Degradation of imidacloprid pesticide in aqueous solution using an eco-friendly electrochemical process

Abstract

The aim of this study was to evaluate the efficiency of electrochemical degradation process in the removal of imidacloprid (IM), a pesticide, from aqueous solutions. Experiments were conducted using a batch glass reactor and two leads as anodes, and stainless steel electrode as a cathode. The influence of various experimental parameters including initial IM concentration (1–150 mg/L), pH (3–11), electrolysis time (20–120 min), current density (12.5–50 mA/cm2) and NaCl concentration (4.28–26.74 mmol/L) were assessed to determine the optimum conditions. Scanning electron microscopy and X-ray diffraction analyses were used to study the type of materials formed on the electrode surfaces at the electrode preparation stage. The results from this investigation show that at pH = 5, current density = 25 mA/cm2, electrolysis time = 30 min, initial pesticide concentration = 100 mg/L and NaCl concentration = 10.69 mmol/L are optimum experimental conditions for achieving maximum IM and chemical oxygen demand (COD) removal from water. Accordingly, the maximum IM and COD removal efficiencies of 99.69 and 85.66 were achieved, respectively. At optimum conditions and applied voltage of 23.95 V, the electrical energy consumption was calculated about 5.35 kWh/kg COD. Based on the results, electrochemical degradation method was found to be a highly efficient technology in comparison with existing conventional methods and could be considered as a cost-effective method to remove IM from water and wastewater. © 2017 Desalination Publications. All rights reserved.