Optimization of electrocoagulation process for efficient removal of ciprofloxacin antibiotic using iron electrode; kinetic and isothermstudies 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 15 mA·cm−2, initial CIP concentration of 60 mg·L−1, pH 7.5, inter-electrode distance 1.58 cm and electrolyte dose of 0.07 M NaCl within the equilibrium time of 20 min. The obtained experimental results are in good accordance with the Langmuir isotherm model for CIP adsorption on iron hydroxide by predicting themaximum adsorption capacity of 476.19 mg·g−1. The predictedmodel for treatment of synthetic wastewater is in satisfactory agreement with real hospital wastewater treatment. First and second order kinetic modelswere studied to figure out the exactmechanismof 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 chemisorptionmechanismcontrolled the adsorption of CIP. Under the optimal conditions of EC process, electrode consumption (ELC) and electrical energy consumption (EEC) were found to be 0.0625 g during a single run and 0.522 kWh·m−3, respectively