How 'Hydrophilic Sites' Work in Water Adsorption/Desorption by Natural Clinoptilolite

The kinetic mechanism of water adsorption/desorption on samples of natural clinoptilolite-K has been investigated by using an electrical method based on measurements of variation of AC current intensity during the time. In particular, a high-frequency sinusoidal voltage (5kHz) was applied to the sample (high frequency was required to avoid sample/electrode interface polarization phenomena) and the resulting AC micro-current intensity was monitored during the time. The sample was hydrated by exposition to a 75% humidity atmosphere, while dehydration was achieved by exposing the sample to activated silica gel in a close container or simply taking it in air. The hydration reaction followed a pseudo-zero-order kinetics, while the dehydration reaction followed a first-order kinetics both in air or dry atmosphere. The observed kinetic behaviors can be explained on the basis of a 'catalytic effect' of cations in both water adsorption and desorption from the 3D-framework walls.

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Electrical Investigation of the Mechanism of Water Adsorption/Desorption by Natural Clinoptilolite Desiccant Used in Food Preservation

Materials Proceedings ◽

10.3390/ciwc2020-06800 ◽

2020 ◽

Vol 2 (1) ◽

pp. 15

Author(s):

Gianfranco Carotenuto

Keyword(s):

Electrostatic Interactions ◽

Water Adsorption ◽

Food Preservation ◽

Diffusion Control ◽

Time Behavior ◽

Electrical Measurements ◽

Desorption Process ◽

Cereal Grain ◽

Natural Clinoptilolite ◽

Adsorption Desorption

Powdered zeolites are used as a desiccant in the preservation of many types of vegetable foods (e.g., cereal grain, corn, etc.). Natural clinoptilolite is a very abundant, inexpensive, nontoxic, regenerable, and environmentally friendly zeolite with good desiccant properties. Here, water adsorption/desorption properties of natural clinoptilolite have been investigated by a novel technique based on a.c. electrical measurements. In particular, owing to the presence of extra-framework cations, zeolites are ionic conductors. The presence of water in cationic sites significantly modifies cation mobility, because strong electrostatic interactions act between cations and nucleophilic areas in 3D-frameworks, and non-hydrated cations have a near zero mobility, while hydrated cations have enough mobility at room temperature. The type of law controlling the adsorption/desorption process has been established by monitoring the real-time behavior of relative current intensity moving in the sample surface biased by a sinusoidal voltage signal of 20Vpp (5 kHz) and exposed to a constant moisture atmosphere (75%) at 25 °C. An intergranular diffusion control was active at the beginning of hydration because of the lamellar texture, then Lagergren irreversible pseudo-first-order kinetics took place. To confirm the adsorption mechanism and possibility of regenerating the clinoptilolite desiccant, dehydration by silica gel was electrically monitored and an exponential kinetic law found.

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ELECTRICAL INVESTIGATION OF THE WATER ADSORPTION MECHANISM ON NATURAL CLINOPTILOLITE

10.32545/encyclopedia202003.0007.v4 ◽

2020 ◽

Author(s):

Gianfranco Carotenuto

Keyword(s):

Water Adsorption ◽

Electrical Mobility ◽

Ionic Conductors ◽

Desorption Process ◽

First Order ◽

Hydrogen Bond Interactions ◽

First Order Kinetics ◽

Cation Framework ◽

Natural Clinoptilolite ◽

Adsorption Desorption

Zeolites are ionic conductors and the cation electrical mobility in zeolites depends on their hydration state; consequently, the water adsorption/desorption process can be simply investigated by measuring the temporal evolution of current intensity in samples exposed to an environment with constant humidity or dry air, respectively. According to this kinetic analysis, a mechanism has been formulated for the water adsorption process able to justify the Lagergren pseudo-first-order kinetics observed for adsorption and the first-order kinetics observed for desorption. In this mechanism water molecules are first attract by the electric field of the cations and then they move at cation-framework interface to maximize the hydrogen bond interactions.

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Adsorption–Desorption Characteristics of ss-DNA on 2D TpTta-COF Studied by Fluorescently Labeled Oligonucleotides

NANO ◽

10.1142/s1793292021500508 ◽

2021 ◽

pp. 2150050

Author(s):

Zhaoyu Han ◽

Sen Li ◽

Shaoxian Yin ◽

Zhi-Qin Wang ◽

Yanfei Cai ◽

...

Keyword(s):

Chemical Properties ◽

Kinetic Mechanism ◽

Optical Biosensors ◽

Desorption Kinetic ◽

Wide Range ◽

Potential Applications ◽

Fluorescently Labeled Oligonucleotides ◽

Adsorption Desorption ◽

Physical And Chemical ◽

And Chemical Properties

Being the newest member of the 2D materials family, 2D-nanosheet possesses many distinctive physical and chemical properties resulting in a wide range of potential applications. Recently, it was discovered that 2D COF can adsorb single-stranded DNA (ss-DNA) efficiently as well as usefully to quench fluorophores. These properties make it possible to prepare DNA-based optical biosensors using 2D COF. While practical analytical applications are being demonstrated, the fundamental understanding of binding between 2D COF and DNA in solution received relatively less attention. In this work, we carried out a systematic study to understand the adsorption and desorption kinetic, mechanism, and influencing factors of ss-DNA on the surface of 2D COF. We demonstrated that shorter DNAs are adsorbed more rapidly and bind more tightly to the surface of 2D COF. The adsorption is favored by a higher pH. The different buffer types also can affect the adsorption. In Tris-HCl solution, the adsorption reached highest efficiency. By adding the complementary DNA (cDNA), desorption of the absorbed DNA on 2D COF can be achieved. Further, desorption efficiency can also be exchanged by various surfactant in solution. These findings are important for further understanding of the interactions between DNA and COFs and for the optimization of DNA and COF-based devices and sensors.

