Photovoltaic / photothermal coupling driven sewage treatment device and treatment method thereof

Abstract

The present application relates to a kind of photovoltaic / photothermal coupling driven sewage treatment device and method, the device or method is by integrating photovoltaic panel and electrolytic device, makes photovoltaic device power supply electrolytic device, and using the heat of photovoltaic device heats sewage, makes sewage conversion gas state water, and makes VOCs in sewage escape in gas state, by electrolytic device processing gas state water and gas state VOCs, avoid the problem that VOCs is not degraded completely and electrolytic device is easily corroded by being placed in water, the heat of photovoltaic panel can reduce the energy barrier of oxidation-reduction reaction, improves the efficiency of hydroxyl production.

Description

TECHNICAL FIELD

[0001] The application relates to a sewage treatment device driven by photovoltaic / photothermal coupling and a treatment method thereof, and belongs to the field of water treatment. BACKGROUND

[0002] The petrochemical industry and the mining, metal electroplating, paint coating and other industries are the main sources of volatile organic compound (VOCs) sewage. VOCs are the precursors of ozone layer destruction and the main components of smog. In the process of treating sewage containing VOCs, various VOCs are also emitted from each treatment unit into the gas phase to cause new pollution to the atmospheric environment. With the continuous acceleration of industrialization, the amount of sewage treatment is significantly increased, and the environmental pollution problem caused by VOCs volatilization will become increasingly prominent.

[0003] In the existing method for disposing industrial VOCs sewage, Fenton is considered to be a sewage treatment technology with great application prospect due to its strong oxidation ability and wide application range, and is widely valued and researched at home and abroad. The electro-Fenton technology is based on the Fenton technology and uses the electrochemical reaction to continuously generate H2O2, which reacts with Fe 2+ in the solution to generate a large amount of hydroxyl radicals (·OH) to degrade VOCs contained in the sewage, and the generated Fe 3+ is reduced to Fe 2+ on the cathode, so that the reuse is realized. However, in the actual application process of the traditional electro-Fenton reaction device, an external power supply needs to be added for driving, and the contact type structure design is easy to cause poor stability of the plate catalyst, thereby causing poor service stability of the whole device, and it is difficult to meet the long-term stable operation requirement; in addition, the Fe 2+ in the reaction system needs to obtain electrons by means of an additional conductive carrier to realize the Fe cycle, which leads to low current utilization efficiency and high reaction energy barrier of oxygen reduction, which is not conducive to the production of H2O2, thereby limiting the yield of ·OH and affecting the working efficiency of the device. SUMMARY

[0004] In order to solve the problem of low VOCs degradation efficiency in the prior art, the application provides a sewage treatment device and method driven by photovoltaic / photothermal coupling. The device or method integrates a photovoltaic panel with an electrolytic device to make the photovoltaic device supply power for the electrolytic device, heats the sewage by using the heat of the photovoltaic device to convert the sewage into gaseous water, and makes the VOCs in the sewage escape in a gaseous state. The electrolytic device processes the gaseous water and the gaseous VOCs, avoids the problems of incomplete degradation of VOCs and corrosion of the electrolytic device caused by placing the electrolytic device in water, and the heat of the photovoltaic panel can reduce the energy barrier of the oxidation-reduction reaction and improve the production efficiency of H2O2.

