Hydrothermal synthesis of uniform and dense NaA zeolite membrane in the electric field

Uniform and dense NaA zeolite membranes were prepared on the tubular porous α-Al₂O₃ supports in the electric field, where the charged zeolite particles attracted and transported to the support surface for membrane preparation homogeneously. The membranes properties were characterized by XRD, SEM and pervaporation for dehydration of 95 wt% isopropanol/water mixture at 343 K, respectively. The applied potential had great effect on membrane morphology, membrane thickness and separation performance. Under the action of the applied electric field, the negatively charged zeolite particles could migrate to the support surface homogenously and rapidly, facilitating to form uniform and dense membranes in a short time. Most zeolite particles transported to the support surface for membrane formation in the electric field, which increased the percentage of the product contained in the support surface and thus fully utilized the zeolite particles. High-quality NaA zeolite membrane, i.e., with a separation factor (water/isopropanol) of 3281 and a flux of 1.24 kg/(m² h), could be prepared with the electrical potential of 1.0 V.