Reduction of Cr(VI) by soil humic acids

被引:99
作者
Wittbrodt, PR [1 ]
Palmer, CD [1 ]
机构
[1] OREGON GRAD INST SCI & TECHNOL, DEPT ENVIRONM SCI & ENGN, PORTLAND, OR 97291 USA
关键词
D O I
10.1111/j.1365-2389.1997.tb00194.x
中图分类号
S15 [土壤学];
学科分类号
0903 ; 090301 ;
摘要
The rate of hexavalent chromium reduction by a soil humic acid (SHA) was investigated in aqueous solutions where concentrations of Cr(VI), H+, and SHA were independently varied. Rate experiments were done with a large excess of SHA over Cr(VI). Rates of reduction depend strongly on [H+], increasing with decreasing pH, Typical Cr(VI)-SHA reactions display a nonlinear reduction of Cr(VI) with time that cannot be modelled with simple first- or second-order; rate equations. An empirical rate equation is developed for Cr(VI)-soil humic acid reactions over a range of experimental conditions. The model is in part based on a reactive continuum concept developed for soil fulvic acids. The rate equation describing Cr(VI) reduction by SHA is: R=-(k(0)+k[H+](1/2))[HCrO4-](1/2)X(e)(-1), where k(0) is (8.3+/-1.2)x 10(-12), s(-1), k is (2.04+/-0.05)x10(-9) 1(1/2) mol(-1/2) s(-1), and X(e) is the equivalent fraction of SHA oxidized. The rate equation adequately models Cr(VI) reduction in an experiment with [Cr(VI)](0) four times greater than the maximum concentration used in its derivation. Cr(VI) reduction at pH 3 by two other SHAs can also be modelled using the rate equation. The difference between the rate coefficients for the humic acid and the fulvic acid from the same soil was greater than the difference in the rate coefficients for humic acids from different soils.
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页码:151 / 162
页数:12
相关论文
共 38 条
[2]  
Aiken G. R., 1985, HUMIC SUBSTANCES SOI, P1
[3]   ELEMENTAL MERCURY EVOLUTION MEDIATED BY HUMIC ACID [J].
ALBERTS, JJ ;
SCHINDLER, JE ;
MILLER, RW ;
NUTTER, DE .
SCIENCE, 1974, 184 (4139) :895-896
[4]  
[Anonymous], 1989, STANDARD METHODS EXA, V17th
[5]  
[Anonymous], 1980, Gos. Izd-vo Fiz.-Mat. Literatury
[6]   MEASUREMENT OF ELECTROSTATIC AND SITE-SPECIFIC ASSOCIATIONS OF ALKALI-METAL CATIONS WITH HUMIC-ACID [J].
BONN, BA ;
FISH, W .
JOURNAL OF SOIL SCIENCE, 1993, 44 (02) :335-345
[7]   ON A REACTIVE CONTINUUM REPRESENTATION OF ORGANIC-MATTER DIAGENESIS [J].
BOUDREAU, BP ;
RUDDICK, BR .
AMERICAN JOURNAL OF SCIENCE, 1991, 291 (05) :507-538
[8]   CHROMITE ORE PROCESSING RESIDUE IN HUDSON COUNTY, NEW-JERSEY [J].
BURKE, T ;
FAGLIANO, J ;
GOLDOFT, M ;
HAZEN, RE ;
IGLEWICZ, R ;
MCKEE, T .
ENVIRONMENTAL HEALTH PERSPECTIVES, 1991, 92 :131-137
[9]  
CALDER LM, 1988, CHROMIUM NATURAL HUM, P215
[10]   LUMPING COUPLED NONLINEAR REACTIONS IN CONTINUOUS MIXTURES [J].
CHOU, MY ;
HO, TC .
AICHE JOURNAL, 1989, 35 (04) :533-538