Method for removing thallium through cooperation of electric membrane catalytic oxidation filtration and adsorption

Abstract

The invention provides an electromembrane catalytic oxidation filtration and adsorption synergetic thallium removal method which comprises the following steps: applying an external electric field to an electrochemical reactor, so that thallium-containing wastewater flows into the electrochemical reactor to be subjected to electromembrane catalytic oxidation filtration and adsorption reaction, and the thallium-containing wastewater sequentially passes through an anode and a cathode in the electrochemical reactor; the anode and the cathode are both graphite carbon felt membrane electrodes, and the graphite carbon felt membrane electrodes have three-dimensional net-shaped porous structures, so that the specific surface area is remarkably increased, a relatively strong catalytic effect on electrooxidation is achieved, and meanwhile, a relatively good membrane filtration function is achieved. According to the invention, the anode and the cathode can carry out membrane filtration type efficient thallium removal on thallium-containing wastewater by utilizing electromembrane catalytic oxidation filtration and adsorption reaction based on a non-oxidizing membrane electrode material, and thallium can be analyzed and concentrated through reverse electrification, so that a foundation is laid for thallium recovery, and the repeated use of the electrode can be realized.

Description

Technical Field

[0001] This invention belongs to the field of wastewater treatment, and in particular relates to a method for thallium removal by electro-membrane catalytic oxidation filtration and adsorption synergistic. Background Technology

[0002] Thallium-containing wastewater contains a large amount of Tl + How to implement Tl + The efficient removal of thallium remains a major challenge. Existing electrochemical thallium removal methods typically involve adjusting or optimizing the electrode materials to improve the removal rate. For example, Chinese invention patent CN114790019A describes a method for removing thallium using manganese dioxide electrodes via electroadsorption. This method places thallium-containing wastewater in a capacitive deionization device and applies an external electric field to the device to remove thallium; both the cathode and anode in this patent are manganese dioxide electrodes.

[0003] The aforementioned patent primarily utilizes electroadsorption through the synergistic effect of the electric double layer and pseudocapacitance. Manganese dioxide is chosen as the electrode material due to its large theoretical capacitance, allowing it to undergo a Faraday reaction with thallium ions and embed them into the electrode. After applying a voltage, Tl... + The cathode stores data in two ways: firstly, through physical adsorption by forming an electrical double layer; and secondly, by embedding the data into manganese dioxide lattice tunnels. Simultaneously, the aforementioned patent will... + Anodized to Tl 3+ Tl 3+ Under the influence of the electric field, it migrates towards the cathode to interact with Tl. + The same method is used to fix and store the cathode; the aforementioned patent will Tl + Anodized to Tl 3+ This is due to the cathode material's effect on Tl. 3+ The adsorption capacity is stronger, and its anode must be an oxidizing material to ensure that the thallium removal rate is above 95%. When a non-oxidizing material is selected, the thallium removal rate is not high.

[0004] Therefore, it is necessary to provide a method for synergistic removal of thallium by electro-membrane catalytic oxidation filtration and adsorption, in order to solve the technical problem of how to efficiently remove thallium based on non-oxidizing membrane electrode materials. Summary of the Invention

[0005] The main objective of this invention is to provide a method for thallium removal through electro-membrane catalytic oxidation filtration and adsorption synergistic, aiming to solve the technical problem of how to efficiently remove thallium based on non-oxidizing membrane electrode materials.

[0006] To achieve the above objectives, the present invention provides a method for the synergistic removal of thallium by electromembrane catalytic oxidation filtration and adsorption, comprising: applying an external electric field to an electrochemical reactor and allowing thallium-containing wastewater to flow into the electrochemical reactor, thereby causing an electromembrane catalytic oxidation filtration and adsorption reaction; wherein the thallium-containing wastewater contains Tl + ; The electrochemical reactor includes: an inlet channel, an anode, a cathode, and an outlet channel arranged in sequence; the thallium-containing wastewater flows along the inlet channel to the anode, passes through the anode and flows to the cathode, passes through the cathode and is discharged from the outlet channel; both the anode and the cathode are graphite carbon felt film electrodes, and the graphite carbon felt film electrodes have a three-dimensional network porous structure.

[0007] Furthermore, the thallium-containing wastewater is pumped along the inlet passage to the anode.

[0008] Furthermore, the flow rate of the thallium-containing wastewater is 80-140 mL / min.

