A method for treating sulfur-containing wastewater using solar light-electricity-heat coupling

Abstract

A method for treating sulfur-containing wastewater by using solar light-electricity-heat coupling is designed to overcome the shortcomings of the prior art in treating sulfides in sulfur-containing wastewater, which cannot take into account high removal rate, energy saving and avoidance of secondary pollution. The method uses sunlight as a light source to treat sulfur ions by photocatalytic oxidation, solar cells provide electricity for electrolytic treatment of sulfur ions, and a solar thermal collector provides heat energy; the photocatalyst for photocatalytic oxidation treatment of sulfur ions and the anode for electrolytic treatment of sulfur ions are TiO2 NTs or Fe 3+ / TiO2 NTs, the cathode is a Pt electrode, the voltage is 0.5V-2.5V, the applied current is 1mA-4mA; the temperature of photocatalytic oxidation and electrolysis treatment is 55℃-95℃, and the time is 0.5h-2h. The present invention combines photocatalysis and electrolysis to treat sulfur ions, promotes the reaction by heating, comprehensively utilizes the full spectrum of solar energy, improves the efficiency of removing sulfide from wastewater, and reduces the reaction energy consumption.

Description

Technical Field

[0001] The invention relates to the field of wastewater treatment, and in particular to a method for treating sulfur-containing wastewater by utilizing solar light-electricity-heat coupling. Background Art

[0002] Sulfur-containing wastewater is very harmful because sulfides are not only toxic and corrosive, but also have a strong odor, which not only affects the environment, but also affects the normal operation of sewage treatment system structures.

[0003] The treatment methods for sulfides in wastewater are generally: adding chemical agents, which is costly and causes secondary pollution; using electrochemical oxidation, which has excellent environmental compatibility, but the efficiency of removing sulfides is low and the energy consumption is high; photocatalytic oxidation to remove sulfides has high requirements for photocatalysts and generally requires ultraviolet light, resulting in high energy consumption. If natural light is used, the efficiency is relatively low.

[0004] In view of the above defects, it is necessary to propose a method for treating sulfur-containing wastewater, which can improve the removal rate, save energy, and have no secondary pollution and other advantages. Summary of the invention

[0005] The present invention overcomes the shortcomings of the prior art in which high removal rate, energy saving and avoidance of secondary pollution cannot be achieved when treating sulfides in sulfur-containing wastewater, and provides a method for treating sulfur-containing wastewater using solar light-electricity-heat coupling.

[0006] The technical solution adopted by the present invention to achieve the above invention purpose is: a method for treating sulfur-containing wastewater by using solar light-electricity-heat coupling, using sunlight as the light source to treat sulfur ions by photocatalytic oxidation, solar cells provide electricity for electrolytic treatment of sulfur ions, and solar thermal collectors provide heat for photocatalytic oxidation and electrolytic treatment; the photocatalyst for photocatalytic oxidation treatment of sulfur ions and the anode for electrolytic treatment of sulfur ions are the same material. The photocatalyst and electrolytic anode are TiO2NTs or Fe 3+ / TiO2 NTs, the electrolytic cathode is a Pt electrode; the temperature for photocatalytic oxidation treatment of sulfur ions and electrolytic treatment of sulfur ions is: 55°C-95°C; the voltage for the electrolytic treatment of sulfur ions is: 0.5V-2.5V, the external current is 1mA-4mA; the time for the photocatalytic and electrolytic treatment is: 0.5h-2h.

[0007] Furthermore, the TiO2 NTs or Fe 3+ The TiO2 NTs in the / TiO2 NTs are TiO2 nanotubes that have been subjected to secondary anodization. The method for preparing the TiO2 nanotubes that have been subjected to secondary anodization comprises the following steps:

[0008] S1, using a titanium sheet as an anode, a platinum sheet as a cathode, and a mixed solution of ethylene glycol, ammonium fluoride and ultrapure water as an electrolyte, electrolytic oxidation was performed at a voltage of 60V for 30 minutes in a constant temperature water bath at 30°C to obtain a primary titanium oxide sheet;

