Dechlorination of chlorinated phenols by catalyzed and uncatalyzed Fe(0) and Mg(0) particles

Abstract

Uncatalyzed, and palladium-catalyzed Fe(0) and Mg(0) systems were examined for their efficiencies of dechlorination of 2.86mM 4-chlorophenol (4-CP), 2.52mM 2, 6-dichlorophenol (2, 6-DCP), 3.03mM 2, 4, 6-trichlorophenol (2, 4, 6-TCP), and 2.48mM pentachlorophenol (PCP) in 50/50 (v/v) 2-propanol/water under room temperature and pressure conditions. Previous investigators have found that PCP is extremely recalcitrant under these conditions. In this investigation, complete dechlorination of 5.0ml of 2.48mM PCP was observed for 1.0g of 2659ppm Pd/Mg (20mesh) after 48h. The only detectable products were cyclohexanol and cyclohexanone at 25% yield. No other chlorinated or otherwise products were observed by mass spectral analysis. It is hypothesized that volatile low molecular weight species were formed from the Pd/Mg dechlorination of PCP. Under conditions of equal surface area (0.0786m2), the approximate order of PCP dechlorination power of these systems followed as 2659ppm Pd/Mg >319ppm Pd/Mg >Mg≈4856ppm Pd/Fe>Fe. Degradation of the other chlorinated phenols by all metallic systems was more facile than PCP. © 2002 Elsevier Science B.V.