PERVAPORATION USING ADSORBENT-FILLED MEMBRANES

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 com pounds from water, dehydration of azeotropic mixtures, and organic/org anic separation. Three different types of adsorbents have been evaluat ed: zeolites, activated carbon, and carbon molecular sieves. Experimen tal 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-diffu sion mechanism. Sorption of species in the filled rubbery membranes ca n be described by a dual sorption model. Modeling of the transport pro cess through filled membranes involves mass-transfer resistances in th e different phases of the membranes: in the polymer phase, in the adso rbent phase, and in a polymer-adsorbent interface. Several models base d on resistance-in-series mechanisms that were developed to describe t he experimental results were reviewed.