Studies on the stability of a supported liquid membrane and its cleaning protocol

This paper is a logical continuation of the previous work published by Manna et al. in RSC Adv., 2014, 4, 26247. The referenced paper established a technique for the separation and recovery of trace amounts of bioactive catechins from tea extract and their subsequent iron complexation through a Flat Sheet Supported Liquid Membrane (FS-SLM). However the technique suffers problems such as instability and fouling of the membrane support. In this work, the issues related to the instability and fouling of the SLM have been investigated. The components of the process such as the solvent, aqueous phases, membrane support, electrolyte, surfactant etc. were extensively studied to detect the best operating condition that would yield a better stability. Critical displacement pressure differentials (Delta P-c) for the liquid membrane were determined. Thermodynamic aspects of emulsion formation were investigated with the addition of surfactants. Under the best conditions, the membrane was found to be stable for 120 hours with a flux (of catechin) of 23.34 x 10(-8) kg m(-2) s(-1). The best conditions for the FS-SLM were re-employed in a similar experiment using a hollow fiber supported liquid membrane (HF-SLM) module. An experimentally evolved membrane cleaning protocol is reported.s