title: Kinetics and equilibrium studies for the adsorption of Acid Red 57 from aqueous solutions onto calcined-alunite.
abstract: The adsorption of Acid Red 57 (AR57) onto calcined-alunite was examined in aqueous solution in a batch system with respect to contact time, pH and temperature. The first-order, pseudo-second-order kinetic and the intraparticle diffusion models were used to describe the kinetic data and the rate constants were evaluated. The experimental data fitted very well the pseudo-second-order kinetic model and also followed the intraparticle diffusion model up to 90 min. The Langmuir and Freundlich adsorption models were applied to describe the equilibrium isotherms and the isotherm constants were also determined. The equilibrium data are successfully fitted to the Langmuir adsorption isotherm. The Langmuir isotherm constant, K(L), was used to evaluate the changes of free energy, enthalpy and entropy of adsorption for the adsorption of AR57 onto calcined-alunite. The results indicate that calcined-alunite could be employed as low-cost material for the removal of acid dyes from textile effluents.
authors.affiliation: Department of Chemistry, Faculty of Arts and Science, Eskişehir Osmangazi University, 26480 Eskişehir, Turkey. stunali@ogu.edu.tr
authors.forename: Sibel
authors.initials: S
authors.lastname: Tunali
authors.forename: A Safa
authors.initials: AS
authors.lastname: Ozcan
authors.forename: Adnan
authors.initials: A
authors.lastname: Ozcan
authors.forename: Tevfik
authors.initials: T
authors.lastname: Gedikbey
mesh_terms: D000327:Adsorption; D017607:Aluminum Compounds / Q000737:chemistry*; D001391:Azo Compounds / Q000737:chemistry*; D004396:Coloring Agents / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D015394:Molecular Structure; D009281:Naphthalenes / Q000737:chemistry*; D017680:Potassium Compounds / Q000737:chemistry*; D012996:Solutions / Q000737:chemistry; D013431:Sulfates / Q000737:chemistry*; D013696:Temperature; D013816:Thermodynamics
chemical_list: D017607:Aluminum Compounds; D001391:Azo Compounds; D004396:Coloring Agents; D009281:Naphthalenes; D017680:Potassium Compounds; D012996:Solutions; D013431:Sulfates; C499746:acid red 57; C473131:alunite