[0009] Furthermore, the pH of the thallium-containing wastewater is not less than 5; in the thallium-containing wastewater, Tl + The concentration is 0.002-10 mg / L.

[0010] Furthermore, during the electro-membrane catalytic oxidation filtration and adsorption reaction, the thallium-containing wastewater flows from the feed tank into the liquid inlet passage; and the water discharged from the liquid outlet passage flows back to the feed tank and then continues to flow into the liquid inlet passage.

[0011] Furthermore, in the graphite carbon felt film electrode, the pores between the carbon fibers constitute macroscopic channels, and the fiber body of the carbon fibers contains micropores and mesopores.

[0012] Furthermore, the voltage of the applied electric field is 2-5V; the duration of the electro-membrane catalytic oxidation filtration and adsorption reaction is 1-6h.

[0013] Furthermore, the electrochemical reactor also includes a partition plate; the partition plate has multiple through holes; The partition is disposed between the anode and the cathode; one side of the partition is in contact with the anode, and the other side of the partition is in contact with the cathode; the thickness of the partition is 4-6 mm.

[0014] Furthermore, the electromembrane catalytic oxidation filtration and adsorption reaction process includes at least the following: A. Tl + Catalytic oxidation to Tl in the region of the anode 3+ Tl 3+ With OH in water -After forming Tl(OH)3 precipitate, it is retained or adsorbed by the graphite carbon felt of the anode and the cathode; B. Tl + Catalytic oxidation to Tl in the region of the anode 3+ Tl 3+ OH generated by hydrogen evolution in the cathode region - After the reaction forms Tl(OH)3 precipitate, it is retained or adsorbed by the graphite carbon felt of the cathode; C. Tl + Catalytic oxidation to Tl in the region of the anode 3+ Then, under the action of an electric field, it is directly adsorbed by the graphite carbon felt of the cathode; D. Tl + After being reduced to elemental Tl in the region of the cathode, it is retained or adsorbed by the graphite carbon felt of the cathode. E. Tl + Under the influence of an electric field, it is directly adsorbed by the graphite carbon felt of the cathode.

[0015] Furthermore, once the electrochemical reactor reaches saturation for thallium adsorption, a reverse electrochemical desorption process is performed to achieve thallium concentration and recovery and electrode reuse.

[0016] Compared with the prior art, the present invention has at least the following advantages: This invention utilizes non-oxidizing membrane electrode materials and electro-membrane catalytic oxidation filtration and adsorption reactions to achieve highly efficient thallium removal from thallium-containing wastewater via filtration at the anode and cathode. Specifically, this invention involves electro-membrane catalytic oxidation filtration and adsorption reactions catalyzed by a three-dimensional network graphite carbon felt membrane electrode. In this invention, the graphite carbon felt serves as an essential channel for the flow of thallium-containing wastewater. Its complex pore structure and catalytic effect on electro-oxidation ensure that when wastewater first passes through the anode, the reaction space between Tl ions in the wastewater and the anode surface increases, resulting in highly efficient catalytic oxidation and promoting Tl removal. + To Tl 3+ The transformation; at the same time, Tl 3+ With OH - The generated Tl(OH)3 precipitate is effectively retained or physically adsorbed on the surface of the cathode graphite carbon felt, or directly electro-adsorbed onto the cathode; in addition, a small portion of Tl that is not effectively oxidized by the anode... + Tl is partially reduced to elemental form and physically adsorbed onto the cathode due to the cathode's inherent reducing properties, and partially adsorbed onto the cathode surface due to electroadsorption. This invention forms a multiple combination of oxidation precipitation, physical adsorption, and electroadsorption, ultimately causing Tl to adhere to the cathode in various forms, achieving highly efficient removal of Tl from wastewater.

