Porosity, characteriza-tion and structural properties of natural zeolite – clinoptilolite – as a sorbent

Abstract

The characterization and porous structure of raw and modified clinoptilolite as a sorbent has been investigated by nitrogen adsorption, X-ray diffraction, X-ray fluorescence, Fourier transform infrared spectroscopy, differential thermal analysis, scanning electron microscopy and atomic force microscopy methods. The nitrogen adsorption data revealed that the total pore volume and specific surface area were increased after modification. The nitrogen adsorption was used to determine percent of mesoporosity. The TG data show that 14 wt. % of clinoptilolite is lost after heating up to 1200 °C. Two types of porosities-primary porosity (microporosity) and secondary one (meso-and macroporosity) have been observed.

Effect of chemically modified clinoptilolite on the thermal, morphological, and gas separation properties of mixed matrix membranes

“…XRD patterns of clinoptilolite samples which were chemically modified by cation exchange are shown in Figure . XRD patterns for unmodified samples are in agreement with the characteristic peaks reported for clinoptilolite . Modified clinoptilolite at both test temperatures showed reflection peaks located at similar 2θ values than control samples.…”

Amine‐impregnated natural zeolite as filler in mixed matrix membranes for CO2/CH4 separation

“…All spectra showed a strong band at 1060–1010 cm −1 due to the stretching vibration of both Si─O and Al─O bonds characteristic of the tetrahedral aluminosilicate structure of this zeolite. The presence of the band at 1630 cm −1 is often attributed to the physically adsorbed water . Besides, the broad band centered at 3420 cm −1 was assigned to the O─H stretching of hydroxyl groups.…”

“…The assembly of SiO 4 and AlO 4 tetrahedrons originates channels and microporous/mesoporous structure occupied by exchangeable cations (Ca 2+ , Na + , K + , and Mg 2+ ) bonded to water molecules, which compensate the negative charge derived from AlO 4. Since the 1990s decade, scientific reports and patents have recognized the high thermal stability, acid resistance, good CO 2 selective adsorption, and gas‐mixture separation properties of this kind of natural zeolite with respect to other, indicating its utility in natural gas purification . Moreover, attractive adsorption rates and removal of CO 2 instead of N 2 or CH 4 have been recorded in several sorption tests and pressure swing adsorption process .…”

Adsorption and Separation of the H2O/H2SO4 and H2O/C2H5OH Mixtures: A Simulated and Experimental Study

“…Increasing the dividing ability shows separate plates or bars (microns in size) are not individual crystal grains of the Heulandite and Clinoptilolite, but only aggregates presented by finer grains of the mineral. Such splitting of zeolite grains is typical for Heulandite and Clinoptilolite cleavage and is a consequence of hydrothermal solution filtration [2]. Figures A14-A16 show the micrographs of the matter prima (Clinoptilolite and Heulandite).…”

“…Some of their main characteristics for use as adsorbents are: selectivity on the element (molecule) that it is desired to adsorb or retain on its surface, great adsorption capacity (many pores), and the ability to withstand high temperatures for regeneration. There are many works found on the used of zeolites to adsorb water molecules [1][2][3][4][5][6][7][8][9][10][11]. In particular, García-Soto et al [12] presented an experimental study of a Na-A synthetic zeolite used for separation of the H 2 O/C 2 H 5 OH mixture, at temperatures of 120 and 140 • C , and at each of them different compositions by weight of ethanol: 50%, 60%, 70%, 80%, 85%, 90%, 95%, 97%, and 99%.…”