scholarly journals How the Solid/Liquid Ratio Affects the Cation Exchange Process and Porosity in the Case of Dioctahedral Smectite: Structural Analysis?

2021 ◽  
Vol 2021 ◽  
pp. 1-24
Author(s):  
Chadha Mejri ◽  
Walid Oueslati ◽  
Abdesslem Ben Haj Amara
Keyword(s):  
Structural Analysis ◽  
Cation Exchange ◽  
Layer Structure ◽  
Structural Parameters ◽  
Exchange Process ◽  
Xrd Analysis ◽  
Exchangeable Cations ◽  
Structural Parameter ◽  
Liquid Ratio ◽  
Solid Liquid

The performance of a clay mineral geomembrane used in the context of a geological barrier for industrial and radioactive waste confinement must pass through the understanding of its hydrous response as well as the limits of the cation exchange process which are closely related to the solid/liquid ratio constraint. The Na-rich montmorillonite is used, as starting material, to evaluate the link between the applied external constraint (variable solid/liquid ratio) and the structural response of the material. The geochemical constraint is realized at the laboratory scale, and the possible effects are investigated in the cases of Ba2+ and Ni2+ heavy metal cations. The structural analysis is achieved using the XRD profile modeling approach to quantify the interlayer space (IS) deformation. The quantitative XRD analysis, which consists of the comparison of experimental 001 reflections with the calculated ones deduced from structural models, allowed us to determine the optimal structural parameters describing IS configuration along the c ∗ axis. The obtained result showed an interstratified hydration character, for both studied exchangeable cations, regardless of the solid/liquid ratio being described probably by a partial cation exchange process. The theoretical mixed layer structure (MLS) suggests the coexistence of more one cristallite species saturated by more than one exchangeable cations, indicating a partial saturation of all exchangeable sites. The optimum structural parameter values, from the theoretical model, allowed us to follow the evolution of several intrinsic properties versus the applied constraint strength. The variable solid/liquid ratio effect on the material porosity is examined by the BET-specific surface area and BJH pore size distribution (PSD) analyses. The adsorption measurement outcomes confirm XRD results concerning mainly the link between several intrinsic clay properties and the constraint strength.

scholarly journals Discretization of the Water Uptake Process of Na-Montmorillonite Undergoing Atmospheric Stress: XRD Modeling Approach

2018 ◽  
Vol 2018 ◽  
pp. 1-17 ◽  
Author(s):  
Walid Oueslati ◽  
Mahdi Meftah
Keyword(s):  
Structural Analysis ◽  
Layer Structure ◽  
Structural Parameters ◽  
Xrd Analysis ◽  
Structural Parameter ◽  
Atmospheric Conditions ◽  
In Situ Xrd ◽  
Before And After ◽  
Geological Barrier ◽  
Uptake Process

This work focuses on the water-montmorillonite interaction under variable atmospheric conditions in order to characterize the interlamellar space (IS) configuration for possible use in the context of geological barrier for radioactive and industrial waste confinement. Atmospheric stress is achieved by applying, for Na-rich montmorillonite, a water sorption/desorption constraint, created at the laboratory scale. This hydrological disturbance allows the “demolition” of the clay history and to highlight the clay hydrous performance. The structural analysis is achieved using modeling of XRD profiles, which allowed us to determine the optimal structural parameters describing the IS configuration along thec∗axis. During the “in situ” XRD analysis, a sorption/desorption cycle is envisaged by variation of the relative humidity rate (%RH) from the saturated condition (94 %RH) towards extremely dry ones (2-3 %RH). Qualitatively, a new hydration hysteresis behavior of the “stressed” sample appears. Structural analysis achieved before and after perturbation allowed us to identify, respectively, the homogeneous hydration states, the hydrous transition domains, and the hydration heterogeneity degree. This latter parameter is characterized, quantitatively, by variable relative abundances of mixed-layer structure (MLS) population discerned over a wide explored RH range. Using the optimum structural parameter, the water molecule distribution versus the applied hydrous strain was quantified.