[0005] Based on the above purpose, the present application provides a photovoltaic / photothermal coupling driven sewage treatment device in one aspect, which comprises a container, a photovoltaic panel, a water guide belt and an electrolytic device, the container is used for containing sewage to be treated; the photovoltaic panel is used for being placed at the opening of the container to absorb sunlight and convert it into electric energy, the photovoltaic panel seals the opening of the container to make the space in the container airtight; the water guide belt is used for conveying the sewage to be treated to the photovoltaic panel, the photovoltaic panel heats and evaporates the sewage to generate water vapor, and emits VOCs in the sewage to be treated; the electrolytic device is placed in the container and above the water surface of the sewage to be treated, the electrolytic device comprises a cathode and an anode, at the cathode, oxygen is converted into hydrogen peroxide by obtaining electrons, the hydrogen peroxide reacts with metal ions to obtain hydroxyl radicals, and the hydroxyl radicals are used for degrading VOCs in water. The electrolytic device electrolyzes the gas generated by the photovoltaic device heating the sewage, and the oxygen required by the electrolytic device can be conveyed by an aeration device. The electrolytic device does not need to be placed in the sewage, thereby reducing the possibility of being corroded by the sewage, the electrolytic device electrolyzes gaseous VOCs, compared with electrolyzing VOCs in water, which can avoid VOCs overflowing into the air to cause air pollution; the device integrates the photovoltaic panel, which can provide power for the electrolytic device in an environmentally friendly way, provide heat for converting the sewage into gaseous water, and further reduce the redox reaction energy barrier and improve the reaction efficiency.

[0006] As a preferred scheme, oxygen is introduced into the cathode of the electrolytic device or oxygen is injected into the water, the oxygen is released into the space where the electrolytic device is located and reacts at the cathode, the oxygen is converted into hydrogen peroxide at the cathode, the hydrogen peroxide reacts with the cathode electrode material to generate hydroxyl radicals, and the hydroxyl radicals are used for degrading volatile VOCs gas.

[0007] As a preferred scheme, the cathode material in the present application is Ti3C2 in the Mxene material, which not only has redox properties and can continuously convert hydrogen peroxide into hydroxyl radicals, but also has good conductivity and two-dimensional layered structure, can freely flow electrons, increases the electron transport capacity, and does not need additional electron transport materials. The reaction occurring at the cathode is as follows:

[0008] O2+2H + +2e→H2O2 Formula I

[0009] Ti 3+ +H2O2→Ti 4+ +OH - +·OH Formula II

[0010] Ti 4+ +e→Ti 3+ Formula III

[0011] As a preferred solution, the anode material in the application is one of Cu, Pt, Ti, Ni, graphite, and the reaction at the anode is: 2H2O-2e→O2+4H + A diaphragm is arranged between the cathode and the anode, and the diaphragm is used to realize proton exchange between the cathode and the anode.

[0012] As a preferred solution, the water guide belt in the application is a flexible material, at least one end of which extends into sewage, and the middle region is attached to the back side of the photovoltaic panel. The photovoltaic panel heats the water guide belt in the middle region, which converts water into gaseous water and releases VOCs gas in the water. The water guide belt in the application transports the water-absorbed sewage to the middle region through a water delivery channel or capillary force, thereby continuously providing moisture to the middle region. As a preferred solution, the water guide belt is a water-absorbing cotton cloth, the circumferential side of which extends vertically downward into the water body, and the middle region is attached to the back side of the photovoltaic panel. The cotton cloth forms a containing cavity with the water surface, which is preferably a closed space, and the electrolytic device is arranged in the space. This arrangement has the advantages of: (1) allowing the evaporated water or VOCs to fall into the space, which facilitates sufficient contact with the electrolytic device and degradation of VOCs; and (2) facilitating storage of the heat generated by the photovoltaic panel, which allows the electrolytic device to be placed in a higher temperature space, thereby reducing the reaction energy barrier of the electrolytic device and increasing the production efficiency of hydroxyl radicals.

[0013] As a preferred solution, the cathode and the anode of the electrolytic device are arranged oppositely, with the cathode on top and close to the photovoltaic panel. The distance between the cathode and the photovoltaic panel is preferably 1-10 cm. In this distance, the gas generated by the heating of the photovoltaic panel first contacts the cathode and reacts in time. In addition, the heat of the photovoltaic panel is also transmitted to the cathode in the first place, thereby improving the efficiency of the cathode reaction.

[0014] As a preferred solution, the diaphragm between the cathode and the anode is a perfluorinated proton exchange membrane, which provides an ion channel for the cathode and anode reactions.

