form a pole chamber; the water distribution hole is used for connecting a water inlet pipe and a water outlet pipe; the silica gel gasket is arranged at the joint of the pole frame and the membrane stack and plays roles in preventing water leakage and adjusting uneven thickness;

the membrane stack comprises N structural units which are connected in parallel, wherein N is a positive integer; from the cathode to the anode, the structural units respectively comprise a bipolar membrane, a first clapboard, an electroactive cation extraction membrane, a second clapboard, an electroactive anion extraction membrane and a third clapboard which are sequentially arranged; the two ends of the membrane stack are both bipolar membranes; alternately placing a first partition plate, a second partition plate and a third partition plate between adjacent membranes to form an alkali chamber, a feed liquid chamber and an acid chamber which are independent among the membranes; the baffle plate consists of a plate frame body, a plate core separation net, semicircular flow guide holes, circular flow guide holes and a water distribution flow channel, wherein the flow guide holes are completely symmetrically designed and distributed at the upper end and the lower end of the plate frame body, each end is provided with 2 circular flow guide holes with alternate sizes and 1 semicircular flow guide hole, and the semicircular flow guide holes are communicated with the cavity through the water distribution flow channel; the partition boards are of the same structure, 3 kinds of partition board flow guide holes are communicated with the liquid conveying channel, and liquid supply of different chambers can be realized through semicircular flow guide holes and water distribution channels at different positions;

the compressing device mainly comprises a draw bar bolt and a nut, and is characterized in that a cathode area is → (a bipolar membrane → a first clapboard → an electroactive cation extraction membrane → a second clapboard → an electroactive anion extraction membrane → a third clapboard)_N→ bipolar membrane → anodeRegion → clamp bolt → sequence of uniform tightening makes the membrane stack and polar region form a whole;

the pulse power supply is applied to the electroactive anion and cation extraction membranes, and oxidation-reduction potentials are alternately applied to the electroactive anion and cation membrane electrodes; the direct current power supply is applied to the cathode and anode chamber electrodes, the cathode region, the chamber, the anode region and the direct current power supply form a series circuit, and finally current passes through the chamber;

the auxiliary equipment comprises a pump, a buffer tank and an electromagnetic valve; the automatic control of the electromagnetic valves and the pumps adopts a PLC programmable logic control system, the opening and the closing of each electromagnetic valve and each liquid supply pump are controlled according to requirements, so that the control of an external liquid supply system is realized, and the buffer tank enables materials to be accumulated in a certain amount, so that the purposes of stabilizing voltage and stabilizing flow are achieved.

2. The device for acid and alkali production of salt lake brine by using the bipolar membrane-electric control ionic membrane extraction method according to claim 1, which is characterized in that: the electroactive anion extraction membrane is a bismuth oxyiodide functional membrane containing an iodide ion binding site, polypyrrole and a composite membrane material of the bismuth oxyiodide functional membrane and the polypyrrole; the electroactive cation extraction membrane is a lithium manganate/polypyrrole and lithium manganate/graphene composite membrane; the electroactive extraction membrane has high selectivity to iodide ions and lithium ions, and the membrane material has high stability; the electric control ion extraction performance of the membrane material is to control the selective implantation and release of target ions by adjusting the oxidation-reduction potential of the membrane electrode.

3. The device for acid and alkali production of salt lake brine by using the bipolar membrane-electric control ionic membrane extraction method according to claim 1, which is characterized in that: the cathode and anode electrodes are one of a titanium platinum plating electrode, a titanium ruthenium plating electrode, a graphite electrode and a stainless steel electrode and are connected to two ends of a direct current power supply.

4. The device for acid and alkali production of salt lake brine by using the bipolar membrane-electric control ionic membrane extraction method according to claim 1, which is characterized in that: the structure of the separator is as follows: the first clapboard is rotated by 180 degrees to form the structure of a second clapboard, and the first clapboard is turned over front and back to form the structure of a third clapboard.