[0009] S2, ultrasonically cleaning the primary titanium oxide sheet obtained in step S1 to remove the oxide film on the surface of the primary titanium oxide sheet, thereby obtaining a titanium sheet with orderly arranged hexagonal grooves on the substrate;

[0010] S3, using the titanium sheet with orderly arranged hexagonal grooves on the substrate obtained in step S2 as an anode, the platinum sheet as a cathode, and a mixed solution of ethylene glycol, ammonium fluoride and ultrapure water as an electrolyte, and electrolytically oxidizing at a voltage of 30 V for 30 min in a constant temperature water bath at 30° C. to obtain a secondary titanium oxide sheet;

[0011] S4, placing the secondary titanium oxide sheet obtained in step S3 in a muffle furnace, and heating the muffle furnace at 5 o The temperature was programmed to 450 C / min. o C and then kept warm for 1 h to obtain secondary anodized TiO2 nanotubes.

[0012] Furthermore, the Fe 3+ The preparation method of TiO2 NTs is as follows: TiO2 NTs are immersed in Fe(NO3)3 solution for 1 hour, then placed in a muffle furnace, and the temperature of the muffle furnace is programmed to 450℃ at a rate of 5℃ / min and then kept at this temperature for 2 hours to obtain Fe 3+ / TiO2 NTs.

[0013] Furthermore, the concentration of the Fe(NO3)3 solution is 0.05-0.2 mol / L.

[0014] Furthermore, in the method of treating sulfur-containing wastewater by utilizing solar light-electricity-heat coupling: the solar thermal collector provides heat energy for photocatalytic oxidation and electrolysis by heating a water bath.

[0015] The beneficial effects of the present invention are: (1) applying the solar thermal electrochemical photo-process (STEP) theory to the treatment of sulfur-containing wastewater, constructing a solar photo-electric-thermal three-field coupled reaction system, comprehensively utilizing the full spectrum of solar energy, improving the efficiency of removing sulfides from wastewater, and effectively utilizing solar energy to reduce the energy consumption required by the reaction system.

[0016] (2) In the method of the present application, the ultraviolet light portion of solar energy is used to excite the photocatalyst to achieve photocatalytic treatment of sulfur ions, the visible light portion of sunlight is converted into electrical energy through solar cells to provide electrical energy for electrolytic treatment of sulfur ions, and the infrared light region of sunlight is converted into thermal energy through solar collectors to provide heat for the photocatalytic and electrolytic treatment systems, thereby achieving full spectrum application of sunlight, effectively utilizing solar energy as a "green energy", reducing the consumption of other energy sources, and promoting the "green treatment" of wastewater to remove sulfides.

[0017] (3) In the method of treating sulfur-containing wastewater by using solar light-electricity-heat coupling of the present application, TiO2 NTs (titanium dioxide nanotubes) or Fe 3+ / TiO2 NTs(Fe 3+ Doped titanium dioxide nanotubes) as photocatalysts and electrolytic anodes, the main advantages are: TiO2 NTs, Fe 3+ / TiO2 NTs are used in sulfur-containing wastewater systems and have high sulfur resistance. The microscopic pore structure of nanotubes can ensure sufficient light path and high catalytic activity.

[0018] (4) TiO2 catalyst has strong redox ability, good catalytic activity, strong corrosion resistance, safe use, non-toxic and harmless, no secondary pollution and other characteristics. It is suitable for use in the sulfur-containing wastewater of this application as a catalyst for treating sulfur ions and an electrolytic anode.

[0019] (5) Based on the advantages of TiO2 in the system of this application, Fe 3+ / TiO2 NTs also have the following advantages: i) Fe 3+ 、Ti 4+ With matching band structures, Fe 3+ Doped TiO2 can produce active groups, which have strong oxidizing ability and can oxidize sulfides, helping solar, thermal and electrical systems to process sulfides; ii) Fe 3+ It changes the bandgap of TiO2, increases the absorption width of sunlight and the efficiency of solar energy utilization; iii) Due to the different coordination and electronegativity of metal ions, excess charge is generated, which increases the ability of the semiconductor to attract protons or electrons, thereby improving the activity of the electrode.

