CN110711500B - Preparation method and application of bifunctional photoelectrochemical composite membrane - Google Patents

Preparation method and application of bifunctional photoelectrochemical composite membrane Download PDF

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CN110711500B
CN110711500B CN201910986854.4A CN201910986854A CN110711500B CN 110711500 B CN110711500 B CN 110711500B CN 201910986854 A CN201910986854 A CN 201910986854A CN 110711500 B CN110711500 B CN 110711500B
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antimony
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刘艳彪
李墨华
沈忱思
李方
杨波
马春燕
刘富强
郭东丽
胡雪梅
任伊凡
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Donghua University
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    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
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    • B01D71/00—Semi-permeable membranes for separation processes or apparatus characterised by the material; Manufacturing processes specially adapted therefor
    • B01D71/06—Organic material
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    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
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    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
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    • C02F1/28—Treatment of water, waste water, or sewage by sorption
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    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
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    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00—Treatment of water, waste water, or sewage
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    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
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    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
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    • C02F2305/10—Photocatalysts

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Abstract

The invention discloses a preparation method of a bifunctional photoelectrochemical composite membrane and application of the bifunctional photoelectrochemical composite membrane in treating antimony (III) under a continuous flow photoelectrocatalysis system. The preparation method comprises the following steps: adding acidified CNT into N, N-dimethylformamide solution, and adding FeCl3·6H2O; dissolving terephthalic acid in N, N-dimethylformamide solution, adding the solution into the mixed solution, and heating for reaction; and (4) carrying out suction filtration on the support membrane to obtain the bifunctional photoelectrochemical composite membrane. The composite film material of the present invention has both a response to an electric field and a response to light. The separation and transfer of electron-hole pairs generated in the photocatalysis process are accelerated by means of an external electric field, so that more holes and OH are promoted to participate in the oxidation process of antimony (III); in addition, because Fe-O clusters in the membrane components have strong affinity to antimony ions, the high-efficiency oxidation and removal of antimony (III) are synchronously realized under the synergistic action of an external electric field and continuous flow enhanced mass transfer.

Description

Preparation method and application of bifunctional photoelectrochemical composite membrane
Technical Field
The invention relates to a preparation method and application of a bifunctional photoelectrochemical composite membrane, in particular to a preparation method of a metal organic framework and carbon nano tube composite membrane material (MIL-88B (Fe) @ O-CNT) and oxidation and adsorption of the composite membrane material on high-toxicity heavy metal trivalent antimony in a water body, belonging to the technical field of water treatment.
Background
In recent years, a series of water environment pollution and ecological safety problems caused by the over-standard of new pollutants antimony (Sb, heavy metal and arsenic) are of high concern to scholars at home and abroad. In a natural water environment, antimony is mainly present in inorganic trivalent antimony (III)) and pentavalent antimony (V)). Wherein antimony (III) is more than 10 times more toxic than antimony (V) (environ. Sci. technol.,2016,50, 6974-6984). Studies have shown that antimony (III) tends to remain in the body for a longer period of time than antimony (V), and can therefore exhibit higher ecotoxicity. The treatment technologies widely adopted at home and abroad at present comprise adsorption, membrane separation and coagulating sedimentation. Among them, adsorption is considered as a promising technology for treating antimony contamination because of its low energy consumption, easy operation, and reusability. Antimony (III) exhibits an electrically neutral state over a wide pH range (3-10) compared to antimony (V) which exists predominantly in its charged form, resulting in generally lower adsorptive removal efficiency. To increase the efficiency of antimony (III) treatment, it is usually pre-oxidized to low-toxicity and negatively-charged antimony (V) and then subjected to a subsequent chemical treatment (chem. eng.j.,2019,369, 414-421). However, this "two-step" method has three significant disadvantages in practical applications, which severely limits its wide application: (1) the system is complex; (2) the low concentration of antimony (III) in the water body limits its reaction kinetics; (3) chemicals (such as flocculants for precipitating antimony (V)) are consumed too much (sci. total. environ.,2018,644, 1277-.
