Adsorption of Water and Ethanol in MFI-Type Zeolites

Abstract

Influences of drying and nondrying steps on structures of layer-by-layer (LbL) assembled sodium silicate/TiO(2) nanoparticles films (donated as silicate/TiO(2) films) have been systematically investigated. The nondrying LbL assembly produces highly porous silicate/TiO(2) films with large thickness. In contrast, the silicate/TiO(2) films fabricated with a drying step after each layer deposition are flat and thin without porous structures. In situ atomic force microscopy (AFM) measurements confirm that the sodium silicate and TiO(2) nanoparticles are deposited in their aggregated forms. A N(2) drying step can disintegrate the aggregated silicate and TiO(2) nanoparticles to produce thin silicate/TiO(2) films with compact structures. Without the drying steps, the aggregated silicate and TiO(2) nanoparticles are well retained, and their LbL assembly produces highly porous silicate/TiO(2) films of large thickness. The highly porous silicate/TiO(2) films are demonstrated to be useful as reusable film adsorbents for dye removal from wastewater because they can adsorb a large amount of cationic organic dyes and decompose them under UV irradiation. The present study is meaningful for exploring drying/nondrying steps for tailoring structure and functions of LbL assembled films.

Facile preparation of hierarchically porous diatomite/MFI-type zeolite composites and their performance of benzene adsorption: The effects of NaOH etching pretreatment

“…Hence, extensive efforts have been focused on finding alternative adsorbents [11][12][13][14][15]. MFI-type zeolites with low Al content or purely siliceous form (silicalite-1) have been proposed as potential adsorbents due to their high hydrophobicity/organophilicity, large surface area, and superior thermal stability [16,17]. However, these zeolites possess only micropore channels (sinusoidal channels with 0.54 nm circular cross sections interconnected with straight channels with 0.51 nm × 0.57 nm elliptical cross sections [18]), resulting in both relatively slow mass transport and their high price, which is caused mainly by the need to use expensive templates during the preparation process.…”

Discovery of optimal zeolites for challenging separations and chemical transformations using predictive materials modeling

“…Nearly defect-free silicalite-1, an all-silica zeolite with the framework type MFI, has been proposed as an effective sorbent and membrane for this separation 7,8 . All-silica zeolites by themselves are very hydrophobic, but the adsorption of ethanol can promote water co-adsorption through hydrogen bond formation and lower the selectivity 8,9 . For this application, the desired zeolite possesses a pore/channel system that accommodates ethanol molecules but disfavours hydrogen bonding with water molecules.…”

Zeolite MFI adsorbent for recovery of butanol from ABE fermentation broths produced from an inexpensive black liquor-derived hydrolyzate

“…The density of structural defects was decreased by synthesizing the zeolite at neutral pH using fluoride ions as mineralizing agent. With a reduced concentration of structural defects, much less water adsorbs in the zeolite which results in an increase in the adsorption selectivity [26,39,40]. In future work, it would be interesting to evaluate also these materials as adsorbents in real fermentation broths.…”