title: Investigation of hexavalent chromium sorption in serpentine sediments.
abstract: In this study the removal of hexavalent chromium (Cr6+) by serpentine sediments was investigated in order to delineate Cr6+sorption behavior in aquifers with ultramafic geologic background. Batch experiments were conducted in order to determine the influence of several parameters on Cr6+removal, including the pH of the sediment solution, mineralogy, sediment's particle size and Cr6+initial concentration. The results showed that Cr6+removal was due to both adsorption and reduction phenomena. Reduction was attributed to the presence of a magnetic fraction in the sediment, mostly related to magnetite, which contributed almost 50% of the total removal in the pH range 3-7. Adsorption behavior was dominated by the finer sediment fraction (d<0.075mm). The amount of Cr6+adsorbed was constant in the pH range 3-7, while it decreased sharply in the range 7-8.5. Cr6+adsorption was found to increase and decrease proportionally with increasing initial Cr6+concentration of and particle size, respectively. The linear Langmuir and Freundlich adsorption isotherms were used to describe the experimental data, with Freundlich providing a better fit to determine distribution factors for transport modeling.
authors.affiliation: School of Civil Engineering, Department of Water Resources and Environmental Engineering, National Technical University of Athens, Iroon Polytechniou 9, 157 80 Zografou, Greece. Electronic address: th.mpouras@gmail.com.
authors.forename: Thanasis
authors.initials: T
authors.lastname: Mpouras
authors.affiliation: Department of Civil and Environmental Engineering, University of Connecticut, Storrs, CT, USA.
authors.forename: Maria
authors.initials: M
authors.lastname: Chrysochoou
authors.affiliation: School of Civil Engineering, Department of Water Resources and Environmental Engineering, National Technical University of Athens, Iroon Polytechniou 9, 157 80 Zografou, Greece.
authors.forename: Dimitris
authors.initials: D
authors.lastname: Dermatas
mesh_terms: D000327:Adsorption; D002857:Chromium / Q000737:chemistry* / Q000302:isolation & purification*; D019015:Geologic Sediments / Q000737:chemistry*; D006115:Greece; D060587:Groundwater / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D010316:Particle Size; D012996:Solutions / Q000737:chemistry; D014874:Water Pollutants, Chemical / Q000737:chemistry* / Q000302:isolation & purification*
chemical_list: D012996:Solutions; D014874:Water Pollutants, Chemical; D002857:Chromium; C074702:chromium hexavalent ion
keywords: Adsorption; Hexavalent chromium; Reduction; Serpentine sediment