Compared with the traditional oxidation technology, the photocatalytic oxidation technology is a new green and sustainable heavy metal treatment technology. As a novel photocatalytic material, Metal Organic Frameworks (MOFs) have attracted extensive attention by researchers due to their unique high specific surface area, open pore channels, and tunable topological structure. Compared with conventional inorganic semiconductors, MOFs have abundant and uniform active sites (metal or organic chains), and their open pore structure can be fully contacted with guest molecules (Energy environ. sci.,2014,7,
2831-2867). For example, Du et al reported that amino-modified UIO-66(Zr/Hf) catalysts can reduce highly toxic hexavalent chromium (Cr (VI)) to less toxic trivalent chromium (Cr (III)) (chem. Eng. J.,2019,356, 393) 399). However, photocatalytic technology is still limited by the serious problem of photogenerated electron-hole recombination. It is reported that the recombination rate of photogenerated electron-hole pairs in the photocatalytic technology is 2-3 orders of magnitude higher than the separation rate of electron-hole pairs, which greatly limits the large-scale application of the photocatalytic technology (appl. Catal., B,2017,203, 108-115). This limitation can be improved by assisting the applied electric field, i.e. the photoelectrocatalytic oxidation. The technology accelerates the separation of photogenerated electron holes by applying an external electric field between electrodes, and promotes more holes to participate in the oxidation reaction of the surface and more photogenerated electrons to participate in the reduction reaction of the surface.
The MOFs also show wide application prospects in the field of heavy metal adsorption in water bodies due to the advantages of high specific surface area, adjustable pore size, many active sites and the like. Recent studies have shown that some MOFs (e.g. UIO-66, ZIF-8 and Fe-BTC) can adsorb heavy metals (such as arsenic and antimony) in water (chem.SOC.Rev.,2018,47, 2322-doped 2356). Despite some research progress in the adsorption of heavy metals, MOFs still have a significant room for improvement in the kinetics of heavy metal adsorption (j.hazard. mater, 2019,378,120721). In addition, the nano-scale adsorbent is easy to agglomerate and difficult to separate, and the application of the nano-scale adsorbent in practical engineering is restricted. . For this investigator attempts to support them on a support material, encapsulate them in a polymer or blend into a membrane, but the above improvements often block the active sites and lead to limited adsorption efficiency and insufficient stability. The prior research is usually carried out in a traditional batch filtration system, mass transfer process of a target object to the surface of the material is dominated by diffusion, and reaction kinetics are limited by the near-surface and internal diffusion properties of the adsorption material. Electrostatic repulsion further reduces reaction kinetics once the adsorbate and the adsorbate have the same charge polarity.
Disclosure of Invention
The invention aims to solve the problems that: meanwhile, the high-toxicity antimony (III) in the water body is oxidized and adsorbed by photocatalysis.
In order to solve the problems, the invention provides a preparation method of a bifunctional photoelectrochemical composite membrane, which is characterized by comprising the following steps:
step 1): adding the acidified CNT into an N, N-dimethylformamide solution, and performing ultrasonic dispersion uniformly;
step 2): FeCl is added3·6H2Adding O into the mixed solution obtained in the step 1), and uniformly stirring;
step 3): dissolving terephthalic acid in N, N-dimethylformamide solution, then dropwise adding the solution into the mixed solution obtained in the step 2), uniformly stirring the solution, transferring the solution into a hydrothermal kettle with a polytetrafluoroethylene substrate, and putting the hydrothermal kettle into an oven for heating reaction;
step 4): and (3) carrying out vacuum filtration on the mixed solution reacted in the step 3) to a PTFE support membrane, and then sequentially cleaning with ethanol and ultrapure water to obtain an MIL-88B (Fe) @ O-CNT membrane, namely the bifunctional photoelectrochemical composite membrane.
Preferably, the ratio of the acidified CNT to the N, N-dimethylformamide solution in step 1) is 3 g: 5 mL; the ultrasonic power is 50-200W, and the ultrasonic time is 20-60 min.
Preferably, the molar ratio of the Fe ions to the acidified CNTs in the step 2) is 0.02-0.08.
Preferably, the molar ratio of the terephthalic acid to the acidified CNT in the step 2) is 0.02-0.08.
Preferably, the heating temperature in the step 4) is 100-200 ℃, and the heating time is 2-6 h.
