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

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.

Download Full-text

ADSORPTION PROPERTIES OF TITANIA-SILICA MEMBRANES OBTAINED ON CERAMIC SUBSTRАTE

Proceedings of the National Academy of Sciences of Belarus Chemical Series ◽

10.29235/1561-8331-2018-54-3-274-280 ◽

2018 ◽

Vol 54 (3) ◽

pp. 274-280

Author(s):

T. F. Kouznetsova ◽

A. I. Ivanets ◽

J. D. Sauka

Keyword(s):

Surface Area ◽

Quartz Substrate ◽

Cetylpyridinium Chloride ◽

Nitrogen Adsorption ◽

Mesoporous Structure ◽

Adsorption Properties ◽

Molar Ratio ◽

Silica Membranes ◽

Metal Silicate ◽

Adsorption Desorption

Titania-silica membranes on a porous quartz substrate are prepared by its direct contact with metal silicate sol at various Ti/Si ratios in the conditions of coagel sedimentation and presence of cetylpyridinium chloride. The study of textural and adsorption properties of membranes is conducted by low-temperature nitrogen adsorption-desorption, including methods of t-plots and DFT theory. It was shown that obtained membranes have mesoporous structure with the specific surface area and pore hydraulic diameter varied in intervals of 64–217 m2 /g and 4–11 nm, respectively. Developed values of surface area remain up to molar ratio of Ti/Si = 50/50.

Download Full-text

Effects of Carbonation on the Specific Surface BET of Cement Mortar Measured by Two Different Methods: Nitrogen Adsorption and Water Adsorption

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.931-932.421 ◽

2014 ◽

Vol 931-932 ◽

pp. 421-425 ◽

Cited By ~ 2

Author(s):

Son Tung Pham ◽

William Prince

Keyword(s):

Specific Surface ◽

Surface Area ◽

Specific Surface Area ◽

Water Adsorption ◽

Cement Mortar ◽

Nitrogen Adsorption ◽

Accelerated Carbonation ◽

Molecular Sizes ◽

The Difference ◽

Adsorption Desorption

The objective of this work was to examine the microstructural changes caused by the carbonation of normal mortar. Samples were prepared and subjected to accelerated carbonation at 20°C, 65% relative humidity and 20% CO2concentration. The evolutions of the pore size distribution and the specific surface area during carbonation were calculated from the adsorption - desorption isotherms of water vapour and nitrogen. Conflicts observed in the results showed that the porous domains explored by these two methods are not the same due to the difference in molecular sizes of nitrogen and water. These two techniques therefore help to complementarily evaluate the effects of carbonation. The study also helped to explain why results in the literature diverge greatly on the influence of carbonation on specific surface area.

Download Full-text

Water Adsorption Properties of Free and Dehydrated β-Cyclodextrin Studied by near Infrared Spectroscopy and Gravimetry

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.689.143 ◽

2016 ◽

Vol 689 ◽

pp. 143-147 ◽

Cited By ~ 1

Author(s):

Alfred A. Christy

Keyword(s):

Hydrogen Bonds ◽

Infrared Spectra ◽

Water Adsorption ◽

Near Infrared ◽

Adsorption Properties ◽

Water Molecules ◽

Hydroxyl Groups ◽

Oh Groups ◽

Near Infrared Spectra ◽

Adsorption Of Water

β-cyclodextrin, like other carbohydrates has a tendency to adsorb water molecules and the properties are attributed to the hydroxyl groups in the molecules. β-cyclodextrin, the cyclic oligomer of glucose has a hydrophobic interior and hydrophilic exterior. The cyclic structure favours the formation of hydrogen bonds between the OH groups on the adjacent glucose units and affects the formation of hydrogen bonds with water molecules. The hydoxyl groups engaged in hydrogen bondings can be eliminated at high temperatures and the adsorption properties of the dehydrated β-cyclodextrin will depend on the new functional groups formed. The aim of the report is to discuss the issue of the water adsorption properties of free and dehydrated β-cyclodextrin. Dry β-cyclodextrin and dehydrated β-cyclodextrin at temperatures 250, 300 and 350 °C were allowed to adsorb water from a humidity controlled air environmennt and the evolving near infrared spectra were measured using a near infrared spectrometer equipped with a transflectance accessory. The near infrared spectra in the region 10,000-4000 cm-1 and their second and fourth derivative profiles were used in studying the variation in the adsorption characteristics of dehydrated β-cyclodextrin. The results of the analyses show that the adsorption of water by β-cyclodextrin decreses at 300 °C compared to 200 and 250 °C. Dehydration forms more of the ethereal type-O-bonds in the molecule and explains the decrease in the water molecular adsorption at higher dehydration temperatures.