[0020] The present invention is further described below in conjunction with specific implementation modes and accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Attached Figure 1The SEM images of the catalyst and electrode materials of this application include: (a) SEM top view of one-step TiO2 NTs; (b) SEM top view of two-step TiO2 NTs; (c) SEM top view of Fe 3+ SEM top view of Fe / TiO2NTs; (d) 3 + SEM side view of / TiO2 NTs.

[0022] Attached Figure 2 This is the Tafel curve of the TiO2NTs electrode of this application.

[0023] Attached Figure 3 Fe for this application 3+ XPS spectrum analysis of / TiO2 NTs, where: (a) Fe 3+ XPS full spectrum of / TiO2 NTs; (b) high-resolution scanning spectrum of Fe 2p; (c) Ti 2p 3 / 2 High-resolution scanning spectrum; (d) High-resolution scanning spectrum of O 1s.

[0024] Attached Figure 4 The activity spectrum of the catalyst and electrode material of this application after treating sulfur-containing wastewater for 5 times, including: (a) stability comparison of one-step TiO2 NTs after 5 cycles; (b) stability comparison of two-step TiO2 NTs after 5 cycles; (c) Fe 3+ / TiO2 NTs stability comparison after five cycles of use; (d) Stability comparison of three types of nanotubes after the first and fifth use.

[0025] Attached Figure 5 Fe 3+ / The action mechanism of TiO2 nanotubes in solar photo-electric-thermal coupling treatment of sulfur-containing wastewater. DETAILED DESCRIPTION

[0026] The present invention is a method for treating sulfur-containing wastewater by using solar light-electricity-heat coupling, which is to convert sulfur ions (S 2- ) are further removed by photocatalytic oxidation and electrolytic oxidation to polysulfides.

[0027] The overall reaction equation for direct electrolysis of alkaline sodium sulfide solution is:

[0028] (n+1) HS - + (n-1) H2O → S n S 2- + (n-1) OH - + nH2↑

[0029] The reaction of the sodium sulfide solution at the anode in the reaction system is relatively complex. In the highly alkaline sodium sulfide solution, the following reactions may occur:

[0030] S 2- +6OH - =SO 3- +3H2O+6e (E 0 =-0.6 V)

[0031] S+6OH - =SO 3- +3H2O+4e (E 0 =-0.66 V)

[0032] 2S 2- +6OH - =S2O3 2- +3H2O+4e (E 0 =-0.63 V)

[0033] S+8OH - =SO4 2- +4H2O+6e (E 0 =-0.685 V)

[0034] S+8OH - = SO4 2- +4H2O+6e (E 0 =-0.75 V)

[0035] 2S 2- +4OH - =SO4 2- +4H2O+4e (E 0 =-0.93 V)

[0036] From the above reactions, we can see that no matter which reaction, the corresponding electrode potential is less than 0, which means that without external energy, sodium sulfide cannot be oxidized to polysulfide faster. Therefore, when treating sulfur ions in sulfur-containing wastewater, external energy must be provided to ensure effective treatment of sulfur ions.

[0037] Taking TiO2 photocatalyst as an example, the reaction mechanism of photocatalytic oxidation is as follows: when the TiO2 surface is irradiated by a beam of light with a bandgap width less than or equal to the energy level of the outer valence band, the electrons attached to VB (low-energy valence band full of electrons) are excited to jump to CB (high-energy conduction band without electrons), and electrons with higher reduction performance (e) are generated on VB and CB respectively. - ) and holes with strong oxidizing properties (h + ), leaving a positively charged h on VB+ , thus generating hole-electron pairs. Under the action of the external electric field, the electrons and holes move in a directional manner and gradually migrate to the surface of TiO2, reacting with dissolved oxygen and water molecules respectively, thereby generating hydroxyl radicals with strong oxidizing properties, which oxidize and decompose compounds (such as sodium sulfide) attached to the surface of TiO2.

