Synthesis of 4A Zeolite and Characterization of Calcium- and Silver-Exchanged Forms

Golbad, Saeed; Khoshnoud, Parisa; Abu‐Zahra, Nidal

doi:10.4236/jmmce.2017.55020

Cited by 12 publications

(11 citation statements)

References 45 publications

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“…Changes in peaks intensities and slight shifts are observed when sodium cations are replaced by other silver or zinc cations. These results were already observed in the literature [ 33 , 44 , 45 , 46 , 47 , 48 ] and were explained as a consequence of the difference of the scattering power which is specific to each cation and also by a slightly different sites occupation in the pores [ 33 , 48 , 49 ].…”

Section: Resultssupporting

confidence: 77%

Synthesis of FAU-Type Zeolite Membranes with Antimicrobial Activity

et al. 2020

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In this study, a layer of a pure and dense phase of FAU-type zeolite was synthesized directly on the surface of α-Al2O3 plane macroporous support. Before hydrothermal synthesis, a step of cleaning of the support by an anionic detergent was performed, a roughness surface is created, allowing the anchoring of the zeolite nuclei and then their growth, favoring in this sense the formation of a homogeneous zeolite layer. The obtained membranes were fully characterized using X-ray diffraction analysis (XRD), nitrogen sorption, scanning electron microscopy (SEM), and mercury porosimetry. After 24 h of thermal treatment at 75 °C, a homogeneous zeolite layer composed of bipyramidal crystals of FAU-type zeolite is obtained with a thickness of about 2.5 µm. No obvious defects or cracks can be observed. It was found that the increase in heating temperature could lead to the appearance of an impurity phase, GIS-type zeolite. Then the ideal zeolite membrane was exchanged with Ag+ or Zn2+ cations to studies their antimicrobial properties. Zeolites membranes exchanged with Ag+ showed an agar-diffusive bactericidal activity against gram negative Escherichia coli (E. coli) bacteria. Zn2+ exchanged zeolite membrane presented a bacteriostatic activity that is less diffusive in agar. As expected, non-exchanged zeolite membrane (in its Na+ form) have no effect on bacterial activity. This process is particularly interesting for the synthesis of a good quality FAU-type zeolite membranes with antimicrobial properties.

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Section: Resultssupporting

confidence: 77%

Synthesis of FAU-Type Zeolite Membranes with Antimicrobial Activity

et al. 2020

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“…Changes in peaks intensities and slight shifts are observed when sodium cations are replaced by other alkali or alkali earth metal cations. These results were already observed in the literature [47][48][49] and were explained as a consequence of the difference of the scattering power which is specific to each cation and also by a slightly different sites occupation in the pores [49,50]. This is also an indication of a successful cation exchange.…”

Section: X-ray Diffractionsupporting

confidence: 79%

Influence of the Compensating Cation Nature on the Water Adsorption Properties of Zeolites

et al. 2020

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The influence of the compensating cation (Na+, Li+, Mg2+) nature on the water adsorption properties of LTA and FAU-type zeolites was investigated. Cation exchanges were performed at 80 °C for 2 h using 1 M aqueous solutions of lithium chloride (LiCl) or magnesium chloride (MgCl2). XRF and ICP-OES analyses indicate that the cation exchange yields reach values between 59 to 89% depending on the number of exchange cycles and the nature of the zeolite and cation, while both zeolites structures are preserved during the process, as shown by XRD and solid state NMR analyses. Nitrogen adsorption-desorption experiments indicate a higher available microporous volume when sodium cations are replaced by smaller monovalent lithium cations or by divalent magnesium cations because twice less cations are needed compared to monovalent cations. Up to 15% of gain in the available microporous volume is obtained for FAU-type zeolites exchanged with magnesium cation. This improvement facilitates the adsorption of water with an increase in the water uptake up to 30% for the LTA and FAU type zeolites exchanged with magnesium. These exchanged zeolites are promising for uses in water decontamination because a smaller amount is needed to trap the same amount of water compared to their sodium counterparts.

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“…The smaller cation radius of magnesium (0.72 Å) in comparison with sodium (1.02 Å) [ 61 ], leads to a structure contraction as well as slight changes in peak intensity ratios and shifts when the sodium cations are replaced by other alkali or alkali earth metal cations. These results are in agreement with the literature [ 62 , 63 , 64 ] and are explained as a consequence of the difference between the scattering power, which is specific to each cation, and the slightly different occupation sites in the pores [ 64 , 65 ].…”

Section: Resultssupporting

confidence: 92%

Zeolite-Polymer Composite Materials as Water Scavenger

et al. 2021

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The influence of the charge compensating cation nature (Na+, Mg2+) on the water adsorption properties of LTA-type zeolites used as filler in composite materials (zeolite/polymers) was investigated. Large scale cation exchanges were performed on zeolite powder at 80 °C for 2 h using 1 M magnesium chloride (MgCl2) aqueous solutions. XRF, ICP, and EDX analyses indicate a successful cationic exchange process without the modification of the zeolite structure as shown by XRD and solid-state NMR analyses. Composite materials (granulates and molded parts) were manufactured using to extrusion and injection processes. In the case of MgA zeolite, nitrogen adsorption–desorption experiments allowed us to measure a microporous volume, unlike NaA zeolite, which is non-porous to nitrogen probe molecule. SEM and EDX analyses highlighted the homogeneous distribution of zeolite crystals into the polymer matrix. Water adsorption capacities confirmed that the trends observed in the zeolite powder samples are preserved after dragging zeolites into composite formulations. Granulates and molded parts composite samples containing the magnesium exchanged zeolite showed an increase of their water adsorption capacity up to +27% in comparison to composite samples containing the non-exchanged zeolite. The MgA composite is more promising for water decontamination applications due to its higher water adsorption properties than the NaA composite.

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Synthesis of 4A Zeolite and Characterization of Calcium- and Silver-Exchanged Forms

Cited by 12 publications

References 45 publications

Synthesis of FAU-Type Zeolite Membranes with Antimicrobial Activity

Synthesis of FAU-Type Zeolite Membranes with Antimicrobial Activity

Influence of the Compensating Cation Nature on the Water Adsorption Properties of Zeolites

Zeolite-Polymer Composite Materials as Water Scavenger

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