title: Interactions of chromium ions with starch granules in an aqueous environment.
abstract: In this study, interactions of dichromate ions with potato starch granules in highly acidic aqueous solutions and at different temperatures were investigated. It was found that the process underwent a reduction of Cr(2)O(7)(2-) to Cr(3+) accompanied by the formation of intermediate Cr(5+) ions detected by electron paramagnetic resonance (EPR) spectroscopy. The reactions took place after the attachment of dichromate anions to the granules and resulted in a lowering of the Cr(2)O(7)(2-) initial content in the solution. The newly formed Cr(3+) ions were both accumulated by the granules or remained in the solution. It was observed for the first time that the quantity of such ions taken by the granules from the solution was noticeably higher than that delivered by trivalent chromium salt solution. It was revealed by scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy (SEM-EDX) that the chromium ions were not only adsorbed on the granule surface but also introduced into the granule interior and evenly distributed there. An activation energy of the reduction reaction equal to 65 kJ·mol(-1) and the optimal parameters of the process were established. The proposed mechanism could be useful for the bioremediation of industrial effluents polluted by hexavalent chromium compounds.
authors.affiliation: Faculty of Chemistry, Jagiellonian University , 3 Ingardena Str., 30-060 Krakow, Poland.
authors.forename: Jadwiga
authors.initials: J
authors.lastname: Szczygieł
authors.forename: Krystyna
authors.initials: K
authors.lastname: Dyrek
authors.forename: Krzysztof
authors.initials: K
authors.lastname: Kruczała
authors.forename: Ewa
authors.initials: E
authors.lastname: Bidzińska
authors.forename: Zuzanna
authors.initials: Z
authors.lastname: Brożek-Mucha
authors.forename: Elżbieta
authors.initials: E
authors.lastname: Wenda
authors.forename: Jerzy
authors.initials: J
authors.lastname: Wieczorek
authors.forename: Joanna
authors.initials: J
authors.lastname: Szymońska
mesh_terms: D000327:Adsorption; D002857:Chromium / Q000737:chemistry*; D004578:Electron Spin Resonance Spectroscopy; D006863:Hydrogen-Ion Concentration; D007477:Ions / Q000737:chemistry; D010084:Oxidation-Reduction; D013052:Spectrometry, X-Ray Emission; D013213:Starch / Q000737:chemistry*; D013696:Temperature; D014867:Water / Q000737:chemistry
chemical_list: D007477:Ions; D014867:Water; D002857:Chromium; D013213:Starch