Apparatus for pervaporation separation of liquid mixtures by flat polymer membranes

An apparatus for pervaporation of liquid mixtures by flat polymer membranes is described. Two different methods for determination of pervaporation flu xes - the classic direct gravimetric method (whereby the pervaporate is con densed and then weighed) and the sorption method (where the pervaporate is adsorbed into the active carbon and the mass is determined from the change in length of the quartz spring balance on which the active carbon is suspen ded) are described and the results are compared with the system l-butanol-t oluene-low density polyethylene membrane at 25 degrees C. It was found that over shorter periods of time the sorption method gave more accurate result s even for very small fluxes than with the direct method.