[0038] In the method for treating sulfur-containing wastewater by using solar light-electricity-heat coupling provided in the present application, the full spectrum of solar energy is effectively applied in the following three aspects: (1) Using sunlight as the light source to treat sulfur ions by photocatalytic oxidation, the ultraviolet light in sunlight is used for photocatalytic treatment. (2) Using solar cells to provide electrical energy for electrolytic treatment of sulfur ions, generally using silicon solar panels to convert visible light in sunlight into electrical energy. (3) A solar thermal collector provides thermal energy for photocatalytic oxidation and electrolytic treatment. The solar thermal collector gathers infrared light in sunlight and provides thermal energy for the reaction by heating a water bath device: the entire electrolytic reaction device is placed in a water bath reactor, and the concentrator of the solar thermal collector gathers infrared light to the bottom of the electrolytic reaction device (both electrolytic reaction and photocatalytic reaction are carried out in the electrolytic reaction device), and the reaction temperature is adjusted by adjusting the angle of the concentrator, thereby reducing the overpotential of the reaction, making the electrolytic reaction easier to occur, and increasing the temperature of the electrolytic reaction and photocatalytic reaction in the electrolytic reaction device, thereby accelerating the reaction rate. Under heating conditions, the sulfur-containing wastewater is treated by photocatalytic oxidation and electrolysis to achieve the purpose of removing sulfide from the sulfur-containing wastewater.

[0039] In the method for treating sulfur-containing wastewater by using solar light-electricity-heat coupling provided in the present application, the photocatalyst for photocatalytic oxidation treatment of sulfur ions and the anode for electrolytic treatment of sulfur ions are the same material: TiO2 NTs or Fe 3+ / TiO2 NTs, the electrolytic cathode is a Pt electrode, the sulfur-containing wastewater is the electrolyte, the constant temperature water bath is 55℃-95℃, the voltage is 0.5V-2.5V, the external current is 1mA-4mA, and the sulfur-containing wastewater is treated by photocatalytic oxidation and electrolytic oxidation process for 0.5-2h.

[0040] In the method of the present application, TiO2 NTs or Fe 3+ / TiO2 NTs can be used as both photocatalyst and electrolytic anode. 3+ / TiO2 NTs are both photosensitive materials and electrolytic materials. They are also used to treat sulfur-containing wastewater and are also required to be corrosion-resistant. In order to meet these conditions, the preferred TiO2 NTs or Fe 3+The TiO2 NTs in the TiO2 NTs are secondary anodized TiO2 nanotubes, and are secondary anodized TiO2 nanotubes obtained by the following preparation steps:

[0041] S1, using a titanium sheet as an anode, a platinum sheet as a cathode, and a mixed solution of ethylene glycol, ammonium fluoride and ultrapure water as an electrolyte, electrolytic oxidation was performed at a voltage of 60V for 30 minutes in a constant temperature water bath at 30°C to obtain a primary titanium oxide sheet;

[0042] S2, ultrasonically cleaning the primary titanium oxide sheet obtained in step S1 to remove the oxide film on the surface of the primary titanium oxide sheet, thereby obtaining a titanium sheet with orderly arranged hexagonal grooves on the substrate;

[0043] S3, using the titanium sheet with orderly arranged hexagonal grooves on the substrate obtained in step S2 as an anode, the platinum sheet as a cathode, and a mixed solution of ethylene glycol, ammonium fluoride and ultrapure water as an electrolyte, and electrolytically oxidizing at a voltage of 30 V for 30 min in a constant temperature water bath at 30° C. to obtain a secondary titanium oxide sheet;

[0044] S4, placing the secondary titanium oxide sheet obtained in step S3 in a muffle furnace, and heating the muffle furnace at 5 o The temperature was programmed to 450 C / min. o C and then kept warm for 1 h to obtain secondary anodized TiO2 nanotubes.

[0045] The secondary anodized TiO2 nanotubes obtained by the above preparation method are anatase TiO2, and their morphology is a honeycomb mesh tube-type layered structure (such as Figure 1 (b) The pore size of the upper layer of the mesh tube is about 150 nm, and the wall thickness is about 25 nm; the pore size of the lower layer of the mesh tube is about 30 nm, and the wall thickness is about 15 nm. The titanium substrate is evenly covered with grooves, and about 5 to 6 grooves are embedded in an upper layer of hexagonal nanotubes. The surface of the nanotubes grown on the upper layer of the titanium substrate is regular and the outer wall is smooth. This uniform microscopic pore structure can ensure sufficient light path.