[0017] It should be noted that the graphite carbon felt membrane electrode is unique in this invention. Besides exhibiting the conductivity of typical graphite and titanium electrodes, its high specific surface area and three-dimensional porous structure also provide catalytic and membrane filtration functions, making it possible for thallium-containing wastewater to pass through the anode first under pump suction. During this mass transfer process, the Tl in the thallium-containing wastewater... + Catalytic oxidation by the anode to produce Tl 3+ Partial Tl 3+ With OH in water - Tl(OH)3 precipitate forms, and some unprecipitated Tl 3+ Adsorbed into the cathode region, it reacts with OH- produced by hydrogen evolution at the cathode. - Further reaction and precipitation occur. The mass transfer at the anode in thallium-containing wastewater lays the foundation for subsequent thallium precipitation. Other electrode materials, such as activated carbon fiber, have poor conductivity, and graphite and titanium electrodes cannot filter the wastewater; none of them possess both high conductivity and mass transfer capabilities. Furthermore, in this invention, Tl(OH)3 at the cathode is trapped or physically adsorbed by the graphite carbon felt material, and a small amount of unprecipitated Tl... 3+ It can also be adsorbed onto the cathode surface. This invention fully embodies the synergistic thallium removal mechanism of oxidation precipitation-reduction precipitation-physical adsorption-electroadsorption. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention 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 some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0019] Figure 1 This is a structural breakdown diagram of the electrochemical reactor in this invention; Figure 2 SEM analysis of the graphite carbon felt material in Example 1 of this invention, with a scale bar of 4 μm; Figure 3 XRD analysis of the graphite carbon felt material (Original) in Example 1 of this invention, and the post-reaction anode (Anode) and post-reaction cathode (Cathode) in Example 2; Figure 4 This is a SEM analysis of the anode after the reaction in Example 2 of the present invention, with a scale bar of 4 μm; Figure 5 This is a SEM analysis of the cathode after reaction in Example 2 of the present invention, with a scale bar of 4 μm; Figure 6 XPS analysis of the cathode after reaction in Example 2 of this invention; Figure 7XPS analysis of the anode after reaction in Example 2 of this invention; Figure 8 This is an analysis of the thallium removal efficiency at different liquid flow rates in Example 3 of the present invention.

[0020] Attached diagram labels: 1. Liquid inlet passage; 2. Anode; 3. Baffle; 4. Cathode; 5. Liquid outlet passage.

[0021] The realization of the objective, functional characteristics and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0022] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0023] Furthermore, the technical solutions of the various embodiments of the present invention can be combined with each other, but only if they are based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such combination of technical solutions does not exist and is not within the scope of protection claimed by the present invention.

[0024] When numerical ranges are given in the embodiments, it should be understood that, unless otherwise stated in the present invention, both endpoints of each numerical range and any value between the two endpoints may be selected. Unless otherwise defined, all technical and scientific terms used in this invention, as well as the prior art known to those skilled in the art and the description of this invention, may be implemented using any prior art methods, devices, and materials similar to or equivalent to those described, used, or made of materials in the embodiments of this invention.

[0025] The present invention provides a method for synergistic removal of thallium by electro-membrane catalytic oxidation filtration and adsorption, comprising: applying an external electric field to an electrochemical reactor, and pumping thallium-containing wastewater into the electrochemical reactor to carry out electro-membrane catalytic oxidation filtration and adsorption reactions.

[0026] In this invention, the voltage of the external electric field is 2-5V, further 2.25-5V, 2.5-5V, 2-4V, 3-4V, 2.8-3.2V, or 2.9-3.1V.

[0027] The thallium-containing wastewater of the present invention has Tl + Furthermore, Tl +The concentration is 0.002-10 mg / L, further 0.1-1 mg / L, and further 0.3-0.5 mg / L.

[0028] In this invention, the pH of the thallium-containing wastewater is not less than 5; further, the pH of the thallium-containing wastewater is 5-11, 7-11, 7-9, 9-11, 6.8-7.2, 8.8-9.2, or 10.8-11.2.

[0029] In this invention, the electrochemical reactor includes: an inlet passage, an anode, a cathode, and an outlet passage arranged sequentially in a first direction; the inlet passage and the outlet passage extend along the first direction, and the anode and the cathode extend along a second direction, with the first direction and the second direction being perpendicular to each other; specifically, the first direction is transverse, and the second direction is vertical.

[0030] In this invention, the electrochemical reactor further includes a partition plate; the partition plate has multiple through holes along the first direction, the through holes providing a liquid flow path between the anode and the cathode, and the through holes are evenly distributed on the partition plate; the partition plate is disposed between the anode and the cathode; one side of the partition plate contacts the anode, and the other side of the partition plate contacts the cathode. Specifically, the anode and the cathode are separated by the partition plate, and the anode and cathode are arranged in parallel and have the same size; the longitudinal cross-sectional dimension of the partition plate is equal to the longitudinal cross-sectional dimension of the anode and the cathode.

