title: Adsorption of Zinc(II) on diatomite and manganese-oxide-modified diatomite: a kinetic and equilibrium study.
abstract: The removal of Zn(II) ions from aqueous solution was studied using natural and MnO(2) modified diatomite samples at different temperatures. The linear Langmuir, Freundlich and Dubinin-Radushkevich (D-R) adsorption equations were applied to describe the equilibrium isotherms. From the D-R model, the mean adsorption energy was calculated as >8 kJ mol(-1), indicating that the adsorption of Zn(II) onto diatomite and Mn-diatomite was physically carried out. In addition, the pseudo-first-order, pseudo-second-order and intraparticle diffusion models were used to determine the kinetic data. The experimental data were well fitted by the pseudo-second-order kinetic model. Thermodynamic parameters such as the enthalpy (ΔH(0)), Gibbs' free energy (ΔG(0)) and entropy (ΔS(0)) were calculated for natural and MnO(2) modified diatomite. These values showed that the adsorption of Zn(II) ions onto diatomite samples was controlled by a physical mechanism and occurred spontaneously.
authors.affiliation: Department of Physical Chemistry, Faculty of Science, Yüzüncü Yıl University, Van 65080, Turkey. ncaliskan7@hotmail.com
authors.forename: Necla
authors.initials: N
authors.lastname: Caliskan
authors.forename: Ali Riza
authors.initials: AR
authors.lastname: Kul
authors.forename: Salih
authors.initials: S
authors.lastname: Alkan
authors.forename: Eda Gokirmak
authors.initials: EG
authors.lastname: Sogut
authors.forename: Ihsan
authors.initials: I
authors.lastname: Alacabey
mesh_terms: D000327:Adsorption; D007692:Diatomaceous Earth / Q000737:chemistry*; D007700:Kinetics; D017895:Manganese Compounds / Q000737:chemistry*; D008962:Models, Theoretical; D010087:Oxides / Q000737:chemistry*; D013816:Thermodynamics; D015032:Zinc / Q000737:chemistry*
chemical_list: D017895:Manganese Compounds; D010087:Oxides; D007692:Diatomaceous Earth; C027424:manganese oxide; C033787:diatomite; D015032:Zinc