Preparation of high flux hydrophobic composite membranes

Due to emerging scarcity of oil resources associated with increase in oil prices, it is acceptable that the fossil sources of our energy supplywill be gradually replaced by renewable substrates. It comprises of intermittent energy sources such as solar, wind, etc. Biomass energy is considered as one of the most immediate and important renewable source for several reasons. The most important is that biomass energy can contribute to sustainable development with reduction in the emission of greenhouse gases. Moreover, biomass energy has a potential to produce new employment opportunities especially in the rural areas of the developing countries. Ethanol represents one ofthe major important source of renewable energy. Fermentation is an attractive process to produce ethanol from renewable biomass. In order to improve the efficiency of ethanol fermentation it is convenient to remove the produced ethanol from the fermentation broth periodically, to reducethe inhibitory effect of excess ethanol concentration. Existing techniques applied for the recovery of ethanol from fermentation broth are vacuum distillation, solvent extraction, gas stripping and membrane pervaporation. Amongst all, pervaporation is one of the most significant technique for the recovery of ethanol from the fermentation broth. It has many advantages over other techniques such as energy saving, cost effectiveness, and ecofriendly process. Pervaporation process comprises of amembrane for separation. It is unit operation in which two components are separated by using either polymeric or inorganic membrane through thecombination of different permeation rates of the components. Commonly, vacuum is applied to the downstream side of the membrane since, evaporative phase change occurs. The separation membrane is the key element in pervaporation equipments. Many membrane materials are considered for the purpose of recovering ethanol from dilute fermentation broth. Amongst these, hydrophobic membrane materials such as polydimethylsiloxane (PDMS) is the promising option. Since, PDMS membranes are hydrophobic innature and has high diffusivity for the ethanol owing to its low Tg resulting from the free rotation of Si-O bond. Although, pure PDMS membranes are less efficient in ethanol recovery, their efficiency can be increased by incorporation of certain class of additives / fillers. Objective of the present proposal is to prepare hydrophobic PDMS composite membranes incorporated with fillers / additives for enhanced bio-ethanol recovery from the dilute fermentation broth. These composite membranes comprises of a porous layer ofan organolphilic polymer as a support, synthesized by phase inversion method (PIM). A thin film of dense PDMS polymer incorporated with hollow fillers such as (MOFs, Silicates, ZIFs, HS etc.) will be applied on the surface of porous support layer by using different techniques such as dip coating, spin coating etc. The nature of the fillers / additives to be incorporated in these membranes will be hollow centered with functional shells forming the outer part. The hollow central part will increase the permeability, while outer part with shells will act as sieve to increase the selectivity. These membranes will be characterized by different techniques (AFM, SEM, Contact angle etc.). The permeation study of these membranes will be performed in order to monitor their pervaporation performance using model ethanol feed solution. Finally, the membranes withbetter performance can be tested in actual bioethanol process with realistic feed solution. Owing to the dual nature of fillers / additivesincorporated in the membranes, these membranes will be tested in organic solvent nanofiltration and gas separation as well.nrpages: 156status: publishe