Adsorption and Desorption of Zn,Cu, and Cr by Sediments from the Raisin River (Michigan) |
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| Affiliation: | 1. Civil Engineering Department, University of Sistan and Baluchestan, Zahedan, Iran;2. Dept. of Chemical and Environmental Engineering, University of Arizona, P.O. Box 210011, Tucson, AZ, USA;3. National University of Singapore, NUS Environmental Research Institute (NERI), 5 A Engineering Drive 1, T-Lab Building, #02-01, Singapore 117411, Singapore;4. Department of Veterinary Biomedical Sciences and Toxicological Center, University of Saskatchewan, Saskatoon, Saskatchewan, Canada;1. College of Environmental Science and Engineering, North China Electric Power University, Beijing, 102206, China;2. North China Electric Power Research Institute Co Ltd., Beijing, 100045, China;1. Leibniz Institute of Surface Modification, Permoserstr. 15, 04303 Leipzig, Germany;2. Department of Chemistry, Faculty of Science, Al-Azhar University, Nasr City, 11884, Cairo, Egypt;3. Wilhelm-Ostwald-Institute for Physical and Theoretical Chemistry, Faculty of Chemistry and Mineralogy, University of Leipzig, Permoserstr. 15, 04318 Leipzig, Germany;1. Irstea, UR HHLY, Hydrology-Hydraulics, 5 rue de la Doua, CS 70077, F-69626 Villeurbanne, France;2. Irstea, UR MALY, Freshwater Systems Ecology and Pollution, 5 rue de la Doua, CS 70077, F-69626 Villeurbanne, France;1. Department of Civil Engineering, Inje University, 197 Inje-ro, Gimhae, Gyeongnam 621-749, South Korea;2. Department of Environmental Science and Engineering, Inje University, 197 Inje-ro, Gimhae, Gyeongnam 621-749, South Korea;3. Division of Civil Engineering, University of Dundee, Perth Road, Dundee DD5 3LE, UK |
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| Abstract: | Metal adsorption by Raisin River sediments in vitro depended linearly on soluble metal concentration to adsorption densities of 6,000–9,000 μg/g with 48 hr partition coefficients of approximately 50, 30, and 25 L/g for Cu, Cr, and Zn, respectively. Partition coefficients computed from field data spanned a comparatively wider range of values in a manner consistent with the often reported adsorbent concentration effect, but other factors likely contributed, too. Desorption of Zn was complete and rapid (24–48 hr) in contrast to Cr, which was incomplete and much slower; Cu desorption was intermediate to Zn and Cr. A reversible-resistant equilibrium model (DiToro et al. 1986) could not describe the observations as Cu and Cr had not reached metastable desorption equilibria after 24 days. Metal desorption, however, could be described kinetically by distributing sorbed cations between either of two classes: rapidly desorbing and slowly desorbing cations. Sequential and simultaneous desorption models gave similar predictions. Aqueous chemical considerations suggested precipitated as well as adsorbed species could give rise to the observations, but available data did not permit adequate tests of this hypothesis. The extent to which kinetic constraints rather than irreversible reactions account for the desorption-resistant binding signifies a potentially greater metal mobility or bioavailability than would otherwise be assumed. |
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