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water-activity
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Calculation of the density and activity of water in ATPS systems for separation of biomolecules
, Article Journal of Solution Chemistry ; Volume 42, Issue 7 , 2013 , Pages 1423-1437 ; 00959782 (ISSN) ; Shirazian, S ; Pour, A. F ; Ziary, M ; Sharif University of Technology
2013
Abstract
In this study, the perturbed hard sphere chain equation of state is utilized to calculate the activity of water in binary and ternary solutions of polyethylene glycol (PEG), salt and water. The liquid density of the binary and ternary solutions is also predicted. To estimate the water activity in PEG-water binary systems, a linear correlation is obtained for the binary interaction parameter between water and PEG. Then, using this correlation and without introducing any additional binary parameters, the water activities are predicted in ternary solutions of water, salt and PEG with different molecular weights (MW). Our results show that the mean absolute average relative deviation (AARD %) of...
Prediction of hydrate formation for the systems containing single and mixed electrolyte solutions
, Article Iranian Journal of Chemistry and Chemical Engineering ; Volume 26, Issue 1 , 2007 , Pages 35-45 ; 10219986 (ISSN) ; Rashtchian, D ; Ghotbi, C ; Taghikhani, V ; Khayat, G ; Sharif University of Technology
Iranian Journal of Chemistry and Chemical Engineering
2007
Abstract
In this work the effect of electrolytes on hydrate formation was investigated. To do so, a new model was used in predicting the hydrate formation conditions in presence of both single and mixed electrolyte solutions. The new model is based on the van der Waals - Platteeuw hydrate equation of state. In order to evaluate the values for the activity of water in electrolyte solutions the simplified version of the Ghotbi-Vera Mean Spherical Approximation (SGV-MSA) model was used. According to the SGV-MSA model the ions in the solutions are considered as charged hard spheres with different sizes. The values of the parameters for the SGV-MSA model are independent of temperature and depend only on...
Measurement and correlation of vapor-liquid equilibria of the aqueous poly(ethylene glycol) + sodium citrate and poly(ethylene glycol) + potassium citrate systems
, Article Fluid Phase Equilibria ; Volume 262, Issue 1-2 , 2007 , Pages 137-148 ; 03783812 (ISSN) ; Zafarani Moattar, M. T ; Taghikhani, V ; Ghotbi, C ; Sharif University of Technology
Elsevier
2007
Abstract
In this study, water activities for the ternary systems of PEG6000 + sodium citrate (Na3Cit) + H2O and PEG6000 + potassium citrate (K3Cit) + H2O have been measured using an improved isopiestic method over the entire homogeneous mixing range at 298.15 K. From these measurements, values of the vapor pressure of solutions were also determined. The experimental data for the activity of water, collected in this work, were accurately correlated with local composition based models of the NRTL, modified NRTL, Wilson and modified Wilson. The results showed that these models can accurately correlate the water activity data generated in this work. © 2007 Elsevier B.V. All rights reserved