COLL 268 |
| Heavy metals exist widely in industrial effluents such as those of metallurgy, tanneries, and mining areas. Such waters need to be purified before use through different physicochemical processes such as filtration, precipitation, reverse osmosis and sorption/ion exchange. Among these processes, sorption/ion exchange offers the best prospects for the overall treatment, especially for effluents which contain moderate or low concentrations of metal cations. This work investigated the sorption properties of the manganese dioxide in the presence of phosphate which is one of the most important complexes forming species. Solid manganese dioxide was characterized by surface area, point of zero charge, TG/DTA and SEM prior to sorption studies. Cd2+ sorption studies were carried out on manganese dioxide as a function of pH, temperature and phosphate concentration. Cd2+ sorption increased with increasing pH, temperature and phosphate concentration. Phosphate formed both outer and inner sphere complexes on the oxide surfaces. In addition, Cd2+ form ligand-like complexes at lower pH while metal-like complexes at higher pH with oxide surfaces in the presence of phosphate. Langumiur equation fit well to the sorption data. From the constants of this equation different thermodynamic parameters such as DG°, DH° and DS° were evaluated. |
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The Physical Chemistry of Environmental Interfaces
6:00 PM-8:00 PM, Monday, April 7, 2008 Morial Convention Center -- Rm. 244/245, Poster
Division of Colloid & Surface Chemistry |