Faculty Publications
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Item Nonionic surfactants induced cloud point extraction of Polyhydroxyalkanoate from Cupriavidus necator(Taylor and Francis Inc. 325 Chestnut St, Suite 800 Philadelphia PA 19106, 2017) Murugesan, S.; Iyyaswami, R.Polyhydroxyalkanoate synthesized by Cupriavidus necator DSM 428 was purified from the crude fermentation broth as such by performing nonionic surfactants (Triton X100, Triton X114 & Tergitol 6) induced cloud point extraction. Polyhydroxyalkanoate was extracted into the micelle-rich bottom phase (coacervate phase), while most of the cellular impurities partitioned into the aqueous phase. Cloud point temperatures and the extraction efficiency of different cloud point systems were studied at different pH value and in the presence of additives. Maximum extraction of biopolymer was achieved (recovery of 84.4%) with a purity of 92.49% at 3 pH with the addition of 0.1 M ammonium chloride in the mixed surfactant system at a reduced cloud point temperature of 33°C. © 2017 Taylor & Francis.Item Low frequency sonic waves assisted cloud point extraction of polyhydroxyalkanoate from Cupriavidus necator(Elsevier B.V., 2017) Murugesan, S.; Iyyaswami, R.Low frequency sonic waves, less than 10 kHz were introduced to assist cloud point extraction of polyhydroxyalkanoate from Cupriavidus necator present within the crude broth. Process parameters including surfactant system variables and sonication parameters were studied for their effect on extraction efficiency. Introduction of low frequency sonic waves assists in the dissolution of microbial cell wall by the surfactant micelles and release of cellular content, polyhydroxyalkanoate granules released were encapsulated by the micelle core which was confirmed by crotonic acid assay. In addition, sonic waves resulted in the separation of homogeneous surfactant and broth mixture into two distinct phases, top aqueous phase and polyhydroxyalkanoate enriched bottom surfactant rich phase. Mixed surfactant systems showed higher extraction efficiency compared to that of individual Triton X-100 concentrations, owing to increase in the hydrophobicity of the micellar core and its interaction with polyhydroxyalkanoate. Addition of salts to the mixed surfactant system induces screening of charged surfactant head groups and reduces inter-micellar repulsion, presence of ammonium ions lead to electrostatic repulsion and weaker cation sodium enhances the formation of micellar network. Addition of polyethylene glycol 8000 resulted in increasing interaction with the surfactant tails of the micelle core there by reducing the purity of polyhydroxyalkanoate. © 2017 Elsevier B.V.Item Nonionic surfactant-based cloud point extraction of polyhydroxyalkanoate from the fermentation crude in a rotating disc contactor(Bellwether Publishing, Ltd., 2021) Murugesan, S.; Iyyaswami, R.; J Khandelwal, P.Nonionic surfactant-based cloud point extraction of polyhydroxyalkanoate from fermentation broth was implemented in a modified rotating disc contactor. The effect of rotor speed and phase flowrates on dispersed micellar phase holdup, mass transfer coefficient, yield, and purity were studied with micellar system contains TX114 (4.5 wt %)+ TMN6 (0.5 wt %) and 0.1 M ammonium chloride at broth pH of 3. The rotor speed and the micellar phase flowrate had a significant effect. A maximum PHA recovery of 85.48% and purity of 86.01% were achieved. The correlation was developed to predict the dispersed-phase holdup. © 2020 Taylor & Francis Group, LLC.