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Water adsorption/desorption isotherms for characterization of microporosity in sandstone and carbonate rocks

Studies in Surface Science and Catalysis - Characterization of Porous Solids VII - Proceedings of the 7th International Symposium on the Characterization of Porous Solids (COPS-VII), Aix-en-Provence, France, 26-28 May 2005 ◽

10.1016/s0167-2991(07)80039-5 ◽

2007 ◽

pp. 295-302 ◽

Cited By ~ 2

Author(s):

H. Fischer ◽

N.R. Morrow ◽

G. Mason

Keyword(s):

Carbonate Rocks ◽

Water Adsorption ◽

Desorption Isotherms ◽

Adsorption Desorption

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Mixed-Solvothermal Synthesis of MIL-101(Cr) and Its Water Adsorption/Desorption Performance

Industrial & Engineering Chemistry Research ◽

10.1021/acs.iecr.8b05243 ◽

2019 ◽

Vol 58 (8) ◽

pp. 2983-2990 ◽

Cited By ~ 10

Author(s):

Bingqiong Tan ◽

Yanshu Luo ◽

Xianghui Liang ◽

Shuangfeng Wang ◽

Xuenong Gao ◽

...

Keyword(s):

Solvothermal Synthesis ◽

Water Adsorption ◽

Adsorption Desorption

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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.

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Facilitating role of Pd for hydrogen, oxygen and water adsorption/desorption processes from bulk CeO2 and CeO2/γ-Al2O3

Catalysis Today ◽

10.1016/j.cattod.2018.04.063 ◽

2019 ◽

Vol 323 ◽

pp. 141-147 ◽

Cited By ~ 1

Author(s):

Deniz Kaya ◽

Dheerendra Singh ◽

Serkan Kincal ◽

Deniz Uner

Keyword(s):

Water Adsorption ◽

Adsorption Desorption

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Pore Size-Dependent Structure of Confined Water in Mesoporous Silica Films from Water Adsorption/Desorption Using ATR–FTIR Spectroscopy

Langmuir ◽

10.1021/acs.langmuir.9b01435 ◽

2019 ◽

Vol 35 (37) ◽

pp. 11986-11994 ◽

Cited By ~ 7

Author(s):

Bettina Baumgartner ◽

Jakob Hayden ◽

Jérôme Loizillon ◽

Sophia Steinbacher ◽

David Grosso ◽

...

Keyword(s):

Mesoporous Silica ◽

Ftir Spectroscopy ◽

Pore Size ◽

Water Adsorption ◽

Confined Water ◽

Silica Films ◽

Size Dependent ◽

Adsorption Desorption

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Optimization of ultrasonic-assisted copper ion removal from polluted water by a natural clinoptilolite nanostructure through a central composite design

Clay Minerals ◽

10.1180/clm.2019.46 ◽

2019 ◽

Vol 54 (4) ◽

pp. 339-347 ◽

Cited By ~ 1

Author(s):

Mohsen Sheydaei ◽

Ali Balanejad Gasemsoltanlu ◽

Asadollah Beiraghi

Keyword(s):

Ftir Spectroscopy ◽

Polluted Water ◽

Sonication Time ◽

X Ray ◽

Ion Removal ◽

Initial Ph ◽

Ultrasonic Assisted ◽

Natural Clinoptilolite ◽

Adsorption Desorption ◽

Central Composite

AbstractA natural clinoptilolite nanostructure (CNS) along with ultrasonic irradiation was used to remove Cu2+ ions from polluted water. In the first part of this work, natural clinoptilolite was converted to CNS by ball milling. The natural clinoptilolite and prepared CNS samples were characterized by scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy, Fourier-transform infrared (FTIR) spectroscopy, X-ray diffraction, N2 adsorption/desorption and pH at the point of zero charge analyses. The SEM images showed the development of CNS from natural clinoptilolite by ball milling. The N2 adsorption/desorption and FTIR spectroscopy confirmed the greater specific surface area, pore volume and number of surface groups of the CNS compared to the natural clinoptilolite. In addition, the crystalline phase of the CNS was the same as the natural clinoptilolite. In the second part of this work, the ultrasonic-assisted sorption of Cu2+ ions from polluted water by CNS was investigated. These experiments were optimized with response surface methodology based on central composite designs. The effects of initial pH of solution, CNS dosage, sonication time and temperature on Cu2+ ion-removal efficiency were investigated. By using a CNS dosage of 500 mg L−1, an initial pH of 6, a sonication time of 12 min and a sonication temperature of 45°C as optimal conditions, 97% of Cu2+ ions were removed from contaminated water. The initial pH was the most effective variable. Ultrasonic-assisted sorption of Cu2+ was more effective than sorption alone, onto the CNS.

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