Effect of solution matrix and pH in Z-nZVI-catalyzed percarbonate system on the generation of reactive oxygen species and degradation of 1,1,1-trichloroethane

This study primarily focuses on evaluating the effects of solution matrix and pH for the generation of reactive oxygen species (ROSs) in Z-nZVI-catalyzed sodium percarbonate (SPC) system to degrade 1,1,1-trichloroethane (1,1,1-TCA) in the absence and presence of reducing agent (RA) i.e. hydroxylamine. 1,1,1-TCA degradation was 49.5% and 95% in the absence and presence of RA. Probe tests confirmed the generation of major hydroxyl radicals (OH•) and minor superoxide species (O 2 –• ), and scavenger tests verified the key role of OH• and less of O 2 –• radicals. 1,1,1-TCA degradation decreased significantly in the presence of Cl − and HCO 3 – , while NO 3 – and SO 4 2– have negligible effects in absence of RA. Addition of RA significantly enhanced 1,1,1-TCA degradation by generating more OH• and O 2 –• radicals in presence of anions. 1,1,1-TCA degradation increased in acidic range (1–5) while, an inhibitive trend from neutral to basic (7–9) was observed. On the contrary, a significant increase in 1,1,1-TCA degradation was observed with addition of RA in all pH values (1–9). In conclusion, the anions and pH significantly influenced the generation and intensity of ROSs and 1,1,1-TCA was effectively degraded in Z-nZVI-catalyzed SPC system in the presence of RA.