title: Adsorption of chromate by clinoptilolite exchanged with various metal cations.
abstract: Unmodified zeolite surfaces show no affinity for anions, due to the fact that zeolites are negatively charged. Thus, adsorption of anions by zeolites has not been given much attention. In this work, after modification of clinoptilolite by different cations, the mineral was found to adsorb a considerable amount of the divalent anion chromate. Chromate adsorption was proportional to the K(sp) of the chromate precipitate and the amount of the exchangeable cation. The amount of chromate adsorbed was maximized when the Pb-exchanged form was used. Chromate desorption in deionized water indicated that between 2.50% and 18.60% of the adsorbed chromate was released depending upon the exchangeable cation. Some of the exchanged forms are candidate materials for adsorption and immobilization of chromate.
authors.affiliation: Department of Chemistry, University of Isfahan, Darvazehshiraz, Isfahan, Iran New Mexico Institute of Mining and Technology, Socorro NM 87801-4796, USA. h.faghih@sci.ui.ac.ir
authors.forename: H
authors.initials: H
authors.lastname: Faghihian
authors.forename: Robert S
authors.initials: RS
authors.lastname: Bowman
mesh_terms: D000327:Adsorption; D002412:Cations; D002840:Chromates / Q000302:isolation & purification*; D006863:Hydrogen-Ion Concentration; D007854:Lead / Q000737:chemistry; D008670:Metals / Q000737:chemistry*; D012989:Soil Pollutants / Q000032:analysis* / Q000302:isolation & purification*; D012995:Solubility; D013696:Temperature; D017641:Zeolites / Q000737:chemistry*
chemical_list: D002412:Cations; D002840:Chromates; D008670:Metals; D012989:Soil Pollutants; C083175:clinoptilolite; D017641:Zeolites; D007854:Lead