TY - JOUR
T1 - Comparative studies of the reduction behavior of chromium(VI) by humic substances and their precursors
AU - Nakayasu, Ken
AU - Fukushima, Masami
AU - Sasaki, Keiko
AU - Tanaka, Shunitz
AU - Nakamura, Hiroshi
PY - 1999/5/27
Y1 - 1999/5/27
N2 - Hexavalent chromium (Cr[VI]) is reduced by dissolved organic carbons (DOCs) such as humic substances, tannic acid (TA), and gallic acid (GA). The kinetic constants and the resulting chemical species after the reduction were compared with each other. The kinetic constants for GA and TA, which are model precursors of humic substances, were two to three orders of magnitude larger than those for the humic substances when these kinetic constants were expressed as a function of the molar concentration of the reductive functional group (F(red)) in various DOCs. After the reduction of Cr(VI), the percentages of the species complexed with GA and TA were higher than those with the humic substances. This appears to be due to the formation of high molecular weight compounds by polymerization during the reduction of Cr(VI) and complexation of Cr(III) with the polymerized compounds. The UV-vis spectrophotometric data and gel permeation chromatography support this view.
AB - Hexavalent chromium (Cr[VI]) is reduced by dissolved organic carbons (DOCs) such as humic substances, tannic acid (TA), and gallic acid (GA). The kinetic constants and the resulting chemical species after the reduction were compared with each other. The kinetic constants for GA and TA, which are model precursors of humic substances, were two to three orders of magnitude larger than those for the humic substances when these kinetic constants were expressed as a function of the molar concentration of the reductive functional group (F(red)) in various DOCs. After the reduction of Cr(VI), the percentages of the species complexed with GA and TA were higher than those with the humic substances. This appears to be due to the formation of high molecular weight compounds by polymerization during the reduction of Cr(VI) and complexation of Cr(III) with the polymerized compounds. The UV-vis spectrophotometric data and gel permeation chromatography support this view.
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U2 - 10.1897/1551-5028(1999)018<1085:CSOTRB>2.3.CO;2
DO - 10.1897/1551-5028(1999)018<1085:CSOTRB>2.3.CO;2
M3 - Article
AN - SCOPUS:0032955937
SN - 0730-7268
VL - 18
SP - 1085
EP - 1090
JO - Environmental Toxicology and Chemistry
JF - Environmental Toxicology and Chemistry
IS - 6
ER -