5. A process for producing acid and alkali from salt lake brine by using a bipolar membrane-electronic control ionic membrane extraction method, which is a device for producing acid and alkali from salt lake brine by using the bipolar membrane-electronic control ionic membrane extraction method as claimed in any one of claims 1-4, and is characterized in that: the method comprises the steps of ingeniously combining an electroactive anion and cation extraction membrane with a bipolar membrane to form a membrane stack by utilizing an electronic control extraction principle of the electroactive membrane material on target ions and the water dissociation characteristic of the bipolar membrane, alternately applying an oxidation-reduction potential on the membrane electrode through a circuit control system under the synergistic action of an external direct current and pulse electric field and a liquid circuit supply system to realize synchronous putting in and putting out of the target anions and cations, combining the liquid circuit control system to realize selective continuous electronic control separation of the target anions and cations, and simultaneously converting the target anions and cations into corresponding acid-base products by coupling the bipolar membrane technology.

6. The process for producing acid and alkali from salt lake brine by using the bipolar membrane-electronic control ionic membrane extraction method according to claim 5, which is characterized by comprising the following specific process steps:

(1) introducing 1-2L of raw material liquid and electrode liquid into a raw material tank and an electrode liquid tank, and introducing equivalent initial solution into an acid tank and an alkali tank;

(2) when the liquid level percentages of the raw material tank, the electrode liquid tank, the acid tank and the alkali tank reach 33% -67%, starting a water pump, and combining an electromagnetic valve control circuit to realize the control of the direction, the flow and the speed parameters of the fluid; the polar liquid is sequentially introduced into the anode chamber and the cathode chamber and then is subjected to closed cycle, the feeding chamber, the acid chamber and the alkali chamber adopt a 'feeding-discharging' operation mode, and the inlet and outlet flow rates of the acid chamber, the alkali chamber and the feeding chamber and the cycle flow rate of the solution in each compartment in the membrane stack are controlled, so that a part of the solution is circulated in the system, and a part of the solution continuously flows out of the system;

(3) after the flow of each water flow in the device is balanced and stable, a direct current power supply and a pulse power supply are switched on;

applying an oxidation potential on the anion electrode of the anion electric control ion extraction membrane to ensure that target anions are selectively adsorbed and placed in the anion electrode of the anion electric control membrane respectively; applying opposite reduction potential on the anion electrode of the electrically controlled ion extraction membrane to release target anions adsorbed in the membrane electrode in the electrically controlled membrane electrode;

applying reduction potential on the cation electric control ion extraction membrane electrode to enable target cations to be selectively adsorbed and placed into the cation electric control membrane electrode respectively; applying opposite oxidation potential on the cation electric control ion extraction membrane electrode to release target cations adsorbed in the membrane electrode in the electric control membrane electrode; under the coupling action of a direct current electric field, anions and cations released by the membrane electrode permeate the membrane and enter the acid chamber and the alkali chamber respectively;

(4) meanwhile, H between the bipolar membrane composite layers is generated under the action of a direct current electric field₂Dissociation of O into H⁺、OH^-And respectively transferred to an acid chamber and a base chamber;

(5) finally, the anions and cations penetrating through the anion and cation membrane electrodes are respectively ionized with OH ionized by the bipolar membrane^-、H⁺LiOH and HI were formed in the acid and base chambers, respectively.

7. The bipolar membrane-electric-control ionic membrane extraction process for producing acid and alkali from salt lake brine according to claim 6, which is characterized in that: in the separation process, the cell voltage is 20V; alternately applying pulse potentials of-0.5 to + 0.8V to the anion and cation extraction membranes, wherein the pulse width is 50 s; the circulation flow rate of the solution in each compartment in the membrane stack is 30L/h; the flow rate of the acid, the alkali and the raw material liquid is 1-100 ml/min.

