Malathion removal by electrocoagulation process: iron and stainless-steel electrodes, direct and alternating current and determining energy and electrode consumption and kinetic study

Abstract

The aim of this study was to investigate the effect of electrocoagulation (EC) process for malathion removal from aqueous solution. Iron and stainless-steel rod electrodes were used in the electrochemical cell and effective operation parameters on the electrochemical process were studied. The results showed that with increasing reaction time, current density, removal efficiency of the malathion increased, but the initial concentration of malathion had a reverse effect on the malathion removal. The maximum removal efficiency was acquired at pH: 6 (94.6). In the inter-electrode distance of 2 cm, the removal efficiency of malathion was 95.6 and 95.8 for iron and 92.7 and 88.1 for stainless steel rod electrodes using alternating and direct current, respectively. The maximum energy consumption was 0.91 and 3.12 kWh/m(3) using iron rod electrodes, and 0.99 and 3.18 kWh/m(3) by stainless steel rod electrodes for the alternating and direct current, respectively. Sludge produced in direct current mode is higher than alternative current mode. The pseudo-second-order model was better fitted for the removal of malathion by the EC process than the pseudo-first-order model (R-2: 0.99). According to the results, this process is suggested as an effective and efficient method for removing malathion pesticide.