Abstract
Sorptive removal of Co2+, Sr2+ and Cs+ from aqueous solution by phosphate-modified montmorillonite (PMM) was studied considering the influencing factors (initial metal ion concentrations, initial solution pH and temperature). The Freundlich, Langmuir and Dubinin-Radushkevich (DR) models were used to fit single-solute sorption data. The Freundlich model was the best, indicating heterogeneous surface property of PMM. The maximum sorption capacity (qmL) of Langmuir model was in the order of Cs+>Co2+>Sr2+. The mean sorption energy (E) values of DR model (<8kJ/mol) at pH 5 for all metals indicated physical sorption. However, Cs+ sorption mainly occurred by chemical sorption. In bi-solute competitive sorption, the sorption of one metal ion was suppressed by the presence of competing metal ion. The Sheindorf-Rebhun-Sheintuch (SRS) model, the extended Freundlich model (EFM), the modified extended Langmuir model (MELM) and the IAST-Freundlich model predicted the competitive sorption adequately. Sorptions of Co2+ and Sr2+ were strongly dependent on the initial solution pH but that of Cs+ was not. The calculated thermodynamic parameters such as {increment}H, {increment}S, and {increment}G showed that sorptions of Co2+ and Sr2+ onto PMM were endothermic, whereas that of Cs+ was exothermic and that all sorption occurred spontaneously.
Original language | English |
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Pages (from-to) | 336-346 |
Number of pages | 11 |
Journal | Desalination |
Volume | 276 |
Issue number | 1-3 |
DOIs | |
State | Published - 2 Aug 2011 |
Keywords
- Cesium
- Cobalt
- Competitive sorption
- Phosphate-modified montmorillonite
- Strontium