Adsorption of thorium cation on modified clays MTTZ derivative

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Diquite (D) and bentonite (B) mineral samples from the Amazon region, Brazil. were modified by MTTZ derivative (5-mercapto-1-methyltetrazole) using heterogeneous route. These materials were characterized by textural and elemental analysis, transmission electron microscopy (TEM), power X-ray diffraction and (13)C NMR spectroscopy. The chemically modified clay (D(MTTZ) and B(MTTZ)) samples showed modification of its physical-chemical properties including: specific area 41.4 (B) to 398.5 m(2) g(-1) (B(MTTZ)) and 25.0 (D) to 178.8 m(2) g(-1) (D(MTTZ)). The adsorption experiments performed under batch process with Th(IV) concentration, pH and contact time as variables. The ability of these materials to remove thorium from aqueous solution was followed by a series of adsorption isotherms adjusted to a Sips equation at room temperature and pH 2.0, with variable concentration of Th(IV). The maximum number of moles adsorbed was determined to be 10.45 x 10(-2) and 12.76 x 10(-2) mmol g(-1) for D(MTTZ) and B(MTTZ), respectively. The energetic effects (Delta(int)H degrees, Delta(int)G degrees and Delta(int)S degrees) caused by thorium cation adsorption were determined through calorimetric titrations. (C) 2009 Published by Elsevier B.V.1684170015041511Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP