Adsorptive removal of cadmium by natural red earth : equilibrium and kinetic studies
Natural red earth (NRE), an iron-coated sand found in the north western part of Sri Lanka, was used to examine the retention behaviour of cadmium, a heavy metal postulated as a factor of chronic kidney disease in Sri Lanka. Adsorption studies were conducted as a function of pH, ionic strength, initi...
| Veröffentlicht in: | Environmental technology. - 1998. - 33(2012), 4-6 vom: 16. Feb., Seite 597-606 |
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| Weitere Verfasser: | , , |
| Format: | Aufsatz |
| Sprache: | English |
| Veröffentlicht: |
2012
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| Zugriff auf das übergeordnete Werk: | Environmental technology |
| Schlagworte: | Journal Article Research Support, Non-U.S. Gov't Water Pollutants, Chemical Cadmium 00BH33GNGH Silicon Dioxide 7631-86-9 |
| Zusammenfassung: | Natural red earth (NRE), an iron-coated sand found in the north western part of Sri Lanka, was used to examine the retention behaviour of cadmium, a heavy metal postulated as a factor of chronic kidney disease in Sri Lanka. Adsorption studies were conducted as a function of pH, ionic strength, initial Cd loading and time. The Cd adsorption increased from 6% to 99% with the pH increase from 4 to 8.5. The maximum adsorption was reached at pH > 7.5. Cadmium adsorption was not changed over 100-fold variations of NaNO3, providing evidence for the dominance of an inner-sphere bonding mechanism for both 10-fold variation of initial Cd concentrations. Surface complexation modelling suggests a monodentate bonding mechanism. Isotherm data were fairly fitted to a two-site Langmuir isotherm model and sorption maximums of 9.11 x 10(-6) and 3.89 x 10(-7) mol g(-1) were obtained for two surface sites. The kinetic study reveals that Cd uptake by NRE is so fast that the equilibrium was reached within 15 min and - 1 h for 4.44 and 44.4 microM initial Cd concentrations, respectively, and the chemisorption was the dominant mechanism over intra-particle diffusion. The study indicates the potential of NRE as a material for decontaminating environmental water polluted with Cd |
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| Beschreibung: | Date Completed 28.06.2012 Date Revised 21.11.2013 published: Print Citation Status MEDLINE |
| ISSN: | 0959-3330 |