Degradation of ribavirin by potassium ferrate(VI): Kinetics, degradation pathway and toxicity assessment

The degradation of ribavirin(RBV) by ferrate(Fe(VI)) was systematically investigated for the first time by experiment and degradation process fitting. The results indicated that the reaction between Fe(VI) and RBV is pH dependent and followed second order kinetics. The species-specific rate constants of the Fe(VI) species(HFeO4-) were higher than FeO42-species when react with RBV. Fe(VI) made significant contribution to the removal of RBV. Liquid chromatography-triple quadrupole mass spectrometry(LC-TQ-MS) was used to determine the intermediate of RBV which degradated by Fe(VI), in order to infer its main degradation pathway. This study used Dual Descriptor and Fukui function to calculate the active sites of RBV and its intermediates during the degradation of RBV by Fe(VI), then verified their accuracy with actual reaction sites deduced based on LC-TQ-MS data. The results showed that Dual Descriptor prediction was more accurate than Fukui function in the process of RBV degradation by Fe(VI). Some common anions in natural waters, such as SO42-, NO3-, Cl- and CO32-had no effect on the removal of RBV by Fe(VI). 50 mg/L HA reduced the 120 min removal efficiency of RBV by 15.07%. Both toxicity analysis by ECOSAR software and E. coli toxicity experiments showed that Fe(VI) achieves toxicity reduction of RBV. This study indicated that Fe(VI) can effectively remove RBV from water and using Dual Descriptor to analyze the active sites of intermediates in the RBV degradation pathway can enhance the ratio-nality of predicting the reaction pathway.