RESUMO
Lithium aluminates (LiAlO(2) and Li(5)AlO(4)) were synthesized, characterized, and tested as possible CO(2) captors. LiAlO(2) did not seem to have good qualities for the CO(2) absorption. On the contrary, Li(5)AlO(4) showed excellent behavior as a possible CO(2) captor. Li(5)AlO(4) was thermally analyzed under a CO(2) flux dynamically and isothermically at different temperatures. These results clearly showed that Li(5)AlO(4) is able to absorb CO(2) in a wide temperature range (200-700 degrees C). Nevertheless, an important sintering effect was observed during the thermal treatment of the samples, which produced an atypical behavior during the CO(2) absorption at low temperatures. However, at high temperatures, once the lithium diffusion is activated, the sintering effect did not interfere with the CO(2) absorption. Eyring's model was used to determine the activation enthalpies of the CO(2) absorption (15.6 kJ/mol) and lithium diffusion (52.1 kJ/mol); the last one is the limiting process.
Assuntos
Compostos de Alumínio/química , Dióxido de Carbono/química , Compostos de Lítio/química , Temperatura , Absorção , Compostos de Alumínio/síntese química , Compostos de Lítio/síntese química , Tamanho da Partícula , Fatores de Tempo , Difração de Raios XRESUMO
A new water-soluble lithium salt of thiazolidine-4-carboxylic acid was synthesized and characterized by chemical and spectroscopic techniques. Elemental and mass spectrometric (ESI-MS) analyses of the solid compound fit to the composition LiC(4)H(6)NSO(2). (1)H, (13)C nuclear magnetic resonance (NMR), [(1)H-(15)N] NMR and infrared (IR) analyses permitted to elucidate the structure of the compound. Biological activity was evaluated by cytotoxic analysis using HeLa cells. Determination of cell death was assessed using a tetrazolium salt colorimetric assay, which reflects the cells viability.