Monitoring the effect of hydrothermal treatments on the structure of a natural zeolite through a combined XRD, FTIR, XRF, SEM and N2-porosimetry analysis (original) (raw)
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Effect of calcination on the structure of a natural Mexican zeolite: Study by XRD and SEM-EDS (Atena Editora), 2023
En el trabajo presente se da a conocer la caracterización morfológica de polvos zeolíticos, por medio de microscopia electrónica de barrido (SEM por sus siglas en inglés), además se anexan los resultados obtenidos por espectroscopia de rayos X por energía dispersiva (EDS). Este material se sometió a una molienda de 3 horas (ZNM025) y, posteriormente se trató térmicamente por un periodo de 4 horas, a temperaturas de 250 (ZNM250), 350 (ZNM350) y 500°C (ZNM500), respectivamente. El conjunto de muestras fue caracterizado para conocer los cambios producidos con respecto a la muestra original (ZNM025). Al mantener una amplificación fija de 1000x, las micrografías muestran lo siguiente: una distribución no uniforme en el tamaño de partícula, la cual puede ser agrupada en 4 tipos; pequeña (< 1 μm), mediana (1 – 5 μm), grande (6 – 10 μm) y extragrande (> 10 μm). El análisis elemental por EDS confirma la presencia de nanopartículas de óxidos de hierro (Fe x O y ); que se encuentran ocluidos en los canales y en los poros de las zeolitas; los cuales se transforman o sufren un cambio en su estructura, debido al proceso térmico; además se confirma la existencia de otros elementos como el aluminio, silicio, sodio, calcio, oxígeno, entre otros.
Transformation of Indonesian Natural Zeolite into Analcime Phase under Hydrothermal Condition
IOP conference series, 2018
Natural zeolite is abundantly available in Indonesia and well distributed especially in the volcano area like Java, Sumatera, and Sulawesi. So far, natural zeolite from Klaten, Central Java is one of the most interesting zeolites has been widely studied. This research aims to know the effect of seed-assisted synthesis under a hydrothermal condition at 120 °C for 24 hours of Klaten's zeolite toward the structural change and phase transformation of the original structure. According to XRD and XRF analysis, seed-assisted synthesis through the addition of aluminosilicate mother solution has transformed Klaten's zeolite which contains (mordenite and clinoptilolite) into analcime type with decreasing Si/Al ratio from 4.51 into 1.38. Morphological analysis using SEM showed the shape changes from irregular into spherical looks like takraw ball in the range of 0.3 to 0.7 micrometer. Based on FTIR data, structure of TO4 site (T = Si or Al) was observed in the range of 300-1300 cm-1 and the occupancy of Brønsted acid site as OH stretching band from silanol groups was detected at 3440-3650 cm-1. Nitrogen adsorptiondesorption analysis confirmed that transformation Klaten's zeolite into analcime type has decreased the surface area from 55.41 to 22.89 m 2 /g and showed inhomogeneous pore distribution which can be classified as micro-mesoporous aluminosilicate materials.
International Journal of Advanced Research (IJAR), 2019
The objective of the present work was to study transformation of Georgian natural zeolites, analcime and phillipsite, during their recrystallization in the aim to obtain zeolites A and X, widely used for adsorption, separation, ion exchange and catalysis. It is found that phase-pure zeolite NaA (Na11.25(25) (K,?Ca,?Mg)0.7(1) (Al11.95(25)Si12.3(3)O48).18H2O) can be prepared in the form of cubic/rhombus crystallites with uniform micrometric (3-5 μm) dimensions by hydrothermal crystallization (95oC) of aged (72 hr) at room temperature gel (4.5Na2O: 0.45Al2O3: 1SiO2: 178H2O) obtained from natural analcime, treated with hydrochloric acid before suspending in water and mixing with sodium hydroxide. Phase-pure zeolite NaX (|Na66(3) [K,?Ca,?Mg,?Cu,?Zn]12(1) (H2O)248(10)| (Al78(3)Si114(4)O384)) with specific surface area of 589 m2/g and total pore volume of 0.578 cm3/g can be prepared in the form of octahedral crystallites with uniform micrometric (2-7 μm) dimensions by hydrothermal crystallization (95oC) of aged (96 hr) at room temperature gel (2.9Na2O: 0.26Al2O3: 1SiO2: 150H2O) obtained from water suspension of natural phillipsite, treated with hydrochloric acid and mixed with sodium hydroxide. The resulting zeolites in their characteristics are competitive with commercially available materials.
