Liquid Membrane Based Technology for Removel of Pollutants from Wastewater

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Liquid membrane (LM) technology has drawn attention of the research community since the early D90s 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 lignosulfonate (LS) and mercury (II) from their aqueous solutions. A suitable LM that can extract the said solutes is identified through equilibrium study. Experimentation with various solvents and carrier agents reveal that the dichloroethane (solvent) and trioctylamine (carrier) are the best combination for separation of the LS and Hg(II). The performance of various LM based processes viz. in the area of bulk liquid membrane (BLM), supported liquid membrane (SLM) and emulsion liquid membrane (ELM) in the separation of LS and mercury using the identified LM is then investigated. Coupled transport of LS and coupled transport of mercury through BLM is carried out to identify the best set of operating conditions and mode of transport that would yield optimum performance of the BLM. The effects of operating conditions, viz. pH, temperature, carrier concentration, stirring speed, initial feed and strip phase concentrations on the transport of LS as well as on mercury are investigated and optimized. Co-transport mode of transfer is found to be more efficient in comparison to counter-transport mode so far as recovery is concerned. It is understood that LM based transport is highly dependent on feed phase pH. The optimized values of pH, carrier concentration and stirring speed in BLM are 2, 4% (v/v) and 500 rpm for LS and 2.5, 1.5%(v/v) and 500 rpm for mercury respectively. The study of LM was continued with a flat sheet supported liquid membrane (FSSLM). The SLM combination DNylon 6,6-TOA-dichloroethaneD was found to be the suitable for both separation of LS and separation of mercury(II). The SLM is found to be stable till 10 hours. It is observed that extraction of LS is increased with increase in concentration of NaOH up to...
Supervisors: A. K. Ghosal and P. K.Saha