Membrane permeation of a binary compound for co-current and cross flow modes

Abstract

This study reveals the behavior of air-sweep pervaporation in a mixture of two volatile organic compounds (VOCs) combination from a solution for two flow modes of operation, namely co-current and cross flow mode. Two models, single compound and binary compound permeation, were studied. Results indicated that the membrane shows a higher affinity for one of the compounds compared to the other. Higher affinity may have led to higher sorption and a higher permeability rate. The flux production in the cross flow mode is found to be higher than the co-current flow mode. However, selectivity is unaffected by the flow mode of operation. A study on the mutual coupling effect shows that, due to the presence of one compound, the flux of the other compound is reduced. The reduction in the flux production is found to be higher in the co-current flow mode than the cross flow mode, especially for a higher concentration of the interfering compound. The model study indicates that the transfer of the VOC through the bulk liquid phase to and sorption on the membrane surface is the rate-limiting step. A difference in the flux values from the experiments and that predicted by the binary compound permeation model is noted. The difference was found to be constant irrespective of the compound used. This may be mainly due to the flow mode of operation. To incorporate this effect and various other influencing effects, preliminary modification of the model is proposed in the form of an empirical constant.