Removal of Lead and Cadmium Ions from Aqueous Solution by Polyvinyl Alcohol-Modified Kaolinite Clay: A Novel Nano-Clay Adsorbent
Kaolinite clay was modified with polyvinyl alcohol (PVA) to obtain a PVA–nano-clay adsorbent. X-Ray diffraction measurements of the adsorbent showed no observable change in the d-spacing of its crystal lattice. Scanning electron microscopy of the PVA-modified nano-clay adsorbent indicated the presen...
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| Main Authors: | , , , |
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| Format: | Article |
| Language: | English |
| Published: |
SAGE Publishing
2008-07-01
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| Series: | Adsorption Science & Technology |
| Online Access: | https://doi.org/10.1260/0263-6174.26.6.383 |
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| Summary: | Kaolinite clay was modified with polyvinyl alcohol (PVA) to obtain a PVA–nano-clay adsorbent. X-Ray diffraction measurements of the adsorbent showed no observable change in the d-spacing of its crystal lattice. Scanning electron microscopy of the PVA-modified nano-clay adsorbent indicated the presence of irregular crystal structures. Infrared spectroscopy suggested that the PVA–nano-clay adsorbent basically possessed outer –OH functional groups. This adsorbent was found to have an adsorption capacity of 56.18 mg/g for Pb 2+ ions and 41.67 mg/g for Cd 2+ ions. The adsorption data obtained was well explained by the Diffuse Layer Model (DLM), which implies that the adsorption of both metal ions onto the modified adsorbent was via an inner-sphere surface complexation mechanism. The ΔH 0 values for the adsorption of both metal ions onto the PVA–nano-clay were −12.48 kJ/mol for Pb 2+ ions and −13.49 kJ/mol for Cd 2+ ions, with both ions exhibiting negative adsorption entropies. Data-fitting indicated that both the PVA–nano-clay and the unmodified adsorbent possessed homogeneous and heterogeneous adsorption sites. Virtually complete desorption (ca. 99%) of both metal ions occurred from PVA–nano-clay within 3 min. |
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| ISSN: | 0263-6174 2048-4038 |