For the first time pervaporation separation of miscible liquids have been investigated with three and five layered composite membranes with layers of Natural Rubber Latex (NRL) and layers of hydrophilic, hydrophobic or organophilic polymers which are placed on top of each other. NRL was used in all different types of the membranes, mixed with hydrophilic polymers in blend membranes and in a layer shape in the three or five layered composite membranes. Methyl Cellulose (MC), Carboxymethyl Cellulose (CMC) and Hydroxypropyl Methyl Cellulose (HMC) were used as hydrophilic polymers to increase the water selectivity of the membrane and in contrast, Ultra-High Molecular Weight Polyethylene (UHMWPE) and Polydimethylsilane were used to increase organic component selectivity in the membranes. These membranes were used to separate miscible liquid solutions including ethanolwater, propanol 2-water and acetone-waterT. he composition of organic componenti n the feed was varied within the range of 20 to 90% w/w. The temperature of operation was kept constant to 20'C. Scanning Electron Microscope (SEM) has been used to study the distribution of polymers within the membranes. Morphological features of the cross section and top surface of the membranes have been used to develop a probable mechanism of water or organic component transfer through the membrane. For the first time ever, DMTA technique has been used to identify the type of membranes which can be used to increase the water selectivity (by studying the changes in the glass transition temperatureo f the NRL, blend and compositem embranes). Both SEM and DMTA techniques have proved that the presence of hydrophilic polymers as in layer forms in the three or five layered composite membranes was the reason for good distribution of polymers throughout the membrane. It has been established that a very strong correlation exists between a good distribution of the polymer bridged clusters of rubber particles within the membrane and the maximum increase in water selectivity. The influence of using different types of alcohols (ethanol, propanol 2 and acetone) on the pervaporation separation performance of the membranes has been thoroughly examined. Using ethanol, having the lowest molecular weight as compared with the other solutions, leads to the best performance in pervaporation separation.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:486971 |
| Date | January 2007 |
| Creators | Jazebi-Zadeh, Mohammad Hossein |
| Publisher | University of East London |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://roar.uel.ac.uk/1270/ |
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