Lj. Matheson et Pg. Tratnyek, REDUCTIVE DEHALOGENATION OF CHLORINATED METHANES BY IRON METAL, Environmental science & technology, 28(12), 1994, pp. 2045-2053
Reduction of chlorinated solvents by fine-grained iron metal was studi
ed in well-mixed anaerobic batch systems in order to help assess the u
tility of this reaction in remediation of contaminated groundwater. Ir
on sequentially dehalogenates carbon tetrachloride via chloroform to m
ethylene chloride. The initial rate of each reaction step was pseudo-f
irst-order in substrate and became substantially slower with each deha
logenation step. Thus, carbon tetrachloride degradation typically occu
rred in several hours, but no significant reduction of methylene chlor
ide was observed over 1 month. Trichloroethene (TCE) was also dechlori
nated by iron, although more slowly than carbon tetrachloride. Increas
ing the clean surface area of iron greatly increased the rate of carbo
n tetrachloride dehalogenation, whereas increasing pH decreased the re
duction rate slightly. The reduction of chlorinated methanes in batch
model systems appears to be coupled with oxidative dissolution (corros
ion) of the iron through a largely diffusion-limited surface reaction.