[0046] In addition, the Tafel curve was measured with the prepared secondary anodized TiO2 nanotubes as the working electrode (20 mm× 20 mm), Pt as the auxiliary electrode (20 mm× 20 mm), and saturated calomel electrode SCE as the reference electrode to analyze the corrosion resistance of the prepared secondary oxidized TiO2 nanotube electrodes (such as Figure 2 ), it can be seen that: as the temperature in the reaction system continues to rise, the electrochemical corrosion current density on the surface of the TiO2 nanotube electrode increases from 10 -9 Increase to 10 -8 mA / cm 2The variation of corrosion current in the whole temperature range is not large, which means that even if the reaction system temperature reaches 85 oC The secondary anodized TiO2 nanotube electrode still has good corrosion resistance and can fully exert its photocatalytic effect even in a strong alkaline corrosion environment.

[0047] Based on the TiO2 NTs prepared above, Fe 3+ Fe 3+ / TiO2 NTs, in order to further expand the application scope of TiO2 NTs and further improve the treatment effect of the present invention on treating sulfur-containing wastewater by using solar light-electricity-heat coupling. 3+ / TiO2 NTs: TiO2 NTs were immersed in a 0.05-0.2 mol / L Fe(NO3)3 solution for 1 h, then placed in a muffle furnace, which was heated to 450°C at a rate of 5°C / min and kept at that temperature for 2 h to obtain Fe 3+ / TiO2 NTs.

[0048] Through SEM images (such as Figure 1 From (c) and (d) in Figure 1, we can see that the upper layer of TiO2 NTs has Fe particles evenly distributed on it. From the side view, we can also see that some Fe particles have successfully entered the tube and loaded Fe 3+ After treatment, the overall morphology of TiO2 NTs did not change significantly.

[0049] Through the XPS spectrum (such as Figure 3 In, (a) Fe 3+ XPS full spectrum of / TiO2 NTs; (b) high-resolution scanning spectrum of Fe 2p; (c) Ti 2p 3 / 2 High-resolution scanning spectrum; (d) High-resolution scanning spectrum of O 1s. (a) shows that the Fe element has been successfully loaded on TiO2 NTs; (b) shows that there are two obvious characteristic peaks at 710.7 eV and 724.1 eV, which are basically consistent with the standard peaks of iron element at 710.7 eV and 724.3 eV. The reason for the slight deviation is that some Fe ions enter the Ti-O lattice to form Ti-Fe-O bonds, causing the characteristic peak position to shift to the low-energy direction. It can be determined that the Fe element is Fe 3+ The morphology of TiO2 NTs is loaded on the TiO2 NTs. (c) In the figure, the Ti 2p3 / 2 peak at 458.5 eV and the Ti2p1 / 2 peak at 464.2 eV are located at the same position as the Ti 4+ The positions of the characteristic peaks of the ions are very close, indicating that the Ti element in TiO2 NTs is mainly in the form of Ti4+ The reason for the slight shift in position is that some Ti 3+ ; and, Ti 3+ It can effectively inhibit the recombination of photogenerated electrons and holes and improve the photocatalytic activity of TiO2 NTs.

[0050] The following experiments were conducted to verify the effect of the method of the present application on treating sulfur-containing wastewater, wherein: 1) the initial concentration of the sulfur-containing wastewater, the amount of the sulfur-containing wastewater, the size of the electrode sheet, the reaction time (reaction time 2h), etc. were the same, including the use of the Pt sheet as the electrolytic cathode during electrolysis treatment, the applied current of 1mA, and the heating temperature of 85°C; 2) Comparative Examples 1-3 were TiO2 nanotubes with secondary anodization, respectively, and the effects of the thermoelectric, photothermal, and photoelectric coupling on the sulfur-containing wastewater. 2- 3) Examples 1-5 are Fe (NO3)3 solutions of different concentrations and TiO2 nanotubes that have been anodic oxidized. 3+ When TiO2 nanotubes are used as photocatalysts and electrolytic anode materials, the photocatalytic effect of S in sulfur-containing wastewater is studied under the coupling of light, electricity and heat. 2- The results of the treatment of sulfide ions by control examples 1-3 and embodiments 1-5 are shown in the following table.