[0031] In this invention, the distance between the anode and the cathode is 4-6 mm; the distance is equal to the thickness of the partition. In this invention, the anode, the partition, and the cathode are sealed together, receiving liquid only through the inlet passage and discharging liquid only through the outlet passage.

[0032] In this invention, the thallium-containing wastewater is pumped along the inlet path to the anode, flows through the anode to the cathode, and then exits through the outlet path. As the thallium-containing wastewater passes through the anode and cathode, the anode and cathode perform thallium removal through filtration; the electrochemical reactor is a reactor based on a filtration structure.

[0033] To achieve the recycling treatment of thallium-containing wastewater, the thallium-containing wastewater is placed in a feed tank; the thallium-containing wastewater flows from the feed tank into the liquid inlet passage; the water discharged from the liquid outlet passage flows back to the feed tank and continues to flow into the liquid inlet passage.

[0034] Specifically, the thallium-containing wastewater sequentially passes through the inlet passage, the anode, the cathode, and the outlet passage, then passes through the inlet passage, the anode, the cathode, and the outlet passage again, undergoing multiple cycles until a preset time is reached. During these multiple cycles, the flow rate and the applied electric field remain constant. It should be understood that when the baffle is installed, the thallium-containing wastewater, after passing through the anode, must pass through the baffle and then through the cathode.

[0035] To achieve flow direction and rate control of the thallium-containing wastewater, a corresponding transfer pump can be installed to control the flow of the thallium-containing wastewater; and a corresponding power supply component can be installed to provide the applied electric field.

[0036] In this invention, the flow rate of the thallium-containing wastewater is 80-140 mL / min; further, the flow rate of the thallium-containing wastewater is 80-100 mL / min, and more specifically, 80-85 mL / min. In this invention, the duration of the electromembrane catalytic oxidation filtration and adsorption reaction is 1-6 h, and more specifically, 3-5 h, 3-3.5 h, or 5-5.5 h; the time for the electromembrane catalytic oxidation filtration and adsorption reaction corresponds to the preset duration.

[0037] In this invention, both the anode and the cathode are plate-shaped, block-shaped, or sheet-shaped. Both the anode and the cathode are graphite carbon felt membrane electrodes, made of graphite carbon felt. The graphite carbon felt membrane electrode has a three-dimensional network porous structure, specifically a disordered interwoven three-dimensional network porous structure, which significantly increases the specific surface area and has a strong catalytic effect on electro-oxidation, while also providing membrane filtration. In the graphite carbon felt membrane electrode, the pores between the carbon fibers constitute macroscopic channels, and the fiber body of the carbon fibers contains micropores and mesopores, which catalyze electro-oxidation and also provide membrane filtration, with an overall porosity of 90-98%.

[0038] The main mechanism of thallium removal in this invention includes the synergistic effect of oxidation, precipitation, and adsorption. 3+ Adsorption and precipitation in the cathode region are among the key reactions. In this invention, the process of electromembrane catalytic oxidation filtration and adsorption reactions includes at least the following: A. Tl + Catalytic oxidation to Tl in the region of the anode 3+ Tl 3+ With OH in water - After forming Tl(OH)3 precipitate, it is retained or adsorbed by the graphite carbon felt of the anode and the cathode; B. Tl + Catalytic oxidation to Tl in the region of the anode 3+ Tl 3+ OH generated by hydrogen evolution in the cathode region- After the reaction forms Tl(OH)3 precipitate, it is retained or adsorbed by the graphite carbon felt of the cathode; C. Tl + Catalytic oxidation to Tl in the region of the anode 3+ Then, under the action of an electric field, it is directly adsorbed by the graphite carbon felt of the cathode; D. Tl + After being reduced to elemental Tl in the cathode region, it is retained or adsorbed by the graphite carbon felt of the cathode. E. Tl + Under the influence of an electric field, it is directly adsorbed by the graphite carbon felt of the cathode.

