Pervaporation Using Adsorbent-Filled Membranes

Abstract

Membranes containing selective fillers, such as zeolites and activated carbon, can improve the separation by pervaporation. Applications of adsorbent-filled membranes in pervaporation have been demonstrated by a number of studies. These applications include removal of organic compounds from water, dehydration of azeotropic mixtures, and organic/organic separation. Three different types of adsorbents have been evaluated: zeolites, activated carbon, and carbon molecular sieves. Experimental results show the most promising filled membrane is the silicalite-filled poly(dimethylsiloxane) (PDMS) membrane which can be effectively used in the removal of organic compounds from water. The transport of species through adsorbent-filled membranes occurs by a sorption−diffusion mechanism. Sorption of species in the filled rubbery membranes can be described by a dual sorption model. Modeling of the transport process through filled membranes involves mass-transfer resistances in the different phases of the membranes: in the polymer phase, in the adsorbent phase, and in a polymer−adsorbent interface. Several models based on resistance-in-series mechanisms that were developed to describe the experimental results were reviewed.