[0015] As a preferred embodiment, the preparation method of the cathode electrode material Ti3C2 is as follows: Ti3C2 material is obtained by acid etching of Ti3AlC2; the acid used in the acid etching technology is one or more of hydrofluoric acid, sulfuric acid, and nitric acid. These acids have strong oxidizing properties, which can not only react with the Al element in Ti3AlC2 to remove the Al element and obtain Ti3C2 material, but also make the formed Ti3C2 material a two-dimensional layered MXene material, which is beneficial to electron transport; the acid etching time is 0.5 to 48 hours. Sufficient etching time can ensure the effective removal of Al element in Ti3AlC2. If the time is less than this, Al element cannot be effectively removed by etching. If the time is more than this, the structure of the generated Ti3C2 material will be destroyed, and its conductivity will be impaired; the acid etching temperature is 40 to 180°C. By controlling the etching temperature, the sufficient removal of Al element can be ensured. If the temperature is less than this, the etching efficiency will be affected. If the temperature is more than this, high-temperature side reactions will occur, affecting the quality of the material; the acid concentration used in the acid oxidation etching is 1 to 30 mol / L. By controlling the acid concentration, the sufficient removal of Al element can be ensured.

[0016] As a preferred option, the anode material is one of Cu, Pt, Ti, Ni, and graphite;

[0017] As a preferred option, the photovoltaic panel is one of monocrystalline silicon, polycrystalline silicon, amorphous silicon, or multi-component compound silicon.

[0018] On the other hand, the present invention provides a wastewater treatment method driven by photovoltaic / photothermal coupling. The method first heats and evaporates the wastewater, converting the water into water vapor and releasing VOCs (volatile organic compounds) in the water. The released mixed gas is then treated by an electrolysis device containing water vapor, VOCs, and oxygen. The electrolysis device includes a cathode and an anode. At the cathode, oxygen is converted into hydrogen peroxide. The hydrogen peroxide reacts with the cathode electrode material to generate hydroxyl radicals, which are used to degrade the released VOCs.

[0019] As a preferred option, the cathode electrode material is Ti3C2, and Ti3C2 is an MXene material.

[0020] The beneficial effects of the present invention include: (1) The present invention provides a photovoltaic / photothermal coupling driven sewage treatment device, which is essentially a photovoltaic / photothermal coupling driven non-contact Ti3C2-based electro-Fenton treatment device for VOCs sewage. The device efficiently combines photovoltaic technology, photothermal technology and electro-Fenton technology to form a photoelectric / photothermal-Fenton degradation method, which significantly improves the in-situ efficient treatment capacity of VOCs in sewage and presents advantages such as simple structure, low cost and significant effect.

[0021] (2) This invention uses green and renewable solar energy as the sole energy source, and low-carbon and environmentally friendly photovoltaic panels to provide electricity to replace the external power source in traditional electric Fenton devices. At the same time, it cleverly and efficiently utilizes the waste heat generated by the photovoltaic panels to reduce the energy barrier of the oxygen reduction reaction, increase the yield of H2O2, and utilizes the high conductivity of Ti3C2 material and Ti 4+ / Ti 3+ The valence state changes between these parameters enable efficient production of ·OH, improving the overall efficiency of the device. Furthermore, the novel non-contact structural design avoids direct contact between the electrode material and VOCs wastewater, thus ensuring the long-term stable operation of the entire device.

[0022] (3) The VOCs wastewater in-situ treatment device provided by the present invention can be used as a mobile wastewater processor. It has a flexible structure, is easy to transport and assemble, and achieves harmless treatment of VOCs wastewater with near-zero energy consumption. It meets the needs of today's market and has broad market prospects and significant social benefits. Attached Figure Description

[0023] Figure 1 Structural diagram of the wastewater treatment device in this invention;

[0024] Figure 2 Electrolysis device structure and electrode reaction diagram;

[0025] Figure 3 Traditional contact wastewater treatment devices;

[0026] Figure 4 The effect of different voltages on phenol removal rate;

[0027] Figure 5 The phenol removal rates of Example 1 and Comparative Example 1 at the same voltage are shown in the graph.

