Generation of adsorbed atomic hydrogen by Pd(II) doped Fe(OH)2 enables ultra-fast reductive dechlorination of trichloroethylene

Abstract

Trichloroethylene (TCE) is a notorious persistent pollutant in groundwater, while most reductive dechlorination processes result in the formation of toxic less-chlorinated by-products. In this work, adsorbed atomic hydrogen (H*) was produced by Pd(II) doped Fe(OH)2, which was used for ultra-fast reductive dechlorination of TCE without the formation of less-chlorinated by-products. When the Fe(OH)2 dosage is 0.5 mM and the Pd(II) dosage is 20 μM, TCE (42 μM) is completely removed in 60 min with the pseudo first-order reaction rate constant of 7.74 h−1. Radical quenching experiment and electrochemical analysis both confirmed that adsorbed H* rather than absorbed H* contribute to the reduction of TCE. Density function theory calculation demonstrated that small Pd clusters were more beneficial to TCE dechlorination than large Pd clusters. The pseudo first-order rate constant for TCE reduction in real groundwater was as high as 0.018 min–1, demonstrating the potential application of Pd/Fe(OH)2 in groundwater remediation.