[0039] Specifically, this invention mainly consists of Tl + The synergistic effect of oxidation precipitation with physical adsorption and electroadsorption leads to the removal of thallium primarily through the formation of Tl(OH)3 precipitate and the deposition of Tl... 3+ Thallium in wastewater is adsorbed in the form of Tl, etc. The electrode material, graphite carbon felt, needs to possess good conductivity, high porosity, high specific surface area, and electro-oxidation catalysis properties. Thallium in wastewater is mainly removed through three methods: one is by controlling the water flow direction so that the wastewater first passes through the anode, where Tl... + Catalytic oxidation by the anode to produce Tl 3+ Partial Tl 3+ With OH in water - The first is the formation of Tl(OH)3 precipitate, which is either trapped or adsorbed by the graphite carbon felt at both electrodes; the second is the unprecipitated Tl. 3+ Under the influence of the electric field, some Tl is directly adsorbed to the cathode region, and some Tl is also adsorbed to the cathode region. 3+ OH generated by hydrogen evolution at the cathode - Further reaction occurs, and the precipitate is retained or adsorbed; thirdly, some Tl... + Under the influence of an electric field, thallium is directly adsorbed or reduced to elemental thallium at the cathode, where it is then retained or adsorbed by the graphite carbon felt. Characterization analysis of this invention revealed that the cathode is the primary site of thallium precipitation. Furthermore, the catalytic oxidation reaction of the graphite carbon felt anode in this invention is sufficient to ensure the removal rate of thallium in wastewater, eliminating the need for additional oxidizing anode materials and demonstrating economic efficiency.

[0040] As an optional embodiment of the present invention, after the electrochemical reactor reaches saturation for thallium adsorption, reverse electrochemical desorption can be performed to achieve thallium concentration and recovery and electrode reuse.

[0041] The following are specific examples of the present invention: Example 1 See Figure 1To understand, this embodiment provides an electrochemical reactor, which is a reactor based on a filtration structure, specifically including: an inlet passage, an anode, a partition, a cathode, and an outlet passage arranged sequentially in the horizontal direction; the liquid flow direction of the inlet passage and the outlet passage is horizontal; the anode, partition, and cathode all extend vertically and are parallel to each other; one side of the partition is set against the anode and the other side is set against the cathode, and the partition has a porous structure, specifically with a large number of horizontally penetrating through holes evenly distributed.

[0042] Both the anode and cathode are constructed from graphite carbon felt, which is a disordered, interwoven three-dimensional porous network. Both the anode and cathode are disc-shaped, with a diameter of 5 cm, and the partition plate has a diameter of 5 cm. The distance between the anode and cathode is 5 mm, equal to the thickness of the partition plate. The anode, partition plate, and cathode are sealed within the acrylic component, receiving liquid only through the inlet passage and discharging liquid only through the outlet passage. Specifically, the anode, partition plate, and cathode are sealed and tightly stacked within the acrylic component, with the sealed internal chamber of the acrylic component just accommodating the anode, partition plate, and cathode. The inlet passage is connected to the inlet end of the feed tank, and the outlet passage is connected to the outlet end of the feed tank.

[0043] In this embodiment, the graphite carbon felt material was characterized and analyzed. For the SEM analysis of the graphite carbon felt material, please refer to [link to relevant documentation]. Figure 2 As shown, it exhibits a highly smooth surface; XRD analysis of the graphite carbon felt material can be found in [reference needed]. Figure 3 As shown in (original), the original graphite carbon felt exhibits two diffraction peaks, corresponding to the characteristic graphite peaks.

[0044] Example 2 This embodiment provides a thallium removal method, and performs electro-membrane catalytic oxidation filtration and adsorption reactions in the electrochemical reactor of Example 1. The steps are as follows: A 500 mL simulated solution (prepared with TlNO3, thallium concentration of 400 μg / L) was placed in the feed tank as thallium-containing wastewater. The wastewater was pumped into the inlet channel, then passed sequentially through the anode, partition, and cathode before entering the outlet channel. It was then returned to the feed tank and pumped back into the inlet channel, repeating the process. In this embodiment, the above process was continuously repeated within a preset time for electromembrane catalytic oxidation filtration and adsorption reactions.

[0045] In this embodiment, the initial pH of the thallium-containing wastewater is controlled at 9; during the above reaction process, the liquid flow rate is 100 mL / min, and an electric field with a voltage of 3V is applied to the anode and cathode.

[0046] In this embodiment, the total thallium removal rate was 96.4% after 3 hours of reaction, and the total thallium removal rate was over 99% after 5 hours of reaction.