The invention also provides application of the bifunctional photoelectrochemical composite membrane prepared by the preparation method of the bifunctional photoelectrochemical composite membrane in treating antimony (III) in a continuous flow photoelectrocatalysis system.
Preferably, the bifunctional photoelectrochemical composite membrane is used as an anode, and a solution of antimony (III) is filtered by a continuous flow photoelectrocatalysis system through a peristaltic pump.
More preferably, the concentration of the solution of antimony (III) is 500-1000 mug/L, and the flow rate of the solution passing through the continuous flow photoelectrocatalysis system is 0.1-6 mL/min.
More preferably, the potential of an external power supply of the continuous flow photoelectrocatalysis system is 0-2.5V, and the pH range of the solution containing antimony (III) is 3.5-9.5.
More preferably, the continuous flow photoelectrocatalysis system is regenerated by filtration through HCl after saturation of adsorption.
The invention adopts an in-situ synthesis method to coat MIL-88B (Fe) on the O-CNT, and can synthesize a series of composite film materials of different nanoscale MIL-88B (Fe) coated with the acidified CNT by regulating and controlling the amount of MIL-88B (Fe) precursors. Then the mixture is filtered on a Polytetrafluoroethylene (PTFE) membrane by vacuum filtration to prepare the Polytetrafluoroethylene (PTFE) membrane
MIL-88B (Fe) @ O-CNT composite membrane. Under the combined conditions of an external electric field and illumination, the photogenerated carriers of MIL-88B (Fe) can be rapidly separated, so that more holes and hydroxyl radicals (. OH) generated in situ thereof oxidize the high-toxicity antimony (III) into low-toxicity negatively-charged antimony (V). In addition, due to the strong antimony affinity of the Fe-O cluster of the MIL-88B (Fe) in the membrane component, the oxidation of antimony (III) and the adsorption removal of antimony (V) can be simultaneously realized under the synergistic action of the electrostatic adsorption action of an external electric field and the enhancement of convective mass transfer of a system.
The invention provides a novel iron-based MOF (MIL-88B (Fe)) functionalized Carbon Nano Tube (CNT) photoelectrocatalysis filtering membrane, which has double functions of photocatalysis oxidation and adsorption of antimony (III) and can realize the removal of the antimony (III) by a one-step method. The bifunctional filtering membrane can simultaneously respond to light and electricity and also has specific adsorption capacity to antimony (V) oxide. The invention firstly adopts a simple method to uniformly coat the nanometer MIL-88B (Fe) on the wall of the acidified CNT tube to prepare the photoelectrochemical composite film. Commercial filters have also been modified to incorporate both photochemical and electrochemical processes into continuous flow systems. Based on the above principle, can realize: (1) antimony (III) is efficiently oxidized into low-toxicity antimony (V) through a photoelectrocatalysis process, (2) the oxidation product antimony (V) is efficiently adsorbed by the surface-coated iron-based MOF with high antimony affinity, (3) the mass transfer of the antimony (III) and the oxidation product antimony (V) in a continuous flow system is remarkably accelerated by the specific internal convection performance of the continuous flow system, and (4) the recombination of photogenerated electrons and holes in the system is remarkably inhibited by an external electric field.
Compared with the prior art, the invention has the following characteristics:
(1) the photoelectrocatalysis technology is combined with the membrane separation technology, and a traditional granular catalyst or adsorbent is replaced by a continuous flow membrane filtration mode, so that the mass transfer efficiency in the reaction process is enhanced, and the removal efficiency and the kinetics of antimony (III) are effectively improved;
(2) the MIL-88B (Fe) @ O-CNT composite membrane has the advantages of simple and easily obtained preparation raw materials, short preparation period, mild preparation conditions and low raw material and preparation cost;
(3) chelating Fe with carboxyl and hydroxyl groups3+Dripping ligand terephthalic acid (TPA), and grafting the nanometer MIL-88B (Fe) particles on the wall of the O-CNT tube in situ by a simple hydrothermal synthesis method;
(4) by controlling the concentration of the MIL-88B (Fe) precursor, the loading amount of the MIL-88B (Fe) nanoparticles can be effectively controlled, and more active sites can be provided for the rapid oxidation of antimony (III) and the adsorption of an oxidation product antimony (V);
(5) the O-CNT network structure is used as a carrier of MIL-88B (Fe) nano particles, so that the specific surface area and the porosity are increased compared with those of a bulk photocatalyst, the loading capacity of the MOF is improved, and the problem that a granular catalyst/adsorbent is difficult to recover is solved; meanwhile, the material is used as a transmission channel of photoproduction electrons under the condition of photoelectrocatalysis, so that the separation efficiency of the photoproduction electrons and holes is improved, and the high-efficiency oxidation of antimony (III) is realized;
(6) the dual-function MIL-88B (Fe) @ O-CNT can simultaneously respond to light and electricity, and the problem of photo-generated carrier recombination in a photocatalytic system is solved.
