Ibuprofen Removal by Electrochemically Activated Peroxymonosulfate Using Iron Electrolysis: Reaction Kinetics, Optimization Using Response Surface Methodology, and Performance in Continuous Flow Mode

Abstract

In the present study, ibuprofen (nonsteroidal anti-inflammatory drug) removal was investigated by means of electrochemically activated peroxymonosulfate (EC/PMS) using iron as the sacrificial anode in the reverse-osmosis concentrate (ROC). Complete ibuprofen (IBU) removal was achieved in 30 min at near neutral pH with [PMS]0=500 mg/L and current density (CD)=2.5 mA/cm2 using the EC/PMS process. EC/PMS performed extremely well in comparison with PMS alone, electrocoagulation (EC) alone, or FeSO4/PMS where FeSO4 was added at the beginning. However, when FeSO4 was added stepwise, PMS activation was more efficient, and the IBU removal rate was close to that of EC/PMS. A response-surface methodology was carried out to understand the effects of pH, [PMS]0, and CD on %IBU removal over 30 min and removal rate constants. It was observed that acidic initial pH, lesser [PMS]0, and highest CD were favorable for higher removal rate constants. Nevertheless, a higher removal rate constant did not necessarily lead to complete removal. [PMS]0 to CD ratios significantly affected both %IBU removal and the removal rate constant in the batch EC/PMS process. The EC/PMS process functioned quite well in continuous flow mode. The increase in flow rate from 2 to 4 L/h provided higher %IBU removal from 96.5% to 99.5%, and the residual Fe2+ was reduced from 10 to 3 mg/L, respectively. Conclusively, EC/PMS was found to be a promising green treatment method for complex organic compound removal.