Pd/Fe3O4 nano-catalysts for selective dehalogenation in wastewater treatment processes-Influence of water constituents

Palladium catalysts can be used for the selective removal of halogenated organic compounds from aqueous waste via hydrodehalogenation reactions in the presence of other omnipresent constituents of industrial wastewaters. This detoxification of the water and drastic lowering of the AOX value (adsorbable organically bound halogens) can prevent the need for further cost-intensive treatment or discharge into waste incineration plants. Often, the water can then be released to municipal sewage plants. The present paper deals with a highly active, magnetically re-extractable nanoscale Pd-on-magnetite catalyst (Pd/Fe3O4) which has been developed for application in wastewater treatment processes. The study provides insight into the performance of this catalyst and gives information about its general applicability under wastewater conditions and its sensitivity towards constituents of a wastewater matrix. The catalyst can tolerate various inorganic and organic substances in relevant concentrations. Wastewaters containing a high background concentration of organic solvents can also be cleaned from halogenated pollutants. However, waters which contain heavy metals such as lead or mercury or reduced sulphur species such as sulphides need specific pre-treatments prior to Pd-catalysed hydrodehalogenation. (C) 2009 Elsevier B.V. All rights reserved.