Effect of Water Adsorption on Cation-Surface Interaction Energy in the Na-Mordenite of 5.5 : 1 Si/Al Ratio

Diaby, Sekou

doi:10.1155/2016/2152180

Cited by 5 publications

(5 citation statements)

References 28 publications

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“…Intensive research is being made on zeolites for their outstanding properties and application in heterogeneous catalysis (catalytic cracking and isomerization), gas storage, separation of gases, ion exchange, and production of fine chemicals [1][2][3][4][5][6]. Zeolites are extensively used in large-scale petrochemical reactions and oil refining processes.…”

Section: Introductionmentioning

confidence: 99%

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Ammonia and water in zeolites: Effect of aluminum distribution on the heat of adsorption

Zhakisheva

Gutiérrez‐Sevillano²,

Calero³

2023

Separation and Purification Technology

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Section: Introductionmentioning

confidence: 99%

“…The so-called 'side pockets' that are in the [0 1 0] direction link together these channels. They are 8 -membered rings with a more circular shape of the size of about 3.4-4.8 Å passing through the b-axis [1,3].…”

Section: Introductionmentioning

confidence: 99%

Ammonia and water in zeolites: Effect of aluminum distribution on the heat of adsorption

Zhakisheva

Gutiérrez‐Sevillano²,

Calero³

2023

Separation and Purification Technology

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“…The change in the pH e of the surrounding medium in the above-mentioned wide pH range shows the buffering properties of SZ due to the negative charge of the lattice. It can be seen from Figure 2 that a plateau is broader for SZ (3)(4)(5)(6)(7)(8)(9)(10) in comparison to NZ (6-9) and for four pH units higher, indicating a higher affinity of SZ toward H + ions due to ahigher net negative charge. Thus, the increase in pH e is due to neutralization of the negative charge of the zeolite lattice as a consequence of sulfur modification.…”

Section: Mineralogical and Physico-chemical Characterization Of Sorbentsmentioning

confidence: 97%

Preparation and Characterization of the Sulfur-Impregnated Natural Zeolite Clinoptilolite for Hg(II) Removal from Aqueous Solutions

et al. 2021

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Sulfur-impregnated zeolite has been obtained from the natural zeolite clinoptilolite by chemical modification with Na2S at 150 °C. The purpose of zeolite impregnation was to enhance the sorption of Hg(II) from aqueous solutions. Chemical analysis, acid and basic properties determined by Bohem’s method, chemical behavior at different pHo values, zeta potential, cation-exchange capacity (CEC), specific surface area, X-ray powder diffraction (XRPD), scanning electron microscopy with energy-dispersive X-ray analysis (SEM-EDS), Fourier transform infrared spectroscopy (FTIR), as well as thermogravimetry with derivative thermogravimetry (TG-DTG) were used for detailed comparative mineralogical and physico-chemical characterization of natural and sulfur-impregnated zeolites. Results revealed that the surface of the natural zeolite was successfully impregnated with sulfur species in the form of FeS and CaS. Chemical modification caused an increase in basicity and the net negative surface charge due to an increase in oxygen-containing functional groups as well as a decrease in specific surface area and crystallinity due to the formation of sulfur-containing clusters at the zeolite surface. The sorption of Hg(II) species onto the sulfur-impregnated zeolite was affected by the pH, solid/liquid ratio, initial Hg(II) concentration, and contact time. The optimal sorption conditions were determined as pH 2, a solid/liquid ratio of 10 g/L, and a contact time of 800 min. The maximum obtained sorption capacity of the sulfur-impregnated zeolite toward Hg(II) was 1.02 mmol/g. The sorption mechanism of Hg(II) onto the sulfur-impregnated zeolite involves electrostatic attraction, ion exchange, and surface complexation, accompanied by co-precipitation of Hg(II) in the form of HgS. It was found that sulfur-impregnation enhanced the sorption of Hg(II) by 3.6 times compared to the natural zeolite. The leaching test indicated the retention of Hg(II) in the zeolite structure over a wide pH range, making this sulfur-impregnated sorbent a promising material for the remediation of a mercury-polluted environment.

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“…The adsorption of water on mordenites has been extensively studied. ,,− Chibani et al , investigated the adsorption of water and iodine in different cation-exchanged mordenites via density functional theory (DFT) studies. They found that, for Ag mordenite (AgZ), water was adsorbed preferentially in the small channels (5 Å) or the side pockets of mordenite crystals while iodine preferred the large (main) channels (7 Å).…”

Section: Introductionmentioning

confidence: 99%

Silver-Exchanged Mordenite for Capture of Water Vapor in Off-Gas Streams: A Study of Adsorption Kinetics

Nan

Liu

Tang

et al. 2018

Ind. Eng. Chem. Res.

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Reduced silver-exchanged mordenite (Ag0Z) has been recognized as the benchmark adsorbent for radioactive iodine removal from the nuclear fuel reprocessing off-gases. It has also been shown to have a considerable adsorption capacity for water vapor, which is a major component (tritiated water) in the off-gases of spent nuclear fuel reprocessing facilities. Therefore, understanding the kinetics of water vapor adsorption on Ag0Z is necessary for a better design of off-gas treatment systems. The adsorption kinetics were studied through adsorption experiments of water vapor on Ag0Z pellets and analyses of the kinetic data with adsorption models that describe processes of mass transfer and inter/intracrystalline diffusion. Uptake curves of water vapor on Ag0Z pellets were obtained with a continuous-flow adsorption system at temperatures of 25, 40, 60, 100, 150, and 200 °C and dew points from −53.6 °C to 12.1 °C. The diffusion-controlling factors were determined experimentally and analytically. It was found that the diffusion process of water vapor in Ag0Z pellets was controlled by macropore diffusion. Gas film mass-transfer resistance also contributed to the adsorption process of the 0.9 mm Ag0Z pellets, but it could be minimized with a high gas velocity and small pellet radius. Kinetic models including macropore diffusion (MD), linear driving force (LDF) and shrinking core (SC) were used to fit the uptake curves. The macropore diffusivity for water vapor adsorption on Ag0Z pellets was determined using the three models. It was found that the LDF and SC models could well describe the kinetic process, while the fitting with the MD model was not quite as good due to the existence of external mass-transfer resistance for the 0.9 mm Ag0Z pellets.

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Effect of Water Adsorption on Cation-Surface Interaction Energy in the Na-Mordenite of 5.5 : 1 Si/Al Ratio

Cited by 5 publications

References 28 publications

Ammonia and water in zeolites: Effect of aluminum distribution on the heat of adsorption

Ammonia and water in zeolites: Effect of aluminum distribution on the heat of adsorption

Preparation and Characterization of the Sulfur-Impregnated Natural Zeolite Clinoptilolite for Hg(II) Removal from Aqueous Solutions

Silver-Exchanged Mordenite for Capture of Water Vapor in Off-Gas Streams: A Study of Adsorption Kinetics

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