Emulsion-based synthesis of NaA zeolite nanocrystals and its integration towards NaA membranes

• Published in: Bulletin of materials science 2011-07, Vol.34 (4), p.651-659
• Main Authors: Naskar, M. K., Das, A., Kundu, D., Chatterjee, M.
• Format: Article
• Language: English
• Subjects: Chemistry and Materials Science; Cobalt; Crystals; Emulsions; Engineering; Materials Science; Membranes; Nanocrystals; Nanoparticles; Seeds; Surfactants; Zeolites
• ISSN: 0250-4707; 0973-7669
• DOI: 10.1007/s12034-011-0177-2

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 (N 2 ) 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).