title: Cd (II) removal from aqueous solution by Eleocharis acicularis biomass, equilibrium and kinetic studies.
abstract: Batch experiments were carried out to determine the capacity of Eleocharis acicularis biomass to adsorb Cd(2+) ions from contaminated solutions with respect to pH, initial Cd(2+) concentration, contact time, solution ionic strength and biomass dose. The experimental data were modeled by Langmuir, Freundlich and Dubinin-Radushkevich (D-R) isotherm models. Freundlich and D-R models resulted in the best fit of the adsorption data. The maximum adsorption capacity for Cd(2+) was 0.299 mmol g(-1) (33.71 mg g(-1)) with efficiency higher than 80% (pH 6.0 and 5 g L(-1) biomass dose). The mean adsorption free energy value derived from the D-R model (8.058 kJ mol(-1)) indicated that adsorption was governed by an ionic exchange process. The pseudo-first order, pseudo-second order, Elovich kinetic models and the intra-particle diffusion models were used to describe the kinetic data and to evaluate rate constants. The best correlation was provided by the second-order kinetic model, implying that chemical sorption was the rate-limiting step, although intra-particle diffusion could not be ignored. The practical implication of this study is the development of an effective and economic technology for Cd(2+) removal from contaminated waters. The macrophyte biomass used in this study did not undergo any chemical or physical pre-treatment, which added to macrophyte abundance and its low cost makes it a good option for Cd(2+) removal from waste water.
authors.affiliation: Centro de Geociencias-Universidad Nacional Autónoma de México, Campus Juriquilla, Boulevard Juriquilla 3001, Queretaro 76230, Mexico. patovior@geociencias.unam.mx
authors.forename: Patricia
authors.initials: P
authors.lastname: Miretzky
authors.forename: Carolina
authors.initials: C
authors.lastname: Muñoz
authors.forename: Alejandro
authors.initials: A
authors.lastname: Carrillo-Chavez
mesh_terms: D001673:Biodegradation, Environmental; D018533:Biomass; D002104:Cadmium / Q000378:metabolism*; D031256:Eleocharis / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008800:Mexico; D008956:Models, Chemical; D014865:Waste Disposal, Fluid / Q000379:methods*; D014874:Water Pollutants, Chemical / Q000378:metabolism*; D018508:Water Purification / Q000379:methods*
chemical_list: D014874:Water Pollutants, Chemical; D002104:Cadmium