A coaxial cable type electrically controlled ion selective permeation device

Abstract

This invention provides a coaxial cable-type electro-controlled ion selective permeation device, relating to the field of electrochemical separation technology. The coaxial cable-type electro-controlled ion selective permeation device includes, from the inside out, a carbon rod 1, a receiving liquid chamber 2, a lithium manganese oxide ion permeation membrane 3, a feed liquid chamber 4, and a conductive tubular electrode 5, all coaxially arranged. The device also includes a power supply 10, with the carbon rod 1 connected to the negative terminal and the conductive tubular electrode 5 connected to the positive terminal. The lithium manganese oxide ion permeation membrane 3 is connected to either the carbon rod 1 or the conductive tubular electrode 5 via an electronic switch 11. By applying a periodic redox potential through the electronic switch 11, Li ions on the feed liquid side migrate through the permeation membrane to the receiving liquid, while the oxidation potential repels Mg ions, achieving a self-cleaning and anti-clogging function. This device can continuously and efficiently process lithium-containing feed liquids.

Description

Technical Field

[0001] This utility model relates to the field of electrochemical separation technology, and in particular to a coaxial cable type electrically controlled ion selective permeation device and its application in lithium ion extraction. Background Technology

[0002] Lithium, as a core material for power batteries, is experiencing exponential growth in demand. Salt lake brines are a major carrier of lithium resources, but most salt lakes have a high magnesium-to-lithium ratio (Mg²⁺). 2+ / Li + ≥20:1), complex coexisting ions, and other problems. Traditional membrane separation technologies (such as nanofiltration and electrodialysis) rely on sieving effects or charge repulsion principles, but for Li ions with similar ionic radii... + (0.076nm) and Mg 2+ (0.072nm) Insufficient selectivity [The Journal of Physical Chemistry C, 2020, 124(48): 26106-26116]. In the prior art, although electrochemical lithium extraction can selectively adsorb lithium ions through electrode materials, parallel plate electrodialysis devices suffer from severe concentration polarization and high energy consumption due to the long ion migration path.

[0003] Existing technologies for lithium extraction from high magnesium-to-lithium ratio salt lake brines have inherent drawbacks: on the one hand, the static adsorption-desorption mechanism is difficult to implement for continuous production, and on the other hand, high concentrations of Mg... 2+ Organic compounds compete with lithium ions for adsorption sites, significantly reducing extraction efficiency. On the other hand, while solvent extraction can improve selectivity, it presents challenges such as organic phase toxicity, emulsification and stratification, and wastewater treatment. In the field of seawater lithium extraction, the concentration of lithium ions in seawater is extremely low (0.1–0.2 ppm) and it competes with high concentrations of sodium (Na₂O₃). + K + The coexistence of these two methods is problematic. Traditional adsorption methods are difficult to apply economically due to their low adsorption capacity and high acid consumption during desorption. While electrochemical technology can drive lithium-ion migration through an electric field, conventional devices experience a surge in membrane stack resistance at low concentrations, resulting in energy consumption and operating costs far exceeding acceptable levels.

[0004] In response to the existing technology's requirements for lithium-ion extraction, those skilled in the art urgently need to develop a coaxial cable-type electrically controlled ion selective permeation device with high selectivity and low energy consumption to achieve efficient capture and directional migration of lithium ions. Utility Model Content

[0005] The main objective of this invention is to provide a coaxial cable-type electrically controlled ion selective permeation device to solve the aforementioned technical problems. The device consists of a central conductive carbon rod auxiliary electrode, a lithium manganese oxide ion permeation membrane, and a conductive tubular outer electrode. A periodic redox potential is set within the device via an electrically controlled switch to achieve the directional migration of lithium ions and to cause the lithium manganese oxide ion permeation membrane to repel magnesium ions, thus preventing membrane blockage.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A coaxial cable type electrically controlled ion selective permeation device includes a carbon rod 1, a receiving liquid chamber 2, a lithium manganese oxide ion permeation membrane 3, a raw material liquid chamber 4, and a conductive tubular electrode 5, which are coaxially wrapped from the inside to the outside.

[0008] The coaxial cable type electro-controlled ion selective permeation device also includes a power supply 10, wherein the carbon rod 1 is connected to the negative terminal of the power supply 10, the conductive tubular electrode 5 is connected to the positive terminal of the power supply, and the lithium manganese oxide ion permeation membrane 3 is connected to the carbon rod or the conductive tubular electrode through an electro-controlled switch 11.

[0009] Furthermore, the thickness of the lithium manganese oxide ion permeation membrane is 0.5-2 mm, preferably 0.7-1.8 mm, more preferably 1-1.5 mm, and even more preferably 1.2-1.3 mm.

[0010] Furthermore, the inner diameter of the lithium manganese oxide ion permeation membrane is 10-60 mm, preferably 20-50 mm, more preferably 30-45 mm, and even more preferably 40 mm.

[0011] Furthermore, the diameter of the carbon rod is 5-20 mm, preferably 8-15 mm, more preferably 10-12 mm, and even more preferably 12 mm.

