Synthesis of acid-resistant Phillipsite (PHI) membrane and its pervaporation performance

Phillipsite (PHI) membranes have been prepared by the secondary growth method on the outer surface of porous mullite tubular supports, with a molar composition of SiO2:Al2O3:Na2O:H2O = 1:0.25:0.625:20. The thicknesses of the membrane layer increased with increasing the secondary growth time from 10 to 40 μm, and an intermediate layer that was densely packed was observed under the PHI top surface layer. It was found that the pervaporation (PV) performance of water/ethanol can be improve by the post-treatments of the PHI membrane such as a polishing the top surface layer of the membrane, and its ultrasonic washing the membrane. The PHI membranes showed excellent hydrophilic behavior with selectivity exceeding 5000 at fluxes of 0.8 kg m−2 h−1 in the PV of 90 wt% ethanol/water mixtures at 353 K. The PHI membrane also showed high PV performance under the acidic condition (pH 3.5) and were stable for at least 10 days.