title: Reduction of nitrobenzene with alkaline ascorbic acid: Kinetics and pathways.
abstract: Alkaline ascorbic acid (AA) exhibits the potential to reductively degrade nitrobenzene (NB), which is the simplest of the nitroaromatic compounds. The nitro group (NO2(-)) of NB has a +III oxidation state of the N atom and tends to gain electrons. The effect of alkaline pH ranging from 9 to 13 was initially assessed and the results demonstrated that the solution pH, when approaching or above the pKa2 of AA (11.79), would increase reductive electron transfer to NB. The rate equation for the reactions between NB and AA at pH 12 can be described as r=((0.89±0.11)×10(-4) mM(1-(a+b))h(-1))×[NB](a=1.35±0.10)[AA](b=0.89±0.01). The GC/MS analytical method identified nitrosobenzene, azoxybenzene, and azobenzene as NB reduction intermediates, and aniline (AN) as a final product. These experimental results indicate that the alkaline AA reduction of NB to AN mainly proceeds via the direct route, consisting of a series of two-electron or four-electron transfers, and the condensation reaction plays a minor route. Preliminary evaluation of the remediation of spiked NB contaminated soils revealed that maintenance of alkaline pH and a higher water to soil ratio are essential for a successful alkaline AA application.
authors.affiliation: Department of Environmental Engineering, National Chung Hsing University 250, Kuo-kuang Road, Taichung 402, Taiwan. Electronic address: cliang@nchu.edu.tw.
authors.forename: Chenju
authors.initials: C
authors.lastname: Liang
authors.affiliation: Department of Environmental Engineering, Chung Yuan Christian University, 200 Chung Pei Road, Chung Li District, Taoyuan City 320, Taiwan.
authors.forename: Ya-Ting
authors.initials: YT
authors.lastname: Lin
authors.affiliation: Department of Environmental Engineering, National Chung Hsing University 250, Kuo-kuang Road, Taichung 402, Taiwan.
authors.forename: Jia-Wei
authors.initials: JW
authors.lastname: Shiu
keywords: Chlorinated solvents; Explosive; In situ chemical reduction (ISCR); Soil and groundwater remediation; Vitamin C