Effect of the Acid Type on the Natural Zeolite Structure
2019
In this study, Clinoptilolite-rich zeolitic tuff was treated with acids such as HCl, HNO 3 , H 2 SO 4 , and H 3 PO 4 . The effect of periods of time (3 hours and 6 hours), concentration (1 M, 2 M, 3 M, 5 M, and 10 M) and acid type were taken as parameters. In the characterization of the zeolites, XRD, ICP-AES, FTIR, and SEM techniques were used. As the acid concentration and the treatment time were increased, the aluminum and cation removal from the structure was increased. HCl and HNO 3 were more effective acids for the dealumination than H 2 SO 4 and H 3 PO 4 . It was found out that considerable change in the texture of the zeolitic tuff didn’t take place during the H 3 PO 4 treatment. On the other hands, acid treatment resulted in an increase in the micropore surface area and volume of the zeolite. Specific surface area of the zeolitic tuff (19 m 2 /g) was increased up to 213 m 2 /g, 236 m 2 /g, 202 m 2 /g, 118 m 2 /g with HCl, HNO 3 , H 2 SO 4, and H 3 P O 4 treatments, respecti...
Improvement of Cation Exchange Capacity of Natural Zeolite with Alkali Treatments
2004
The natural zeolite was treated with alkali (NaOH) solution and heating at 100 oC for 12 and 24 hours. The natural zeolite was collected from Gunungkidul, Jogjakarta, Indonesia. The series of NaOH solutions was 0.5, 1.0, 1.5, 2.5, 3.5 and 4.5 M. The final product of the reaction (precipitate) was designated as ‘activated natural zeolite (ANZ)’. The cation exchange capacity (CEC) of the ANZ increased with increasing NaOH concentration up to 1.5-3.5 M. Treatment with NaOH 3.5 M and 12 hours in period of hydrothermal reaction resulted in a maximum CEC (395.6 cmol kg-1). The maximum CEC also observed for treatment with NaOH 1,5 M, but consumed a longer time (24 hours). The increase in the CEC of the ANZ about 300 % higher than the original one. The XRD (X-ray Diffraction) peaks of the ANZ appear at 2.7, 3.2, 4.1, 5.1, 7.2 A, this indicated a new crystalline matters (possibility phillipsite) present. Electron micrograp showed that the ANZ has a large cubic/prismatic structure with a perf...
For the past several decades, researchers have studied the zeolitization of coal fly ash (class-F) by following different methods (viz., open and closed hydrothermal, and fusion followed by hydrothermal). In fact, these methods involve sequential processes like (i) dissolution of silica and alumina from the fly ash, (ii) nucleation of zeolite, and (iii) crystallization (growth of zeolite) in the reactant solution. Also, performance of these processes has been reported to vary with the type of alkali used as reactant and often, NaOH has been preferred for high cation exchange capacity, resulting in sodium zeolites. However, large scale applications of Na-based zeolites in soil and water are questionable due to the presence of high sodium, thereby increasing the sodicity and salinity of the soil/water. In addition, performance of the zeolites, as adsorbent, synthesized by different methods is expected to depend on various characteristics (viz., mineralogy, structural bonding, specific surface area, pore volume, and morphology), of the zeolites. In order to address the above issues, the present study is focused to investigate the various characteristics of the synthesized zeolites by (i) the above mentioned three methods, (ii) using Ca(OH) 2 as reactant, and (iii) considering Na and Ca present in the fly ash. Thus, the aim of the study was to ascertain (i) a suitable method out of the three and (ii) characteristics of the blend of Na-and Ca-zeolites from the fly ash, which can Manuscript be used as a controlled release fertilizer, as sorbent for water and soil decontamination.
