Study On The Degeneration Of Phenol Wastewater By Electrochemical Method

With the enhancement of people's environmental consciousness, the treatment of high-concentration organic wastewater with high toxicity and hard biodegradation were studied as the focus. Phenols are among the most common organic pollutants in industrial and agricultural wastewaters. It is therefore important to assess the fate of these compounds in the environment and develop effective methods to remove them from water. Based on the research and development of catalytic oxidation of poor degradable organic wastewater, the studies on wastewater containing phenols are selected and the corresponding electro-catalytic oxidation degradation behaviors and kinetic characteristics on Fe electrode and graphite electrode were investigated in this paper. Furthermore, the effects of technical parameters on the degradation ratio were evaluated.Firstly, the standard curve of C6H5OH was established by UV spectrophotometry. Because of the low overpotential of oxygen on Fe electrode, the likelihood that C6H5OH was straightly oxidated by adsorption was little. C6H5OH can be degraded by acceding H2O2 to last system. The main reason is that·OH is produced through the decomposability of H2O2 catalysed by Fe2+. The influence of treatment time, pH, current density and the concentration of electrolyte NaCl were studied on Fe electrode in the process. Based on the results, the optimum operating conditions were identified. The main technical parameters are determined.The graphite electrode is unsolvable material. The overpotential of oxygen on graphite electrode is high. C6H5OH can be degraded by·OH from activated OH- adsorbing on graphite electrode. Then the influence of treatment time, pH, current density and the concentration of NaCl was studied on graphite electrode in the process. The main technical parameters are determined.The electrochemical behaviors of C6H5OH on the graphite electrode were studied by Cyclic voltammetry. When the potential reaches 1.0V by the plus scanning, there appears an apparent peak current. It corresponding the C6H5OH was oxidatedC6H4O2 by analyzing. The peak current of deoxidization process at 0.85V result from the deoxidizing of O2 adsorbing on graphite electrode. It indicates that the oxidation of C6H5OH on graphite electrode is unreversible. Then the scanning begins with different speeds which are from 10mV/s to 90mV/s. The results show that the ip was increased regularly as the scanning speed increases. There is apparent linear relationship between them. And this indicates that the rate dominated step is the oxidation process of C6H5OH on graphite electrode .The diffusion coefficient is 3.56×10-8(cm2/ s). Based on the analysis to the relationship between potential and time, it can be concluded that electrode oxidization process of phenols is controlled by diffusion mass transfer and potential oscillation resulted from convective mass transfer restoring of phenol concentration brought about by diffusion mass transfer consumption and oxygen evolution of phenols oxidation. When the electrolysis time less than 60 minute, the ln(C0/C)and electrolysis time appears linear relationship. This indicates that the electro-oxidation process was first order reaction rate macroscopically.