| Summary: | 碩士 === 長庚大學 === 化工與材料工程學系 === 98 === This study was to prepare various materials for pervaporating ethanol solutions. The pure liquids, solubilities diffusion coefficients and pervaporation fluxes were measured. The tested materials included polydimethylsiloxane (PDMS), polyurethane (PU) and poly(vinylidene fluoride-co-hexafluoropropene) P(VDF-HFP).
The solubility selectivities form pure solvents using PDMS-1310, PDMS-3001, 90PU and P(VDF-HFP) of solubility selectivity for 15.97, 47.76, 21.69 and 16.97(ethanol over water) respectively. These membranes are hydrophobic and ethanol-selective. The diffusion selectivities were 0.30, 0.54, 0.56 and 0.46, respectively. The water molecule is smaller than the ethanol molecule, therefore water molecule diffuses faster than ethanol.
The pure solvent flux selectivities were for 2.84, 8.92, 4.34 and 6.99, respectively, for PDMS-3001, 90PU and P(VDF-HFP).
The PDMS-3001, 90PU and P(VDF-HFP) were used for pervaporation on 10 wt% ethanol solution. We found the ethanol normalized flux to be 1.15±0.025, 0.66 and 0.33 ×10-9 kg/ms with selectivities of 9.21, 6.29 and 3.77. PDMS-3001 had the best performance, so we used PDMS-3001 membrane to separate different concentrations of ethanol solutions. The PDMS-3001 was used to prepare composite membrane containing zeolite to separate ethanol solutions.
On 10 wt% ethanol solution, the separation factor increase with the zeolite content. Thus, we confirm zeolite addition can improve separate efficiency on ethanol solutions. With 30 wt% zeolite loading in PDMS-3001, the ethanol normalized flux was increased to 10.71 ± 0.75 ×10-9 kg/ms, with a selectivity of 12.45 ± 0.10.
Incorporation of zeolite post-addition PDMS-3001 A component and B component mixed (post-addition PDMS-3001 mixed) is better than zeolite pre-addition PDMS-3001 A component and B component mixed (pre-addition PDMS-3001 mixed).
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