Kinetics and mechanism of the enhanced reductive degradation of nitrobenzene by elemental iron in the presence of ultrasound
Journal
Environmental Science & Technology
Journal Volume
34
Journal Issue
9
Pages
1758-1763
Date Issued
2000
Author(s)
Abstract
Sonolysis, reduction by elemental iron (Fe0), and a combination of the two processes were used to facilitate the degradation of nitrobenzene (NB) and aniline (AN) in water. The rates of reduction of nitrobenzene by Fe0 are enhanced in the presence of ultrasound. The first-order rate constant, kUS, for nitrobenzene degradation by ultrasound is 1.8 × 10-3 min-1, while in the presence of Fe0, the rate was found to be substantially faster. The observation of similar degradation rates for aniline in each system suggests that the sonication process was not affected by the presence of Fe0. The observed rate enhancements for the degradation of nitrobenzene can be attributed primarily to the continuous cleaning and chemical activation of the Fe0 surfaces by acoustic cavitation and to accelerated mass transport rates of reactants, intermediates, and products between the solution phase and the Fe0 surface. The relative concentrations of nitrosobenzene and aniline, the principal reaction intermediates generated by Fe0 reduction, are altered substantially in the presence of ultrasound.
Type
journal article