title: Chromium removal with cross-linked chitosan adsorption and base-precipitation combination.
abstract: A novel technique for a complete removal of both Cr(VI) and Cr(III) ions, namely cross-linked chitosan (CCTS) adsorption and base-precipitation combination, was studied in this work in great detail. The optimum conditions for Cr(VI) adsorption onto CCTS were determined as a function of pH, CCTS dosage and contact time, while Cr(III) precipitation was investigated as a function of pH value. The Langmuir, Freundlich and Dubinin-Radushkevich (D-R) models were applied to describe the Cr(VI) adsorption isotherm on CCTS. The Langmuir model agreed much better with experimental data than the Freundlich and D-R by a correlation coefficient (R²) of 0.994. The capacity and ΔG° of CCTS for Cr(VI) were 70.4 mg/g and -26.6 kJ/mol respectively, indicating the feasible and spontaneous nature of the Cr(VI) sorption process. This combined technique was applied for real wastewater treatment from the electroplating industry and obtained a one-off retention in solution not more than 0.5 mg/L for both Cr(VI) and Cr total. These results meet the Chinese standards for effluent discharge.
authors.affiliation: Department of Applied Chemistry, School of Chemistry and Chemical Engineering, Hebei University of Technology, 300130 Tianjin, China. persistent2006@sina.com
authors.forename: Huixin
authors.initials: H
authors.lastname: Zhang
authors.forename: Feng
authors.initials: F
authors.lastname: Wang
authors.forename: Xiuhong
authors.initials: X
authors.lastname: Jin
authors.forename: Yuchao
authors.initials: Y
authors.lastname: Zhu
authors.forename: Xiaona
authors.initials: X
authors.lastname: Li
authors.forename: Hongyong
authors.initials: H
authors.lastname: Zhou
mesh_terms: D000327:Adsorption; D048271:Chitosan / Q000737:chemistry*; D002857:Chromium / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D014874:Water Pollutants, Chemical; D018508:Water Purification / Q000379:methods
chemical_list: D014874:Water Pollutants, Chemical; D002857:Chromium; D048271:Chitosan