Synthesis and Evaluation of nanopore NaA zeolite membranes basedon the Maxwell–Stefan theory and experimental results

Zeolite membranes have uniform and molecular-sized pores, and they separate molecules based on ifferences in the molecules’ adsorption and diffusion properties. Strong electrostatic interaction between ionic sites and water molecules (due to its highly polar nature) makes the zeolite NaA membrane very hydrophilic. Zeolite NaA membranes are thus well suited for separating liquid-phase mixtures by pervaporation. In this study, experiments were conducted with various Ethanol–water mixtures (1–20 wt. %) at 25 C  . Total flux for Ethanol–water mixtures was found to vary from 0.331 to 0.229 kg/m2.h with increasing Ethanol concentrationfrom 1 to 20 wt.%. Ionic sites of the NaA zeolite matrix play a very important role in water transport through the membrane. These sites act both as water sorption and transport sites. Surface diffusion of water occurs in an activated fashion through these sites. The precise nanoporous structure of the zeolite cage helps in a partial molecular sieving of the large solvent molecules leading to high separation factors. A comparison between experimental flux and calculated flux using Stephan Maxwell (S.M.) correlation was made and a linear trend was found to exist for water flux through the membrane with Ethanol concentration.

Keywords:

Nano pores , Pervaporation , Ethanol separation , Zeolite NaA membrane