Reverse Osmosis Separations of Some Inorganic Solutes in Ethanol Solutions Using Cellulose Acetate Membranes

Abstract

Reverse osmosis separations of 20 inorganic solutes from ethanol solutions were studied by using porous cellulose acetate membranes. The experimental results were analyzed by basic transport equations developed by Kimura and Sourirajan. On the basis of the above analysis the free energy parameters of ions were calculated and compared with the values obtained from water and methanol solvent systems. The study confirms that the difference in the free energy parameters among univalent cations and univalent anions is widened in the solvent of a lower dielectric constant; such an enhanced difference is further reflected in the increase of the difference among inorganic solute separations from the solvent of a lower dielectric constant. Consequently, fractionation of inorganic solutes can be performed more easily in ethanol solvent than in water and in methanol solvent.

Solvent and pH resistance of surface crosslinked chitosan/poly(acrylonitrile) composite nanofiltration membranes

“…This clearly indicates that swelling of membranes strongly depends on membranesolvent polar interactions. Farnand et al 6 have also emphasized the importance of dielectric constant of solvent on the performance of cellulose acetate reverse-osmosis membranes for separation of inorganic salts from water, methanol, and ethanol solutions. The trend in swelling of membranes with various solvents can also be correlated to solubility parameters of solvent (␦ s ) and membrane (␦ m ).…”

“…There are some studies on permeation of either pure solvents or solutions in organic solvents using commercial membranes. [5][6][7][8][9][10][11][12] Polymeric membranes after contact with organic solvent may result in one of the following: 13 (a) no chemical effect; (b) little swelling, membrane may be compatible for short-term use; (c) extensive swelling and slow dissolution of membranes; (d) complete dissolution or disintegration of membranes; or (e) the relaxation of polymer chains due to plasticization in solvent results in swelling with subsequent pore size reduction.…”

Cholesterol removal by nanofiltration: Applications in nutraceutics and nutritional supplements

“…The stability of a membrane in an organic solvent such as ethanol depends on the physicochemical characteristics of the solvent and of the membrane. The membrane-solvent interaction may result in swelling, plasticization or dissolution of the membrane material and subsequent loosening of the membrane structure, leading to modified separation properties and/or loss of mechanical strength under pressure [3][4][5][6][7][8]. Besides, the cut-off of a membrane determined in aqueous solutions (e.g., as provided by the manufacturer) is insufficient to characterize its MWCO in organic solutions [3].…”

Reverse osmosis separations of some organic and inorganic solutes in ethanol solutions with cellulose acetate membranes

“…The reverse osmosis separation data of 21 organic solutes from ethanol solutions were newly added in this work, and they were analyzed by using transport equations based on the surface force-pore flow model. As well, the data on inorganic solute separations reported in an earlier work (Farnand et al, 1984) were reinterpreted by using the above transport equations. It is expected that the interaction force working between the solute and the cellulose acetate membrane material in different solvent environments and its effect on solute transport through membrane pores will be elucidated by this approach.…”

“…The experimental data were analyzed either by fundamental transport equations developed by Kimura and Sourirajan (Sourirajan, 1970) when the preferential sorption of the solute is not very strong or by the generalized transport equations based on the surface force-pore flow model ; which is applicable for both solvent and solute preferential sorption in the foregoing studies. The effect of the progressive change of solvent from water to methanol and to ethanol on the separation characteristics of cellulose acetate membranes was also discussed (Farnand et al, 1983(Farnand et al, , 1984.…”