Optimization of electrocoagulation process for efficient removal of ciprofloxacin antibiotic using iron electrode; kinetic and isotherm studies of adsorption

Abstract

The present study focused on the removal of ciprofloxacin from hospital wastewater using electrocoagulation (EC) process by iron electrode and the kinetic and isotherms of adsorption were investigated. Response surface methodology (RSM) was used to evaluate the main effects of parameters, their simultaneous interactions and quadratic effect to achieve the optimum condition for EC process. The maximum removal rate was achieved at the current density of 15mA·cm−2, initial CIP concentration of 60mg·L−1, pH7.5, inter-electrode distance 1.58cm and electrolyte dose of 0.07M NaCl within the equilibrium time of 20min. The obtained experimental results are in good accordance with the Langmuir isotherm model for CIP adsorption on iron hydroxide by predicting the maximum adsorption capacity of 476.19mg·g−1. The predicted model for treatment of synthetic wastewater is in satisfactory agreement with real hospital wastewater treatment. First and second order kinetic models were studied to figure out the exact mechanism of the CIP removal using EC process. The obtained results revealed that the second order kinetic model best fitted the experimental results and suggested that the chemisorption mechanism controlled the adsorption of CIP. Under the optimal conditions of EC process, electrode consumption (ELC) and electrical energy consumption (EEC) were found to be 0.0625g during a single run and 0.522kWh·m−3, respectively.