Degradation of diclofenac in water using a pulsed corona discharge

•Efficient removal of diclofenac in water was obtained by pulsed corona discharge.•Diclofenac in solution was completely removed after 15 min plasma treatment.•Total Organic Carbon (TOC) decreased by 50% after 30 min exposure to plasma.•No chlorinated degradation products are present at the end of plasma treatment.•Short-chain carboxylic acids were detected as by-products in the treated solution.

The oxidative degradation of the pharmaceutical drug diclofenac (DCF) in water was studied using a pulsed corona discharge generated above liquid. It was found that DCF in solution was completely removed after 15 min non-thermal plasma treatment. The mineralization degree of DCF, expressed as the decrease of Total Organic Carbon (TOC), was approximately 50% after 30 min exposure to plasma. A good correlation between the evolution of the Total Carbon and the amount of CO2 released was observed. The elimination of chlorine from DCF occurs rapidly: over 95% is released as Cl− after 15 min non-thermal plasma treatment, indicating the absence of chlorinated degradation products in the treated solution. Several reaction by-products are identified and based on this a tentative degradation pathway of DCF under plasma conditions is proposed.