Technical Field

The invention relates to a device and a process for producing acid and alkali from salt lake brine by using a bipolar membrane-electronic control ionic membrane extraction method, in particular to a method for continuously and electrically controlling, separating and recovering lithium ions and iodine ions in salt lake brine by using the bipolar membrane-electronic control ionic membrane extraction method and converting the lithium ions and the iodine ions into lithium hydroxide and hydroiodic acid products; belongs to the technical field of high-efficiency utilization of salt lake resources.

Background

The salt lake brine contains abundant inorganic salt resources, and reserves of some high-value rare elements such as lithium, rubidium, cesium and iodine are considerable. Therefore, how to efficiently extract high-value ions in salt lake brine becomes a focus problem in the field of salt lake resource utilization.

Lithium is an important strategic resource, the salt lake lithium resource accounts for about 85 percent of the total reserve of China, and the product is widely applied to the fields of battery industry, lubricating grease, nuclear industry and the like. With the rapid development of new energy automobiles, ternary high-nickel battery materials become mainstream, so that the demand of lithium hydroxide, a basic lithium salt product, is remarkably increased. In addition, the iodine has wide application, is an important resource for national economic development, and about 90 percent of iodine in China depends on import every year. Hydroiodic acid is an iodine inorganic strong acid and is widely applied to the fields of high-end catalysts, new materials such as graphene and the like, preparation of high-purity iodides and the like. Therefore, the method has good application prospect for continuously and efficiently extracting lithium ions and iodine ions in the brine and converting the lithium ions and the iodine ions into corresponding products.

The separation technology aiming at the target ions in the salt lake brine mainly comprises an ion exchange method, an adsorption method, a membrane separation method and the like. The traditional ion separation technology has the defects of complex operation, limited selectivity, low adsorption and desorption efficiency, easy generation of secondary pollution and the like.

Recently, electronically controlled ionic membrane extraction (ESIE) technology has been attracting attention as an environmentally friendly ion separation technology. The quick input and output of low-concentration target ions are realized by adjusting the oxidation/reduction potential of the electroactive functional membrane material, and no secondary pollution is generated. Chinese patent CN108441881A discloses a process for producing iodine products by an electric control membrane extraction coupling electrolysis method, which mainly aims at single target ion (I)^-) The separation and operation of the method are batch processes, which are not beneficial to the industrial application of the method. Chinese patent CN102718292A discloses a double-diaphragm electrode reactor, which adopts a double-diaphragm selective permeation membrane electrode and realizes the purpose of synchronously separating anions and cations under the action of the electric field force applied by an auxiliary electrode, but because the double-diaphragm selective permeation membrane electrode is a single-group pair membrane system, the treatment capacity and the separation efficiency are limited, and the double-diaphragm selective permeation membrane electrode cannot be further utilized as resources.

The bipolar membrane is a novel ion exchange composite membrane which can dissociate water into H under the action of a direct current electric field⁺、OH^-And migrate to both sides of the membrane. By utilizing the characteristic, the bipolar membrane electrodialysis system combining the bipolar membrane and other anion-cation exchange membranes can convert the salt in the aqueous solution into corresponding acid and alkali. Chinese patent CN112939295A discloses a method for preparing acid and alkali by electrodialysis of a sodium sulfate bipolar membrane, which skillfully combines the bipolar membrane with an anion-exchange membrane and a cation-exchange membrane to form a bipolar membrane electrodialysis process, and solves the problems of complexity and high cost of the existing acid and alkali preparation process. However, because the selectivity of ions in the electrodialysis process is limited, the import water quality is particularly important, and therefore, the pretreatment process of the acid and alkali production process by bipolar membrane electrodialysis is complicated.

Although the electric control ionic membrane extraction technology and the bipolar membrane acid and alkali production technology have been researched at present, the theory and process of coupling the electric control ionic membrane extraction technology with the bipolar membrane acid and alkali production technology have not been reported.