Download Full-text

Preparation of GO/MIL-101(Fe,Cu) composite and its adsorption mechanisms for phosphate in aqueous solution

10.21203/rs.3.rs-191207/v1 ◽

2021 ◽

Author(s):

You Wu ◽

Zuannian Liu ◽

Bakhtari Mohammad Fahim ◽

Junnan Luo

Keyword(s):

Adsorption Capacity ◽

Photoelectron Spectroscopy ◽

Adsorption Mechanism ◽

Nitrogen Adsorption ◽

Adsorption Properties ◽

Maximum Adsorption Capacity ◽

X Ray Diffraction ◽

X Ray ◽

Adsorption Mechanisms ◽

Adsorption Desorption

Abstract In this study, MIL-101(Fe), MIL-101(Fe,Cu), and Graphene Oxide (GO) /MIL-101(Fe,Cu) were synthesized to compose a novel sorbent. The adsorption properties of these three MOFs-based composites were compared toward the removal of phosphate. Furthermore, the influencing factors including reaction time, pH, temperature and initial concentration on the adsorption capacity of phosphate on these materials as well as the reusability of the material were discussed. The structure of fabricated materials and the removal mechanism of phosphate on the composite material were analyzed by Scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), nitrogen adsorption-desorption analysis and zeta potential. The results show that the maximum adsorption capacity of phosphate by the composite GO/MIL-101(Fe,Cu)-2% was 204.60 mg·g− 1, which is higher than that of MIL-101(Fe,Cu) and MIL-101(Fe). likewise the specific surface area of GO/MIL-101(Fe,Cu)-2% is 778.11 m2/g is higher than that of MIL-101(Fe,Cu) and MIL-101(Fe),which are 747.75 and 510.66m2/g respectively. The adsorption mechanism of phosphate is electrostatic attraction, form coordination bonds and hydrogen bonds. The fabricated material is a promising adsorbent for the removal of phosphate with good reusability.

Download Full-text

Comparison of Water Adsorption Properties of Cellulose and Cellulose Nanocrystals Studied by Near-Infrared Spectroscopy and Gravimetry

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.735.235 ◽

2017 ◽

Vol 735 ◽

pp. 235-239 ◽

Cited By ~ 1

Author(s):

Thamonwan Angkuratipakorn ◽

Jirada Singkhonrat ◽

Alfred A. Christy

Keyword(s):

Infrared Spectroscopy ◽

Near Infrared Spectroscopy ◽

Cellulose Nanocrystals ◽

Water Adsorption ◽

Near Infrared ◽

Adsorption Properties ◽

Water Molecules ◽

Oh Groups ◽

Adsorption Processes ◽

Adsorption Of Water

The adsorption properties of water molecules on cellulose and cellulose nanocrystals (CNCs), isolated from defatted rice bran (DRB) by 55% sulfuric acid hydrolysis under sonication were investigated. The powdered samples of cellulose and CNCs were analysed by using near infrared spectroscopy (NIR) and gravimetry at 38% and 55% humidities. Small amounts of samples were dried under vacuum at 120°C and the NIR spectra of the dry samples and their spectra during the adsorption water molecules were measured by using an NIR spectrometer equipped with a transflectance accessory and a DTGS detector. The quantitative adsorption of water molecules by the samples was determined by gravimetry. Second and fourth derivative profiles of the NIR spectra were used in understanding the chemistry of adsorption of water molecules and the adsorption processes by the samples. The results show that the adsorption of water molecules by the cellulose samples gives rise to three prominent peaks that can be related to the water molecules engaged in hydrogen bonding with C2, C3 and C6-OH groups on the glucose units of the cellulose polymers. Furthermore, the cellulose nanocrystals adsorb twice as much of water as the cellulose polymer. It is also clear from the results that C2 and C3-OH groups in the glucose units adsorb water molecules at a faster rate than the C6-OH group and responsible for nearly 50% of the water adsorption.

Download Full-text

Enhanced Adsorption Properties of Ag-Loaded β-Zeolite towards Toluene

Materials Science Forum ◽

10.4028/www.scientific.net/msf.917.180 ◽

2018 ◽

Vol 917 ◽

pp. 180-184 ◽

Cited By ~ 4

Author(s):

Victor Temerev ◽

Aleksey Vedyagin ◽

Kristina Iost ◽

Tatyana Afonasenko ◽

Pavel Tsyrulnikov

Keyword(s):

Nitrogen Adsorption ◽

Adsorption Properties ◽

Content Increase ◽

Transmission Electron ◽

Vis Spectroscopy ◽

Silica Alumina ◽

Physicochemical Methods ◽

Enhanced Adsorption ◽

Adsorption Desorption ◽

Silica Alumina Ratio

Two series of Ag-loaded β-zeolites with silica/alumina ratio of 25 and 36 were prepared by ion exchange technique. The silver loading was varied in a range of 2-10 wt%. The samples were characterized by low-temperature nitrogen adsorption, Infrared and UV-vis spectroscopy, and transmission electron microscopy. Adsorption/desorption properties of zeolites were examined using a specially designed setup. Toluene was used as a model hydrocarbon. It was found that adsorption capacity of zeolites grows up along with silver content increase till 8%, and reduces then. According to data of physicochemical methods, at low loading the silver exists in cluster and ionic forms, while at high loading agglomerated particles predominate, which worsens the adsorption properties.