Drawings
FIG. 1 is a scanning electron microscope image of acidified CNT (O-CNT) in example 1;
FIG. 2 is a scanning electron microscope image of the MIL-88B (Fe) @ O-CNT composite membrane of example 1 and comparative examples 1-3;
FIG. 3 is a photograph of a CM (50:3) composite film in example 2;
FIG. 4 is a schematic diagram of an apparatus for a continuous flow photoelectrocatalytic system;
FIG. 5 is a graph comparing the removal effect of the composite films of example 2 and comparative examples 8 and 9 on antimony (III);
FIG. 6 is a graph comparing the removal efficiency of antimony (III) from the composite films of example 2 and comparative examples 6-8 in the presence or absence of light and under different voltages;
FIG. 7 is a graph comparing the removal of antimony at different pH conditions for the composite membranes of example 2 and comparative example 9;
FIG. 8 is an X-ray diffraction pattern for the composite films of example 3 and comparative example 10.
Detailed Description
In order to make the invention more comprehensible, preferred embodiments are described in detail below with reference to the accompanying drawings.
Example 1
MIL-88B (Fe) @ O-CNT complex preparation method:
(1) soaking 15mg of multi-wall CNT in nitric acid (37 wt%) at 70 deg.C, stirring for 12h, vacuum filtering to obtain block, washing off excessive acid solution with ultrapure water, and drying at 70 deg.C to obtain O-CNT;
(2) dissolving O-CNT in 25mL of N, N-dimethylformamide, and uniformly dispersing the O-CNT by using an ultrasonic cell disruptor, wherein the ultrasonic power is 50-200W, and the ultrasonic time is 20-60 min;
(3) 0.225mmol of FeCl3·6H2Adding O into the dispersion liquid of the O-CNT and stirring the mixture overnight;
(4) adding 0.225mmol of terephthalic acid into 8mL of N, N-dimethylformamide solution, stirring uniformly, then dripping into the mixed solution in the step (3) at the flow rate of 16mL/h, and stirring for 40min to mix uniformly;
(5) and (3) transferring the mixed solution in the step (4) to a 50mL hydrothermal kettle with a polytetrafluoroethylene substrate, and putting the hydrothermal kettle into a blast drying oven, wherein the heating temperature is 100-200 ℃, and the heating time is 2-6 h, so that the MIL-88B (Fe) can uniformly grow on the wall of the O-CNT tube in situ.
The O-CNT prepared in example 1 is shown in FIG. 1. Based on O-CNT and MIL-88B (Fe) (C)24H4O13Fe3M667.8 g/mol), the MIL-88b (fe) @ O-CNT composite membrane prepared in example 1 was simplified to CM (50:3) having a specific surface area of 382.3M2G, about 2.6 times the specific surface area of the O-CNT (147.4 m)2G) as shown in c in fig. 2.
Comparative example 1
This comparative example differs from example 1 in that O-CNT is different from MIL-88B (Fe) (C)24H4O13Fe3M-667.8 g/mol) is 50:1, abbreviated as CM (50:1), as shown in fig. 2 a.
Comparative example 2
This comparative example differs from example 1 in that O-CNT is different from MIL-88B (Fe) (C)24H4O13Fe3M-667.8 g/mol) in a molar ratio of 25:1, abbreviated as CM (25:1), as shown in fig. 2 b.
Comparative example 3
This comparative example differs from example 1 in that O-CNT is different from MIL-88B (Fe) (C)24H4O13Fe3M-667.8 g/mol) in a molar ratio of 25:2, abbreviated as CM (25:2), as shown in fig. 2 at d.
