Ball-milled NaA zeolite seeds with submicron size for growth of NaA zeolite membranes

NaA zeolite membranes were prepared by secondary growth method using ball-milled NaA particles with submicron size. Three average particle sizes (~0.3μm, ~0.5μm and ~1μm) were obtained by ball-milling treatment of NaA zeolite powders (~2.8μm) with a high-energy ball mill. The effect of ball-milled seeds on membrane growth was investigated. It was found that the small size and defective surface for the ball-milled seeds accelerated the growth of NaA zeolite membrane. Compared with original NaA zeolite seeds, the ball-milled seeds can induce well-intergrown NaA zeolite membranes with large reduction of synthesis time. High-quality NaA zeolite membranes were synthesized at 373-383K for 4h using the milled seeds with an average particles size of ~0.3μm, which showed a permeation flux of ~2.6kgm ^-2h ^-1 and water/ethanol separation factor of >10,000 for separating 90:10 (wt.%) ethanol/water mixture at 343K.