title: Removal of hexavalent chromium by using red mud activated with cetyltrimethylammonium bromide.
abstract: The removal of hexavalent chromium [Cr(VI)] from aqueous solution by using red mud activated with cetyltrimethylammonium bromide (CTAB) was studied. The optimum operation parameters, such as CTAB concentration, pH values, contact time, and initial Cr(VI) concentration, were investigated. The best concentration of CTAB for modifying red mud was found to be 0.50% (mCTAB/VHCl,0.6 mol/L). The lower pH (<2) was found to be much more favourable for the removal of Cr(VI). Red mud activated with CTAB can greatly improve the removal ratio of Cr(VI) as high as four times than that of original red mud. Adsorption equilibrium was reached within 30 min under the initial Cr(VI) concentration of 100 mg L(-1). The isotherm data were analysed using Langmuir and Freundlich models. The adsorption of Cr(VI) on activated red mud fitted well to the Langmuir isotherm model, and the maximum adsorption capacity was estimated as 22.20 mg g(-1) (Cr/red mud). The adsorption process could be well described using the pseudo-second-order model. The result shows that activated red mud is a promising agent for low-cost water treatment.
authors.affiliation: a Institute of Environmental and Analytical Sciences, College of Chemistry and Chemical Engineering, Henan University , Kaifeng 475004 , People's Republic of China.
authors.forename: Deliang
authors.initials: D
authors.lastname: Li
authors.forename: Ying
authors.initials: Y
authors.lastname: Ding
authors.forename: Lingling
authors.initials: L
authors.lastname: Li
authors.forename: Zhixian
authors.initials: Z
authors.lastname: Chang
authors.forename: Zhengyong
authors.initials: Z
authors.lastname: Rao
authors.forename: Ling
authors.initials: L
authors.lastname: Lu
mesh_terms: D000327:Adsorption; D000077286:Cetrimonium; D002593:Cetrimonium Compounds / Q000737:chemistry*; D002857:Chromium / Q000302:isolation & purification*; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D013816:Thermodynamics; D014874:Water Pollutants, Chemical / Q000302:isolation & purification*
chemical_list: D002593:Cetrimonium Compounds; D014874:Water Pollutants, Chemical; D002857:Chromium; D000077286:Cetrimonium
keywords: adsorption; cetyltrimethylammonium bromide; chromium; red mud