The scanning electron microscope images of the composite materials of example 1 and comparative examples 1, 2 and 3 are shown in FIG. 2. As can be seen from fig. 2, the surface of comparative example 1 becomes rough compared to the O-CNT in fig. 1; the MIL-88B (Fe) particle size on the surface of the support O-CNT in the comparative example 2 is increased to 7-15 nm; in the embodiment 1, MIL-88B (Fe) (10-20nm) with in-situ surface growth is uniformly coated on the wall of the O-CNT tube to form a three-dimensional network framework structure; in comparative example 3, due to the further increase in the MIL-88B (Fe) precursor concentration, large-scale agglomeration of the MIL-88B (Fe) particles occurred on the surface.
Example 2
A method for removing antimony (III) by a continuous flow photoelectrocatalysis system comprises the following steps:
(1) vacuum filtering the CM (50:3) mixed solution prepared in the example 1 to a PTFE support membrane, and then sequentially cleaning with ethanol and ultrapure water to obtain a CM (50:3) composite membrane;
the pore size of the composite membrane is within the range of 3-8nm, and the mesoporous pore size distribution is shown in figure 3.
(2) As shown in fig. 4, a CM (50:3) composite membrane 3 as a photo-anode and a porous titanium sheet 5 as a cathode were placed in a two-layer membrane filtration apparatus with a plastic gasket 4 between the composite membrane and the porous titanium sheet 5 so that the composite membrane was in close contact with a titanium ring 2 to which a positive potential was applied. Under illumination 1 and applied potential 2, a continuous flow filtration mode is adopted, 1000 mu g/L of antimony (III) wastewater flows through a double-layer membrane filtration device shell by a peristaltic pump at a flow rate of 0.1mL/min along the direction of a solid arrow in the figure 4, and flows out along the direction of an open arrow in the figure 4 through a CM (50:3) composite membrane 1 and a porous titanium sheet 5 (the reaction condition is set to be 5.5, the applied potential is 2.0V, and visible light irradiates).
Comparative example 4
This comparative example differs from example 2 in that an O-CNT film was used as the photo-anode, and antimony (III) wastewater was passed through the double-membrane filter device housing at a flow rate of 6mL/min in the direction of the solid arrows in FIG. 4.
Comparative example 5
This comparative example differs from example 2 in that CM (50:1), CM (25:2) films were used as the photo-anode.
Comparative example 6
This comparative example differs from example 2 in that different applied voltages of 0.3V, 0.7V, 1.0V, 1.5V, 2.5V were used.
Comparative example 7
This comparative example differs from example 2 in that only light irradiation, no potential application.
Comparative example 8
This comparative example differs from example 2 in the simple adsorption.
Comparative example 9
This comparative example differs from example 2 in that the reaction conditions were pH 3.5, 7.5, 9.5, respectively.
The experimental data for example 2 and comparative examples 8 and 9 are shown in figure 5. As can be seen from FIG. 5, the O-CNT film of comparative example 1 can respond only to electricity under the action of photoelectrocatalysis, with antimony (III) and total antimony (antimony)total) The removal rates of (A) and (B) were 55.1. + -. 3.2% and 12.7. + -. 2.0%, respectively. The composite films in comparative example 2 and example 2 were both responsive to light and electricity, corresponding antimony (III) and antimonytotalThe removal rate of the catalyst is obviously improved. The highest antimony (III) and antimony contents were obtained in example 2totalThe removal rate respectively reaches 97.7 +/-1.5 percent and 92.9 +/-2.3 percent. The reason is mainly that in example 2, MIL-88b (fe) nanoparticles are uniformly and tightly coated on the surface of O-CNT, so that it has more exposed active sites and more uniform pore size distribution.
The experimental data for example 2 and comparative examples 6-8 are shown in figure 6. As can be seen from FIG. 6, both photocatalysis and electrochemistry were carried out together, and at a suitable voltage (1.5V), the removal efficiency of antimony (III) could reach 96% + -3.0%.
The experimental data for example 2 and comparative example 9 are shown in fig. 7. As can be seen from fig. 7, antimony was observed at pH 3.5, 5.5, and 7.5totalThe removal rates of the materials are 73 +/-1.2 percent, 92.0 +/-2.6 percent and 73.0 +/-2.4 percent respectively, which shows that the material can keep excellent removal efficiency in a wider pH range.
