Influence of NaOH post-treatment on the pervaporation performance of PVA membranes
Date Issued
2004
Date
2004
Author(s)
Tsai, I-Wen
DOI
zh-TW
Abstract
In this study, two kinds of poly(vinyl alcohol) in different degrees of hydrolysis （86~89% and 98.5~99%）were used. The results of experiments demonstrate that if the dried poly(vinyl alcohol) membrane was immersed into a 2N NaOH solution bath, the hydrolysis would become more completely and the structure of the polymer chains would be rearranged which could make the membrane more hydrophobic.
The performances of the NaOH-treated membrane on perpavoration in ethanol aqueous solution, isopropanol aqueous solution, and tetrafluropropanol aqueous solution were tested. For a feed containing 70 wt% of isopropanol, the NaOH-treated membrane possessed a flux of 1500 g/m2-hr with a permeation containing 97 wt% of water. With a feed containing 70 wt% of ethanol, the flux was 2000 g/m2-hr and the permeation was 94 wt% of water. With a feed containing 90 wt% of tetrafluro- propanol, the flux was 320 g/m2-hr and the permeation was 94 wt% of water. The long-term test indicated that the prepared membrane could be stored in pure water for about 100 days which continuous swelling and still could keep a good separation performance in perpavoration.
In this study the in-situ IR spectrums of poly(vinyl alcohol) reacted with NaOH in various time were measured and recorded by FTIR microscope. From the spectrum results, the total reaction time in different depth of poly(vinyl alcohol) membrane could be estimated and the diffusivity of NaOH in poly(vinyl alcohol) membrane could be obtained.
Subjects
聚乙烯醇
滲透蒸發
poly(vinyl alcohol)
pervaporation
Type
thesis
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