title: Biosorption of hexavalent chromium by raw and acid-treated green alga Oedogonium hatei from aqueous solutions.
abstract: The hexavalent chromium, Cr(VI), biosorption by raw and acid-treated Oedogonium hatei were studied from aqueous solutions. Batch experiments were conducted to determine the biosorption properties of the biomass. The optimum conditions of biosorption were found to be: a biomass dose of 0.8 g/L, contact time of 110 min, pH and temperature 2.0 and 318 K respectively. Both Langmuir and Freundlich isotherm equations could fit the equilibrium data. Under the optimal conditions, the biosorption capacities of the raw and acid-treated algae were 31 and 35.2 mg Cr(VI) per g of dry adsorbent, respectively. Thermodynamic parameters showed that the adsorption of Cr(VI) onto algal biomass was feasible, spontaneous and endothermic under studied conditions. The pseudo-first-order kinetic model adequately describe the kinetic data in comparison to second-order model and the process involving rate-controlling step is much complex involving both boundary layer and intra-particle diffusion processes. The physical and chemical properties of the biosorbent were determined and the nature of biomass-metal ions interactions were evaluated by FTIR analysis, which showed the participation of -COOH, -OH and -NH(2) groups in the biosorption process. Biosorbents could be regenerated using 0.1 M NaOH solution, with up to 75% recovery. Thus, the biomass used in this work proved to be effective materials for the treatment of chromium bearing aqueous solutions.
authors.affiliation: Department of Chemistry, Indian Institute of Technology Roorkee, Roorkee 247 667, India. vinodfcy@iitr.ernet.in
authors.forename: V K
authors.initials: VK
authors.lastname: Gupta
authors.forename: A
authors.initials: A
authors.lastname: Rastogi
mesh_terms: D000143:Acids / Q000494:pharmacology*; D000460:Chlorophyta / Q000187:drug effects* / Q000378:metabolism*; D002857:Chromium / Q000378:metabolism*; D004058:Diffusion; D006863:Hydrogen-Ion Concentration; D012996:Solutions; D013696:Temperature; D013816:Thermodynamics; D013997:Time Factors
chemical_list: D000143:Acids; D012996:Solutions; D002857:Chromium; C074702:chromium hexavalent ion