Example 3
Example 2 the synthesized CM (50:3) had the highest antimony (III) and antimonytotalThe removal rate, the stability of the CM (50:3) composite membrane, was mainly tested in this example.
(1) The wastewater containing antimony (III) was passed through the CM (50:3) composite membrane prepared in example 2 (reaction conditions set to a concentration of 500 μ g/L antimony (III) solution, pH 5.5, applied potential 1.5V, irradiated with visible light) by a peristaltic pump at a flow rate of 0.5mL/min by means of afterflow filtration until antimony (III) in the effluent solution was presenttotalNo longer changed;
(2) cleaning the CM (50:3) composite membrane saturated in antimony adsorption with 5mM HCl solution (200mL) at a flow rate of 1mL/min by means of circulating flow filtration to desorb antimony ions, cleaning with deionized water at a flow rate of 1mL/min to a pH of 7, and vacuum freeze-drying;
(3) and (3) repeating the steps (1) and (2) twice in sequence, and characterizing the stability of the CM (50:3) composite membrane after three times of cyclic regeneration by utilizing X-ray diffraction (XRD).
Comparative example 10
Fresh CM (50:3) composite membranes were characterized using X-ray diffraction (XRD).
The test results of example 3 and comparative example 10 are shown in fig. 8. As can be seen from FIG. 8, the positions and intensities of the diffraction peaks of the fresh CM (50:3) composite film and the CM (50:3) composite film in example 3 are not significantly changed, which proves that the CM (50:3) photoelectrochemical composite film in example 3 has excellent stability after the photoelectrocatalysis system is subjected to 12 hours.

Claims (6)

1. The application of the bifunctional photoelectrochemical composite membrane in treating antimony (III) under a continuous flow photoelectrocatalysis system is characterized in that the preparation method of the bifunctional photoelectrochemical composite membrane comprises the following steps:
step 1): adding the acidified CNT into an N, N-dimethylformamide solution, and performing ultrasonic dispersion uniformly;
step 2): FeCl is added3•6H2Adding O into the mixed solution obtained in the step 1), and uniformly stirring; the ratio of the acidified CNT to the N, N-dimethylformamide solution was 3 g: 5 mL; the molar ratio of Fe ions to CNT is 0.02-0.08;
step 3): dissolving terephthalic acid in N, N-dimethylformamide solution, then dropwise adding the solution into the mixed solution obtained in the step 2), uniformly stirring the solution, transferring the solution into a hydrothermal kettle with a polytetrafluoroethylene substrate, and putting the hydrothermal kettle into an oven for heating reaction; the terephthalic acid and N, N-dimethylformamide solution, wherein the molar ratio of the terephthalic acid to the acidified CNT in the step 2) is 0.02-0.08;
step 4): carrying out vacuum filtration on the mixed solution reacted in the step 3) to a PTFE support membrane, and then sequentially cleaning the PTFE support membrane with ethanol and ultrapure water to obtain an MIL-88B (Fe) @ O-CNT membrane, namely the bifunctional photoelectrochemical composite membrane;
the potential of an external power supply of the continuous flow photoelectric catalytic system is 0-2.5V, and the pH range of the solution containing antimony (III) is 3.5-9.5.
2. The application of claim 1, wherein the ultrasonic power in the step 1) is 50-200W, and the ultrasonic time is 20-60 min.
3. The use according to claim 1, wherein the heating temperature in step 4) is 100 to 200 ℃ and the heating time is 2 to 6 hours.
4. The use according to claim 1, wherein the bifunctional photoelectrochemical composite membrane is used as an anode and the solution containing antimony (III) is filtered through a continuous flow photoelectrocatalysis system by means of a peristaltic pump.
5. The use according to claim 4, wherein the concentration of the solution containing antimony (III) is 500-1000 μ g/L and the flow rate through the continuous flow photoelectrocatalysis system is 0.1-6 mL/min.
6. The use according to claim 1, wherein the continuous flow photoelectrocatalytic system is regenerated by filtration through HCl after saturation of the adsorption.
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