Disclosure of Invention

The invention aims to provide a device and a process for acid and alkali production of salt lake brine by using a bipolar membrane-electronic control ionic membrane extraction method, and multi-target ions (Li) are constructed⁺、I^-) An electrically controlled ion membrane extraction system with continuous and synchronous separationThe technology for producing lithium hydroxide and hydroiodic acid products by recycling salt lake brine is designed by combining the bipolar membrane technology.

The invention utilizes the electric control extraction principle of the electroactive membrane material on target ions and the water dissociation characteristic of the bipolar membrane, skillfully combines the electroactive anion and cation extraction membranes and the bipolar membrane to form a membrane stack, and under the synergistic action of an external direct current, a pulse electric field and a liquid circuit supply system, Li in a raw material chamber⁺、I^-Respectively penetrate through the cation extraction membrane and the anion extraction membrane to reach the alkali chamber and the acid chamber, and are separated from the bipolar membrane by water dissociation⁺、OH^-The acid and alkali are generated in a combined manner, so that the aim of selectively separating metal ions in the salt lake brine and generating acid-base products with high added values is fulfilled. The invention takes the electrode potential as the driving force, greatly improves the adsorption and desorption efficiency of ions, generates no by-products, generates corresponding acid-base products by utilizing the bipolar membrane, is a clean production process with continuous operation, high ion selectivity and high separation efficiency, and has wide application prospect.

The invention provides a device for acid and alkali production from salt lake brine by a bipolar membrane-electric control ionic membrane extraction method, which adopts a one-cavity multi-chamber plate frame structure, and comprises a cathode/anode area at two ends, a membrane stack between the cathode and the anode, a pressing device, a pulse power supply, a direct-current stabilized power supply and auxiliary equipment;

the cathode/anode area consists of a supporting plate, a pole frame, a cathode/anode chamber electrode and a silica gel gasket; a pole frame and a pole water connecting pipe are arranged in the supporting plate, and a water distribution hole and a bolt hole are formed in the supporting plate; an electrode is arranged in the pole frame and is communicated with the pole water connecting pipe to form a pole chamber; the water distribution hole is used for connecting a water inlet pipe and a water outlet pipe; the silica gel gasket is arranged at the joint of the pole frame and the membrane stack and plays roles in preventing water leakage and adjusting uneven thickness;

the membrane stack comprises N structural units which are connected in parallel, wherein N is a positive integer; from the cathode to the anode, the structural units respectively comprise a bipolar membrane, a first clapboard, an electroactive cation extraction membrane, a second clapboard, an electroactive anion extraction membrane and a third clapboard which are sequentially arranged; the two ends of the membrane stack are both bipolar membranes; alternately placing a first partition plate, a second partition plate and a third partition plate between adjacent membranes to form an alkali chamber, a feed liquid chamber and an acid chamber which are independent among the membranes; the baffle plate consists of a plate frame body, a plate core separation net, semicircular flow guide holes, circular flow guide holes and a water distribution flow channel, wherein the flow guide holes are completely symmetrically designed and distributed at the upper end and the lower end of the plate frame body, each end is provided with 2 circular flow guide holes with alternate sizes and 1 semicircular flow guide hole, and the semicircular flow guide holes are communicated with the cavity through the water distribution flow channel; the partition boards are of the same structure, 3 compartments can be shared, the first partition board is rotated by 180 degrees to form a structure of a second partition board, the first partition board is turned over back and forth to form a structure of a third partition board, the 3 partition board flow guide holes are communicated with the liquid conveying channel, and liquid supply of different chambers can be realized through semicircular flow guide holes and water distribution flow channels at different positions;

the compressing device mainly comprises a draw bar bolt and a nut, and is characterized in that a cathode area is → (a bipolar membrane → a first clapboard → an electroactive cation extraction membrane → a second clapboard → an electroactive anion extraction membrane → a third clapboard)_NThe sequence of → bipolar membrane → anode area → clamp bolt → uniform tightening makes the membrane stack and the anode area form a whole;