The Effect on Physical, Electrical and Structural Parameters of RF Sputtered Molybdenum Thin Film

2011 ◽  
Vol 403-408 ◽  
pp. 5092-5096 ◽  
Author(s):  
Mukter Zaman ◽  
Gunawan Witjaksono ◽  
Teh Aun Shih ◽  
Shabiul Islam ◽  
Masuri Othman ◽  
...  
Keyword(s):  
Thin Film ◽  
Deposition Rate ◽  
Rate Increase ◽  
Structural Parameters ◽  
Rf Sputtering ◽  
Xrd Analysis ◽  
Device Fabrication ◽  
Structural Parameter ◽  
Rf Power ◽  
Deposition Parameters

In this study, the physical, electrical, and structural parameter on radio frequency (RF) sputtered molybdenum thin film is investigated as a function of two deposition parameters: rf power, and argon (Ar) pressure. Films are sputtered onto the substrates nominally held in room temperature in a RF sputtering system at partial argon (Ar) pressure. A number of 10 films are deposited at 8 sccm of Ar pressure while varying the rf power from 90 to 360 watt. Besides, another set of 7 films are deposited at 240 watt RF power while varying the Ar pressure from 8 to 32 watts. All the films are characterized using FESEM, AFM, XRD, and four points probe. The analysis results substantiate that, to fabricate a low resistive thin layer of molybdenum (Mo) both sputtering power, and deposition time Ar pressure plays significant rules. It is found that, with the increase of the RF power (90 to 280 watt) the deposition rate increase from 1.2 A0/sec to 4.4 A0/sec. But at a RF power higher than 280 watt the deposition rate saturated and it does not increase as linear as before. Also resistivity continuously decreases as the RF power increases from 90 watt up to 270 watt, after that the resistivity remain almost same regardless the RF power increased. Besides, by varying the Ar pressure it is found that with the increase of the Ar pressure the deposition rate increase until 20 sccm (up to 2.4 A0/sec). With further increase of the Ar pressure deposition rate start reducing and reached 2.1 A0/sec at 32 sccm. Based on the above investigation and analysis optimized film is deposited and further analyzed. The surface roughness is analyzed using AFM characterization tool and found 27.4519 nm. The FESEM and XRD analysis along with the resistivity of the film is used to measure the strain of the deposited film and found a strain of less than 0.01% on the optimized film, which is essential for MEMS/NEMS device fabrication and energy harvesting applications.

Effect of Hydrothermal Conditions on the Cation Exchange Capacity of MSWI Fly Ash

2006 ◽  
Vol 510-511 ◽  
pp. 110-113
Author(s):  
Young Sook Shim ◽  
Woo Keun Lee
Keyword(s):  
Fly Ash ◽  
Reaction Time ◽  
Cation Exchange ◽  
Reaction Temperature ◽  
Cation Exchange Capacity ◽  
Exchange Capacity ◽  
Waste Incinerator ◽  
Liquid Ratio ◽  
Hydrothermal Conditions ◽  
Solid Liquid

In this study, we studied to find the most suitable condition for the preparation of adsorbent by hydrothermal treatment of fly ash from the municipal solid waste incinerator (MSWI). There are many variables that affect the adsorptive characteristics in our study. With the variation of which discussed the effect such as the concentration of NaOH, reaction temperature, reaction time, solid/liquid ratio, and so on. The phase of adsorbent, its morphology and cation exchange capacity (CEC) were analyzed to evaluate their effects. The phase of adsorbent after treatment was identified by X-ray diffraction (XRD), the morphology was examined by scanning electron microscopy (SEM), and the CEC was analyzed by the ammonium acetate method. The maximum CEC value was obtained under the condition of 3N NaOH, 100°C of reaction temperature, 12 hr of reaction time, and 1:10 of solid/liquid ratio. The CEC was 68 meq/100g in this condition, which was 8 times the amount of raw fly ash.

scholarly journals STRUCTURAL ANALYSIS OF ZINC OXIDE THIN FILMS PREPARED BY THERMAL EVAPORATION TECHNIQUE

2017 ◽  
Vol 4 (3) ◽  
pp. 7-9
Author(s):  
Balaganesh A.s ◽  
Chandar Shekar B
Keyword(s):  
Thin Films ◽  
Zinc Oxide ◽  
Structural Analysis ◽  
Thermal Evaporation ◽  
Structural Parameters ◽  
Xrd Analysis ◽  
Zno Films ◽  
Thermal Evaporation Technique ◽  
Oxide Thin Films ◽  
Evaporation Technique

Zinc oxide thin films of 800nm were successfully prepared by thermal evaporation technique. XRD analysis revealed polycrystalline nature of the as prepared ZnO films. The structural parameters such as crystallite size, dislocation density and micro strain were evaluated and discussed.

scholarly journals Exo⇔Endo Isomerism, MEP/DFT, XRD/HSA-Interactions of 2,5-Dimethoxybenzaldehyde: Thermal, 1BNA-Docking, Optical, and TD-DFT Studies

