Application Of New Electro-Fenton Phenol And Methyl Orange Wastewater

The dye and phenolic wastewater have done a serious harm to aquatic organisms and human body, because of their toxicity, carcinogenicity and mutagenicity. So, in order to protect our water resource and natural environment, it is necessary to do some wasterwater treatment before discharging. Phenol and azo dyes are the representive of phenolic and dye wastewater, respectively. In this paper, mese two kinds of materials were treated as the aimed targets, phenol wastewater was disposed by induced electro-Fenton process, methyl orange (MO) wastewater was delt with electro-Fenton-like process with the aid of chloride ions. The catalyst of kaolin which is modified with iron molybdate was added into electrochemical process, and its role of promoting the methyl orange wastewater degradation was also investigated.In the first part, the source, main features, applications, harms and the treatment methods of phenolic and dyes wastewater at this stage were all introduced for a more detailed review. More attentions are focused on the introduction of Fenton and electrochemical oxidation technology and their application in the organic wastewater treatment. At last, we presented the research purpose, meaning, content and innovation point of this study.In the second part, the experimental reagents, instruments and the analysis methods were presented.In the third part, the degradation of simulated phenol wastewater was investigated by the induced electro-Fenton process. The graphite was applied as the anode and cathode, and iron plate was applied as induced anode. The effect of phenol concentration, pH, current density and Fe2+concentration on the phenol removal rate and COD removal were investigated. The best reaction condition was determined by orthogonal method. The results showed that the removal rate and COD removal efficiency of phenol reached78.23%and74.09%when Fe2+dosage was0.8g/L and phenol concentration100mg/L at pH4, the current density was33.33mA/cm2in170mm.In the fourth part, the degradation of simulated methyl orange wastewater by homogeneous Electro-Fenton process with the aid of the chloride irons was investigated. Firstly, the degradation of azo dye methyl orange (MO) wastewater was studied by four electrochemical processes:the direct electrochemical oxidation with or without Cl", the electro-Fenton-like process with or without Cl-. The electro-Fenton-like process with the synergistic effect of chloride ion was prominent, the effect of some important operating parameters, such as dosages of Fe3+, and the initial concentration of the dye, especially the concentration of chloride ion, on the decolorization and COD removal of MO in aqueous solution also have been investigated systematically.The oxidation kinetics of the reaction process was analysed and the initial reaction rate was also determined in the best condition. The response surface methodology was selected to optimize the operating conditions, and the results showed that for a solution of106mg/L MO,98.96%color removal and78.93%COD removal efficiency were obtained respectively, when Fe3+dosage was2.14mM and chloride ions concentration16.36mM at pH3,0.05M Na2SO4at the applied current of2.1A in90min, the initial reaction rate was r0=11933.6mg·L-1·min-1. This showed that the process is a fast process for the oxidation of MO.In the fifth part, the heterogeneous electro-Fenton-like process was applied for the degradation of methyl orange wastewater. The kaolin-based iron molybdate Fe2(MoO4)3-kaolin-450(FM-kaolin-450) catalysts were successfully prepared through dipping method and applied in electrochemical process for degradation of MO in aqueous solution. The FM-kaolin-450catalysts were characterized by SEM-EDXS, XRD, BET, FT-IR and XPS. The effects of initial pH, FM-kaolin-450dosage, initial MO concentration, and current density on color removal rate and COD removal efficiency of MO were investigated. The results showed the color removal rate and COD removal of methyl orange could research99.24%and92.48%when FM-Kaolin-450dosages was6.6g/L, current density was33.33mA/cm2at pH4.34in60min, catalysts have good stability and reusability for five times use. In order to test the catalytic performance of the process, some other dyes degradation were also studied and the results showed that the decolorization ratio all could reach above97%in60min, indicating that this is an efficient process in color removal in most dye wastewater.