Wa. Arnold et Al. Roberts, Inter- and intraspecies competitive effects in reactions of chlorinated ethylenes with zero-valent iron in column reactors, ENV ENG SCI, 17(5), 2000, pp. 291-302
Citations number
26
Categorie Soggetti
Environment/Ecology,"Environmental Engineering & Energy
Reaction kinetics are a key component of process models used to design Fe(0
) permeable barriers employed to treat groundwater contaminated with chlori
nated solvents. In this work, columns packed with a mixture of zero-valent
iron and glass microbeads were used to assess whether the competitive effec
ts observed in batch systems also occur in column reactors. As with the bat
ch studies previously conducted, both inter- and intraspecies competition w
ere observed, in qualitative agreement with predictions obtained from a mod
ified Langmuir-Hinshelwood-Hougen-Watson (LHHW) kinetic model in which spec
ies compete for a limited number of reactive sites. The observed changes in
pseudo first-order rate "constant" at different initial concentrations or
in the presence of competitors could not be attributed to alterations in th
e transport properties of the column packing or to "aging" of the iron. Num
erical simulations were used to explore the consequences of applying a pseu
do first-order kinetic model instead of the LHHW model. The results demonst
rate that intraspecies competitive effects are sufficiently important to me
rit explicit consideration in permeable barrier design.