[0012] Furthermore, the inner diameter of the conductive tubular electrode is 40-120 mm, preferably 50-100 mm, more preferably 60-80 mm, and even more preferably 60 mm.

[0013] Compared with the prior art, the present invention has the following beneficial effects:

[0014] The coaxial cable-type electrically controlled ion selective permeation device of this invention comprises, from the inside out, a central conductive carbon rod auxiliary electrode, a lithium manganese oxide ion permeation membrane, and a conductive tubular outer electrode. The feed solution and the receiving solution flow counter-currently in the annular space and the central pipe. A periodic redox potential is applied by an electrically controlled switch to selectively drive the Li-type feed solution side... + The lithium manganese oxide ions migrate through the permeation membrane into the receiving liquid, while simultaneously repelling Mg using their oxidation potential. 2+This device achieves self-cleaning and anti-clogging functions. It is suitable for lithium extraction from high magnesium-to-lithium ratio salt lake brines and seawater, and has advantages such as high separation efficiency, low energy consumption, and environmental friendliness. Moreover, the device is a pipeline type, requiring no liquid path switching, and can be operated continuously, making it suitable for industrial applications.

[0015] When this device is used to extract lithium ions from salt lake brine, Li + / Mg 2+ The separation factor has been increased from below 10 in traditional technology to 50-80; the shortened ion migration path and the synergistic effect of pulsed potential have reduced the energy consumption per unit lithium extraction to 3-5 kWh / kg, which is 60% lower than that of traditional electrodialysis technology; after the lithium manganese oxide ion permeation membrane has been running under pulsed potential for 100 hours, the lithium flux decay rate is ≤5% and there is no lattice collapse phenomenon. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0017] Figure 1 A schematic diagram of a coaxial cable type electrically controlled ion selective permeation device;

[0018] Wherein, 1-carbon rod; 2-receiving liquid chamber; 3-lithium manganese oxide ion permeation membrane; 4-raw material liquid chamber; 5-conductive tubular electrode; 6-upper inlet / outlet of receiving liquid chamber; 7-lower inlet / outlet of receiving liquid chamber; 8-lower inlet / outlet of raw material liquid chamber; 9-upper inlet / outlet of raw material liquid chamber; 10-power supply; 11-electric control switch;

[0019] Figure 2 This is a schematic diagram illustrating the ion migration principle of a coaxial cable-type electrically controlled ion selective osmosis device. Figure 2 In the diagram, (a) represents the ion migration direction when the lithium manganese oxide ion-permeable membrane is connected to the carbon rod via an electronically controlled switch. Figure 2 (b) in the figure represents the direction of ion migration when the lithium manganese oxide ion permeation membrane is connected to the conductive tubular electrode via an electronically controlled switch.

[0020] Figure 3 This is a schematic diagram of the apparatus used to treat simulated salt lake brine in Example 1. Detailed Implementation

[0021] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0022] Example 1

[0023] according to Figure 1 The schematic diagram of the device shows a coaxial cable-type electrically controlled ion selective permeation apparatus, including a coaxially encased carbon rod 1, a receiving liquid chamber 2, a lithium manganese oxide ion permeation membrane 3, a raw material liquid chamber 4, and a conductive tubular electrode 5. The carbon rod 1 has a diameter of 12 mm, the lithium manganese oxide ion permeation membrane 3 has a thickness of 1.2 mm and an inner diameter of 40 mm, and the conductive tubular electrode 5 is a 316L stainless steel tube with an inner diameter of 60 mm. The power supply 10 is set to 1.2V, and a time relay combined with an electronically controlled switch 11 switches the connection to the lithium manganese oxide ion permeation membrane, thereby applying a periodic redox potential.

[0024] The preparation method of the lithium manganese oxide ion permeation membrane is as follows: Li2CO3 and Mn3O4 are weighed in a molar ratio of 3:4 and ground to make them uniformly mixed. The resulting powder is placed in a muffle furnace and heated at a rate of 5℃ / min. It is calcined at 750℃ for 12h and then naturally cooled to room temperature to obtain lithium manganese oxide powder. Subsequently, the prepared lithium manganese oxide powder is mixed with PVDF and conductive carbon black in a mass ratio of 8:1:1 and ground uniformly. Finally, an appropriate amount of NMP is added and stirred for 24h to make a uniform slurry. The slurry is coated on both sides of a pretreated stainless steel wire mesh and dried at 120℃ for 12h to obtain the lithium manganese oxide ion permeation membrane (the preparation method refers to "Co-doping induced Mn-vacancy LiMn2O4 based membrane electrode for lithium extraction by electrochemically switched ion permselective process. Desalination 591(2024)118016").

