Termodinâmica e otimização da transferência de norbixina em sistemas aquosos bifásicos

• Autor(a) principal: Senra, Tonimar Domiciano Arrighi
• Data de Publicação: 2010
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/2126
• topic: Termodinâmica de partição; Norbixina; Purificação; Sistemas aquosos bifásicos; Thermodynamics partition; Norbixin; Purification; Aqueous two-phase systems; CNPQ::CIENCIAS EXATAS E DA TERRA::QUIMICA::FISICO-QUIMICA

Partition of natural dye norbixin have been studied in aqueous biphasic systems formed by mixing solutions of polymer or copolymer with an aqueous solution of salt (sodium tartrate or succinate). The partition coefficient of dye norbixin, , was investigated as a function of pH, polymer molecular weight, hydrophobicity, Tie-Line Length (TLL) of the system and nature of the electrolyte. Using a face-centered central composite design (CCF) it was determined the optimum conditions for the partitioning process of the norbixin, where it was found that this phenomenon is higly dependent on the nature of the electrolyte, polymer hydrophobicity and values of TLL. Values between 8 and 130 were found, indicating the potential of ATPS as a method of pre-concentration/purifying dye norbixin. The molecules of norbixin concentrated on polymer-rich phase indicating a specific interaction enthalpy between the solute and pseudo-polycation, which is formed by the cation adorption along the polymer chain. Thermodynamic parameters of transfer (ΔtrG, ΔtrH e ΔtrS) indicate that the preferencial concentration of norbixin the top phase is favored by enthalpic and entropic factors, since both contribute to a reduction for the Gibbs free energy of the system.