[0047] In this embodiment, the anode and cathode of the electro-membrane catalytic oxidation filtration and adsorption reaction were characterized and analyzed after 5 hours; the XRD analysis of the anode and cathode after the reaction is described in [reference needed]. Figure 3 As shown, no additional components were detected at the anode, but the peak intensity decreased due to the formation of slight deposits on the anode surface, which blocked the signal from the graphite peaks. The cathode exhibited multiple diffraction peaks, mainly Tl and Tl2O3, indicating that Tl elemental and its oxides were formed on the cathode surface.

[0048] SEM analysis of the post-reaction anode and post-reaction cathode is shown in [reference]. Figure 4-5 As shown, the anode displays tiny particulate matter, which may represent Tl. + Oxidation to Tl 3+ The cathode showed significantly more precipitation, with extensive crystalline precipitates on its surface, approximately 4 micrometers in size. These crystalline particles likely represent thallium or Tl₂O₃ precipitates, which are formed by the hydrolysis of Tl(OH)₃. Amorphous deposits were also present, possibly representing unhydrolyzed Tl(OH)₃, indicating that the cathode is the primary site for Tl ion removal.

[0049] XPS analysis of the post-reaction cathode and post-reaction anode can be found in [reference]. Figure 6-7 As shown, both spectra contain two sets of double peaks, corresponding to Tl respectively. + and Tl 3+ The chemical state of Tl detected at the anode 3+ It is mainly physically adsorbed by graphite carbon felt, and Tl in the anodic spectrum 3+ The relative peak intensity is more obvious, Tl + The relatively weaker peak intensity proves that the anode is less effective against Tl. + The oxidation effect was observed at the cathode, where Tl was also detected. + 、Tl 3+ This indicates that electroadsorption plays an important role, and together they demonstrate a significant synergistic effect between anodic oxidation and cathodic adsorption.

[0050] In addition, stability tests were conducted in this embodiment; specifically, the electrochemical reactor was subjected to reverse electrolytic desorption treatment; one electro-membrane catalytic oxidation filtration and adsorption reaction and one desorption treatment were recorded as one cycle; after three cycles, the total thallium removal rate of the 5-hour reaction under the same conditions was over 95%.

[0051] Example 3 Compared to Example 2, this embodiment only adjusts the flow rate to 80 mL / min, 100 mL / min, 120 mL / min, 140 mL / min, and 160 mL / min, while keeping other conditions unchanged.

[0052] The experimental results of this embodiment are as follows: When the liquid flow rate was 80 mL / min, the total thallium removal rate was 98.9% after 3 hours of reaction. When the flow rate was 100 mL / min, the total thallium removal rate was 96.4% after 3 hours of reaction. When the flow rate was 120 mL / min, the total thallium removal rate was 87.3% after 3 hours of reaction. When the flow rate was 140 mL / min, the total thallium removal rate was 82.4% after 3 hours of reaction. When the liquid flow rate is 160 mL / min, the total thallium removal rate after 3 hours of reaction is 61.6%.

[0053] In this embodiment, the changes in thallium removal efficiency over 3 hours at various flow rates are as follows: Figure 8 As shown.

[0054] Example 4 Compared to Example 2, this embodiment only adjusts the pH of the thallium-containing wastewater to 3, 5, 7, 9, and 11 respectively, while keeping other conditions unchanged.

[0055] The experimental results of this embodiment are as follows: At pH 3, the total thallium removal rate after 3 hours of reaction was 54.1%. At pH 5, the total thallium removal rate after 3 hours of reaction was 71.2%. At pH 7, the total thallium removal rate was 95.0% after 3 hours of reaction. At pH 9, the total thallium removal rate after 3 hours of reaction was 96.4%. At pH 11, the total thallium removal rate was 98.8% after 3 hours of reaction.

[0056] Example 5 Compared to Example 2, this embodiment only adjusts the voltage of the applied electric field to 0V, 1V, 2V, 3V, and 4V respectively, while keeping other conditions unchanged.

[0057] The experimental results of this embodiment are as follows: When the applied electric field voltage is 0V, the total thallium removal rate after 3 hours of reaction is 2.1%. When the applied electric field voltage is 1V, the total thallium removal rate after 3 hours of reaction is 25.4%. When the applied electric field voltage is 2V, the total thallium removal rate after 3 hours of reaction is 88.3%. When the applied electric field voltage is 3V, the total thallium removal rate after 3 hours of reaction is 96.4%. When the applied electric field voltage is 4V, the total thallium removal rate after 3 hours of reaction is 95.1%.

