Degradation of PCE, TCE and 1,1,1-TCA by nanosized FePd bimetallic particles under various experimental conditions

The degradation of chlorinated organic compounds, such as PCE (tetrachloroethene), TCE (trichloroethene) and 1,1,1-TCA (1,1,1-trichloroethane), was conducted using nanosized FePd bimetallic particles. In order to enhance the reactivity of ZVI (zero valent iron) nanoparticles, surface modification of ZVI nanoparticles was performed using Pd and CMC (carboxymethyl cellulose). The surface modification was found to form CMC-stabilized FePd bimetallic nanoparticles (CMC-FePd). The average TCE removal efficiency by the CMC-FePd was significantly increased by ∼85% compared to employing conventional ZVI nanoparticles (∼15%). This increase in the TCE removal efficiency was most likely due to the increased amount of atomic hydrogen produced by the formation of CMC-FePd. For PCE and 1,1,1-TCA, the removal efficiencies by CMC-FePd were approximately 80% and 56%, respectively. For all three chlorinated organic compounds, the amount of Cl- ions in the aqueous phase during the degradation increased with increasing reaction time. This result suggests that the main degradation mechanism of the chlorinated compounds by CMC-FePd was reductive dechlorination.