the pulse power supply is applied to the electroactive anion and cation extraction membranes, and oxidation-reduction potentials are alternately applied to the electroactive anion and cation membrane electrodes; the direct current power supply is applied to the cathode and anode chamber electrodes, the cathode region, the chamber, the anode region and the direct current power supply form a series circuit, and finally current passes through the chamber;

the auxiliary equipment comprises a pump, a buffer tank and an electromagnetic valve; the automatic control of the electromagnetic valves and the pumps adopts a PLC programmable logic control system, the opening and the closing of each electromagnetic valve and each liquid supply pump are controlled according to requirements, so that the control of an external liquid supply system is realized, and the buffer tank enables materials to be accumulated in a certain amount, so that the purposes of stabilizing voltage and stabilizing flow are achieved.

In the device, the electroactive anion extraction membrane is a bismuth oxyiodide functional membrane containing an iodide ion binding site, polypyrrole and a composite membrane material of the bismuth oxyiodide functional membrane and the polypyrrole; the electroactive cation extraction membrane is a lithium manganate/polypyrrole and lithium manganate/graphene composite membrane; the electroactive extraction membrane has high selectivity to iodide ions and lithium ions, and the membrane material has high stability; the electric control ion extraction performance of the membrane material is to control the selective implantation and release of target ions by adjusting the oxidation-reduction potential of the membrane electrode.

In the device, the cathode and anode chamber electrodes are one of a titanium platinum plating electrode, a titanium ruthenium plating electrode, a graphite electrode and a stainless steel electrode, and are connected with two ends of a direct current power supply.

The invention provides a process for producing acid and alkali from salt lake brine by using a bipolar membrane-electric control ionic membrane extraction method⁺、I^-Respectively penetrate through the cation extraction membrane and the anion extraction membrane to reach the alkali chamber and the acid chamber, and are separated from the bipolar membrane by water dissociation⁺、OH^-The acid and alkali are generated in a combined manner, so that the aim of selectively separating metal ions in the salt lake brine and generating acid-base products with high added values is fulfilled. The specific process steps are as follows:

(1) introducing 1-2L of raw material liquid (namely salt lake brine) and electrode liquid (namely 3wt.% Na) into the raw material tank and the electrode liquid tank₂SO₄Solution), introducing equal amount of initial solution (namely pure water) into an acid tank and an alkali tank;

(2) when the liquid level percentages of the raw material tank, the electrode liquid tank, the acid tank and the alkali tank reach 33% -67%, the water pump is started, and the control of parameters such as the direction, the flow rate and the speed of the fluid is realized by combining with an electromagnetic valve control circuit. The polar liquid is sequentially introduced into the anode chamber and the cathode chamber and then is circulated in a closed loop, the feeding liquid chamber, the acid chamber and the alkali chamber adopt a 'feeding-discharging (FB)' operation mode, and the inlet and outlet flow rates of the acid chamber, the alkali chamber and the feeding liquid chamber and the circulating flow rate of each compartment solution in the membrane stack are controlled, so that a part of solution is circulated in the system, and a part of solution continuously flows out of the system;

(3) after the flow of each water flow in the device is balanced and stable, a direct current power supply and a pulse power supply are switched on;

applying an oxidation potential on the anion electrode of the anion electric control ion extraction membrane to ensure that target anions are selectively adsorbed and placed in the anion electrode of the anion electric control membrane respectively; applying opposite reduction potential on the anion electrode of the electrically controlled ion extraction membrane to release target anions adsorbed in the membrane electrode in the electrically controlled membrane electrode;

applying reduction potential on the cation electric control ion extraction membrane electrode to enable target cations to be selectively adsorbed and placed into the cation electric control membrane electrode respectively; applying opposite oxidation potential on the cation electric control ion extraction membrane electrode to release target cations adsorbed in the membrane electrode in the electric control membrane electrode; under the coupling action of a direct current electric field, anions and cations released by the membrane electrode permeate the membrane and enter the acid chamber and the alkali chamber respectively;

