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

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 center dot OH increased when the pH was shifted toward the basic region while center dot SO4 radicals' intensity increased in the acidic pH. Different scenarios have been observed in center dot O-2(-) generation in the neutral and strong basic pH and decreased in acidic or slightly basic pH. In addition, the intensity of center dot OH was increased with the addition of HCO3- (10 mM) and NO3- (100 mM) but decreased in the presence of Cl( 10 and 100 mM), HCO3- (100 mM), and NO3- (10 mM). The degradation of anisole, probe for both center dot OH and center dot SO4-, was slightly enhanced by 10 mM NO3- anions but decreased in 100 mM salt solution. center dot O-2(-) intensity was increased while HCO3- (10 and 100 mM) and NO3- (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.