[0058] Example 6 Comparative analysis of different fluid flow patterns: 1. Experiment on non-directional controlled fluid flow: Experimental procedure: 500 mL of simulated solution (prepared with TlNO3, thallium concentration of 400 ug / L) was placed in the feed tank as thallium-containing wastewater. The anode and cathode were placed in the thallium-containing wastewater in the feed tank, and an electric field was applied. The liquid flow through the anode and cathode was not controlled. The dimensions of the anode and cathode were the same as in Example 1. The initial pH of the thallium-containing wastewater was controlled at 9, the applied electric field voltage was 3V, and the reaction was carried out for 5 hours.

[0059] Experimental results: The total thallium removal rate was 48%.

[0060] 2. Experiments involving directional control of liquid flow only at the cathode: Experimental procedure: 500 mL of simulated solution (prepared with TlNO3, thallium concentration of 400 ug / L) was placed in the feed tank as thallium-containing wastewater. After the cathode and separator were installed on the acrylic component, they were placed in the thallium-containing wastewater in the feed tank. The thallium-containing wastewater was controlled to pass through the cathode and then flow back to the feed tank by connecting pipelines and pumping.

[0061] The anode was placed in the thallium-containing wastewater in the feed tank, but the flow of liquid through the anode was not controlled; an electric field was applied to both the anode and the cathode; the specifications of the anode, cathode, and partition were the same as in Example 1, the initial pH of the thallium-containing wastewater was controlled at 9, the flow rate of the thallium-containing wastewater through the cathode was 100 mL / min, the applied electric field voltage was 3V, and the reaction was carried out for 5 hours.

[0062] Experimental results: The total thallium removal rate was 63.6%.

[0063] 3. Experiments involving directional control of liquid flow only at the anode: Experimental procedure: 500 mL of simulated solution (prepared with TlNO3, thallium concentration of 400 ug / L) was placed in the feed tank as thallium-containing wastewater. After the anode and partition were installed on the acrylic component, they were placed in the thallium-containing wastewater in the feed tank. The thallium-containing wastewater was controlled to pass through the anode and then flow back to the feed tank by connecting pipelines and pumping.

[0064] The cathode was placed in the thallium-containing wastewater in the feed tank, but the flow of liquid through the cathode was not controlled; an electric field was applied to both the anode and the cathode; the specifications of the anode, cathode, and partition were the same as in Example 1, the initial pH of the thallium-containing wastewater was controlled to be 9, the flow rate of the thallium-containing wastewater through the anode was 100 mL / min, the applied electric field voltage was 3V, and the reaction was carried out for 5 hours.

[0065] Experimental results: The total thallium removal rate was 68.3%.

[0066] 4. Experiment involving flow from cathode to anode: Experimental procedure: Compared with Example 2, only the flow direction of the inlet and outlet channels was reversed, while other conditions remained unchanged. That is, after the thallium-containing wastewater flows into the outlet channel of Example 2, it passes through the cathode, the partition, and the anode in sequence, flows out from the inlet channel and flows back to the feed tank, and then flows into the outlet channel again through the pump. The above process is repeated for 5 hours.

[0067] Experimental results: The total thallium removal rate was 88.8%.

[0068] 5. Experiment involving flow from the anode to the cathode: Experimental procedure: Same as in Example 2, with a reaction time of 5 hours.

[0069] Experimental results: Total thallium removal rate exceeded 99%.

[0070] In this embodiment, the reaction effects of thallium-containing wastewater passing through the filter via five different paths were compared: 1. Undirected flow control; 2. Directed flow control only at the cathode; 3. Directed flow control only at the anode; 4. Flow from cathode to anode; 5. Flow from anode to cathode. The results showed that the fifth method had the highest thallium removal rate and the strongest synergistic effect.

[0071] Comparative Example 1 Compared to Example 2, this comparative example only adjusts the material combination type of the anode and cathode, while keeping other conditions unchanged; in this comparative example, the anode is a graphite carbon felt film electrode (material is graphite carbon felt), and the cathode is an activated carbon fiber electrode (material is activated carbon fiber).

[0072] In this comparative example, the total thallium removal rate after 5 hours of reaction was less than 30%.

