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Abbas Rahmani,Abbas Ali Rostami,Mohsen Pirdashti,Poorya Mobalegholeslam 한국화학공학회 2017 Korean Journal of Chemical Engineering Vol.34 No.4
Liquid-liquid equilibrium data for poly vinyl pyrrolidone (PVP) K30+K2HPO4+H2O system were measured at 298.15 K and different pH values (7.54, 8.05, and 9.47). A binodal curve was fitted to the Merchuk equation and the tie line compositions were fitted to both the Othmer-Tobias and Bancroft equations. The refractive indices and densities of several homogeneous binary and ternary solutions used for calibration were also measured within a range of 0-30 mass% of PVP and 0-50 mass% of K2HPO4. Then, the viscosities, densities, electrical conductivities, and refractive indices of binary (PVP K30+water; potassium phosphate+water) and ternary (PVP K30+potassium phosphate+ water) systems were measured and correlated at different pH values. The density data showed a linear variation of the polymer and salt mass fractions. The viscosity data of PVP K30 solutions were correlated as a function of the mass fractions by using a nonlinear equation. The effects of the tie line lengths on the densities and viscosities of the aqueous two-phase systems were represented. Also, the modified UNIFAC-NRF is used to calculate the phase equilibria of the mention system. The fitted binary interaction parameters of the model were reported.
Mohsen Pirdashti,Kamyar Movagharnejad,Abbas Ali Rostami,Behnia Shahrokhi 한국화학공학회 2017 Korean Journal of Chemical Engineering Vol.34 No.7
The current study employed response surface methodology (RSM) with a face-centered central composite design (CCD) to indicate the essential variables on the partition coefficient of guanidine hydrochloride (GuHCl) in the poly (ethylene glycol) (PEG)-phosphate aqueous two-phase system (ATPS). To evaluate the partition coefficients of GuHCl in the mentioned ATPS, the pH (7.0, 8.5 and 10.0), GuHCl concentration (1.0, 3.5 and 6.0% w/w), PEG molecular weight (2,000, 4,000 and 6,000 gmol−1) and PEG/potassium phosphate concentrations ratio were selected as independent variables. A quadratic model is suggested to find the impact of these variables. The suggested model has a strong harmony with the experimental data. The results of the model display that the GuHCl concentration and weight percent of the salt in feed have a large and small influence on the GuHCl partitioning.