[0028] Figure 6 Comparison of phenol removal rates between Example 1 and Example 3.

[0029] In the diagram: 1. Container, 2. Photovoltaic panel, 3. Electrolysis device, 301. Cathode, 302. Diaphragm, 303. Anode, 4. Water guide belt, 5. Sewage. Detailed Implementation

[0030] The present invention will be further explained in detail below with reference to the accompanying drawings and specific embodiments, but it should be understood that the scope of protection of the present invention is not limited to the specific embodiments.

[0031] This invention provides a photovoltaic / photothermal coupled wastewater treatment device, such as... Figure 1As shown, including a container, a photovoltaic panel 2 arranged at the opening of the container, and an electrolytic device 3 placed in the container, the sewage 5 to be treated is placed in the container, and the photovoltaic panel 2 seals the opening to prevent the gas in the container from overflowing out of the container through the opening. The container can be a water storage tank 1, the light absorption side of the photovoltaic panel 2 faces outward, and the back light side faces inward, a water guide belt 4 is arranged on the back light side, the water guide belt 4 is a water absorption cotton cloth, and the sewage 5 is pumped to the back light side of the photovoltaic panel 2 through the capillary device. The circumferential side of the water absorption cotton cloth extends downward into the water body, and the middle region is attached to the back light side of the photovoltaic panel 2. After the circumferential side of the water absorption cotton cloth absorbs the sewage 5, it continuously transports moisture to the middle region. The waste heat of the photovoltaic panel 2 heats the water in the middle region, causing it to convert into water vapor and VOCs gas. The water absorption cotton cloth and the water surface form a containing cavity, and the electrolytic device 3 is placed in the containing cavity. The containing cavity is small in space, the gas released therein has high density and is in full contact with the electrolytic device 3, and the temperature in the containing cavity is high, which further promotes the electrolysis process. The photovoltaic panel 2 supplies power to the electrolytic device 3, so that the electrolytic device 3 can stably operate without external power supply. The photovoltaic panel 2 can be a single crystal silicon cell, a polycrystalline silicon cell, an amorphous silicon cell or a multi-element compound cell, and can be a single-junction cell or a multi-junction cell. The cell can be a parallel structure or a series structure.

[0032] The reaction of the electrolytic device 3 in the present application is as shown in the following formula: Figure 2 As shown, it is an electro-Fenton device, which includes a cathode 301, an anode 303 and a diaphragm 302. Oxygen is transported to the sewage 5 or the containing cavity through an aeration device or other oxygen transport device. The oxygen reacts to generate hydrogen peroxide at the cathode 301, and the material of the cathode 301 is Ti3C2 in the Mxene material. The reaction occurring at the cathode 301 is as follows:

[0033] O2+2H + +2e→H2O2 Formula I

[0034] Ti 3+ +H2O2→Ti 4+ +OH - +·OH Formula II

[0035] Ti 4+ +e→Ti 3+ Formula III

[0036] Ti3C2 in the Mxene material has strong conductivity, and the conversion between Ti 3+ and Ti 4+ does not require additional material assistance, has high conversion efficiency, ensures that the cathode 301 electrode is fully supplied with hydroxyl, and the hydroxyl further degrades VOCs in water. Taking the degradation of phenol as an example, the degradation reaction formula is as follows:

[0037]

[0038] Ti3C2 is obtained by etching Al in Ti3AlC2. Specifically, Ti3AlC2 is placed in an acid solution and stirred until the reaction is complete, washed with deionized water until neutral, and dried in a freeze dryer for 72 hours to obtain Ti3C2 material. The acid solution used can be hydrofluoric acid, sulfuric acid or nitric acid solution, and the concentration of the acid can be 1 mol / L, 5 mol / L, 10 mol / L or 30 mol / L. The concentration of the acid is selected according to the desired etching degree and etching amount. The acid etching time can be 0.5h, 10h, 20h, 35h or 48h. The concentration of the acid and the acid etching time work together to adjust the etching degree. The intermediate separation membrane 302 is used for ion exchange and can be selected from one of the following: a perfluorinated proton exchange membrane, a partially fluorinated polymer membrane, and a new non-fluorinated polymer membrane, which is used to exchange protons.

