Mriganka Sekhar Manna

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 (ΔPc) 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 × 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

Iron complexation of pharmaceutical catechins through selective separation

Catechins, natural polyphenols from tea leaves are important building blocks in pharmaceutical industries due to their chemoprotective and cardioprotective effects. The concept of metal complexation of catechins is integrated with liquid membrane based selective separation technique for recovery of pharmaceutical catechins from natural bio-sources. This is first ever approach to amalgamate the complexation chemistry with engineering approach which is green and energy efficient.

Separation of toxic heavy metals from its aqueous solution using environmentally benign vegetable oil as liquid membrane

This paper presents an experimental investigation of simultaneous extraction and recovery of harmful heavy metals from the industrial wastewater through Bulk Liquid Membrane (BLM) based technology. The selective extraction and stripping are achieved through the transportation of two such heavy metals viz., lead and cadmium. The environmentally benign coconut oil is selected as solvent of the Liquid Membrane (LM) through two phase equilibrium studies. Same studies are performed to optimize various physico-chemical parameters, such as pH of feed phase, concentrations of feed and strip phases, temperature, speed of stirring of feed phase, run time (duration of extraction), concentration of carrier etc., on the extraction of cadmium. The performance of LM is enhanced with respect to run time by the use of a suitable extracting agent i.e. carrier. Three phase transportation studies are thereby conducted through BLM at the same optimized operating parameters obtained in two phase studies. The extraction and recovery are found to be 72% and 64%, respectively. Further experimentations through BLM were conducted for transportation of lead with the same set of operating parameters. Both the extraction (82%) and recovery (77%) are found comparatively higher for lead as opposed to that of cadmium.