Highly efficient degradation of trichloroethylene in groundwater based on peroxymonosulfate activation by bentonite supported Fe/Ni bimetallic nanoparticle

Advanced oxidation processes (AOPs) are promising environmental remediation technologies for in-situ groundwater treatment. In this study, a bentonite supported Fe/Ni bimetallic nanoparticle (BNF) was fabricated for peroxymonosulfate (PMS) activation. The resultant BNF exhibited high catalytic activity for trichloroethylene (TCE) degradation in weak alkaline conditions. The conditions optimal for this activity were assessed in terms of peroxygen type and BNF/PMS dosage ratios. Complete degradation of 0.1 mM TCE was achieved in 25 min at pH = 8.2 when BNF was present at 1 g/L and PMS at 5 mM concentrations. Analysis of the underlying mechanisms indicated that SO₄^- has a dominant role whereas OH was rather trivial. The enhancement of catalytic activity was attributed to the strong oxidization of SO₄^-, dispersion of Fe/Ni nanoparticles and synergistic effects between Fe and Ni. The effects of inorganic anions, pH and temperature on the BNF/PMS activity were also investigated. Cl^- and NO₃^- has little effect on TCE degradation, while PO₄^3- and HPO₄^2- were inhibitory. Higher temperatures favored PMS activation and BNF/PMS exhibited good catalytic activity across a wide range of solution pH. The results indicate that a novel BNF/PMS system holds promise as a superior AOP to remediate emerging organic pollutants in groundwater.