[0051] Table 1 Comparison of treatment effects of sulfur-containing wastewater

[0052]

[0053] The data in the table are analyzed from the following aspects: (1) By comparing the results of control examples 1-3 and example 1, it can be seen that: 1-a) Using the solar light-electricity-heat three-field coupling treatment, S 2- The removal rate of the photocatalytic desulfurization is significantly higher than that of the coupled photocatalytic desulfurization, photocatalytic desulfurization and photocatalytic desulfurization, indicating that the combination of photocatalytic desulfurization, electrolytic desulfurization and heating can greatly improve the removal rate of sulfur ions; 1-b) The synergistic effect of solar photocatalysis and electrolysis has the lowest efficiency in removing sulfur ions (Comparative Example 3). The reason may be that the TiO2 nanotube electrodes are used in both the photochemical process and the electrochemical process, which hinders the charge transfer channel. The addition of solar heat further opens the channel, thereby significantly promoting S 2- Conversion (Example 1).

[0054] (2) Comparing the results of Example 1 and Example 2-5, it can be seen that: Fe 3+ / TiO2 nanotubes are used in the solar light-electricity-heat three-field coupling system to treat sulfur ions. The treatment efficiency of sulfur ions is higher than that of TiO2 nanotubes. The reasons are: 2-a) Fe 3+ / TiO2 NTs can absorb and utilize both ultraviolet light and visible light energy, fully improving the utilization of the spectrum and reducing energy loss; 2-b) Loading Fe 3+ After that, the band gap of TiO2 NTs is significantly reduced, which can effectively improve the photocatalytic activity of TiO2 NTs; 2-c) Fe 3+ A Schottky junction is formed between the Fe and TiO2 NTs. The Schottky junction can effectively accelerate the separation of photogenerated electron-hole pairs in TiO2 NTs and inhibit their recombination, making Fe 3+ / TiO2 NTs have higher photocatalytic activity than TiO2 NTs.

[0055] (3) Comparison of the results of Examples 2-5 shows that when TiO2 nanotubes are immersed in a 0.1 mol / L Fe(NO3)3 solution, the Fe 3+ / TiO2 nanotubes are used in the present application for the treatment of sulfur ions with the solar light-electricity-heat three-field coupling, and the treatment efficiency is the highest. The reason is that with the doping of Fe 3+ As the concentration increases, the conversion rate decreases. It is speculated that the reason is that Fe 3+ A large number of nanotubes leads to blockage of the nanotube mouth, causing Fe 3+ / The amount of light absorbed by the TiO2 nanotubes in the TiO2 nanotubes is greatly reduced, so the utilization rate of light energy is reduced, and finally the reaction conversion rate is reduced.

[0056] Application of one-step TiO2NTs, two-step TiO2NTs and Fe in the photo-electro-thermal treatment of sulfur-containing wastewater 3+ / TiO2 nanotubes and used them five times to verify the stability of the three electrolytic anodes (e.g. Figure 4 ), the specific analysis is as follows: (1) After five cycles of use, the photocatalytic effect of one-step TiO2NTs gradually weakened. The reason is that the grooves of the nanotubes that have only been oxidized once are not stable enough. Once the morphology of the substrate changes, it will have a significant impact on its photocatalytic effect; (2) The photocatalytic effect of two-stepTiO2 and Fe 3+ After five cycles of use, the conversion rate of TiO2 NTs did not change much, especially the stability of the nanotubes doped with iron. Figure 4 It can be clearly seen in (d) that the first and fifth curves have the highest overlap, so the TiO2 NTs and Fe 3+ / TiO2 NTs have high stability.

[0057] About Fe 3+ / TiO2 nanotubes are used as photocatalysts and electrolytic anodes in the mechanism of solar light-electricity-heat coupling treatment of sulfur-containing wastewater in this application, such as Figure 5 As shown:

[0058] (1) When Fe 3+ When the surface of TiO2 nanotubes is irradiated by ultraviolet light, the electrons in the valence band are activated to make them transition to the conduction band, so that electrons with high reduction properties (e - ) and strong oxidizing holes (h + ), leaving positively charged holes in the valence band, thus forming electron-hole electron pairs.

