The separation of ethanol-hexane mixtures by pervaporation

Ferreira, Juanita (1900)

Thesis (M. Sc.) -- University of Stellenbosch, 1990.

Thesis

ENGLISH ABSTRACT: Pervaporation experiments, using polyvinyl alcohol (PVA) and modified PVA membranes cast on permeable polyether sulfone substrates, were performed with ethanol-hexane mixtures. The modified PVA membranes comprised a specially synthesized and well defined series of poly(acrylic acid-co-vinyl alcohol-cohydroxyethyl- acrylate) terpolymers. Experimental variables were investigated. Variation of membrane thickness showed that at least two polymer layers were necessary. The effect of changing the binary feed ratio was that selectivity increased with increasing ethanol content. Pretreatment proved to be effective in terms of both flux and selectivity. Increasing hydrophilicity in the chemical structure of the membrane caused a decrease in the selectivity for ethanol, i.e. GFT-standard (3 300); GFT-wasserreich (270); Gantrez AN 119 (15); best synthesized terpolymer (2 200). These values were measured with a 5% ethanol mixture.

AFRIKAANSE OPSOMMING: Pervaporasie-eksperimente, poli(viniel alkohol) (PVA) en gewysigde PVAmembrane gegiet op deurlaatbare poli-eter sulfoon substrate, is uitgevoer met etanol-heksaan-mengsels. Die gewysigde PVA-membrane behels 'n spesiaal gesintetiseerde en goed gedefinieerde reeks van poli(akrielsuur-ko-viniel alkoholko- hidroksietiel akrilaat) terpolimere. Eksperimentele veranderlikes is ondersoek. Die variasie van membraandikte het getoon dat twee lae polimere voldoende is. Die invloed van veranderinge in die binere voerverhouding was dat die selektiwiteit toeneem met 'n toenemende etanol-inhoud. Die voorbehandeling was effektief ten opsigte van die vloed en selektiwiteit. Toenemende hidrofilisiteit in die chemiese struktuur van die membraan het 'n afname veroorsaak in die selektiwiteit ten opsigte van etanol byvoorbeeld GFT Standard (3 300); GFT-wasserreich (270); Gantrez AN 119 (15); die beste gesintetiseerde polimeer (2 200). Die waardes is verkry deur gebruik te maak van 'n 5%-etanolmengsel.

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