[0073] The above technical solutions of the present invention are merely preferred embodiments and do not limit the patent scope of the present invention. All equivalent structural transformations made under the technical concept of the present invention using the contents of the specification and drawings of the present invention, or direct / indirect applications in other related technical fields, are included in the patent protection scope of the present invention.

Claims

1. A method for synergistic removal of thallium by electromembrane catalytic oxidation filtration and adsorption, characterized in that, include: An external electric field is applied to the electrochemical reactor, and thallium-containing wastewater is allowed to flow into the electrochemical reactor, where electro-membrane catalytic oxidation filtration and adsorption reactions occur; The thallium-containing wastewater has Tl + ; The electrochemical reactor includes, in sequence, an inlet passage, an anode, a cathode, and an outlet passage; The thallium-containing wastewater flows along the inlet channel to the anode, passes through the anode and then flows to the cathode, and passes through the cathode before being discharged from the outlet channel. Both the anode and the cathode are graphite carbon felt film electrodes, and the graphite carbon felt film electrodes have a three-dimensional network porous structure.

2. The method for thallium removal by electromembrane catalytic oxidation filtration and adsorption synergistic as described in claim 1, characterized in that, The flow rate of the thallium-containing wastewater is 80-140 mL / min.

3. The method for synergistic removal of thallium by electromembrane catalytic oxidation filtration and adsorption according to claim 1, characterized in that, The pH of the thallium-containing wastewater is not less than 5; in the thallium-containing wastewater, Tl + The concentration is 0.002-10 mg / L.

4. The method for synergistic removal of thallium by electromembrane catalytic oxidation filtration and adsorption according to claim 1, characterized in that, The thallium-containing wastewater is pumped along the inlet passage to the anode.

5. The method for synergistic removal of thallium by electromembrane catalytic oxidation filtration and adsorption according to claim 1, characterized in that, During the electro-membrane catalytic oxidation filtration and adsorption reaction, the thallium-containing wastewater flows from the feed tank into the liquid inlet passage; and the water discharged from the liquid outlet passage flows back to the feed tank and then continues to flow into the liquid inlet passage.

6. The method for synergistic removal of thallium by electromembrane catalytic oxidation filtration and adsorption according to claim 1, characterized in that, In the graphite carbon felt film electrode, the pores between the carbon fibers form macroscopic channels, and the fiber body of the carbon fibers contains micropores and mesopores.

7. The method for synergistic removal of thallium by electromembrane catalytic oxidation filtration and adsorption according to claim 1, characterized in that, The voltage of the applied electric field is 2-5V; the duration of the electro-membrane catalytic oxidation filtration and adsorption reaction is 1-6h.

8. The method for synergistic removal of thallium by electromembrane catalytic oxidation filtration and adsorption according to claim 1, characterized in that, The electrochemical reactor also includes a partition plate; the partition plate has multiple through holes; The partition is disposed between the anode and the cathode; one side of the partition is in contact with the anode, and the other side of the partition is in contact with the cathode; the thickness of the partition is 4-6 mm.

9. The method for electro-membrane catalytic oxidation filtration and adsorption-synergistic thallium removal according to any one of claims 1-8, characterized in that, The electromembrane catalytic oxidation filtration and adsorption reaction process includes at least the following: A. Tl + Catalytic oxidation to Tl in the region of the anode 3+ Tl 3+ With OH in water - After forming Tl(OH)3 precipitate, it is retained or adsorbed by the graphite carbon felt of the anode and the cathode; B. Tl + Catalytic oxidation to Tl in the region of the anode 3+ Tl 3+ OH generated by hydrogen evolution in the cathode region - After the reaction forms Tl(OH)3 precipitate, it is retained or adsorbed by the graphite carbon felt of the cathode; C. Tl + Catalytic oxidation to Tl in the region of the anode 3+ Then, under the action of an electric field, it is directly adsorbed by the graphite carbon felt of the cathode; D. Tl + After being reduced to elemental Tl in the region of the cathode, it is retained or adsorbed by the graphite carbon felt of the cathode. E. Tl + Under the influence of an electric field, it is directly adsorbed by the graphite carbon felt of the cathode.

10. The method for electro-membrane catalytic oxidation filtration and adsorption-synergistic thallium removal according to any one of claims 1-8, characterized in that, Once the electrochemical reactor reaches saturation for thallium adsorption, a reverse electrochemical desorption process is performed to achieve thallium concentration and recovery and electrode reuse.

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