Pervaporation of ethanol/water mixtures using clinoptilolite and 4A filled sodium alginate membranes

In this study, synthetic (zeolite 4A) and natural zeolite (clinoptilolite-CL) filled sodium alginate (NaAlg) membranes were prepared with solution-casting method. Synthetic zeolite incorporated membranes were cross-linked with glutaraldehyde (GA). The morphologies of the membranes were studied using scanning electron microscopy (SEM). The separation properties of the zeolite filled alginate membranes were characterized by pervaporation of ethanol–water mixtures. The effects of zeolite type, zeolite loading, zeolite particle size and feed composition on pervaporation performance were studied. Both flux and selectivity increased with the increasing of zeolite content in the membrane matrix. As increasing the water concentration in the feed mixtures flux values increased but selectivity decreased. According to the performance values, it was seen that the synthetic 4A zeolite was more proper than natural CL zeolite for the NaAlg matrix. However, results were not sufficient for using these membranes commercially. In order to increase PV performance ‘priming’ procedure was applied to 10 wt.% of 4A loaded NaAlg membrane. It was seen that both flux and selectivity enhanced owing to the use of this procedure. Selectivity of modified membrane was eight times higher than the 10 wt.% 4A loaded membrane.

► We prepared natural and synthetic (clinoptilolite and 4A) filled NaAlg membranes.
► Membranes were used in pervaporation for the dehydration of ethanol–water mixtures.
► Synthetic zeolite filled membranes indicated better pervaporation performance.
► Priming and zeolite size reduction methods have been applied to 4A filled membrane.
► The selectivity value of zeolite primed membrane increased as almost nine times.