This study was performed to investigate the electrochemical oxidation of a solution containing methylene blue dye by using a tin oxide (SnO2) electrode. The effect of several operating factors such as electrolyte types, current density, initial dye concentration, and pH were investigated by following the discoloration and COD removal. The results show that the maximum color was removed by using chloride supporting electrolyte (i. e. KCl and NaCl) indicating that the indirect oxidation was promoted by the strong oxidant species (i. e. Cl2 and ClO– ) generated at the anode surface. The best experimental conditions were attained for i = 60mA/cm2, 1% KCl and pH = 3, in which 100% of color was removed after 30 minutes and the COD removal reached 80. 9% after 120 min. These results reveal that the anodic oxidation technique using SnO2 electrode could be used to remove the methylene blue dye from textile wastewater.

Background: Electrochemical methods, as one of the advanced oxidation processes (AOPs), have recently been applied to remove different contaminants from water and wastewater. This study compares the performance of anodic oxidation (AO) and electro- Fenton (EF) methods on waste sludge treatment.Methods: This experimental study was performed on real sludge and the effect of operating parameters such as solution pH, operating time, current density, supporting electrolyte and hydrogen peroxide concentration were investigated in a batch reactor. For determination of oxidation and treatability of the sludge, chemical oxygen demand (COD) and total coliform (TC) removal were examined. Pb/PbO2 and iron electrodes respectively for AO and EF were applied.Results: Experimental data indicated for both AO and EF as the operating time and current density increased, COD removal increased. pH=4.0 and 3.0 and current density=1.75 and 2 A respectively for AO and EF and the concentration=57.2 mMol of hydrogen peroxide for EF were measured as the optimum amounts of these variables. The removal efficiency of COD in AO and EF process was 76% and 72%, respectively. Of course, the efficiency of EF in TC removal was better and the percentage of TC removal in 60 min for AO and EF was 99.0% and 99.9%, respectively. The amounts of consumed electrical energy for AO and EF were 8.6 and 28.0 kWh kg-1 COD, respectively.Conclusions: AO was more effective in treatment and mineralization of waste sludge and TC removal than EF in terms of environmental economical features.

The nanocomposite consists of the Ag as a core and Pt as shell on the surface of graphene nanosheets (Ag/Pt-G) was synthesized with a simple method and used as a novel electrochemical platform for an efficient catalyst for oxidation of the ethanol, methanol and formic acid. The morphology and electrochemical properties of Ag/Pt-G nanocomposite were investigated by TEM, X-ray diffraction, and voltammetric methods. Based on experimental results, Ag/Pt-G nanocomposite shows high performance toward oxidation of formic acid, ethanol, and methanol, due to the synergistic effect of Pt, Ag, and graphene nanosheets. The presence of Ag in the structure of nanocomposite leads to enhancing the usage of Pt in the core-shell structure. The proposed nanocomposite with good stability and high catalytic activity can be applied as an effective catalyst.