Adsorption of chromium(VI) ions on Brazilian smectite: Effect of contact time,pH, concentration,and calorimetric investigation |
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Authors: | Denis L Guerra Helen CP Oliveira Paulo C Corrêa da Costa Rúbia R Viana Claudio Airoldi |
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Institution: | 1. Universidade Federal de Mato Grosso, DRM-UFMT, Mato Grosso, 78060 900, Brazil;2. Universidade Estadual do Norte Fluminense, UENF, Rio de Janeiro, 28013 602, Brazil;3. Chemistry Institute, State University of Campinas, P. O. Box 6154, 13084-971 Campinas, São Paulo, Brazil |
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Abstract: | The original smectite clay mineral has been collected from Amazon region, Brazil. The compound 2-aminomethylpyridine (AMP) was anchored onto Amazon smectite surface by heterogeneous route. The natural (SMC) and modified (SMCAMP) smectite samples were characterized by elemental analysis, scanning electron microscopy, N2 adsorption, X-ray diffraction, and silicon-29 and carbon-13 nuclear magnetic resonance. Due to the increment of basic centers attached to the pendant chains, the metal adsorption capability of the final chelating material, was found to be higher than the precursor. The ability of these materials to remove Cr(VI) from aqueous solution was followed by a series of adsorption isotherms at room temperature and pH 4.0. The maximum number of moles adsorbed was determined to be 1.16 and 1.87 mmol g− 1 for SMC and SMCAMP, respectively. In order to evaluate the clay samples as adsorbents in dynamic system, a glass column was fulfilled with clay samples (1.0 g) and it was fed with 2.0 × 10− 4 mol dm− 3 Cr(VI) at pH 4.0. The energetic effects caused by metal cation adsorption were determined through calorimetric titrations. Thermodynamics indicated the existence of favorable conditions for such Cr(VI)–nitrogen interactions. |
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Keywords: | Smectite Chromium Adsorption Dynamic adsorption procedures Calorimetry |
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