CATALYTIC REDUCTION OF CARBON TETRACHLORIDE BY TRIMETALLIC Pd-Fe-Al PARTICLES

摘要

Many novel materials such as zero-valent bimetals(e.g.,Pd/Fe,Cu/Fe and Cu/Al)and nanoscale bimetallic particles have been developed for remediation of chlorinated organic compounds.Bimetals consisted of a core metal and a shell metal.In general,the core metal serves as a reductant while the shell metal may have various functionalities depending on the nature of the metal applied.In the use of noble metals(e.g.,palladium and platinum)as the shell metal,degradation rates increase mainly because of their superior catalytic ability through indirect reductive dechlorination.Indirect reduction involves the formation of atomic hydrogen that is readily formed at the surface with the low cathodic hydrogen overpotentials such as palladium.On the other hand,direct reduction,such as hydrogenolysis and beta-elimination in the transformation of TCE by iron,may occur at the metal surface where metal itself serves a direct electron donor.For non-catalytic metals that have the high cathodic hydrogen overpotentials(e.g.,iron and copper),bimetallic structure still enhances degradation rates through the formation of galvanic cells that promote the electron release reactions of galvanic corrosion.