Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
5350881 | Applied Surface Science | 2014 | 8 Pages |
Abstract
Kinetics and thermodynamics of mercury ions sorption onto ZnCl2-MCM-41 sorbent were studied. Several rate models in the form of two main classes of mathematic kinetic models (adsorption reaction models and adsorption diffusion models) were investigated. Pseudo-first-order, pseudo-second-order, Elovich, film and intraparticle diffusion models were used to analyze the kinetic data. Results showed that the pseudo-second order model can well describe the adsorption kinetic data. The thermodynamic parameters, such as Gibb's free energy change (ÎG°), standard enthalpy change (ÎH°) and standard entropy change (ÎS°) were also evaluated. Negative value of free energy at temperature range of 20-55 °C, indicates the spontaneous nature of Hg(II) sorption by ZnCl2-MCM-41 sorbent. The adsorption capacity which was found to decrease with temperature showed the exothermic nature of the mercury sorption process (ÎH° = â49.4 kJ molâ1). The negative ÎS° value (â148.9 J molâ1 Kâ1) revealed a decrease in the randomness at the solid/solution interface and also indicated the fast adsorption of the Hg(II) onto active sites.
Related Topics
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Authors
Foad Raji, Majid Pakizeh,