Chlorophenol dehalogenation in a magnetically stabilized fluidized bed reactor

Aromatic halocarbons are often present in contaminated aquifers, surface waters, wastewater streams, soils, and hazardous wastes. The dehalogenation. of p-chlorophenol as a model compound in both the aqueous phase and in slurries of contaminated solids using a magnetically stabilized fluidized bed (MSFB) reactor is discussed. Composite palladium-iron (Pd/Fe) media are employed as both catalyst and sacrificial reactant for the reductive dechlorination of p-chlorophenol. Calcium alginate beads impregnated with Pd/Fe granules are fluidized in a recirculating aqueous stream containing either dissolved p-chlorophenol or a slurry of soil contaminated with this chlorocarbon. Magnetic stabilization of the fluidized bed allows substantially higher rates of mass transfer than would otherwise be achievable, and allows circulation of contaminated solids while fluidization media are retained. Anoxic conditions are sustained under a nitrogen purge and the solution pH of 5.8 is maintained by active control to minimize surface fouling by hydroxides, and to minimize mass-transfer resistances resulting from the surface accumulation of hydrogen bubbles. A model of this process is described and the resulting predictions are compared to the experimentally derived data. (c) 2005 American Institute of Chemical Engineers.