Removal of alcohols, amines, and aliphatic acids in aqueous solution by NS‐100 membrane

Abstract

SynopsisRemoval of alcohols, amines, and aliphatic acids in single-solute aqueous solution in the concentration range from 0.001 to 0.01M have been studied using the NS-100 membrane. All the tests were conducted at 600 psig, 25"C, and a flow rate of 0.30 gpm. The mechanism of solute separation by the NS-100 membrane differs from that of the cellulose acetate membrane. There was no significant correlation between the removal and the hydrogen bonding ability of the organic solute. Instead, for a given organic solute, its removal increases with the increase in the degree of crosslinkage of the skin layer of NS-100 membrane, and is proportional to its degree of ionization (or degree of dissociation). For organic compounds having a same functional group, the removal of a compound increases with the increase in molecular weight and/or molecular branching. All of these are attributable to the relative nonpolarity and the anion exchanger characteristics of the membrane as well as to the steric resistance for the solute to permeate through the membrane.

Pervaporation of water–alcohol mixtures and acetic acid–water mixtures

“…It can thus be concluded that the influence of molecular size is inferior to the influence of polarity and/or the functional group of the permeating component. This is similar to the findings of Fang and Chian (1975), who concluded that acetic acid rejection in reverse osmosis was determined by charge, and thus by its functional group.…”

Treatment of biomass gasification wastewaters using reverse osmosis

“…Experiments using these two feeds were normally discontinued after a few hrs of operation due to fouled membranes, a fact which may preclude the use of RO for treatment of these feeds. Lower COD removal percentages for those feeds containing acetic acid verify results of Chian and Fang • (1975) which indicated approximately 90% of totally dissociated acetic acid could be removed by the NS-100 membrane. Since nearly 70% of the COD in BGW was from acetic acid (Kao, 1980), the results here are in line with those of previous studies.…”

“…They reported that crosslinked polyethylenimine and aromatic polyamide membranes were much more effective than CA membranes in removing organics. Chian (1975 and also investigated polyethylenimine membranes, including the NS-100, suggesting optimal conditions for membrane formation, and the effectiveness in terms of solute separation of alcohols, amines, and aliphatic acids. They found that the ~vs parameter, used for prediction of solute separation in CA membranes, could not be used to predict separation in the NS-100 membrane.…”

“…2 + CAc-(-1) 2 ] = CAc-since CH+ = CAc-Since the wastewater had a pH of 7-9, all the acids can be assumed to be totally dissociated (Butler, 1964;Fang and Chian, 1975). Assuming…”

Reverse osmosis concentration of ethyl alcohol aqueous solution.

“…As can be seen in Fig. 6, the solute rejection of (1) was better than that of (2). It may be explained that the pore size fcrmed by using (2) type TDI was larger than the other and resulted in the lower solute rejection.…”