Hydrodechlorination of Chlorinated Ethanes by Nanoscale Pd/Fe Bimetallic Particles

Hsing-Lung Lien, Wei-xian Zhang
2005 Journal of environmental engineering  
Chlorinated ethanes are contaminants commonly found in soil and groundwater. The potential of nanoscale bimetallic ͑Fe/ Pd͒ particles for the hydrodechlorination of seven chlorinated ethanes ͑C 2 H 6−x Cl x ͒ was evaluated in batch experiments. Hexachloroethane (HCA) ͑C 2 Cl 6 ͒, pentachloroethane (PCA) ͑C Cl 4 ) were rapidly hydrodechlorinated (9-28 min half-lives) at a nanoparticle loading of 5 g/L. End products were ethane (61-87%) and ethylene (6-16%). Only one chlorinated intermediate, a
more » ... d intermediate, a corresponding ␤-elimination product, appeared temporarily during the reactions. Reductive dechlorination of 1,1,1-trichloroethane (1,1,1-TCA, C 2 H 3 Cl 3 ) to ethane was completed at a relatively slower rate with half-life at 44.9 min. Little reduction of dichloroethane ͑C 2 H 4 Cl 2 ͒ was observed within 24 h. The Pd/Fe bimetallic nanoparticles generally exhibit much higher reactivity when compared with conventional micro-and millimeter scale iron powders. The hydrodechlorination reactions are more complete, with a much higher yield of ethane and lower yield of chlorinated byproducts. A kinetic model incorporating a transition state species was proposed. Results from this work suggest that the Pd/Fe bimetallic nanoparticles may represent a treatment alternative for in situ remediation of chlorinated ethanes.
doi:10.1061/(asce)0733-9372(2005)131:1(4) fatcat:cd6exhgcrje5dh3n45b6bineeu