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Phase Compositions of Aqueous Two-Phase Systems Formed by L35 and Salts at Different Temperatures

2009; American Chemical Society; Volume: 55; Issue: 3 Linguagem: Inglês

10.1021/je900589h

1520-5134

Leandro Rodrigues de Lemos, Igor José Boggione Santos, Guilherme Dias Rodrigues, Gabriel Max Dias Ferreira, Luís Henrique Mendes da Silva, Maria do Carmo Hespanhol da Silva, Raquel Moreira Maduro de Carvalho,

Process Optimization and Integration

The phase compositions in liquid−liquid equilibria of aqueous two-phase systems (ATPS) composed of the poly(ethylene oxide)− poly(propylene oxide)−poly(ethylene oxide) (PEO−PPO−PEO) triblock copolymer L35 and various salt solutions (sodium carbonate, sodium succinate, sodium acetate, ammonium citrate, and ammonium sulfate) at several temperatures, (283.15, 298.15, and 313.15) K, are presented. The influence of temperature in the binodal position was pronounced for almost all of the ATPS's, with the phase-separation process being endothermic. Additionally, the slopes of the tie-lines (STL) tended to increase with increasing temperature. The capability of the various salts to induce formation of the biphasic system was evaluated and followed the order sodium carbonate > ammonium sulfate > sodium succinate > ammonium citrate > sodium acetate. The consistencies of the tie-line experimental compositions were confirmed by applying the Othmer−Tobias correlation, with excellent results, as shown by the regression coefficients acquired. The liquid−liquid equilibrium data of ternary systems have been correlated using the nonrandom two-liquid (NRTL) model for the activity coefficient. The results were considered very satisfactory with global root-mean-square deviations as low as 1.49 %.