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Isotope fractionation and spectroscopic analysis as an evidence of Cr(VI) reduction during biosorption

Šillerová, Hana, Chrastný, Vladislav, Čadková, Eva, Komárek, Michael
Chemosphere 2014 v.95 pp. 402-407
X-ray photoelectron spectroscopy, biocompatible materials, biosorption, chromium, grapes, humic acids, isotope fractionation, models, pH, scanning electron microscopy, stable isotopes, wastes
This work investigates the mechanisms behind Cr(VI) biosorption/reduction on three biomaterials (brewers draff, grape waste and synthetic humic acid). Coupled Cr isotope analysis with ICP-OES, XPS and SEM was tested as a novel approach to study the reduction of Cr(VI) by the biomaterials. The Cr(VI) biosorption process was accompanied with heavier Cr isotopes enrichment in the remaining Cr(VI) fraction. A significant fractionation of Cr stable isotopes was observed with no significant pH effect; δ53Cr of the remaining fraction ranged from 0.2‰ to 1.9‰ while δ53Cr of the product (sorbed Cr) ranged from −1.2‰ to −2.8‰. The Rayleigh fractionation model fitted well the measured data and Cr isotope analysis provides thus an efficient tool to quantify Cr(VI) reduction by different biomaterials. In general, the sorption/reduction potential of the three studied biomaterials decreased in the following order: grape waste>humic acids>brewers draff.