Influence of zeolite crystal expansion/contraction on NaA zeolite membrane separations

2011-01-01
Sorenson, Stephanie G.
Payzant, E. Andrew
Gibbons, William T.
Soydas, Belma
Kita, Hidetoshi
Noble, Richard D.
Falconer, John L.
In situ powder XRD measurements showed that adsorption causes the NaA zeolite unit cell to contract or expand, and these changes depend on adsorbate loading. Changes in zeolite crystal size correlated with permeation changes through NaA zeolite membranes. These membranes had high water/alcohol pervaporation selectivities, even though gas permeation was mainly through defects, as indicated by Knudsen selectivities for single gas permeation. At 300 K and a thermodynamic activity of 0.03, water contracted the NaA crystals by 0.22 vol%, and this contraction increased the helium flux through two NaA membranes by approximately 80%. Crystal contraction also increased the fluxes of i-butane during vapor permeation and i-propanol (IPA) during pervaporation (similar to 0.03 wt% water). At activities above 0.07, water expanded NaA crystals and correspondingly decreased the fluxes of helium, i-butane, and IPA through NaA zeolite membranes. Methanol also contracted NaA crystals, but by only 0.05 vol% at an activity of 0.02, and this contraction slightly increased the helium and i-butane fluxes through a NaA membrane. Above an activity of 0.06, methanol expanded the NaA crystals, and the fluxes of helium and i-butane through a NaA membrane decreased. These adsorbate-induced changes explain some pervaporation behavior reported by others, and they indicate that crystal expansion and contraction may increase or decrease zeolite NaA membrane selectivity by changing the defect sizes.
JOURNAL OF MEMBRANE SCIENCE

Suggestions

Effect of operating parameters on selective separation of heavy metals from binary mixtures via polymer enhanced ultrafiltration
Muslehiddinoglu, J; Uludağ, Yusuf; Ozbelge, HO; Yılmaz, Levent (Elsevier BV, 1998-03-18)
Performance of continuous polymer enhanced ultrafiltration (PEUF) method was investigated for removal of mercury and cadmium from binary mixtures. This method includes the addition of polyethyleneimine (PEI) as a water soluble polymer to bind the metals, which was followed by ultrafiltration operation performed on both laboratory and pilot scale systems. The influence of various operating parameters such as temperature, metal/polymer ratio, presence of calcium ions and pH on retention of metals and permeate...
Development of enhanced ultrafiltration methodologies for the resolution of racemic benzoin
Olceroglu, Ayse Hande; Çalık, Pınar; Yılmaz, Levent (Elsevier BV, 2008-09-15)
In the scope of achieving the separation of chiral molecules, enzyme enhanced ultrafiltration (EEUF), a new method based on polymer enhanced ultrafiltration (PEUF), utilizing apoenzymes as ligands, was developed. Benzoin was chosen as the model chiral molecule. Bovine serum albumin (BSA) and apo form of benzaldehyde lyase (BAL) (E.C. 4.1.2.38) were used as chiral ligands in PEUF and EEUF experiments, respectively. In order to bind to the target enantiomer well, the addition of ligand to the benzoin solution...
Effect of Feed Concentration in Equilibrium Parametric Pumps
Ghasem, Nayef; Orbey, H (Informa UK Limited, 1987-12)
The effect of high initial feed concentration in batch equilibrium parametric pumping was experimentally investigated at different bed temperatures and cycle times. The system studied was benzene-n-hexane over a silica gel bed. It was observed that the initial feed concentration which leads to the best separation is dictated by the shape of the equilibrium isotherms of the system. An increase in the temperature difference between hot and cold cycles was shown to improve the separation because it led to a mo...
Polycarbonate-polypyrrole mixed matrix gas separation membranes
Hacarlioglu, P; Toppare, Levent Kamil; Yılmaz, Levent (Elsevier BV, 2003-11-01)
The gas separation properties of the polycarbonate-polypyrrole mixed matrix membranes were evaluated based on the introduction of conducting polymer as powder fillers. The electrically conductive fillers are obtained from two main synthesis routes namely electrochemical and chemical methods. The permeation properties of polycarbonate-polypyrrole systems are highly dependent on the synthesis method (electrochemical or chemical) and also the membrane casting conditions (casting solvent type). The introduction...
Effect of fabrication and process parameters on the morphology and performance of a PAN-based zeolite-filled pervaporation membrane
Okumus, E; Gurkan, T; Yılmaz, Levent (Elsevier BV, 2003-09-15)
The aim of this study is to develop a novel pervaporation membrane for dehydration of azeotropic ethanol-water mixture and to investigate the effect of membrane preparation and process parameters on the membrane performance. Zeolites (3A, 4A and 13X) are added as fillers to the base polymer poly [acrylonitrile] (PAN). It is observed that the volatility of the casting solvent and the annealing temperature strongly affect the performance and morphology of the manufactured membranes. Scanning electron microgra...
Citation Formats
S. G. Sorenson et al., “Influence of zeolite crystal expansion/contraction on NaA zeolite membrane separations,” JOURNAL OF MEMBRANE SCIENCE, pp. 413–420, 2011, Accessed: 00, 2020. [Online]. Available: https://hdl.handle.net/11511/68403.