Effect of low flow rate on pervaporation of 1,2-dichloroethane with novel polydimethylsiloxane composite membranes

Abstract

Crosslinked oligosilylstyrene–polydimethylsiloxane composite membranes were used to separate trace 1,2-dichloroethane (1,2-DCE) from the mixtures of 1,2-DCE and water by pervaporation. The performances of pervaporation were evaluated by low feed flow rates (0.35–1.0 l/min), corresponding to Reynolds number from 79 to 220. The resistance-in-series model and semi-empirical Sherwood correlations were employed to study the transfer characteristics. For the given hydrodynamic conditions, both mass transfer resistances of the boundary layer and the membrane were found to be important to the overall mass transfer. The transfer resistance of 1,2-DCE through the boundary layer and the membrane decreased as the decrease of thickness of boundary layer. The permeation rate and the separation factor of 1,2-dichloroethane increased, but the permeation rate of water kept unchanged as the feed flow rate increased. The theoretical data from resistance-in-series model were compared with experimental data. The good correlation between the theoretical and experimental data can work as the predication of pervaporation performance and the management of pervaporation process.