Degradation of Pesticide Monochrotophos from Aqueous Solutions by Electrochemical Methods

Abstract

The degradation of toxic monochrotophos (MCP) was comparatively studied by electrochemical methods such as direct electrooxidation, indirect electrooxidation, electrocoagulation and electro-Fenton processes. In the direct electrooxidation process using Ti electrodes in electrolyte solutions (6 g/L of NaCl) at two different current densities of 50 and 100 A/m(2), degradation of MCP from aqueous solutions in different initial concentrations (50, 100, 200, 300 mg/L) was investigated to evaluate MCP degradation. It was determined that increases in the initial MCP concentration and current density lead to increase MCP degradation. In this process, considering the effects of different electrolyte concentrations of NaCl (1, 3, 6 g/L) and different electrolyte (6 g/L Na2SO4), it was observed that high NaCl concentration increases the MCP degradation and decreases the energy consumption. The degradation and removal of 300 mg/L MCP solution by electrocoagulation using Fe electrodes (pH 8.5, 6 g/L NaCl, 93 A/m(2)) was investigated and 78% removal was achieved. The degradation and mineralization of 300 mg/L MCP solution (6 g/L NaCl, 50 A/m(2)) by the indirect electrooxidation processes using Ti electrodes by adding 2 mmol H2O2/min was also investigated and 100 % MCP degradation and 20% TOC removal was obtained. Finally, the degradation and mineralization of 300 mg/L MCP solution (6 g/L NaCl, 93 A/m(2)) by the electro-Fenton process using Fe electrodes by adding 2 mmol H2O2/min was performed. It was observed that MCP was degraded completely in less than 5 min and was mineralized up to the yields of 66% efficiency for 90 min.