title: Adsorption of hexavalent chromium on dunite.
abstract: The paper presents and discusses the effect of various physicochemical parameters (e.g. pH, ionic strength, Cr(VI) initial concentration, amount of the adsorbent, temperature and contact time between metal ion and adsorbent) on the adsorption efficiency of Cr(VI) on dunite in aqueous solutions under atmospheric conditions. Evaluation of the experimental data shows that dunite presents increased affinity for Cr(VI) over a wide pH range and Cr(VI) concentration, and the experimental data are well fitted by the K(d) adsorption model. The relative adsorption is pH dependent and decreases slightly (about 10%) with increasing pH, because of changes in the surface charge of the solid. The effect of the ionic strength is significant (particularly at low pH), indicating the predominance of outer-sphere complexes. Moreover, adsorption experiments at various temperatures, two different pH values (pH 3 and pH 8) and three different ionic strengths (0.0, 0.1 and 1.0 M NaClO(4)), indicate an endothermic but spontaneous entropy-driven processes.
authors.affiliation: Department of Chemistry, University of Cyprus, P.O. Box 20537, 1678 Lefkosia.
authors.forename: Antri
authors.initials: A
authors.lastname: Demetriou
authors.forename: Ioannis
authors.initials: I
authors.lastname: Pashalidis
mesh_terms: D000327:Adsorption; D002857:Chromium / Q000737:chemistry* / Q000302:isolation & purification; D004785:Environmental Pollutants / Q000737:chemistry* / Q000302:isolation & purification; D006863:Hydrogen-Ion Concentration; D008903:Minerals / Q000737:chemistry*; D009994:Osmolar Concentration; D013696:Temperature; D013997:Time Factors; D014867:Water / Q000737:chemistry
chemical_list: D004785:Environmental Pollutants; D008903:Minerals; D014867:Water; D002857:Chromium