Reductive dechlorination of γ-hexachlorocyclohexane using Fe–Pd bimetallic nanoparticles

Nanoscale Fe–Pd bimetallic particles were synthesized and used for degradation of lindane (γ-hexachlorocyclohexane) in aqueous solution. Batch studies showed that 5 mg/L of lindane was completely dechlorinated within 5 min at a catalyst loading of 0.5 g/L and the degradation process followed first-order kinetics. GC–MS analysis in corroboration with GC-ECD results showed the presence of cyclohexane as the final degradation product. The proposed mechanism for the reductive dechlorination of lindane involves Fe corrosion-induced hydrogen atom transfer from the Pd surface. The enhanced degradation efficiency of Fe–Pd nanoparticles is attributed to: (1) high specific surface area of the nanoscale metal particles (60 m 2/g), manyfold greater that of commercial grade micro- or milli-scale iron particles (∼1.6 m 2/g); and, (2) increased catalytic reactivity due to the presence of Pd on the surface. Recycling and column studies showed that these nanoparticles exhibit efficient and sustained catalytic activity.