[0039] The anode 303 is made of one of Cu, Pt, Ti, Ni, and graphite. The following reaction occurs at the anode 303:

[0040] 2H2O-2e→O2+4H + Formula four.

[0041] The above electrolytic device 3 can be an electro-Fenton device. The anode 303 and the cathode 301 are fixed by electrode clamps. The pH value of the wastewater 5 to be treated can be adjusted by adding acid to make it acidic. Specifically, hydrochloric acid can be added to adjust the concentration of hydrochloric acid in the wastewater 5 to 0.05mmol / L.

[0042] The device is provided with a photovoltaic panel 2 at the top to provide the required electric energy for the electro-Fenton VOCs degradation. The water guide belt 4 prepared by the high water absorption material pumps the VOCs wastewater 5 to the lower surface of the photovoltaic panel 2. The waste heat generated by the photovoltaic panel 2 promotes the simultaneous escape of VOCs and water in the wastewater 5, and transports them to the lower electro-Fenton reaction area to achieve VOCs degradation. The device uses green and renewable solar energy as the only energy source, and provides electric energy through the low-carbon and environmentally friendly photovoltaic panel 2 to replace the external power supply in the traditional electro-Fenton device. At the same time, the device efficiently utilizes the waste heat generated by the photovoltaic panel 2 to reduce the oxygen reduction reaction energy barrier, increase the production of H2O2, and utilize the high electrical conductivity of Ti3C2 material and the change of valence between Ti and Ti3C2 to achieve efficient production of ·OH and improve the working efficiency of the device. The device adopts a non-contact structure design, which can avoid direct contact between the electrode material and the VOCs wastewater 5, and improves the structural and service stability of the overall device. The device adopts an integrated structure design, has small occupation area, low cost and is easy to scale up, and can realize rapid and efficient degradation of VOCs in the wastewater 5, overcoming the problem that the existing device cannot treat VOCs in situ, causing secondary air pollution. 4+ / Ti 3+ The device adopts a non-contact structure design, which can avoid direct contact between the electrode material and the VOCs wastewater 5, and improves the structural and service stability of the overall device. The device adopts an integrated structure design, has small occupation area, low cost and is easy to scale up, and can realize rapid and efficient degradation of VOCs in the wastewater 5, overcoming the problem that the existing device cannot treat VOCs in situ, causing secondary air pollution.

[0043] Further description is made in the form of specific embodiments below.

[0044] Embodiment 1

[0045] As Figure 1 , the photovoltaic / photothermal coupling driven sewage treatment device in this embodiment includes a container 1 for realizing non-contact in-situ VOCs degradation, a photovoltaic panel 2 for providing electric energy and Joule heat energy for the whole device is arranged at the top layer of the container 1, and an electrolytic device 3 for degrading VOCs sewage is arranged inside the container; a water guide belt 4 for pumping the bottom VOCs sewage to the back light side of the solar cell panel through capillary action is further arranged in the container.

[0046] The container 1 adopts a square structure, and the material is quartz glass with low thermal conductivity and resistance to sewage corrosion; the photovoltaic panel 2 adopts a single-crystal silicon solar cell panel with an average photoelectric conversion efficiency of 19%; in addition, in order to prevent the water guide belt 4 from directly contacting the photovoltaic panel 2 and causing the panel to fail, a high-thermal-conductivity waterproof adhesive is adhered to the back side of the photovoltaic panel 2, and the water guide belt 4 is connected with the photovoltaic panel 2 through the high-thermal-conductivity waterproof adhesive.

