Termodinâmica de formação de nanoagregados gerados pela interação entre o biopolímero xilana e diferentes surfatantes

• Autor(a) principal: Ferreira, Guilherme Max Dias
• Data de Publicação: 2012
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/2120
• topic: Termodinâmica; Microcalorimetria; Xilana; Surfatante; Thermodynamic; Microcalorimetry; Xylan; Surfactant; CNPQ::CIENCIAS EXATAS E DA TERRA::QUIMICA::FISICO-QUIMICA

Interaction between the xylan biopolymer and ionic surfactants (SDS, DSS and DoTAB) has been examined at different pH values by isothermal titration calorimetry technique. The thermodynamic parameters for these interactions were obtained from the results of the calorimetric titration curves. The pH did not affect the micellization process of studied surfactants. Values of ΔGmico remained almost constants at all pH values. Values of ΔΔGagg were negatives for all investigated conditions showing that the presence of the biopolymer made the aggregation process of the surfactant more favorable. The enthalpy changes associated with binding of surfactant to xylan, ΔHagg(int), were negatives for DoTAB and SDS. On the other hand, aggregation process between DSS and xylan was exothermic, associated to small biopolymer chain rehydration effect. Enthalpic titration curves for xylan-DoTAB interaction were not affected by pH changes, indicating that other interaction, different of electrostatic interactions, play an important role on the aggregation process between xylan and this surfactant.