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 (∼0.3 μm, ∼0.5 μm and ∼1 μm) were obtained by ball-milling treatment of NaA zeolite powders (∼2.8 μm) 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 373–383 K for 4 h using the milled seeds with an average particles size of ∼0.3 μm, which showed a permeation flux of ∼2.6 kg m−2 h−1 and water/ethanol separation factor of >10,000 for separating 90:10 (wt.%) ethanol/water mixture at 343 K.

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► Submicron-size NaA zeolite seeds can be obtained by ball milling zeolite particles.
► The use of ball-milled seeds can reduce synthesis time of NaA zeolite membranes.
► Small seed size and surface defects contribute to quick crystallization of membranes.