Use este identificador para citar ou linkar para este item: https://locus.ufv.br//handle/123456789/22048
Tipo: Artigo
Título: Aqueous two-phase systems of copolymer L64 + organic salt + water: Enthalpic L64–salt interaction and Othmer–Tobias, NRTL and UNIFAC thermodynamic modeling
Autor(es): Andrade, Vivianne Molica de
Rodrigues, Guilherme Dias
Carvalho, Raquel Moreira Maduro de
Silva, Luis Henrique Mendes da
Silva, Maria C. Hespanhol da
Abstract: Phase diagrams of two-phase systems (ATPS) composed by the triblock copolymer L64 + organic salt (sodium tartrate, sodium succinate, sodium citrate, or ammonium citrate) + water, at different temperatures (278, 288, and 298 K) are presented in this work. Contrary to behavior of ATPS formed by inorganic salts, the study of the temperature influence in the liquid–liquid equilibrium behavior of L64–organic salts ATPS showed an exothermic character for phase separation process. Microcalorimetric measurements showed that this phase separation energy is around −0.2 kJ mol−1 for all organic salts. The module of slope of tie line (STL) tends to increase with an increase in temperature. The cation nature effect showed that the salt Na3C6H5O7 was more effective in promoting phase separation than (NH4)3C6H5O7. The capacity of the different anions tested for inducing ATPS formation with L64 followed the order: C6H5O73− > C4H4O62− > C4H4O42−. Because the salt–L64 interaction energy to be very similar, the cation and anion effects on the phase separation could be attribute to a process driven by entropy. The interaction parameters of the NRTL and UNIFAC models were estimated through the experimental data of all ternary systems. The results of the NRTL (with 64 tie-lines) and UNIFAC (with 27 tie-lines) were considered excellent with global root mean square deviations, respectively, of the 1.04% and 0.87%. The consistencies of the all tie-line experimental compositions were improved by applying the Othmer–Tobias correlation.
Palavras-chave: Enthalpic interaction
Thermodynamic modeling
Aqueous two-phase system
Triblock copolymer
Microcalorimetry
Editor: Chemical Engineering Journal
Tipo de Acesso: Elsevier B. V.
URI: https://doi.org/10.1016/j.cej.2011.03.015
http://www.locus.ufv.br/handle/123456789/22048
Data do documento: 15-Jun-2011
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