[0025] To simulate salt lake brine (Li + 0.5 g / L, Mg 2+ 20g / L, Mg 2+ / Li +A lithium-containing feed solution with a ratio of 40:1 is processed using the aforementioned apparatus. Initially, the ion-permeable membrane is connected to the outer stainless steel tube for 60 seconds. After this period, the connection of the lithium manganese oxide ion-permeable membrane is switched to the central carbon rod electrode for another 60 seconds. The connection of the lithium manganese oxide ion-permeable membrane is switched every minute. The lithium-containing feed solution is introduced into the feed solution chamber through inlet 9 on the upper part of the feed solution chamber. The receiving liquid (with an initial lithium ion concentration of 0.01 g / L) is introduced into the receiving liquid chamber through inlet 7 on the lower part of the receiving liquid chamber. The two flow in opposite directions (the receiving liquid and the feed solution circulate independently). The flow rates of the lithium-containing feed solution and the receiving liquid are controlled at 10 mL / min. The apparatus and the flow directions of the lithium-containing feed solution and the receiving liquid are as follows: Figure 3 As shown. The Li content in the feed solution and receiver solution was tested every 10 minutes. + and Mg 2+ Concentration. After running for 2 hours, the Li in the central receiving chamber... + The concentration reached 0.43 g / L, and the Mg in the receiving solution... 2+ With a concentration ≤0.08 g / L, 1.2 L of feed solution was processed, achieving a recovery rate of 84%. After 20 hours of continuous operation, the lithium flux decay rate of the lithium manganese oxide membrane was only 1.2%, and no Mg(OH)2 deposition was detected on the electrode surface. This demonstrates the high efficiency and stability of the device in lithium extraction from high magnesium-to-lithium ratio brines. During continuous processing, when the Li in the receiving solution... + Stop when the concentration reaches 0.45-0.50 g / L (close to 90-100% of the initial concentration of the feed solution), and replace with new feed solution and receiving solution.

[0026] Example 2

[0027] For lithium extraction from low-concentration seawater, simulated seawater was used as the raw material, with a Li+ concentration of 0.15 ppm, a Na+ concentration of 10000 ppm, and a Mg concentration of... 2+ The concentration was 1200 ppm. The reactor configuration was as follows: the outer electrode was a 316L stainless steel tube with an inner diameter of 60 mm; the inner electrode was a high-purity graphite rod with a diameter of 8 mm; and a lithium manganese oxide ion-permeable membrane (1.0 mm thick, 40 mm inner diameter) was placed between the two electrodes. The power supply voltage was set to 2.0V to ensure sufficient electric field driving force even under low concentration conditions. Precise switching control of the potential was achieved through a programmable logic controller. Initially, the ion-permeable membrane was connected to the outer stainless steel tube for 120 seconds, then the connection of the lithium manganese oxide ion-permeable membrane was switched to the central carbon rod electrode for another 120 seconds. The connection of the lithium manganese oxide ion-permeable membrane was switched every 2 minutes to adapt to the slow ion migration rate at low concentrations. The lithium-containing feed liquid was introduced into the feed liquid chamber through the inlet / outlet on the feed liquid chamber, and the receiving liquid (Li) was... +A lithium-ion feed solution (0.1 ppm) was introduced into the receiving chamber through the lower inlet and outlet, flowing in opposite directions. The flow rates of the lithium-containing feed solution and the receiving liquid were controlled at 5 mL / min to ensure sufficient contact time and ion exchange efficiency. During the treatment process, the lithium-ion concentration in the feed solution and the receiving liquid was periodically monitored using atomic absorption spectrometry. After 8 hours of continuous operation, the Li+ concentration in the receiving liquid increased to 5 ppm, achieving the goal of effectively extracting lithium ions from low-concentration seawater. After 72 hours of continuous operation, the lithium flux decay rate of the lithium manganese oxide membrane was controlled within 3.5%, demonstrating the feasibility and stability of the system in lithium extraction from low-concentration seawater. During the treatment process, a 50 mL receiving solution was continuously circulated, processing 2.4 L of feed solution with a recovery rate of 69%.

[0028] The above description of the disclosed embodiments enables those skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A coaxial cable electrically controlled ion permselective device, characterized in that, It includes a carbon rod (1), a receiving liquid chamber (2), a lithium manganese oxide ion permeation membrane (3), a raw material liquid chamber (4), and a conductive tubular electrode (5) arranged coaxially from the inside to the outside. The coaxial cable type electro-controlled ion selective permeation device also includes a power supply (10), wherein the carbon rod (1) is connected to the negative electrode of the power supply (10), the conductive tubular electrode (5) is connected to the positive electrode of the power supply, and the lithium manganese oxide ion permeation membrane (3) is connected to the carbon rod or the conductive tubular electrode through an electro-controlled switch (11).

2. An electrically controlled ion permselective device of coaxial cable type according to claim 1, characterized in that, The thickness of the lithium manganese oxide ion-permeable membrane is 0.5–2 mm; The inner diameter of the lithium manganese oxide ion-permeable membrane is 10–60 mm.

3. A coaxial cable electrically controlled ion permselective device according to claim 2, wherein The diameter of the carbon rod is 5-20 mm; The inner diameter of the conductive tubular electrode is 40–120 mm.

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