Effects of pH and Anions on the Generation of Reactive Oxygen Species (ROS) in nZVI-rGo-Activated Persulfate System

Abstract

In this study, nanosized zero-valent iron-reduced graphene oxide (nZVI-rGO)-activated persulfate (PS) was used to investigate the generation of reactive oxygen species (ROS) for the degradation of trichloroethylene (TCE) in the aqueous solution. More than 98 % of TCE was degraded within 2 min under experimental conditions. The generation of ·OH increased when the pH was shifted toward the basic region while ·SO 4 − radicals' intensity increased in the acidic pH. Different scenarios have been observed in ·O 2 − generation in the neutral and strong basic pH and decreased in acidic or slightly basic pH. In addition, the intensity of ·OH was increased with the addition of HCO 3 − (10 mM) and NO 3 − (100 mM) but decreased in the presence of Cl − (10 and 100 mM), HCO 3 − (100 mM), and NO 3 − (10 mM). The degradation of anisole, probe for both ·OH and ·SO 4 − , was slightly enhanced by 10 mM NO 3 − anions but decreased in 100 mM salt solution. ·O 2 − intensity was increased while HCO 3 − (10 and 100 mM) and NO 3 − (100 mM) anions were used.nZVI-rGO-activated PS process could remove TCE in aqueous effectively, and the ROS generation and intensity were influenced by solution pH values and anions.

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