Removal of simvastatin from aqueous solution by electrochemical process using graphite-PVC as anode: A case study of evaluation the toxicity, kinetics and chlorinated by-products

Abstract

As far as we know, the electrochemical degradation of simvastatin, a widely used as a cholesterol lowering drug, has not been reported yet. The oxidation process has been investigated in pure water and wastewater using graphite-Poly Vinyl Chloride (PVC) composite electrode as anode. Effects of initial concentration of simvastatin, NaCl loading, type of sample and applied voltage were tested to evaluate the electrochemical oxidation process. The results revealed that the electrochemical oxidation rates of simvastatin followed pseudo first-order kinetics, with rate constant values ranged from 0.006–0.23min−1 depending on the operating parameters. Simvastatin was completely removed, after 40min of treatment, at 4g/L NaCl and 10V indicating high concentration of OCl− produced in the solution but at the same time energy consumption (EC) was very high. However, 6V was selected for further experiments (90% removal and 0.093Wh/mg energy consumption) after 40min. The low concentration of simvastatin (30mg/L) exhibited better removal of 97% compared to 50mg/L which gives removal 90% after 40min. In this work the electrochemical oxidation process of simvastatin has been studied by monitoring the by-products and their toxicity using the time–of–flight (TOF/MS) technology. Chlorinated by-products were separated and identified accurately using isotope modern software. Simvastatin was transformed within 20–80min, however, after 100min most of by-products have been removed. Eleven new by-products of simvastatin were identified and monitored in both positive and negative ionization mode.