title: Remediation of hexavalent chromium through adsorption by bentonite based Arquad® 2HT-75 organoclays.
abstract: Unlike hydrophobic organic pollutants, the potential of organoclays to adsorb inorganic ionic contaminants is relatively underexplored. The present study attempts to characterise bentonite (QB) based organoclays synthesised from a commercially available, low-cost alkyl ammonium surfactant Arquad® 2HT-75 (Aq) and test their ability to adsorb hexavalent chromium (Cr (VI)) in aqueous solution. XRD, FTIR and TGA characterisation techniques prove successful modification of the bentonite structure and reveal that higher surfactant loadings gives rise to more ordered surfactant conformation in the organoclays. The zeta potential values indicate that higher surfactant loadings also create positive charges on the organoclay surfaces. Detailed isothermal and kinetic studies show that the organoclays effectively remove hexavalent chromium (Cr (VI)) from aqueous solution by both physical and chemical adsorption processes. Higher surfactant loadings provide better adsorption efficiency. The adsorption performance is reasonably efficient under the levels of pH, temperature, electrolyte concentration and natural organic matter concentration that generally prevail in contaminated soil and water. This study shows that organoclay sorbents offer good potential for remediating Cr (VI) under real environmental conditions.
authors.affiliation: Centre for Environmental Risk Assessment and Remediation, Building X, University of South Australia, Mawson Lakes, SA 5095, Australia.
authors.forename: Binoy
authors.initials: B
authors.lastname: Sarkar
authors.forename: Yunfei
authors.initials: Y
authors.lastname: Xi
authors.forename: Mallavarapu
authors.initials: M
authors.lastname: Megharaj
authors.forename: Gummuluru S R
authors.initials: GS
authors.lastname: Krishnamurti
authors.forename: Dharmarajan
authors.initials: D
authors.lastname: Rajarathnam
authors.forename: Ravi
authors.initials: R
authors.lastname: Naidu
mesh_terms: D000327:Adsorption; D000538:Aluminum Silicates; D001546:Bentonite; D002857:Chromium / Q000302:isolation & purification*; D000077215:Clay; D052918:Environmental Restoration and Remediation / Q000379:methods*; D055672:Static Electricity; D013501:Surface-Active Agents; D014874:Water Pollutants, Chemical / Q000302:isolation & purification
chemical_list: D000538:Aluminum Silicates; D013501:Surface-Active Agents; D014874:Water Pollutants, Chemical; D002857:Chromium; D001546:Bentonite; C074702:chromium hexavalent ion; D000077215:Clay