A study of the pervaporation of isopropyl alcohol/water mixtures by cellulose acetate membranes

Modified pore-flow model for pervaporation mass transport in PVDF hollow fiber membranes for ethanol–water separation

“…It is clearly observed during the experiment that the fibers showed no swelling in pure water but exhibited high swelling in pure ethanol. The same phenomenon has been reported in previous studies [48]. Based on the observations of membrane swelling; it appears that the liquid transport parameters calculated are also intrinsically influenced by the hydrophobicity and the swelling property of the resulting membrane.…”

“…This situation indicates that the assumption of the evaporation occurring at the pore inlet for the negation of the liquid transport parameter (A mix /ı), which has been commonly used to predict the total flux in previous studies [51], is not necessarily applicable to the PVDF hollow fiber membranes utilized in this study. This discrepancy may be due to the fact that most membranes used in earlier studies [23,37,48,51] possess mean pore sizes of less than 15å while the membrane pore sizes in this study are in the scale of nanometers. The ı a /ı ratio as mentioned previously can also be used to support the result.…”

“…For membranes with a higher selectivity, which usually consist of tiny or small pore size, the influence of Knudsen flow contribution in the modified pore-flow model can be neglected and the model transport equations will be reduced to be the same form as the pore-flow model. The predictability of pore-flow model has been proven through many previous studies [37,48,51] using membranes with a high selectivity made of different membrane materials (typical pore size is <1.5 nm) in various pervaporation applications.…”

Liquid Separation by Membrane Pervaporation: A Review

“…Besides the difference in vapor and liquid solubilities, an opposite sorption selectivity has been observed. A sorption study for the system isopropyl alcohol/water/cellulose acetate showed that isopropyl alcohol is preferentially sorbed from the liquid phase, while water is preferentially sorbed from the vapor phase (Deng et al, 1990). Although Blume et al's approach allows an intuitive illustration on how the separation factor changes due to the membrane relative to simple evaporation, it is difficult to make a reliable prediction of the pervaporation separation behavior.…”

Design of a continuous process for the production of highly substituted granular carboxymethyl starch

“…Pervaporation is an attractive method for the dehydration of organic liquids, the permeate is mainly water and the retentate has the speci"ed composition. In a literature study, the following types of membranes were compared: cellulose acetate (Deng, Shiyao, Sourirajan & Matsuura, 1990); Carboxymethyl cellulose (Atra, Vatai & BeH kaH ssy-MolnaH r, 1999); polyetherimide (Huang & Feng, 1993); ceramic (Van Gemert & Cuperus, 1995); zeolite-"lled PVA (Gao, Yue & Li, 1996); chitosan (Nawawi & Huang, 1997); and zeolite 4A (Jafar & Budd, 1997). The performance of a pervaporation unit depends on the #uxs and the selectivity.…”