Hierarchical zeolites Y obtained by desilication: Porosity, acidity and catalytic properties
Microporous and Mesoporous Materials, 2018
The porosity, acidity and catalytic properties of zeolite Y desilicated in NaOH, tetrabutylammonium hydroxide (TBAOH) and NaOH/TBAOH mixture were investigated. The parent dealuminated zeolite Y of Si/Al = 31 contained very strongly acidic Si-OH-Al groups (more acidic than in other zeolites). These OH groups were also homogeneous. Desilication in NaOH solution extracted ca. 80% of Si but caused the amorphization of zeolite, loss of micropore system and of zeolitic acidity. On the other hand, TBAOH removed a small fraction of the Si, and preserved the crystallinity, porosity and acidity. Nevertheless, the NaOH/TBAOH treatment extracted about half of Si without a loss of crystallinity and zeolite microporosity. The mesopore volume and surface increased distinctly. Both concentration of Brønsted and Lewis acid sites also increased. Remarkably, the acid strength of the Si-OH-Al groups did not change upon desilication in the NaOH/TBAOH. The consequence of the enhanced mesoporosity, sites density, preservation of microporosity and Powder X-ray diffraction (XRD) measurements were carried out using a PANalytical Cubix X'Pert Pro diffractometer, with CuK α radiation (λ=1.5418 Å) in the 2θ angle range of 2-40°. Si and Al contents in the zeolites as well as in the filtrate were determined by ICP OES spectroscopy on an Optima 2100DV (PerkinElmer) instrument. In order to determine the composition of zeolites, 70-80 mg of zeolites was treated with the mixture 0.3 ml of HF and 3 ml of concentrated HCl in a teflon vessel for 24 h. After the dissolution of zeolite the liquid was diluted to 50 ml and both Si and Al contents were determined by ICP OES spectroscopy. The accuracy was ca. 5-10 %. The N 2 sorption analyses at 77 K were carried on an ASAP 2420 Micrometrics. apparatus. Before experiments, a sample was evacuated in situ in Micrometrics apparatus at 670 K for 12 h. Surface area (S BET), micropore volume and surface (V micro , S micro) were determined by applying the BET and t-plot methods, respectively. Pore size distribution and Highlights
Ion exchange kinetics and thermodynamics of hydrosodalite, a narrow pore zeolite
Journal of Porous Materials, 2014
The ion-exchange properties of a synthetic hydrosodalite (Na-hS) have been investigated by kinetic and thermodynamic analysis of exchange reactions of the original sodium form for lithium, potassium and calcium forms. Kinetic curves, modelled by a Langmuir-type equation, revealed that exchange rate for lithium and for potassium are of the same order, whereas they are two order faster than for calcium. Thermodynamic analysis of the cation exchange isotherms pointed out that sodalite is selective for sodium over the other three cationic forms examined, which is consistent with the preference exhibited by the sodalite type for sodium environments, either in natural or in laboratory crystallization. Na/Li and Na/Ca exchanges are incomplete, whereas unexpectedly Na/K exchange turns out to be complete, even though K + dimension exceeds the width of the access window to sodalite cages. The obtained results have been discussed in terms of Eisenman-Sherry theory, pointing out agreements and discrepancies.
Effect of Mechanical Treatment on the Structure and Properties of Natural Zeolite
Inorganic Materials: Applied Research, 2018
The morphology, specific surface area, structure, and phase composition of natural zeolite powder from the Tokai deposit which underwent mechanical treatment in a planetary mill was studied using the following methods: scanning electron microscopy (SEM), X-ray structural analysis, Brunauer-Emmett-Teller (BET) method, laser diffraction, and elemental analysis. The identification of natural zeolite X-ray patterns showed that the powder consisted of seven phases with different contents of minerals: smectite, quartz, cristobalite, clinoptilolite, illite, orthoclase, and calcite. Initially, the average size of the zeolite particles was 27 μm; after the treatment for 20 min, it was 5.5 μm; and after 600 min, it was 28 μm. Moreover, most of the particles lost their initial shape during the mechanical activation and acquired a spherical shape. It was shown that, during the first 60 min of mechanical treatment in the planetary mill, powder particles were ground, and the specific surface area increased to 33 m 2 /g. The further mechanical activation was determined by agglomeration of particles and a decrease in the specific surface area. The X-ray structural analysis showed that the studied powder consisted of four phases: hexagonal, monoclinic, orthorhombic, and tetragonal modifications. Mechanical treatment of natural zeolite led to the decrease in the coherent scattering regions and to the growth of microdistortions of the crystal lattice. It was shown that the continuous mechanical effect on zeolite led to the increase in the amount of an amorphous phase in the powder from 13 to 52%. The changes in the specific surface area determined by the BET method and calculated from the coherent scattering region (CSR) had the same character, and the phase composition determined the specific surface area of natural zeolite.