[0059] (2) Under the coupling effect of solar light, electricity and heat, the addition of thermal energy promotes the dissolution of sulfur on the anode surface, alleviating the anode passivation phenomenon. The presence of an external electric field can in turn inhibit the recombination of photogenerated electron-hole pairs, thereby promoting the photocatalytic degradation process.

[0060] (3) Due to the applied electric field, electron-hole pairs are transferred to the surface of the nanotube. During this process, the photogenerated electrons react with oxygen in the air to generate O2 - , photogenerated holes react with water to generate ·OH. Among them, ·O2 - Both ·OH and ·OH have strong oxidizing properties, so that the sulfide in the sulfur-containing wastewater can be captured and oxidized by them.

[0061] (4) During the transfer of electron-hole pairs, a strong photocurrent will be generated, which can further increase the electrical energy intensity of solar energy conversion in the system, thereby improving the efficient use of solar energy.

Claims

1. A method for treating sulfur-containing wastewater by using solar light-electricity-heat coupling, wherein sunlight is used as a light source to treat sulfur ions by photocatalytic oxidation, a solar cell provides electrical energy for electrolytic treatment of sulfur ions, and a solar thermal collector provides thermal energy for photocatalytic oxidation and electrolytic treatment; the photocatalyst for photocatalytic oxidation treatment of sulfur ions and the anode for electrolytic treatment of sulfur ions are the same material; It is characterized in that The photocatalyst and electrolytic anode are TiO2 NTs or Fe 3+ / TiO2 NTs, the electrolysis cathode is a Pt electrode; The temperature for photocatalytic oxidation treatment of sulfur ions and electrolytic treatment of sulfur ions is: 55°C-95°C; The voltage of the electrolytic treatment of sulfide ions is: 0.5V-2.5V, and the applied current is 1mA-4mA; The photocatalytic and electrolytic treatment time is: 0.5h-2h; The TiO2 NTs or Fe 3+ The TiO2 NTs in / TiO2 NTs are TiO2 nanotubes that have been subjected to secondary anodization; The method for preparing the secondary anodized TiO2 nanotubes comprises the following steps: S1, using a titanium sheet as an anode, a platinum sheet as a cathode, and a mixed solution of ethylene glycol, ammonium fluoride and ultrapure water as an electrolyte, electrolytic oxidation was performed at a voltage of 60V for 30 minutes in a constant temperature water bath at 30°C to obtain a primary titanium oxide sheet; S2, ultrasonically cleaning the primary titanium oxide sheet obtained in step S1 to remove the oxide film on the surface of the primary titanium oxide sheet, thereby obtaining a titanium sheet with orderly arranged hexagonal grooves on the substrate; S3, using the titanium sheet with orderly arranged hexagonal grooves on the substrate obtained in step S2 as an anode, the platinum sheet as a cathode, and a mixed solution of ethylene glycol, ammonium fluoride and ultrapure water as an electrolyte, and electrolytically oxidizing at a voltage of 30 V for 30 min in a constant temperature water bath at 30° C. to obtain a secondary titanium oxide sheet; S4, the secondary titanium oxide sheet obtained in step S3 is placed in a muffle furnace, the muffle furnace is heated to 450 ℃ at a rate of 5 ℃ / min and then kept warm for 1 h to obtain secondary anodized TiO2 nanotubes; The preparation method of the Fe3+ / TiO2 NTs is as follows: immersing TiO2 NTs in a Fe(NO3)3 solution for 1 hour, then placing them in a muffle furnace, heating the muffle furnace to 450°C at a rate of 5°C / min and then keeping the temperature for 2 hours to obtain Fe3+ / TiO2 NTs.

2. The method for treating sulfur-containing wastewater by utilizing solar light-electricity-heat coupling according to claim 1, characterized in that: The concentration of the Fe(NO3)3 solution is 0.05-0.2 mol / L.

3. The method for treating sulfur-containing wastewater by utilizing solar light-electricity-heat coupling according to claim 1, characterized in that: In the method for treating sulfur-containing wastewater by utilizing solar light-electricity-heat coupling: a solar thermal collector provides heat energy for photocatalytic oxidation and electrolytic treatment by heating a water bath.

Images