Device for treating organic matters in water by photoelectrocatalysis oxidation
Technical Field
The invention discloses a device for treating organic matters in water through photoelectrocatalysis oxidation, and belongs to the technical field of environmental chemical industry photocatalysis oxidation water treatment. In particular to a fluidized bed photoelectrocatalysis organic water treatment device.
Technical Field
Since the middle of the 20 th century, with the rapid development of industry, a large number of non-living organic matters which do not exist in the nature are generated, and most of the non-living organic matters are organic matters which are difficult to degrade and pose great threat to the ecological environment and human survival.
Photo-active semiconductors (typically TiO is used)2) Photogenerated holes in the valence band (Fujishima a, Honda K, Nature, 1972, 238: 37 to 38; matthews r.w.j.catal.1988, 111: 264-272; ollis D F, Al-Ekabi H.Amsterdam: elsevier, 1993) generates OH free radicals with strong oxidizing ability (standard electrode potential of 2.80eV) in water, can completely mineralize organic pollutants which are difficult to degrade in water, has almost no selectivity to substrates, can carry out the degradation process at normal temperature and normal pressure, does not need to add chemical reagents, has no secondary pollution, and becomes the leading edge of research and development of the current domestic and foreign water purification technology.
To date, numerous studies have revealed that one of the major problems with this process is that the quantum efficiency is too low and the reaction rate is not high. In recent years, researchers have utilized light sources reasonably and nano TiO2Preparation and doping of (2), TiO2A great deal of research has been carried out on immobilization and other aspects, as well as the use of electrochemically assisted photocatalytic methods, or photoelectrocatalytic methods, to prevent simple recombination of photogenerated electrons and holes to improve quantum efficiency (Vinodgopal K, Hotchandani S and Kamat P V.J.Phys.chem., 1993, 97 (26): 9040-. Generally, photocatalytic technologies based on titanium dioxide are suitable for purifying low and/or slightly contaminated media (zhanpengzhe, yungjiang environmental science progress 1998, 6 (5): 50-56).
Much attention has been paid to TiO in the past2The promotion effect of the photoanode on the quantum efficiency improvement of the process is not paid enough attention to the contribution of the photoelectrochemical process cathode, so that the total reaction speed of the process is increasedThe rate cannot be improved. In recent years, air-oxygen electrode cathodes have been introduced into the electro-optic chemistry system (Chuanen, Wangpin, Wang Eifeng, et al. applied chemistry, 1999, 16 (2): 87-89; Tomas Harrington, Derek pletcher.Jthe electrochem. society, 1999, 146 (8): 2983-.
Fluidized bed photoelectrocatalysis reaction device utilizing TiO2the/C is taken as fluidized particles, so that the problem that the photocatalyst is difficult to separate from water can be solved, the solution concentration tends to be uniform by utilizing the severe disturbance of the fluidized particles, and the thickness of a mass transfer membrane on the surface of the particles is effectively reduced, thereby providing a huge electrode activation area and mass transfer rate to improve the photocatalytic quantum efficiency. H produced by the cathodic reduction reaction of the air oxygen electrode2O2OH generated by the anodic oxidation reaction of active groups such as OH, OH-and the like and titanium-based oxide on TiO2The fluidized particles can enter into the bed layer under the severe disturbance, the OH concentration of the system tends to be uniform, and meanwhile, TiO on the surfaces of the fluidized bed particles2OH and TiO are continuously generated under illumination2The particle surface is continuously updated, the reaction system is organically coordinated, and the degradation reaction is comprehensively developed, so that the novel reactor is high-efficient and quick and is suitable for treating wastewater (hospital sewage) containing organic pollutants with higher concentration, particularly refractory organics and toxic inhibitors.
Disclosure of Invention
The invention aims to provide a device for treating organic matters in water through photoelectrocatalysis oxidation, which realizes high-efficiency degradation of organic pollutants in water through the combined action of photocatalysis and electrocatalysis. The combined action can improve the concentration of OH free radicals required by the degradation process, thereby improving the degradation efficiency of process organic matters. In addition, the ultraviolet light can also directly oxidize organic matters with absorption wavelength more than 254nm in the water. The photoelectrochemical reactor can effectively degrade organic matters in water into CO2、H2Small molecular substances such as O, inorganic ions and the like, high treatment efficiency and no secondary pollution problem.
