Faculty Publications
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Item Densities and viscosities of polyethylene glycol 6000 + triammonium citrate + water systems(2009) Iyyaswami, I.; Govindarajan, R.; Amaresh, S.P.; Murugesan, T.The densities and viscosities of binary and ternary solutions of the aqueous two-phase systems created by the polyethylene glycol 6000 + triammonium citrate + water system were measured at different temperatures [(25, 30, 35, 40, and 45) °C] and correlated with empirical equations. The density data were compared with those available in the literature. The density data show a linear variation with the mass fraction of the polymer for all temperatures. The density and viscosity of the top and bottom phases were also measured and reported. © 2009 American Chemical Society.Item Liquid-liquid equilibrium of poly(ethylene glycol) 2000 + diammonium hydrogen citrate + water system at different temperatures(2011) Iyyaswami, I.; Srikanth, C.K.; Sindhu, N.Phase diagrams and liquid-liquid equilibrium (LLE) data of the aqueous poly(ethylene glycol) (PEG-2000) + diammonium hydrogen citrate system (aqueous two-phase system) has been determined experimentally at (298.15, 303.15, 308.15, 313.15, and 318.15) K. The effects of temperature on the binodal curve and tie-lines have been studied. The binodal curve was fitted to an empirical equation relating the concentrations of PEG 2000 and diammonium hydrogen citrate, and the coefficients were estimated for the respective temperatures. Tie line compositions were estimated and correlated using Othmer-Tobias and Bancroft equations, and the parameters are reported. The effect of temperature on the phase-forming ability in the investigated system has been studied based on a salting-out coefficient; obtained from fitting the binodal data to a Setschenow-type equation for each temperature. The effective excluded volume values were also calculated from the binodal data. © 2011 American Chemical Society.Item Development and Evaluation of PEG-Lithium Citrate Salt Based Aqueous Two Phase System and Its Application in Partitioning of Proteins from Fish Industry Effluent(2012) Iyyaswami, I.; Belur, P.D.; Girish, B.; Nagaraj, V.H.A aqueous two phase system (ATPS) comprising of PEG (Average mol. Wt: 4000, 6000, 8000) - lithium citrate salt-water systems were studied. The basic studies like binodal curve data generation and equilibrium studies were carried out. Furthermore, the binodal model and Othmer-Tobias and Bancroft models for phase equilibria were used for reproducing the experimental binodal data and phase equilibrium composition data, respectively. Good agreement was obtained with the experimental binodal data and tie line data with the models. The effective excluded volume values were obtained from the binodal model for the present ATPS. The tie line length was determined through the phase equilibrium composition data. This system was used to partition crude proteins of the fish industry effluent. The effects of PEG and salt weight fraction in terms of tie line length and effective excluded volume on partitioning coefficient of crude protein were studied in detail. From the results it was observed that, the crude proteins present in the fish effluent were partitioned in the PEG rich phase and the maximum partition coefficient of 7.82 was obtained. The results are discussed in the context of practical potential of this citrate based ATPS in separating crude proteins from fish industry effluent. © 2012 Copyright Taylor and Francis Group, LLC.Item Densities and viscosities of binary and ternary mixtures and aqueous two-phase system of poly(ethylene glycol) 2000 + diammonium hydrogen citrate + water at different temperatures(2012) Kalaivani, S.; Srikanth, C.K.; Iyyaswami, I.The densities and viscosities of aqueous solutions of poly(ethylene glycol) (PEG-2000) and diammonium hydrogen citrate were determined for mass fractions from 0.05 to 0.5 at different temperatures of (298.15, 303.15, 308.15, 313.15, and 318.15) K. The density data show a linear variation with mass fraction of the polymer and salt for all temperatures. The viscosity data of PEG 2000 and diammonium hydrogen citrate solutions were correlated as a function of mass fraction, using a nonlinear equation, for the five different temperatures covered in the present work. Densities and viscosities of PEG-diammonium hydrogen citrate two-phase systems have also been measured at (298.15, 303.15, 308.15, 313.15, and 318.15) K and are correlated with composition. The tie-line lengths (TLL) of the aqueous two-phase systems have also been estimated. © 2012 American Chemical Society.Item Phase demixing studies in aqueous two-phase system with polyethylene Glycol (PEG) and sodium citrate(2013) Nagaraja, V.H.; Iyyaswami, I.The kinetics of phase demixing in an aqueous two-phase system (ATPS) consisting of PEG/sodium citrate, with various PEG molecular weights (2000, 4000, and 6000) was investigated at 25°C. The rate of demixing of the phases (top/bottom) is essential to scale up the aqueous two-phase extraction (ATPE) process. The individual phase physical properties like density, viscosity, and interfacial tension are highly dynamic with the phase composition, and are responsible for the demixing of phases. Hence, in the present study, the variation of physical properties with phase compositions in terms of tie line length (TLL) was considered for the analysis of the rate of demixing of phases. The effect of the volume ratio of the phases (top/bottom) on the kinetics of phase separation also studied since the dispersed phase holdup