Effect of operating parameters on trichloroethylene degradation by extended release of nanoscale zero-valent iron

Abstract

This study investigated the effects of various operating parameters on the efficiency and kinetics of trichloroethylene (TCE) degradation by commercial, polyvinyl alcohol-co-vinylacetate-co-itaconic acid (PV3A) stabilized nanoscale zero-valent iron (PV3A-nZVI). The results showed that TCE degradation was a pseudo-first-order reaction. The degradation efficiency and the apparent rate constant of TCE increased with the increasing PV3A-nZVI dosage and decreased with the increasing initial TCE concentration and pH. In addition, the effect of the solution matrix was evaluated. The results suggested that increasing the seawater ratio in the solution suppressed TCE degradation. The apparent rate constants of TCE decreased from 2.79 × 10−2 to 9.10 × 10−3 min−1, and the seawater ratio increased from zero to 100% at 5 g/L PV3A-nZVI and 10 mg/L TCE. Moreover, an investigation of TCE degradation products confirmed that reductive dechlorination through the successive loss of chloride ions is the main pathway of TCE degradation, and ethene is the predominant byproduct during TCE dechlorination. Notably, nearly 100% TCE (10 g/L) removal was achieved with 5 g/L PV3A-nZVI in pure water and seawater within 90 and 120 min, respectively. Hence, PV3A-nZVI is a promising technology for remediating surface water, groundwater, and seawater matrices contaminated with TCE.