title: Immobilization of 5-amino-1,3,4-thiadiazole-thiol onto kanemite for thorium(IV) removal: thermodynamics and equilibrium study.
abstract: The compound 5-amino-1,3,4-thiadiazole-thiol (ATT) was anchored onto an Amazon kanemite surface (K) by homogeneous and heterogeneous routes. Both kanemite modification methodologies resulted in similar products, named K(CTT) and K(ATT), respectively. The modified and natural kanemite samples were characterized by textural analysis, FT-Raman, and nuclear magnetic nuclei of (29)Si and (13)C. Elemental analysis proved that the matrix K(ATT) presented a higher ATT immobilization than K(CTT), with values 1.42 and 1.38 mmol g(-1), respectively. NMR and FT-Raman confirmed the immobilization of ATT on both surfaces. 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 4.0. The maximum number of moles adsorbed was determined to be 7.48x10(-3), 9.82x10(-3), and 12.94x10(-3) mmol g(-1) for K, K(CTT), and K(ATT), respectively. The energetic effects (Delta(int)H(o), Delta(int)G(o), and Delta(int)S(o)) caused by metal cation adsorption were determined through calorimetric titrations.
authors.affiliation: Chemistry Institute, State University of Campinas, P.O. Box 6154, 13084-971 Campinas, São Paulo, Brazil. dlguerra@iqm.unicamp.br
authors.forename: Denis L
authors.initials: DL
authors.lastname: Guerra
authors.forename: Marcos A
authors.initials: MA
authors.lastname: Carvalho
authors.forename: Victor L
authors.initials: VL
authors.lastname: Leidens
authors.forename: Alane A
authors.initials: AA
authors.lastname: Pinto
authors.forename: Rúbia R
authors.initials: RR
authors.lastname: Viana
authors.forename: Claudio
authors.initials: C
authors.lastname: Airoldi