Molecules ◽  
2020 ◽  
Vol 25 (24) ◽  
pp. 5970
Author(s):  
Nabil Al-Zaqri ◽  
Mohammed Suleiman ◽  
Anas Al-Ali ◽  
Khaled Alkanad ◽  
Karthik Kumara ◽  
...  
Keyword(s):  
Density Functional ◽  
Energy Gap ◽  
Structural Parameters ◽  
Population Analysis ◽  
Xrd Analysis ◽  
X Ray Diffraction ◽  
Optical Energy Gap ◽  
Functional Theory ◽  
Reactivity Descriptors ◽  
Td Dft

The exo⇔endo isomerization of 2,5-dimethoxybenzaldehyde was theoretically studied by density functional theory (DFT) to examine its favored conformers via sp2–sp2 single rotation. Both isomers were docked against 1BNA DNA to elucidate their binding ability, and the DFT-computed structural parameters results were matched with the X-ray diffraction (XRD) crystallographic parameters. XRD analysis showed that the exo-isomer was structurally favored and was also considered as the kinetically preferred isomer, while several hydrogen-bonding interactions detected in the crystal lattice by XRD were in good agreement with the Hirshfeld surface analysis calculations. The molecular electrostatic potential, Mulliken and natural population analysis charges, frontier molecular orbitals (HOMO/LUMO), and global reactivity descriptors quantum parameters were also determined at the B3LYP/6-311G(d,p) level of theory. The computed electronic calculations, i.e., TD-SCF/DFT, B3LYP-IR, NMR-DB, and GIAO-NMR, were compared to the experimental UV–Vis., optical energy gap, FTIR, and 1H-NMR, respectively. The thermal behavior of 2,5-dimethoxybenzaldehyde was also evaluated in an open atmosphere by a thermogravimetric–derivative thermogravimetric analysis, indicating its stability up to 95 °C.

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

Processes ◽  
2021 ◽  
Vol 9 (2) ◽  
pp. 217
Author(s):  
Marin Ugrina ◽  
Martin Gaberšek ◽  
Aleksandra Daković ◽  
Ivona Nuić
Keyword(s):  
Chemical Modification ◽  
Aqueous Solutions ◽  
Specific Surface ◽  
Surface Area ◽  
Natural Zeolite ◽  
Contact Time ◽  
Liquid Ratio ◽  
X Ray ◽  
Solid Liquid

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.

scholarly journals Photodegradation of Phenolic Compounds from Water in the Presence of a Pd-Containing Exhausted Adsorbent

2020 ◽  
Vol 10 (23) ◽  
pp. 8440
Author(s):  
Lavinia Lupa ◽  
Laura Cocheci ◽  
Bogdan Trica ◽  
Adina Coroaba ◽  
Adriana Popa
Keyword(s):  
Phenol Degradation ◽  
Magnesium Silicate ◽  
Degradation Process ◽  
Liquid Ratio ◽  
Phenol Solution ◽  
Secondary Sources ◽  
Great Economic Importance ◽  
Phenol Photodegradation ◽  
Cyphos Il 101 ◽  
Solid Liquid

A closed-cycle technology regarding the use of an exhausted Pd-based adsorbent as a photocatalyst in the degradation process of phenol is presented. Pd (II) represents a precious metal of great economic importance. Its obtained from natural sources become more difficult to achieve. Therefore, also considering the regulations of the “circular economy,” its recovery from secondary sources turn out to be a stringent issue in the last years. Pd(II) ions are removed from aqueous solution through adsorption onto Florisil (an inorganic solid support—magnesium silicate) impregnated with Cyphos IL 101 (trihexyl tetradecyl phosphonium chloride). It was observed that the presence of the ionic liquid (IL) in the adsorbent structure doubles the adsorption efficiency of the studied materials. The newly obtained Pd-based photocatalyst was exhaustively characterized and was used in the degradation process of phenol from aqueous solutions. The phenol degradation process was studied in terms of the nature of the photocatalyst used, time of photodegradation and solid: liquid ratio. It was observed that both the presence of IL and Pd lead to an increase in the efficiency of the phenol degradation process. The new Pd-based photocatalyst could be efficiently used in more cycles of phenol photodegradation processes. When is used as a photocatalyst the Florisil impregnated with IL and loaded with 2 mg/g of Pd, a degree of mineralization of 93.75% is obtained after 180 min of irradiation of a phenol solution having a concentration of 20 mg/L and using a solid:liquid ratio = 1:1.

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