The Application Of Gas Diffusion Electrode On Photoelectrocatalysis Oxidation Phenol In Water

In this paper gas diffusion electrode was introduced into photoelectrocatalytic system in order to oxidate organic contamination in water by exerting photocatalysis function of TiO₂/Ti and direct oxidation organic contamination function of H2O2 which was produced by gas diffusion electrode and synergy function of two electrodes.Firstly, gas diffusion electrode was made by hot pressure method and characterized by XRD SEM. The results showed it was a multi-pore electrode composed of graphite, acetylene black, PTEF (60%). Secondly, TiO2/Ti electrode was made by coating and sintering method and characterized by XRD, The crystal of TiO2 film is anatase phase.In this experiment H2O2 not only can directly oxidate organic substance but also it is the source of active species-OH. The favorable condition of preparing H2O2 was investigated before treating water. A two electrodes electrochemistry system including TiO2/Ti electrode as counter electrode (anode) and gas diffusion electrode as work electrode (cathode) was used in preparing H2O2. The pH of solution, component of gas diffusion electrode, sintered temperature of gas diffusion electrode, bath voltage, electrolyte, different catalyst, gas diffusion electrode carrier and so on factors which affect H2O2 output were studied. The change of current and current efficiency with time in the process of reaction was also summarized.Based on above experiments phenol photoelectrocatalytic oxidation was performed A two electrodes photoelectrocatalytic system including 365nm UV-lamp as side light source, TiO2/Ti electrode as anode and gas diffusion electrode as cathode .The pH of solution, sintered temperature of TiO2, load amount of TiO2, different cathode, component of gas diffusion electrode,sintered temperature of gas diffusion electrode, cell voltage and so on factors which affect phenol oxidation were investigated. The effect of adsorption, photoxidation, photocatalysis, photoelectrocatalysis and photoelectrocatalysis with Cu cathode on phenol oxidation was compared The results showed that photoelectrocatalysis process with gas diffusion electrode cathode was better than the others. After 3hour of reaction the phenol was almost completely oxidated. The reaction condition was: anode — TiCVTi electrode(0.45gTiC>2, work area³.6cm2); cathode —gas diffusion electrode(work area 1.5cm2) which was composed of 0.05mL PTEF(60%), graphite and acetylene black (l:l/m, 0.2g) and sintered at 300°C for 30min; V=50mL; pH=3; cell voltage=2Vo The change of solution COD in the photoelectrocatalysis (cathode-gas diffusion electrode) and electrocatalysis process was determined. The degradation of COD in photoelectrocatalysis with gas diffusion electrode was fast and final COD was almost zero. In the sameexperimental condition the degradation of COD in electrocatalysis was slow and final COD was 1/4 of initial COD of reaction. All these proved that phenol was not only oxidated fastly but also mineralized drastically in the process of photoelectrocatalysis with gas diffusion electrode.