Ultrasonic treatment of polyacrylic acid sodium/NaA zeolite hybrid membranes for the pervaporation dehydration of ethanol

摘要

Ultrasonics was used to improve the dispersion of NaA zeolite in polyacrylic acid sodium (PAAS) membranes. The effect of ultrasonication time on the dispersion of NaA zeolite in the membranes, the membrane structure, and performance were investigated. The casting solution and resulting membranes were characterized by viscosity measurement, polarizing optical microscopy (POM), scanning electron microscopy, and X-ray diffraction (XRD). With increasing ultrasonication time, the viscosity of the casting solution decreased as the chain entanglements decreased. The POM and XRD results showed that crystallization occurred in the PAAS membrane after ultrasonic processing. A more homogeneous morphology was obtained due to improvement in the dispersion of zeolite under ultrasonic treatment for 0.5-1.0 h. As a result, the separation performance was enhanced. The water/ethanol separation factor increased from 176.2 to 577.8. However, the relative separation factor decreased when the ultrasonic time exceeded 2.5 h, due to the appearance of a lamellar structure.