[0047] The electrolytic device in this embodiment is an electro-Fenton reaction tank, which includes an anode, a cathode and a diaphragm, wherein the cathode is above, the anode is below, and the diaphragm is arranged between the anode and the cathode; the anode adopts a Pt mesh electrode, the cathode adopts Ti3C2, and the central diaphragm adopts a perfluorinated proton exchange membrane; the electro-Fenton device is arranged in the space above the water surface below the photovoltaic panel; when the photovoltaic panel heats the sewage pumped by the water guide belt to make it release water vapor and VOCs, the electro-Fenton device starts to electrically degrade VOCs.

[0048] The cathode of the electro-Fenton device is obtained by the following method:

[0049] S01 1g of pre-dried Ti3AlC2 precursor is slowly poured into 80mL of hydrofluoric acid (concentration of 30mol / L), and the hydrofluoric acid and the Ti3AlC2 precursor are placed in a magnetic heating stirrer at 80℃ for reaction;

[0050] S02 the acid etching reaction is carried out for 4h; after the reaction is completed, deionized water is used for centrifugal washing until neutral, and then the product is placed in a freeze dryer for drying for 72h; then the Al layer in the Ti3AlC2 precursor is removed by acid treatment to obtain Ti3C2 as a cathode material for standby use.

[0051] The photovoltaic panel 2 is connected with the cathode and the anode of the electro-Fenton reaction tank 3 through wires; the water guide belt 4 adopts dust-free paper with excellent capillary force and mechanical strength, the dust-free paper is tightly attached to the lower surface of the cell panel to which the high-thermal-conductivity waterproof adhesive is adhered at the back side, and the two ends of the dust-free paper are connected with the bottom VOCs sewage, so that the bottom VOCs sewage can be continuously pumped to the back side of the cell panel through the two-dimensional water transmission channel to realize efficient photothermal interface evaporation;

[0052] After the photovoltaic panel 2 and the water guide belt 4 are tightly attached in the above manner, the two ends of the water guide belt 4 are extended to the bottom of the container 1 for conveying sewage, and then the solar cell panel 2 is well sealed with the top surface of the container 1 to ensure that VOCs and water vapor generated by the photo-thermal effect cannot escape from the container (main shell), so as to effectively improve the contact probability of VOCs with the lower electro-Fenton reaction area, thereby significantly improving the in-situ degradation reaction rate of VOCs.

[0053] When the VOCs sewage treatment work is performed, first Figure 1 The device photovoltaic panel 2 is connected with the electro-Fenton reaction tank 3, and the bottom VOCs sewage is pumped to the back side of the solar cell panel through the two-dimensional water transmission channel of the two ends of the dust-free paper. Under the action of the Joule heat of the cell panel, the thin layer of VOCs sewage is heated by the high-efficiency interface and releases VOCs and water vapor at a relatively fast rate. The above water vapor enters the electro-Fenton reaction tank 3 after condensation reflux together with the VOCs gas, and then connects the cathode and anode thereof, so that the in-situ efficient degradation of VOCs in the cathode of the electro-Fenton reaction tank 3 can be realized, which effectively overcomes the problem that the existing device cannot treat VOCs in-situ, thereby causing secondary atmospheric pollution. In addition, the non-contact structure design can protect the electrode plate material from long-term erosion of VOCs sewage, and promote long-term stable operation of the device.

[0054] Example 2

[0055] The difference from example 1 is only that the photovoltaic panel 2 adopts a perovskite solar cell panel with an average photoelectric conversion efficiency of 25%, and the experimental verification further improves the working efficiency of the device by improving the photoelectric conversion efficiency.

