Research Projects

Membrane based separation processes are well-established methods for treatment of ground and wastewater for desalination and removal of arsenic, fluoride, heavy metals, like, lead, organics like, phenol, etc. Removal of such small pollutants need energy intensive reverse osmosis (RO). However, use of nanofiltration (NF) would reduce the energy cost due to the increase in flux but compromising rejection. In order to increase the flux without affecting the solute rejection, functionalized materials are added during interfacial polymerization (either in aqueous or organic phase during thin film composite (TFC) formation) improving the desirable properties, like, membrane hydrophilicity, zeta potential, selective defects, etc. These materials include two dimensional nanomaterials, like, graphitic nitride, molybdenum disulfide, etc., other nanomaterials, like, hydroxyapatite, bismuth sulfide, etc., leading to thin film nanocomposite (TFN) membrane. Anti-bacterial properties of the membrane can be improved by adding conducting polymers, like, polyaniline, polypyrrole, polythiophene, etc., in the thin film composite layer. Although TFN membrane in flat sheet is reported recently, reports in hollow fiber configuration are rare. Additionally, studies on the effect of the conducting polymers in NF membrane are not attempted, either in flat or hollow fiber. Similarly, the use of hydroxyapatite or two dimensional material, like, borophene in NF membrane is not available. For these reasons, the current study is undertaken with the objectives: (i) use of functionalized materials, like, hydroxyapatite, bismuth sulfide, etc., and conducting polymers to produce the functionalized NF membrane (in flat and hollow fiber) with improved selectivity, surface potential, hydrophilicity and anti-bacterial properties; (ii) to address the fundamental understanding of the compatibility of the additives with the polymer and solvent; (iii) to develop the technology for spinning of NF grade hollow fiber; (iv) to quantify the transport of the pollutants, like, inorganics (arsenic, fluoride, lead, etc.) and organics (humic acid, phenol, aniline, etc.) from first principles through NF membrane for various real-life streams, like, wastewater and groundwater. This would be helpful in quantifying the fouling of the membrane, determination of cleaning cycle and finally, the membrane life. Once this project is successful, the country would have developed indigenous technology for preparation of functionalized NF hollow fiber membrane cartridge that is lacking currently. Further, the similar method can be extended for development of functional reverse osmosis grade hollow fiber that would have a lasting impact to the membrane industries worldwide.