(4) meanwhile, H between the bipolar membrane composite layers is generated under the action of a direct current electric field₂Dissociation of O into H⁺、OH^-And respectively transferred to an acid chamber and a base chamber;

(5) finally, the anions and cations penetrating through the anion and cation membrane electrodes are respectively ionized with OH ionized by the bipolar membrane^-、H⁺LiOH and HI were formed in the acid and base chambers, respectively.

In the process, under the synergistic action of an external direct current and a pulse electric field, the redox potential is alternately applied to the membrane electrode through the circuit control system to realize the synchronous putting in and putting out of target anions and cations, the selective continuous electric control separation of the target anions and cations can be realized by combining the liquid circuit control system, and simultaneously the target anions and cations are converted into corresponding acid-base products by coupling the bipolar membrane technology.

Further, during the separation process, the cell voltage is 20V; alternately applying pulse potentials of-0.5 to + 0.8V to the anion and cation extraction membranes, wherein the pulse width is 50 s; the circulation flow rate of the solution in each compartment in the membrane stack is 30L/h; the flow rate of the acid, the alkali and the raw material liquid is 1-100 ml/min.

The invention has the beneficial effects that:

(1) the invention relates to an electric control membrane extraction and bipolar membrane coupling integration technology, which is a multifunctional combined technology for recovering lithium resources and iodine resources in a salt lake and generating lithium hydroxide and hydroiodic acid products with high added values, and the invention strengthens the treatment effect of lithium ions and iodine ions in salt lake brine under the synergistic action of the electric control ionic membrane extraction technology and the bipolar membrane technology, realizes the multi-stage product and the multifunctional property of a device, can effectively reduce the operation cost, and is beneficial to reducing the energy consumption of a system;

(2) the electrode potential oxidation reduction is used as a main driving force, secondary pollution caused by regeneration of a chemical reagent is avoided, the adsorption and desorption efficiency and the extraction rate of ions are greatly improved, and the method is still suitable for the raw material liquid of the target ions with low concentration;

(3) through the ingenious combination of the bipolar membrane and the electric control membrane, acid-base products with high added values (lithium hydroxide and hydroiodic acid are produced), and the resource production of the salt lake brine is realized;

(4) cathode and anode chamber electrode liquid are connected in series, bipolar membrane water dissociation and H generated by cathode and anode electrolysis⁺And OH^-Phase neutralization; can effectively avoid electrode corrosion and H₂、O₂The stability and the safety of the device are improved by the generation of gases;

(5) the 'feeding-discharging' mode is adopted, and the circulating proportion can be changed by controlling the flow rate of the acid-base chamber to flow in and out so as to adjust the content of acid-base products; the continuous output of acid and alkali products and the continuous treatment of salt lake brine can be realized through the precise liquid path control system;

(6) the electric control ion extraction membrane material can be repeatedly used; can continuously operate and is beneficial to industrial production.

Drawings

FIG. 1 is a schematic diagram of acid and alkali production by bipolar membrane-electric control ionic membrane extraction.

FIG. 2 is a schematic structural diagram of a bipolar membrane-electric control ionic membrane extraction device.

FIG. 3 is a process flow diagram of acid and alkali production by bipolar membrane-electric control ionic membrane extraction.

Fig. 4 is a view showing the structure of the first separator.

In the figure: 1-pole chamber; 2-a feed chamber; 3-acid chamber; 4-an alkali chamber; 5-a cathode; 6-an anode; 7-a bipolar membrane; 8-electroactive cation extraction membranes; 9-electroactive anion extraction membranes; 10-a supporting plate; 11-pole frame; 12-water distribution holes; 13-bolt holes; 14-pole water connection pipe; 15-silica gel gasket; 16-a first separator; 17-a second separator; 18-a third separator; 19-a solenoid valve; 20-a pump; 21-acid tank; 22-an alkali tank; 23-a polar liquid tank; 24-a feed solution tank; 25-a plate frame body; 26-plate core grid; 27-semicircular flow guide holes; 28-circular flow guide holes; 29-water distribution channel.

