Degradation of Diclofenac by sonosynthesis of pyrite nanoparticles

The aim of this work is to evaluate the ability of synthesized pyrite nanoparticles (NPs) on the degradation of Diclofenac (DCF) as a model pharmaceutical pollutant. Pyrite NPs were synthesized by sonication with 20 kHz apparatus under optimum conditions. The effects of pyrite loading (0.02-0.20 g/L), DCF concentration (10-50 mg/L) and initial pH (2-10) on the degradation were investigated. The results revealed that the NPs have a great activity in the degradation of DCF with 25 mg/L concentration. A first-order kinetic model was found to match the experimental data. Complete degradation (100%) of DCF was achieved by pyrite within 3 min and 20 min in acidic and natural pH, respectively. To gain an understanding of the degradation mechanism and the role of pyrite, a UV-Vis spectrophotometer was employed to follow the DCF concentration. In addition, the Chemical Oxygen Demand (COD) and the amounts of ammonium and chloride ions verified complete degradation of DCF in both pH values. The results demonstrated that Fe2+ ions were generated by the pyrite surface and the hydroxyl radical (OH center dot) was formed by Fe2+ ions through the Fenton reaction. Based on using radical scavengers in the degradation process, OH center dot was mainly responsible for the fast degradation of DCF. COD measurements confirmed that DCF finally degraded to further oxidized forms (NH4+, Cl-). (C) 2016 Elsevier Ltd. All rights reserved.