[0056] Example 3

[0057] The difference from example 1 is only that the cathode of the electro-Fenton reaction tank 3 is prepared by laser etching Ti defects on the basis of the Ti3C2 prepared in example 1, to obtain Ti defect-Ti3C2 material, and the above material is prepared into a film electrode as the electro-Fenton cathode by means of negative pressure suction filtration. The experimental verification shows that, compared with example 1, as shown in Figure 6 , the in-situ degradation rate of VOCs is improved by 20% or more. Figure 6The removal rate of phenol by the Ti3C2 film electrode prepared in Example 1 and the Ti defect-Ti3C2 film electrode prepared in Example 3 was compared. It can be seen from the figure that under the condition of providing a voltage of 1.8V through a solar panel, the removal rate of phenol by the Ti defect-Ti3C2 film electrode reached 97.9%, which was 1.2 times higher than the removal rate of phenol by the Ti3C2 film electrode. This is because the Ti defects in the Ti defect-Ti3C2 film electrode can improve the activity of the catalyst. In the catalytic degradation reaction, the catalyst needs to effectively adsorb the pollutants and interact, and then realize the degradation of the pollutants. The Ti defects can provide more reaction sites, so that the interaction between the catalyst and the pollutants is more intense, thereby improving the degradation rate. In addition, the Ti defects can also affect the stability of the catalyst. In the catalytic degradation reaction, the catalyst needs to withstand extreme conditions such as high temperature and high pressure, and the Ti defects can improve the stability of the catalyst, thereby prolonging the service life of the catalyst. Therefore, the Ti defect-Ti3C2 film electrode design can greatly increase the contact probability with phenol in the air, thereby improving the removal rate of phenol. In this embodiment, the use of the Ti defect-Ti3C2 film electrode can significantly improve the in-situ degradation rate of VOCs.

[0058] Comparative Example 1

[0059] The traditional contact type sewage treatment device, as shown in Figure 3 , includes a container 1, a sewage 5 to be treated is placed in the container 1, and an electrolysis device 3 is placed in the sewage to be treated. The electrolysis device includes a cathode 301, a diaphragm 302 and an anode 303, and the diaphragm 302 is used for ion exchange between the cathode electrolyte and the anode electrolyte. The electrolysis device is powered by an external power supply, and the electrolysis device is an electro-Fenton device. The VOCs in the sewage are degraded by directly electrolyzing the sewage to be treated.

[0060] Taking the device obtained in Example 1 as an example, the removal rate of phenol under different voltages was tested, as shown in Figure 4 , it can be seen from the figure that as the voltage applied to the anode increases from 0.5V to 1.8V, the removal rate of phenol in water increases from 42.3% to 81.6%. That is, by adjusting the voltage of the electrolysis device, the removal rate of phenol can be as high as 81.6% or more. Compared with the contact type sewage treatment device, the removal rate of phenol by the sewage treatment device in the present application is 1.7 times higher under the same voltage, as shown in Figure 5As shown, the removal rate of the contact type sewage treatment device is 48.3%. This is because when the contact type sewage treatment device degrades phenol in sewage, due to the heat generated by light and the volatile nature of phenol, a large amount of phenol will volatilize into the air, and the electro-catalyst of the contact type sewage treatment device is usually immersed in water, which causes it to be unable to contact the phenol in the air, so it cannot effectively degrade the phenol in the air, ultimately resulting in a low removal rate of phenol by the contact type sewage treatment device. Therefore, the non-contact design can greatly increase the contact probability with the phenol in the air, thereby improving the removal rate of phenol.

[0061] In the present application, the device uses green renewable solar energy as the only energy source, significantly improves the in-situ efficient treatment capacity of VOCs in sewage through coupling of photoelectric / photothermal-Fenton degradation means, and can completely solve the problem of secondary pollution of VOCs. In addition, the new non-contact structure design can avoid direct contact of the plate material with VOCs sewage, thereby ensuring long-term stable operation of the overall device. The device structure is flexible, easy to transport and assemble, significantly saving equipment costs, and can be used as a mobile sewage treatment device to maximize the VOCs sewage treatment rate and treatment capacity on the basis of saving land area, and has a wide market prospect and significant social benefits.

[0062] The above examples are only used to illustrate the technical solutions of the present application and not to limit it. Although the present application has been described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that the technical solutions of the present application can be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present application.

