Study On Degradation Of Chlorophenol By Synergetic Technology Of Anode-Cathode

Chlorophenol is a kind pollutant of difficult biodegradation, which is of great toxicity and harmfulness. It is on the blank list of preferentially controlled pollutant of EPA, and also on the list of toxic and harmful pollutant should be controlled firstly in our nation. Chlorophenol-containing water is difficult to treat in normal technology. With the advantage of non oxidant and flocculating agent in addition, small bulk of equipment, little area needed, simpleness of the operation and low cost, electro-catalytic technology is used widely in the treatment of phenol-containing water. Based on the electro-catalytic technology, direct oxidation of anode and indirect oxidation of cathode was combined in this study. A novel electrochemical system aiming to degrading 4-Chlorophenol was built with synergetic technology of anode-cathode.A novel gas diffusion electrode was prepared from MWCNTs. A electrochemical system, which used novel gas diffusion electrode as cathode and graphite electrode as anode, was built to produce H₂O₂. Statistica software package was used to fitting a model of the factors and the yield of H₂O₂. The result model was of good forecast, and the error between experiment and simulation data was -0.73%～1.05%. The novel MWCNTs gas diffusion electrode had perfect performance in producing H₂O₂ present, the H₂O₂ yield in 60min was 1.6～2.5 times of the other two kind of activated carbon gas diffusion electrode. The result of analysis of influencing factors in H₂O₂ yield showed that current density and aeration quantity were the prominent factors, pH value had little influence. Optimal parameter arrangement was obtained by response surface optimizing method: pH value among 2～4, current density among 20～25mA/cm² and aeration quantity among 1.3～1.8L/min.Using MWCNTs gas diffusion electrode as cathode, 4 different electrochemical systems used to degrading 4-Chlorophenol was built. The experiment result showed that the optimal system was the novel one used MWCNTs diffusion electrode as cathode, Sb-SnO₂/Ti and Fe sheet as anode. The removal efficiency could reach to 96% in 10min, which was 1.94～4.85 times of other systems. COD removal efficiency of the 4 systems was also studied. The results showed that synergetic technology of anode-cathode had excellent performance in compleletlly degradation of pollutants, and it made the reaction tend to electrochemical burning. This is propitious to the completely degradation of organic pollutant. The COD removal efficiency of the novel system could reach to 95% in 60min.The influencing factor of 4-Chlorophenol degradation in novel electrochemical system was studied systemically. The results showed that the optimal condition of 4-Chlorophenol degradation was current density at 20mA/cm², pH value at 3 and aeration quantity at 1.3L/min, at which the 4-Chlorophenol removal efficiency could reach 99% and COD removal efficiency could reach 73% in degradation of initial concentration 100mg/L in 30min. Through analysis of the orthogonal experiment data, the influencing factors in novel electrochemical system was decreasing as initial concentration, aeration quantity, pH value and current density.