Zero-valent iron powder has been determined to be potentially useful for the removal of nitrate in the water
environment. This research is aimed at subjecting the kinetics of denitrification by nanoscale Fe0 to an analysis of
factors aecting the chemical denitrification of nitrate. Nanoscale iron particles with a diameter in the range of 1±100
nm, which are characterized by the large BET specific surface area to mass ratio (31.4 m2/g), removed mostly 50, 100,
200, and 400 mg/l of nitrate within a period of 30 min with little intermediates. Compared with microscale (75±150 lm)
Fe0, endproduct is not ammonia but N2 gas. Kinetics analysis from batch studies revealed that the denitri®cation
reaction with nanoscale Fe0 appeared to be a pseudo ®rst-order with respect to substrate and the observed reaction rate
constant (kobs) varied with iron content at a relatively low degree of application. The eects of mixing intensity (rpm) on
the denitri®cation rate suggest that the denitri®cation appears to be coupled with oxidative dissolution of iron through a
largely mass transport-limited surface reaction (
Zero-valent iron powder has been determined to be potentially useful for the removal of nitrate in the waterenvironment. This research is aimed at subjecting the kinetics of denitrification by nanoscale Fe0 to an analysis offactors aecting the chemical denitrification of nitrate. Nanoscale iron particles with a diameter in the range of 1±100nm, which are characterized by the large BET specific surface area to mass ratio (31.4 m2/g), removed mostly 50, 100,200, and 400 mg/l of nitrate within a period of 30 min with little intermediates. Compared with microscale (75±150 lm)Fe0, endproduct is not ammonia but N2 gas. Kinetics analysis from batch studies revealed that the denitri®cationreaction with nanoscale Fe0 appeared to be a pseudo ®rst-order with respect to substrate and the observed reaction rateconstant (kobs) varied with iron content at a relatively low degree of application. The eects of mixing intensity (rpm) onthe denitri®cation rate suggest that the denitri®cation appears to be coupled with oxidative dissolution of iron through alargely mass transport-limited surface reaction (<40 rpm). Ó 2000 Elsevier Science Ltd. All rights reserved.
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