Detailed Description

The present invention is further illustrated by, but is not limited to, the following examples.

As shown in fig. 1-4, an acid and alkali producing device by bipolar membrane-electric control ionic membrane extraction method is characterized in that: the device adopts a one-cavity multi-chamber plate frame structure and consists of cathode (anode) regions at two ends of the device, a membrane stack between the cathode region and the anode region, a pressing device, a pulse power supply and a direct-current stabilized power supply;

the cathode (anode) region consists of a supporting plate 10, an electrode frame 11, a cathode (anode) chamber electrode and a silica gel gasket 15; the center of the supporting plate 10 is provided with a polar frame 11 and a polar water connecting pipe 14, and is provided with a water distribution hole 12 and a bolt hole 13; an electrode is placed in the pole frame 11 and is communicated with the pole water connecting pipe 14 to form a pole chamber 1; the water distribution hole 12 is used for connecting a water inlet pipe and a water outlet pipe; the silica gel gasket 15 is disposed at the joint of the pole frame 11 and the membrane stack, and has functions of preventing water leakage and adjusting thickness unevenness.

The membrane stack comprises N structural units which are connected in parallel, wherein N is a positive integer; from the cathode to the anode, the structural units respectively comprise a bipolar membrane 7, a first clapboard 16, an electroactive cation extraction membrane 8, a second clapboard 17, an electroactive anion extraction membrane 9 and a third clapboard 18 which are sequentially arranged; the two ends of the membrane stack are both provided with bipolar membranes 7; alternately placing a first partition plate 16, a second partition plate 17 and a third partition plate 18 between adjacent membranes to form an alkali chamber 4, a feed liquid chamber 2 and an acid chamber 3 which are independent among the membranes; the baffle plate consists of a plate frame body 25, a plate core separation net 26, flow guide holes and a water distribution flow channel 29, wherein the flow guide holes are distributed at the upper end and the lower end of the plate frame body, each end is provided with 2 circular flow guide holes 28 with alternate sizes and a semicircular flow guide hole 27, and the water distribution flow channel 29 is connected between the semicircular flow guide holes 27 and the plate core grid net 26; the partition boards are of the same structure, the common use of three compartments can be realized, the first partition board 16 is rotated by 180 degrees and turned back and forth to respectively obtain a second partition board 17 and a third partition board 18, and 3 partition boards with diversion holes and water distribution channels at different positions are obtained after conversion, so that the liquid supply of different chambers is realized;

the compressing device mainly comprises a draw bar bolt and a nut, and is characterized in that a cathode area is → (a bipolar membrane → a first clapboard → an electroactive cation extraction membrane → a second clapboard → an electroactive anion extraction membrane → a third clapboard)_NThe sequence of bipolar membrane → anode region → clamp bolt → uniform tightening makes the membrane stack and the electrode region form a whole.

The pulse power supply is applied to the electroactive anion and cation extraction membranes, and oxidation-reduction potentials are alternately applied to the electroactive anion and cation membrane electrodes; the direct current power supply is applied to the cathode chamber electrode and the anode chamber electrode, the cathode region, the chamber, the anode region and the direct current power supply form a series circuit, and finally current passes through the chamber;

in addition, the device also comprises auxiliary equipment of a pump 20, a buffer tank (namely an acid tank 21, an alkali tank 22, a polar liquid tank 23 and a raw material liquid tank 24) and an electromagnetic valve 19; the automatic control of the electromagnetic valves and the pumps adopts a PLC control system, the opening and the closing of each electromagnetic valve and each liquid supply pump are controlled according to requirements, so that the supply of external liquid is realized, and the buffer tank can enable materials to have certain accumulation, so that the purpose of stabilizing the pressure and the flow is achieved.

