Amino acid encapsulation in zeolite MOR: Effect of spatial confinement.

In this study the absorption of glycine, α-alanine and β-alanine amino acids into the pores of the synthetic zeolite Na-mordenite was investigated with the aim of: (i) evaluating the effectiveness of the MOR framework type in amino acid adsorption ( vapor and aqueous loading); (ii) understanding the host-guest and guest-guest interactions to possibly design a tailor made material and a loading procedure able to maximize the amino acid adsorption; (iii) studying the effect of pressure on the adsorbed amino acids such as, for instance, possible amino acid condensation. The structural characterization, carried out with the combination of diffractometric and infrared spectroscopy analyses, shows that MOR can adsorb amino acids, which are found both in protonated/deprotonated (possibly also generating zwitterions) form. Vapor loading is ineffective for α-alanine, while it is effective in β-alanine and glycine adsorption, even if using different loading degrees.

Structural interpretation of the energetic performances of a pure silica LTA-type zeolite.

The high pressure intrusion-extrusion process of different electrolyte aqueous solutions (NaCl and CaCl2, 2 M and 3 M) in a hydrophobic pure-silica LTA zeolite was investigated for energetic purposes by means of in situ X-ray powder diffraction, porosimeter tests, thermogravimetric analysis and NMR spectroscopy. The intrusion pressure of the saline solutions was proved to be higher than that of pure water, with the highest value measured for CaCl2, thus increasing the energetic performance of the system. The intrusion of NaCl solutions was irreversible (bumper behavior), whereas that of CaCl2 solutions is partially reversible (shock absorber behavior).

High-temperature behavior of natural ferrierite: In-situ synchrotron X-ray powder diffraction study.

In this paper, we report the results of the first study focused on the thermal stability and dehydration dynamics of the natural zeolite mineral ferrierite. A sample from Monastir, Sardinia [(NaKMgCaSr) (AlSi)O·17.86HO; = 19.

Modern Iron Ooids of Hydrothermal Origin as a Proxy for Ancient Deposits.

We constrained the origin and genetic environment of modern iron ooids (sand-sized grains with a core and external cortex of concentric laminae) providing new tools for the interpretation of their fossil counterparts as well as the analogous particles discovered on Mars. Here, we report an exceptional, unique finding of a still active deposit of submillimetric iron ooids, under formation at the seabed at a depth of 80 m over an area characterized by intense hydrothermal activity off Panarea, a volcanic island north of Sicily (Italy). An integrated analysis, carried out by X-ray Powder Diffraction, Environmental Scanning Electron Microscopy, X-ray Fluorescence and Raman spectroscopy reveals that Panarea ooids are deposited at the seafloor as concentric laminae of primary goethite around existing nuclei.

Irreversible Conversion of a Water-Ethanol Solution into an Organized Two-Dimensional Network of Alternating Supramolecular Units in a Hydrophobic Zeolite under Pressure.

Turning disorder into organization is a key issue in science. By making use of X-ray powder diffraction and modeling studies, we show herein that high pressures in combination with the shape and space constraints of the hydrophobic all-silica zeolite ferrierite separate an ethanol-water liquid mixture into ethanol dimer wires and water tetramer squares. The confined supramolecular blocks alternate in a binary two-dimensional (2D) architecture that remains stable upon complete pressure release.

High-pressure-induced structural changes, amorphization and molecule penetration in MFI microporous materials: a review.

This is a comparative study on the high-pressure behavior of microporous materials with an MFI framework type (i.e. natural mutinaite, ZSM-5 and the all-silica phase silicalite-1), based on in-situ experiments in which penetrating and non-penetrating pressure-transmitting media were used.