Dechlorination of PCDD/F by organic and inorganic electron transfer molecules in reduced environments

Reduction of 2,4,6-trichlorophenol with zero-valent zinc and catalyzed zinc

“…Reduction of carbon tetrachloride (CCl 4 ) by zero-valent zinc has been also observed in several researches [26,29,30]. Octachlorodibenzo-p-dioxin (OctaCDD) was dechlorinated to hexa-and pentaCDD under basic and neutral conditions and the dechlorination of pentachlorophenol (PCP) on a zinc electrode in both propylene carbonate solvent and water was investigated [31,32]. In spite of the high reduction potential of zerovalent zinc (−0.76 V), it has not received as much attention as iron because the Zn(II) species released can be a concern in water contamination.…”

Dehalogenation of chlorinated aromatic compounds using a hybrid bioinorganic catalyst on cells of Desulfovibrio desulfuricans

“…Methods for their degradation include oxidative destruction (Fangmark et al 1993) and reductive methods (Adriaens et al 1996;Sayles et al 1997) but there is a need for a simple treatment technology and bioremediation is a possible candidate. Many chlorinated aromatic compounds are not susceptible to aerobic microbial metabolism, attributable to the chlorine substitutent(s) blocking oxygenase attack (Wright et al 1996, Weigel & Wu 2000, although oxidative metabolism of chlorobenzoate has been coupled to the reduction of Fe(III) (Kazumi et al 1995).…”

Microbial Transformations at Aqueous-Solid Phase Interfaces: A Bioremediation Approach

“…The potential importance of reductive dechlorination, and perhaps one of the reasons for the emphasis on this transformation process, is illustrated by recent evidence that 2,3,7,8-TCDD may be in a state of flux, resulting from dechlorination of octaand hepta-CDD and being further dechlorinated to 2-mono-CDD [54]. Beside dechlorination reactions in sediments [4], dioxin dechlorination reactions have been demonstrated in the presence of microorganisms ( [5,12,13,[431][432][433], dihydroxylated monoaromatic compounds [433], vitamin B 12 , and zero valent metals [3].…”

“…Anaerobic microbial respiration in aquatic bottom sediments and aquifers can take place via a variety electron acceptors [309,[394][395][396], and microbial degradation of herbicides and substituted aromatic compounds (herbicide metabolites) can be influenced by the type of electron acceptors present [55,115,397,398]. In general, the electron acceptors are utilized in order of their relative energy potential following the sequence O 2 , NO 3 -, Mn(IV), Fe(III), SO 4 -2 , and the redox zones in anoxic aquifers and sediments can become stratified [276].…”

“…The number of compounds found to date is enormous, and the types of mixtures are similarly numerous [1]. Moreover, the concentrations of individual organic compounds vary appreciably, and they may be higher than 1.0 g/l of water or mg/kg of soil/sediment at sites subject to spills from tank cars, trucks, or oil/cargo ships, to discharge of industrial waste, or to leakages from storage or disposal facilities for industrial chemicals [2][3][4][5][6][7][8][9][10][11]. In contrast, the concentrations may be lower than 1.0 mg/l of water or mg/kg of soil/sediment at some distance from the point of release, marine/terrestrial spill, or storage [12][13][14][15].…”