الفهرس 
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Abstract
Bio-resistant organics like phenol and BTX are toxic, carcinogenic and difficult to be treated by conventional biological treatment. For biological treatment, they are toxic to bacteria and difficult to be digested by bacteria. There are other methods like adsorption and advanced oxidation processes (AOPs). One disadvantages of adsorption needs regeneration of activated carbon. AOPs in a broad sense, are a set of chemical treatment procedures designed to remove organic and inorganic materials in water and wastewater by oxidation through reactions with hydroxyl radical. Among AOPs, electro-Fenton process is powerful for degrading most organic compounds including toxic and non-biodegradable ones, and so has attracted great attention. The electro-Fenton (EF) process is a promising method combining electrochemical reactions and Fenton’s reagent. In this hybrid process, the electrical current induces the in situ generation of H2O2 via reduction of oxygen, and the catalytic reaction is propagated by Fe2+ regeneration, which can take place by reduction of Fe3+ with H2O2. Electro-Fenton technology has been effectively applied to the removal of several pollutants including dyes, amines, herbicides, fertilizers, insecticides, aromatic acids, phenolic compounds, organic acids, petrochemical wastes, and explosives. Compared to the conventional Fenton process, the electro-Fenton process has the advantage of allowing better control of the process and avoiding the storing and transport of the H2O2. Moreover, electricity as a clean energy source is used in the process, so the overall process does not create secondary pollutants. In this study, the performance of Electro-Fenton (EF) process was investigated for degradation of phenol, benzene (B), toluene (T), and p-xylene (X) in aqueous solutions using different electrodes. The cathode was made from carbon felt, while sacrificial stainless steel, carbon, and nickel electrodes were used as anodes. Operational conditions such as initial pollutant concentration, current intensity, Fe+2 dose, pH, and anode material were studied. Moreover, simple predictive models are developed to describe phenol removal at different conditions, using statistical regression analysis and the artificial annual networks (ANNs). The treatment and reuse of the sludge resulting from the experiment of BTX mixture has been evaluated. BTX reactions and intermediate products have also been discussed. Based on the experimental data, at optimal operating conditions, the degradation of phenol was 95.2% using sacrificial stainless steel anode in 90 min and 72% using nickel anode in 120 min. Complete degradation of BTX components were attained within 30 min under optimum conditions. However, TOC removal of BTX in mixture was about 75% after 10 min of electro-oxidation reaction due to the remaining organic by-products. The EF process was able to attain 95.4%, 88.7%, and 87.6% TOC removal efficiencies using sacrificial stainless steel, carbon, and nickel anodes respectively, at initial concentration of 150 mg/L within 60 min. The production and consumption of iron during the EF process was monitored to interpret the favorability of sacrificial stainless steel anode. Regression analysis was employed to develop a prediction model for phenol removal. The model is dependent on operational conditions and initial phenol concentration with coefficient of determination (R2=0.9525). In addition, artificial neural network (ANN) model was developed based on input layer of operating conditions and output layer of phenol degradation efficiency. The ANN model yielded a coefficient of determination (R2=0.9742) and (Se/Sy=0.16). The precipitated sludge during EF process was treated and used to improve the degradation of BTX.