Simultaneous Extraction and Recovery of Catechins using Liquid Membrane

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Liquid membrane (LM) technology has drawn attention of the research community since the early 90s and it has increased manifold in recent years. This thesis aims at exploring the efficacy of LM technology for the separation and pre-concentration of catechins from green tea leaves. A suitable LM that can extract the catechins is identified through equilibrium study. Experimentation with various solvents and carrier agents reveal that the sunflower oiltributyl phosphate (TBP) and n-decane-trybutyl phosphate (solvents) are two favorable combinations for recovery of the catechins. The performance of various LM based processes viz. in the area of bulk liquid membrane (BLM), flat sheet supported liquid membrane (FSSLM) and hollow fiber supported liquid membrane (HF-SLM) in the recovery of catechins using the identified membrane liquid (ML) is then investigated. The components of ML i.e. the solvent and the carrier were selected in two phase equilibrium studies. The distribution coefficient (D1) of catechin between the membrane phase and the aqueous feed phase provides the catechin extraction feasibility of the membrane phase. The stripping agents also selected through two phase equilibrium studies finding the distribution coefficient (D2) of catechin between aqueous stripping phase and the membrane phase. The various physico-chemical parameters like pH of aqueous solutions, concentration of carrier in the membrane phase, concentration of the catechin and the stripping agents in feed phase and stripping phase respectively, experimental temperature etc. were primarily evaluated in two phase equilibrium studies. The optimum parameters obtained in two phase equilibrium studies were later verified and improved in three phase transportation studies. The three phase transportation studies involve the diffusion step in between extraction and re-extraction or stripping of the catechin at the respective interfaces of the liquid membrane.
Supervisors: Aloke Kumar Ghoshal and Prabirkumar Saha