Claims

1. A photovoltaic / photothermal coupled driven wastewater treatment device, characterized in that: The container comprises: a container for containing sewage to be treated; A photovoltaic panel is placed at the opening of the container for converting solar energy into electricity, the light-absorbing side of the photovoltaic panel faces outward, and the back light side faces inward; A water guide belt is used to transport sewage to be treated to the photovoltaic panel, and the photovoltaic panel heats and evaporates the sewage to produce water vapor and releases VOCs in the sewage to be treated; An electrolytic device is placed in the container and above the water surface of the sewage to be treated, the electrolytic device comprises a cathode and an anode, at the cathode, oxygen gains electrons to convert into hydrogen peroxide, and the hydrogen peroxide reacts with metal ions to generate hydroxyl radicals, which are used to degrade VOCs in water; At the anode, water vapor loses electrons to convert into oxygen and hydrogen protons; The anode and cathode are powered by the photovoltaic panel; The cathode is supplied with oxygen by an aeration device; The electrolytic device comprises a cathode, a diaphragm and an anode in turn from the photovoltaic panel to the far end, the cathode material of the electrolytic device is Ti3C2 in MXene material, the Ti3C2 converts hydrogen peroxide into hydroxyl radicals, which are used to degrade VOCs; The preparation method of the Ti3C2 is as follows: Ti3AlC2 is placed in an acid solution for acid etching to remove Al elements in Ti3AlC2 to obtain Ti3C2 material; The acid etching time is 4h, the etching temperature is 80℃, and the acid solution is 30mol / L hydrofluoric acid solution; The obtained Ti3C2 material is subjected to laser etching to form Ti defects to obtain Ti defect-Ti3C2 material as the cathode of the electrolytic device.

2. The photovoltaic / photothermal coupled driven wastewater treatment device according to claim 1, wherein: The water guide belt is made of flexible material, one end or both ends or multiple ends are immersed in the sewage to be treated, and the middle region is arranged on the back light side of the photovoltaic panel, the sewage to be treated is transported to the middle region by the water guide belt immersed in the sewage to be treated, and the water vapor and VOCs are released by heating and evaporation in the middle region.

3. The photovoltaic / photothermal coupled driven wastewater treatment device according to claim 2, wherein: The water guide belt is a water-absorbing cotton cloth, the side of the water-absorbing cotton cloth extends vertically downward to the sewage to be treated, the middle region is arranged on the back light side of the photovoltaic panel, a containing cavity is formed between the water-absorbing cotton cloth and the water surface, and the electrolytic device is arranged in the containing cavity, and the electrolytic device is arranged directly below the middle region of the water-absorbing cotton cloth.

4. The photovoltaic / photothermal coupled driven wastewater treatment device of claim 1, wherein: The distance between the cathode and the photovoltaic panel is 1-10cm.

5. The photovoltaic / photothermal coupled driven wastewater treatment device of claim 1, wherein: The electrolytic device satisfies one or a combination of the following conditions: The anode material is one of Cu, Pt, Ti, Ni and graphite; A diaphragm is arranged between the cathode and the anode, the diaphragm is a perfluorinated proton exchange membrane, and the diaphragm provides an ion channel for the cathode and anode reactions.

6. A method for treating sewage by using the sewage treatment device according to claim 1, characterized in that: The waste heat of the photovoltaic panel is used to heat the sewage to be treated to release a mixed gas of water vapor and VOCs, the mixed gas is electrolyzed to degrade the VOCs, water vapor loses electrons to convert into oxygen and hydrogen protons at the anode, the cathode is supplied with oxygen by an aeration device, oxygen gains electrons to convert into hydrogen peroxide at the cathode, and the hydrogen peroxide reacts with metal ions to generate hydroxyl radicals, which are used to degrade VOCs in water; The electrolytic device is integrated with a photovoltaic panel, the electrolytic device comprises an anode and a cathode, the photovoltaic panel supplies power for the electrolytic device, and heat of the photovoltaic panel is used for heating sewage to be treated and promoting a cathode reaction.

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