Reduction of Halogenated Organic Compounds in Water: Comparison of Available Reduction Systems based on Cu, Pd and ZVI

Catalysts on the basis of copper (Cu) and the reducing agent borohydride (BH4-) have been successfully used for reduction of chlorinated aliphatics with low substitution degree which are usually resistant to zero-valent iron (ZVI) and hydrodehalogenation catalysts, such as Pd. Reactivity screening towards a broad spectrum of halogenated organic compounds (HOCs) helped to reveal the possible application areas of the Cu/BH4- system in water treatment compared to Pd and ZVI. The HOC reactivity was found to depend on: i) the nature of the C-X bond to be cleaved, ii) the functional groups adjacent to the C-X bond and linked to it, iii) the bond dissociation energy (BDE). The use of the deactivation-stable Cu/BH4- can be recommended as alternative reduction method to ZVI and Pd catalysts for on-site treatment of aliphatic HOCs.