Fabrication and characterization of polyvinyl alcohol asymmetric membrane supported by polyvinylidene fluoride for dehydration of ethanol via pervaporation
Membran asimetri poli(vinil alcohol)-tiub nano karbon dinding berlapis/polyvinylidene fluorida/fabrik tanpa tenun (PVA-MWCNT/PVDF/Non-woven) telah dihasilkan untuk proses dehidrasi bagi larutan ethanol (95 wt. % ) dan air (5 wt. %) pada 30 °C melalui penyahhidratan. Tiub nano karbon dinding berlapis yang telah difungsikan dengan kumpulan karboksil (-COOH) telah ditambah ke dalam membran poli(vinil alkohol) sebagai pengisi nano untuk meningkatkan kebolehlarutan dan daya resap antara molekul air dan membran. Lapisan berliang polyvinylidene fluorida telah digunakan sebagai lapisan sokongan bagi membran poli(vinil alkohol) untuk meningkatkan kekuatan mekanik membran. Polimer poli(vinil alkohol) telah ditetapkan di dalam berliang lapisan polyvinylidene fluorida untuk meningkatkan keutuhan struktur membrane melalui proses penurasan. Keputusan ujian tegangan menunjukkan bahawa kekuatan mekanik membran PVA-MWCNT/PVDF/Non-woven telah ditingkatkan. Regang tegangan membran PVA-MWCNT/PVDF/Non-woven telah dikurangkan sebanyak 14 % manakala tegangan tarik ultimat telah ditingkatkan sebanyak 18 %. Apabila membran PVA-MWCNT/PVDF/Non-woven diuji dengan larutan ethanol (95 wt. %) dan air (5 wt. %) dalam ujian pengampulan, sebanyak 15 % kekurangan dalam darjah pengampulan telah dicatat. Dari segi proses penyahhidratan pula, Tiub nano karbon dinding berlapis telah meningkatkan kadar pemisahan sebanyak 4 kali ganda. Namun begitu, fluks telap bagi membran PVA-MWCNT/PVDF/Non-woven merupakan 10 % bagi membran PVA/PVDF/Non-woven sahaja.
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The asymmetric PVA-MWCNT/PVDF/Non-woven membrane is fabricated for dehydration of 95 wt. % aqueous ethanol solution at 30 °C via pervaporation. The functionalized MWCNT containing carboxyl groups (-COOH) functional groups are incorporated in the PVA membrane as hydrophilic nanofillers to enhance the permeate flux and separation factor by increasing the solubility and diffusivity between water molecules and the pervaporation membrane. Besides, the porous PVDF layer is employed as the support layer for the PVA membrane, to increase the mechanical strength of pervaporation membrane. To further enhance the structural integrity of the membrane, the PVA polymer is immobilized into the porous sites of PVDF porous layer via vacuum filtration process. The results obtained from mechanical tensile test showed that the effectiveness of these modifications in improving the mechanical strength. In the presence of functionalized MWCNT, the strain before break of asymmetric PVA-MWCNT/PVDF/Non-woven membrane had reduced approximately 14 % from the values recorded for the asymmetric PVA/PVDF/Non-woven membrane while 18 % increase in tensile stress is observed. For swelling test, 15 % decrease in terms of swelling degree is observed when the asymmetric PVA-MWCNT/PVDF/Non-woven membrane is tested with 95 wt. % aqueous ethanol solution. Besides that, the presence of functionalized MWCNT as filler enhanced the separation factor by 4 folds during dehydration of 95 wt. % aqueous ethanol solution at 30 °C via pervaporation. However, the total flux obtained for the asymmetric PVA-MWCNT/PVDF/Non-woven membrane is only 10 % of the value obtained for the asymmetric PVA/PVDF/Non-woven membrane.
Fabrication and characterization of polyvinyl alcohol asymmetric membrane supported by polyvinylidene fluoride for dehydration of ethanol via pervaporation
Fabrication and characterization of polyvinyl alcohol asymmetric membrane supported by polyvinylidene fluoride for dehydration of ethanol via pervaporation / Tan Chee Yeang