title: Surface interactions of Cs+and Co2+with bentonite.
abstract: Uptake of radioactive metal species from soils and solutions by clay particles could be a treatment option due to simplicity of operation and economic cost. In this concern, adsorption behavior of Cs+or Co2+onto bentonite as a function of contact time, pH, initial metal concentration, ionic strength, and temperature was studied by batch adsorption technique. Adsorption isotherm data were interpreted by Langmuir, Freundlich, and Dubinin-Radushkevich (D-R) isotherm models. Bentonite exhibited maximum adsorption capacity of 83.3 mg g-1for Cs+and 15.9 mg g-1for Co2+. Presence of humic acid (HA) as a representative model of organic matter did not significantly affect the adsorption capacity of bentonite for Cs+, whereas it increased the adsorption capacity of bentonite for Co2+. Thermodynamic parameters, standard enthalpy (ΔH°), standard entropy (ΔS°), and standard free energy (ΔG°) were determined through batch adsorption experiments performed at four different temperatures of 288, 298, 318, and 338 K. Co2+adsorption onto bentonite showed an endothermic reaction (ΔH° = 13.6 kJ mol-1) whereas Cs+adsorption displayed an exothermic nature (ΔH° = -4.65 kJ mol-1). Negative values of ΔG° and positive values of ΔS° indicated the feasibility and spontaneous nature of adsorption processes and more disordered form after adsorption.
authors.affiliation: Division of Radioactivity Measurement, Cekmece Nuclear Research and Training Centre, 34303, Halkali, Istanbul, Turkey. omer.ozsoy@taek.gov.tr.
authors.forename: Omer
authors.initials: O
authors.lastname: Ozsoy
authors.affiliation: Institute of Environmental Sciences, Bogazici University, 34342, Bebek, Istanbul, Turkey.
authors.forename: Miray
authors.initials: M
authors.lastname: Bekbolet
mesh_terms: D000327:Adsorption; D001546:Bentonite / Q000737:chemistry*; D002586:Cesium / Q000737:chemistry*; D003035:Cobalt / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D009994:Osmolar Concentration; D011850:Radioactive Waste / Q000032:analysis*; D013696:Temperature; D013997:Time Factors; D014865:Waste Disposal, Fluid; D014874:Water Pollutants, Chemical / Q000032:analysis*
chemical_list: D011850:Radioactive Waste; D014874:Water Pollutants, Chemical; D001546:Bentonite; D002586:Cesium; D003035:Cobalt
keywords: Adsorption; Adsorption isotherm modeling; Bentonite; Cesium; Cobalt; Thermodynamic properties