The invention relates to a device for treating organic matters in water by photoelectrocatalysis oxidation, which is a reaction device mainly used for a fluidized bed photoelectrocatalysis organic water treatment system and is prepared from titanium-based oxide TiO2/SnO2a/Ti anode (6), an air oxygen electrode cathode (7), TiO2The device comprises/C fluidized particles (8), an ultraviolet lamp light source (9), a potentiostat direct-current power supply (10), an air distribution plate (3), a shell (11), a wastewater inlet (4), a wastewater outlet (5), an air inlet (1), particle fillers (2) and a wire mesh plate (12); the integral porous air distribution plate (3) is positioned at the lower part of the device and forms an air distribution chamber with the shell, the air distribution chamber is filled with particle fillers (2), and the air distribution chamber is provided with an air inlet (1) communicated with the outside; the air oxygen electrode cathode (7) and the titanium-based oxide anode (6) are opposite and respectively close to the wall of the device; the ultraviolet lamp light source (9) is arranged between the cathode and the anode, namely the middle of the device; the air oxygen electrode and the titanium-based oxide electrode are respectively provided with an electric connector connected with a constant potential rectifier direct current power supply (10), and the upper part of the electrode chamber is provided with a TiO-preventing electrode2the/C photocatalytic particles are carried out of the wire mesh plate (12) outside the device.
The cathode electrode is an air oxygen electrode cathode (7) which is composed of a catalytic layer and a conductive framework, wherein the catalytic layer is composed of activated carbon, metal oxide, graphite powder and polytetrafluoroethylene, and the metal oxide is TiO2ZnO or MnO2The catalyst layer contains 70-85% of active carbon, 2-10% of metal oxide, 5-15% of graphite powder and 5-10% of polytetrafluoroethylene; the conductive framework is a nickel net or a silver-plated copper net.
The distance between the cathode and the anode is 4-15 cm.
The wavelength of the uv light source described above is 254 nm.
TiO as described above2The particle size of the/C fluidized particles (8) is 1-2 mm; the air distribution plate (3) is made of ceramic material, and the inner aperture of the air distribution plate is 15-50 mu m; the mesh of the wire mesh plate (12) arranged at the upper part of the electrode chamber is smaller than the TiO2Particle size of the/C fluidized particles.
The device for treating organic matters in water through photoelectrocatalysis oxidation can be provided with a water inlet at the lower part of the shell and a water outlet at the upper part of the shell, so that organic wastewater can be continuously treated.
The process for realizing the treatment of the organic matters in the water comprises the following steps: the wastewater containing organic matters is fed into the photoelectrochemical reactor from a water inlet and added with TiO2the/C fluidizes the particles, at the same time, the air compressor is started to blow compressed air from the air inlet, and the air flow is adjusted. Secondly, turning on an ultraviolet lamp, switching on a direct current power supply, and under the combined action of the ultraviolet light and an electric field, oxidizing and degrading organic pollutants into nontoxic and harmless CO2、H2O, inorganic ions, and the like.
The invention has the advantages that: the fluidized bed photocatalytic reactor and the electrochemical reactor are combined into a whole, so that the structure of a reaction device is compact and reasonable, more importantly, the electrochemical reaction and the photocatalytic reaction can be organically combined to continuously generate required strong oxidizing property OH free radicals, and the reaction and mass transfer of the reaction device are coordinated, so that the organic matters in water can be efficiently degraded. The concrete advantages are that:
1) the anode has two main functions: firstly, photo-generated electrons are captured to produce OH; secondly, organic pollutants in water are directly oxidized electrochemically.
2) The air oxygen electrode has two main functions: first, production of H2O2、OH-And nascent oxygen.
3) Air oxygen electrode and light combined action production
4)TiO
2The fluidized particles have the functions of ① multipole, each particle is a microbattery to perform oxidation-reduction reaction, ② organic matter and O are enriched
2③ production of OH and its combination with an air oxygen electrode,
④ eliminates the effect of mass transfer.
Therefore, the invention can rapidly and thoroughly remove the organic matters in the water, does not need to add chemical reagents, has no secondary pollution, no solid-liquid separation problem and high treatment efficiency, and is a comprehensive, harmonious and sustainable device for organic water treatment.