Download Full-text

Zeolite-Polymer Composite Materials as Water Scavenger

Molecules ◽

10.3390/molecules26164815 ◽

2021 ◽

Vol 26 (16) ◽

pp. 4815

Author(s):

Zakaria Tahraoui ◽

Habiba Nouali ◽

Claire Marichal ◽

Patrice Forler ◽

Julien Klein ◽

...

Keyword(s):

Composite Materials ◽

Large Scale ◽

Water Adsorption ◽

Exchange Process ◽

Nitrogen Adsorption ◽

Adsorption Properties ◽

Homogeneous Distribution ◽

Molded Parts ◽

Edx Analyses ◽

Composite Samples

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.

Download Full-text

Directional Control of the Structural Adsorption Properties of Clays by Magnetite Modification

Journal of Nanomaterials ◽

10.1155/2018/6573016 ◽

2018 ◽

Vol 2018 ◽

pp. 1-9 ◽

Cited By ~ 12

Author(s):

Tetiana A. Dontsova ◽

Elena I. Yanushevskaya ◽

Svitlana V. Nahirniak ◽

Oksana V. Makarchuk ◽

Andrei I. Ivanets ◽

...

Keyword(s):

Nitrogen Adsorption ◽

Adsorption Properties ◽

Lewis Base ◽

Molybdenum Disulphide ◽

Magnetic Sorbent ◽

Surface Areas ◽

Magnetic Sorbents ◽

Third Phase ◽

Directional Control ◽

Adsorption Desorption

This article presents the results of the study on the effect of nanomagnetite modification on textural characteristics of clay matrices, adsorption properties, and parameters of the spent sorbents separation. The nitrogen adsorption-desorption method has shown that the obtained magnetic nanocomposite sorbents have large specific surface areas (in 1.2–2 times more) than the initial clays due to the formation of the secondary porous structure on the surface and in macropores of clay matrices. The best adsorption properties with respect to dyes belong to magnetic sorbents with nanomagnetite content of 7 wt.%. The additional modification of the third phase of graphene-like molybdenum disulphide into magnetic sorbents leads to the significant increase in the sorption capacity of both cationic (up to 1100 mg/g) and anionic (up to 1830 mg/g) dyes. The conducted investigations of the total acidity and acid-base sites on the surface of clay, magnetite-modified clay, and molybdenum disulfide-modified magnetic sorbent indicate the significant influence of the Lewis base cites on the adsorption properties of these materials.

Download Full-text

Kinetics, isotherm and thermodynamic studies of S2− adsorption by (SBA-15)-Hg (II)

Water Practice & Technology ◽

10.2166/wpt.2021.081 ◽

2021 ◽

Author(s):

Xiao-Dong Li ◽

Qing-Zhou Zhai

Keyword(s):

Nitrogen Adsorption ◽

Order Equation ◽

Adsorption Properties ◽

Adsorption Efficiency ◽

X Ray Diffraction ◽

Santa Barbara ◽

Isothermal Adsorption ◽

X Ray ◽

Pseudo Second Order ◽

Adsorption Desorption

Abstract The nano-mesoporous material SBA (Santa Barbara Amorphous)-15 was synthesized using the hydrothermal method. Hg2+ was adsorbed by SBA-15 and then the S2− in the aqueous phase by (SBA-15)-Hg(II), with the hope that materials with better S2− adsorption properties can be obtained. The relevant materials were characterized by X-ray diffraction, scanning electron microscopy, 77 K nitrogen adsorption-desorption, and related product characteristics were determined. In this work, the adsorption conditions of S2− onto (SBA-15)-Hg(II) were optimized. Adsorption efficiency reached about 92% and the adsorption capacity 55.02 mg/g. Studies of the system's adsorption kinetics showed that the pseudo-second-order equation applies. The thermodynamic results indicated that ΔG0 < 0, ΔH0 = −28.56 kJ/mol, ΔS0 = −81.136 J/(mol·K), and that adsorption is exothermic, enthalpy decreases and the reaction is spontaneous. This accords with Freundlich isothermal adsorption equation.

Download Full-text