in the mixture influences the rate of demixing. The higher TLL with a salt-rich phase as continuous phase showed higher reduction in demixing time when than low TLL at the volume ratio of <1. Based on the analysis, empirical correlations were proposed for top and bottom phase demixing rate in terms of Morton's number, volume ratio, and TLL. The coefficients and constants from the literature and the present correlations were estimated through regression analysis. The developed correlation predicted the demixing rate with lower AARD (±7%) for both the phases. The proposed correlation was accurate and simple in predicting the demixing rate of PEG/sodium citrate ATPS at 25°C. © 2013 Copyright Taylor and Francis Group, LLC.Item Partitioning studies of glutaminase in polyethylene glycol and salt-based aqueous two-phase systems(2013) Bolar, S.; Belur, P.D.; Iyyaswami, I.The partitioning behavior of glutaminase produced from Zygosaccharomyces rouxii in polyethylene glycol (PEG)-salt aqueous two-phase systems (ATPSs) was investigated. ATPSs comprising of different PEG-salts were considered. Binodal data and tie lines generated for the selected systems were analyzed and correlated with Othmer-Tobias and Bancroft equations. Effects of salt type, PEG molecular weight, concentrations of phase components, and tie line length on enzyme partitioning were evaluated. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.Item Partitioning studies of ?-lactalbumin in environmental friendly poly (ethylene glycol) - Citrate salt aqueous two phase systems(2013) Kalaivani, S.; Iyyaswami, I.Aqueous two-phase systems (ATPS) formed by polymer and salt have been utilized to enrich the desired biomolecule into one of the phase with higher yield and purity. The eco-friendly, biodegradable poly ethylene glycol (PEG) and different citrate salts were chosen as ATPS phase components to investigate the partitioning behavior of ?-lactalbumin (?-La). System factors and process parameters such as type and concentration of salt, molecular weight and concentration of PEG, pH, temperature and the effect of additives were studied and the results are discussed in detail. PEG 1000-tri-potassium citrate system yields high partition coefficient of 20 with a better yield of 98 % in the top phase. The addition of NaCl as an additive and acidic pH lowers the yield of ?-La in the top phase. Influence of phase volume ratio (V r) on partitioning was studied and found that the partition coefficient remains almost constant along the tie line. High yield was achieved at a V r of 3.5 at the tie line length of 50.63 (%, w/w). © 2013 Springer-Verlag Berlin Heidelberg.Item 1-Hexyl-3-Methylimidazolium Chloride-Potassium Carbonate Aqueous Two Phase System: Equilibrium Characteristics and BSA Partitioning Behavior(Taylor and Francis Inc. 325 Chestnut St, Suite 800 Philadelphia PA 19106, 2014) Iyyaswami, I.; Monteiro, S.L.The partitioning behavior of the model protein (bovine serum albumin) was investigated in ionic liquid (1-hexyl-3-methylimidazolium chloride) -salt (potassium carbonate) based aqueous two phase system (ATPS). The phase diagram with binodal curve and tie lines for the selected ATPS was developed at different temperatures and analyzed through effective excluded volume (EEV) and Othmer-Tobias and Bancroft equations, respectively. The influence of various process parameters like the ionic liquid and salt concentration, system temperature, tie line length, phase volume ratio, and neutral salt addition on partition coefficient/extraction efficiency of BSA protein was evaluated. © 2014 Copyright Taylor & Francis Group, LLC.Item Recovery and Partial Purification of Bovine ?-Lactalbumin from Whey Using PEG 1000 – Trisdoium Citrate Systems(Taylor and Francis Inc. 325 Chestnut St, Suite 800 Philadelphia PA 19106, 2015) Sivakumar, K.; Iyyaswami, R.The extraction of ?-Lactalbumin (?-La) and ?-Lactoglobulin (?-Lg) from whey have been carried out in the Aqueous Two Phase System (ATPS) composed of PEG 1000 – tri sodium citrate. The suitable conditions for the simultaneous partitioning of ?-La into the top phase and ?-Lg in bottom phases was identified using the pure ?-La and ?-Lg. Maximum partition coefficient (k) of 16.67 was achieved for ?-La at the system condition of 28% (w/w) PEG 1000-14% (w/w) tri sodium citrate at pH 8 and 40°C, whereas in this condition k of ?-Lg is 0.27. 30% (w/w) whey loaded to this system yielded the maximum recovery of ?-La and ?-Lg. © , Copyright © Taylor & Francis Group, LLC.Item Synergistic extraction of ?-Lactalbumin and ?-Lactoglobulin from acid whey using aqueous biphasic system: Process evaluation and optimization(Elsevier, 2015) Kalaivani, S.; Iyyaswami, R.The present investigation focused on the simultaneous partitioning of ?-Lactalbumin (?-La) to the PEG rich phase and ?-Lactoglobulin (?-Lg) to the salt rich bottom phase from acid whey using polyethylene glycol 1000-trisodium citrate systems. The effect of Tie Line Length (TLL), pH, volume ratio and whey concentration on the proteins partitioning was evaluated. Further the Response Surface Methodology (RSM) was employed to analyze the synergistic and interactive effect of these variables (TLL, pH and whey loading) on the responses (recovery and purity of ?-La and ?-Lg). Optimum values of these variables were obtained for different goals through desirability based multi response optimization. A system of 54.12% (w/w) TLL with 30.6% (w/w) whey at pH 7.23 separates ?-La with 89% recovery and purity of 96% in the top phase, whereas that of ?-Lg in the bottom phase was 96% and 76% respectively. © 2015 Elsevier B.V.