A new method for producing zeolitic monoliths is used to produce a ZSM-5 based monolith for gas separation. The new method involves the 3DFD (Three Dimensional Fiber Deposition) printing of several layers of zeolite fibers on top of each other in a well-defined way,resulting in an open monolithic structure with open and inter-connected channels. The monolithic structure, consisting of ZSM-5 zeolite, was characterized with SEM, Ar and Hg porosimetry. Single component isotherms of CO 2 , CH 4 and N 2 were recorded on the 3DFDprinted ZSM-5 monolith, at different temperatures (283K, 291K, 302K and 309K) using a gravimetric method. Isosteric heats of adsorption show that CO 2 is the most strongly adsorbing component, in order followed by CH 4 and N 2 . The monolithic structure was subjected to breakthrough separation experiments with CO 2 /N 2 and CO 2 /CH 4 gas mixtures.Excellent separation performance is achieved. Moreover, the ZSM-5 monolith can be easily regenerated in isothermal conditions.
The free volume sizes and interstitial mesopore sizes in poly(1-trimethylsilyl-1-propyne) (PTMSP)/silica nanocomposites and the correlation between nitrogen permeability and cavity sizes were studied with positron annihilation lifetime spectroscopy (PALS) at filler concentrations between 0 and 50 wt %. A bimodal free volume distribution was observed for PTMSP, and the size of the larger free volume cavities was significantly increased upon addition of hydrophobic fumed silica. Nanometer-sized interstitial cavities in filler agglomerates were observed in all PTMSP/fumed silica nanocomposites and in neat hydrophobic fumed silica. The radius of these interstitial mesopores in the nanocomposites decreased with decreasing filler concentration. A strong correlation between nitrogen permeability and the volume of the interstitial mesopores in the nanocomposite membranes was observed.
Perfluorinated alkylated substances (PFASs) are widely used in industrial and commercial applications, leading to a widespread occurrence of these persistent and harmful contaminants in our environment. Removal of these compounds from surface and waste waters is being mandated by European and U.S. governments. Currently, there are no treatment techniques available that lower the concentrations of these compounds for large water bodies in a cost-and energyefficient way. We hereby propose a hydrophobic, all-silica zeolite Beta material that is a highly selective and high-capacity adsorbent for PFASs, even in the presence of organic competitors. Advanced characterization data demonstrate that the adsorption process is driven by a very negative adsorption enthalpy and favorable steric factors.
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