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Zeolite nanocrystals; emulsion synthesis; hydrothermal technique; NaA membrane; microstructure.

NaA zeolite nanoparticles (seed crystals) of size 50–65 nm were synthesized using water-in-oil (w/o) type emulsions at a considerably low temperature of 65 ± 1°C in a short duration of 2 h. The emulsions were stabilized using non-ionic surfactants e.g. sorbitan monooleate (Span 80), sorbitan monolaurate (Span 20), polyoxyethylene(5)nonylphenylether with ethoxy numbers of 5 (Igepal CO-520) and polyoxyethylene sorbitan monooleate (Tween 80) of hydrophilic-lipophilic balance (HLB) values of 4.3, 8.6, 10 and 15 respectively. Among the surfactants, the intermediate HLB values of 8.6 (Span 20) and 10 (Igepal CO-520) were effective in synthesizing highly dispersible NaA nanoparticles of size 50–65 nm. The membrane prepared hydrothermally in multi-steps at 65 ± 1°C, using the Span 20-derived seed crystals deposited on porous support, showed the formation of high quality interlocked NaA coating. Single gas nitrogen (N₂) permeation of the membrane exhibited a permeance value of 1.01 × 10^-8 mol m^-2 s^-1 Pa^-1 at ambient temperature (30°C).

M K Naskar¹ A Das¹ D Kundu¹ M Chatterjee¹

1. Sol-Gel Division, Central Glass & Ceramic Research Institute (CSIR), Jadavpur, Kolkata 700 032, India

Published

July 2011

Manuscript received

2 December 2009

Manuscript revised

2 August 2010