Drawings
FIG. 1 is a schematic structural diagram of a reactor for treating organic matters in water by photoelectrocatalysis oxidation according to an embodiment of the present invention.
FIG. 2 is a schematic cross-sectional view of a longitudinal structure of the photoelectrocatalysis reactor of the present invention.
The reference numbers in the figures are: 1 air inlet, 2 particle fillers, 3 air distribution plates, 4 wastewater inlets, 5 wastewater outlets, 6 titanium-based oxide anode, 7 air oxygen electrode cathode, 8 TiO2The reactor comprises/C fluidized particles, 9 ultraviolet lamp light sources, 10 constant potential rectifier direct current power supplies, 11 reactor shells and 12 wire mesh plates.
Detailed Description
Embodiment mode 1
Referring to fig. 1, the reaction device for treating organic matters in water by fluidized bed photoelectrocatalysis oxidation has the following structure: with titanium-based oxides TiO2/SnO2the/Ti anode 6 is an anode, the air oxygen electrode cathode 7 is a cathode, and the cathode and the anode are respectively provided with an electric connector which can be connected with a direct current power supply 10; compressed air is used as an air source; exterior coating of TiO particles made from commercial activated carbon and graphite powder2Formed TiO2the/C fluidized particles 8 are photocatalyst particles. Compressed air enters the bottom air chamber of the reactor from the air inlet 1 and blows air into the reactor through the micropore air distribution plate 3. The two electrodes are opposed and each is close to one wall of the device. TiO 22TiO fluidized particles are arranged on an air distribution plate and are in a fluidized state under the action of air flow2The concentration of (A) is 0.5-1.5 g/L. The uv lamp source 9 is placed vertically between the two electrodes, i.e. in the middle of the rectangular arrangement. A wire mesh plate 12 is placed on top of the electrode chamber. The whole rectangular reactor shell 11 is formed by welding organic glass. The organic wastewater to be treated enters from a wastewater inlet 4 and exits from a wastewater outlet 5 of the reaction device.
The phenol aqueous solution is treated. The setting conditions are as follows: 15W ultraviolet light source, TiO2Particle size of 1mm, P25 TiO, photocatalytic fluidized particles2Concentration of (2) is 1.0g/L and air flow is 0.3m3/h,TiO2/SnO2The anode is Ti, the cathode is air oxygen electrode, the distance between the anode and the cathode is 5cm, and the electrode area is 20cm2Current density 15mA/cm2. After 1 hour of photoelectrocatalysis reaction, the removal rate of 50mg/L and 120mL of phenol water solution COD is 95.6%.
Embodiment mode 2
The water-soluble humic acid solution was treated in accordance with the apparatus configuration and treatment process of embodiment 1. Is provided withThe conditions are as follows: 15W ultraviolet light source, TiO2Particle size of 1.5mm, P25 TiO, photocatalytic fluidized particles2Concentration of (2) is 1.5g/L and air flow is 0.5m3/h,TiO2/SnO2The anode is Ti, the cathode is air oxygen electrode, the distance between the anode and the cathode is 8cm, and the area of the electrode is 20cm2Current density 15mA/cm2. After 1 hour of photoelectrocatalysis reaction, the removal rate of 20mg/L and 120mL of water-soluble humic acid solution COD is 86.2%, and the decolorization rate is 100%.
Embodiment 3
The formic acid aqueous solution was treated in accordance with the apparatus structure and treatment process of embodiment 1. The setting conditions are as follows: 15W ultraviolet light source, TiO2Particle size of 2mm, P25 TiO, photocatalytic fluidized particles2Concentration of (2) is 0.8g/L and air flow is 0.6m3/h,TiO2/SnO2The anode is Ti, the cathode is air oxygen electrode, the distance between the anode and the cathode is 15cm, and the electrode area is 20cm2Current density 15mA/cm2. After 1 hour of photoelectrocatalysis reaction, the removal rate of 460mg/L and 120mL of formic acid water solution COD is 96.8%, and the decolorization rate is 100%.
Embodiment 4
The same two apparatuses were connected in series to treat the aqueous phenol solution in accordance with the apparatus configuration, treatment process and installation conditions in embodiment 1.