The work demonstrates poly(2,5-benzimidazole), commonly known as ABPBI, based thin, solvent-stable, scalable flat sheet membranes for organic solvent forward osmosis (OSFO). The membranes treated at 60 and 350 degrees C were analyzed for OSFO using solvents of industrial significance (methanol, ethanol, acetonitrile, N,N-dime- thylformamide, and dimethyl sulphoxide). Although LiCl could be employed as a draw solute with methanol as a solvent, its insolubility in other organic solvents led to the use of a new, simple-to-synthesize acid-base salt, viz., triethylammonium benzoate (TB). A study on the effects of membrane treatment temperature on solvent flux, reverse salt flux (RSF), ability to use TB as draw solute with other solvents, long-duration analysis, and use of model organic compounds in the feed side led to an understanding of the applicability of present thin, scalable ABPBI membranes for OSFO. Although membranes treated at 350 degrees C possessed a lower methanol flux than those treated at 60 degrees C, the lowering in its RSF was highly attractive. TB, having a larger molecular size than LiCl, led to a slight reduction in methanol flux and a considerable reduction in RSF. With TB, extremely low RSF was observed with the chosen solvents. The long-duration study using MeOH and acetonitrile was investigated. A complete rejection of all model organic compounds of varying molecular weights and chemical functionality indicated the merits of the present thin, scalable ABPBI membranes for practical applications of OSFO.

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