Role of Cysteine in Enhanced Degradation of Trichloroethane under Ferrous Percarbonate System

The removal of toxic contaminants such as trichloroethane (TCA) from groundwater had a huge impact due to associated health hazards. Advanced oxidation technology has an outstanding potential to remove these toxins. However, the redox cycling of Fe(II)/Fe(III) is mostly a barrier for the efficient removal of these contaminants. In this study, we extracted two in one nature of cysteine (CYS) to enhance TCA degradation in Fe(II)/sodium percarbonate (SPC) system. The chelating and reducing capability of CYS, concentration impact of Fe(II), SPC, and pH role were all thoroughly investigated. The existence of hydroxyl (OH?) and superoxide (O2-?) radicals were confirmed through quencher tests. Furthermore, the electron paramagnetic resonance (EPR) spectra evaluated the enhancement of OH? radicals in the Fe(II)/CYS/SPC system due to the electron transfer capability of CYS. The Fe(II)/CYS/SPC showed excellent recyclability and stability characteristics up to 68% TCA degradation in the fourth round. The degradation products and dechlorination analysis confirmed the existence of nontoxic final products. Similarly, the system demonstrated admirable performance in a real groundwater system, bolstering its real-time industrial applications. Conclusively, Fe(II)/CYS/SPC can be a viable and effective method for degrading chlorinated organic hydrocarbons in groundwater.