Adsorption of thorium(IV) on chemically modified Amazon clays

Abstract

Amostras de caulinita e esmectita oriundas da região Amazônica, Brasil, foram modificadas com 2-mercaptobenzimidazol (MBI) usando rotas homogênea e heterogênea. As amostras de argilas modificadas (K HOM, S HOM , K HET e S HET ) foram caracterizadas por análise textural, MEV e espectroscopia 13 C NMR. As argilas modificadas quimicamente apresentaram modificações em suas propriedades físico-químicas incluindo: área específica 48,0 (S) para 869,8 m 2 g -1 (S HET ). A habilidade destes materiais para remover tório(IV) em soluções aquosas foi investigada por um série de isotermas de adsorção ajustadas pela equação de Sips em temperatura ambiente e pH 2,0. O número máximo de mols adsorvidos foi determinado em 8,29,8,86,9,57 e 9,89 10 -1 mmol g -1 para K HOM , K HET , S HOM e S HET , respectivamente. Os efeitos energéticos causados pela adsorção do cation tório(IV) foram determinados através de metodologia calorimétrica.Kaolinite and smectite clay samples from the Amazon region, Brazil, were modified with 2-mercaptobenzimidazole (MBI) using homogeneous and heterogeneous routes. The modified clay samples (K HOM , S HOM , K HET and S HET ) were characterized by textural analysis, SEM and 13 C NMR spectroscopy. The chemically modified clay samples showed modifications of their physicalchemical properties including: specific area 48.0 (S) to 869.8 m 2 g -1 (S HET ). The ability of these materials to remove thorium(IV) from aqueous solution was followed by a series of adsorption isotherms adjusted to a Sips equation at room temperature, and pH 2.0. The maximum number of moles adsorbed was determined to be 8. 29, 8.86, 9.57 and 9.89 10 -1 mmol g -1 for K HOM , K HET , S HOM and S HET , respectively. The energetic effects (∆ int H, ∆ int G and ∆ int S) caused by thorium(IV) cation adsorption were determined through calorimetry.

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