Ultrasonic Enhanced Zero-Valent Iron-Based Fenton Reaction for Ciprofloxacin Removal under Aerobic Condition

The effect of aeration and ultrasonic irradiation on the performance of nano zero-valent iron (nZVI)-based Fenton reaction was investigated. The purpose of aeration was to create mixing in the system, and the mixing in the reactor was supplied only by using air bubbles without employing a mechanical mixer. The effect of four numerical variables, i.e., H2O2 amount, catalyst dose, aeration, and time, and one categorical one, i.e., ultrasonic (US) irradiation, was examined on the elimination of ciprofloxacin (CIP) from aqueous solution by response surface methodology. The accompanying the aeration and the US irradiation nZVI-based Fenton reaction could accelerate nZVI corrosion and formation of reactive intermediates, thus effectively oxidizing contaminants. A combined treatment of Fenton (nZVI/H2O2)/aeration/US resulted in higher antibiotic removal efficiency in comparison to conventional Fenton (nZVI/H2O2), Fenton (nZVI/H2O2)/aeration and Fenton (nZVI/H2O2)/US processes. A combined treatment of Fenton (nZVI/H2O2)/aeration/US achieved a 94% CIP removal within 60 min of an initial CIP concentration of 100 mg/L under neutral pH condition. Results demonstrated that ultrasonic-assisted nZVI/H2O2 process under aeration condition can be applied as an advisable choice for the treatment of organic wastewaters. Due to employing aeration instead of using mechanical stirring, this proposed process needs low energy consumption.