In the device, the electroactive anion extraction membrane is a bismuth oxyiodide functional membrane containing an iodide ion binding site, polypyrrole and a composite membrane material of the bismuth oxyiodide functional membrane and the polypyrrole; the electroactive cation extraction membrane is a lithium manganate/polypyrrole and lithium manganate/graphene composite membrane; the electroactive extraction membrane has high selectivity to iodide ions and lithium ions, and the membrane material has high stability; the electric control ion extraction performance of the membrane material is to control the selective implantation and release of target ions by adjusting the oxidation-reduction potential of the membrane electrode.

In the device, the cathode and anode chamber electrodes are one of a titanium platinum plating electrode, a titanium ruthenium plating electrode, a graphite electrode and a stainless steel electrode, and are connected to two ends of a direct current power supply.

The application of the present invention is further illustrated by the following specific examples.

Example i:

the acid and alkali production device adopting the bipolar membrane-electric control ionic membrane extraction method shown in fig. 3 is adopted, the cathode and anode chamber electrodes both adopt plate-type titanium ruthenium-coated electrodes, and the electroactive cathode and cation extraction membranes respectively adopt a bismuth oxyiodide functional membrane and a lithium manganate/graphene composite membrane. 1L of salt lake brine is introduced into the raw material tank, and 1L of 3wt.% Na is introduced into the polar liquid tank₂SO₄1L of pure water is respectively introduced into the acid tank and the alkali tank; setting the flow rate of acid, alkali (initially pure water) and raw material liquid to be 10 ml/min, the circulating flow rate of the solution in each compartment in the membrane stack to be 30L/h, controlling the voltage of the tank to be 20V by a direct current power supply, and alternately applying pulse potentials of-0.5 to + 0.8V and pulse width of 50 s on the anion and cation extraction membranes by a pulse power supply.

Mg in the salt lake brine²⁺In a concentration of 9000 ppm, Li⁺Concentration 600 ppm, I^-Concentration 22000 ppm, Cl^-The concentration was 13300 ppm. The extraction efficiency of the iodide ions and the lithium ions reaches 90 percent, the extraction amount of the solution of the hydroiodic acid and the lithium hydroxide is 0.6L/h, and the concentration is 19.96 g/L and 1.85 g/L respectively.

Example 2:

the acid and alkali production device adopting the bipolar membrane-electric control ionic membrane extraction method shown in fig. 3 is adopted, the cathode and anode chamber electrodes both adopt plate-type titanium ruthenium-coated electrodes, and the electroactive cathode and cation extraction membranes respectively adopt a bismuth oxyiodide functional membrane and a lithium manganate/graphene composite membrane. 1L of salt lake brine is introduced into the raw material tank, and 1L of 3wt.% Na is introduced into the polar liquid tank₂SO₄1L of pure water is respectively introduced into the acid tank and the alkali tank; setting the flow rate of acid, alkali (initially pure water) and raw material liquid to be 20 ml/min, the circulating flow rate of the solution in each compartment in the membrane stack to be 30L/h, controlling the voltage of the tank to be 20V by a direct current power supply, and alternately applying pulse potentials of-0.5 to + 0.8V and pulse width of 50 s on the anion and cation extraction membranes by a pulse power supply.

Mg in the salt lake brine²⁺Concentration 10000 ppm, Li⁺At a concentration of 700 ppm, I^-Concentration 25000 ppm, Cl^-The concentration was 15000 ppm. The extraction efficiency of the iodine ions and the lithium ions reaches 89 percent, and the extraction amount of the solution of the hydriodic acid and the lithium hydroxide isThe concentration is 1.2L/h, and the concentration is 22.42 g/L and 2.08 g/L respectively.