scholarly journals Humidity-accelerated spreading of ionic liquids on a mica surface

RSC Advances ◽  
2017 ◽  
Vol 7 (68) ◽  
pp. 42718-42724 ◽  
Author(s):  
Zhantao Wang ◽  
Fuxi Shi ◽  
Cunlu Zhao
Keyword(s):  
Ionic Liquids ◽  
Water Vapor ◽  
Relative Humidity ◽  
Film Formation ◽  
Water Vapor Adsorption ◽  
Precursor Film ◽  
Mica Surface ◽  
Droplet Spreading ◽  
Wetting Behavior

The role of relative humidity (RH) on the wetting behavior of droplets of two [Rmim][NTf2] ionic liquids (ILs) on a mica surface was investigated and water vapor adsorption was found to enhance the ILs precursor film formation and droplet spreading.

Adsorption of water vapor by soil in semi arid ecosystems: reconciling estimates from Lysimeters and Eddy Covariance

2021 ◽  
Author(s):  
Sinikka Paulus ◽  
Tarek S. El-Madany ◽  
René Orth ◽  
Jacob A. Nelson ◽  
Anke Hildebrandt ◽  
...  
Keyword(s):  
Water Vapor ◽  
Soil Water ◽  
Eddy Covariance ◽  
Water Vapor Adsorption ◽  
Dry Season ◽  
Climate Change Scenarios ◽  
Field Scale ◽  
Vapor Adsorption ◽  
Semi Arid

<p>Current climate change scenarios project altered rainfall frequencies which boosts scientific interest in ecosystems' responses to prolonged dry conditions. Under less rainfall, NRWI may play an increasingly important role, Yet, only sparse data are available to assess the role of non-rainfall water input (NRWI) during times of low water availability across ecoregions. Particularly, soil water vapor adsorption has received little attention at field scale. This term is used for the phase change of water from gas to liquid at highly negative matric potential. Under such conditions, water condensates already at relative humidity < 100%. The process has been broadly studied in laboratories but little is known from field experiments, which rarely cover periods longer than one month. Yet, several studies report soil water uptake from the atmosphere during soil surface cooling and in the early mornings. Lysimeters have played a strong role in quantifying these NRWI. Eddy Covariance (EC) measurements, in contrast, are known for their limited data quality under nighttime conditions when a stable boundary layer hinders the turbulent exchange of mass and energy. Therefore, EC has not been tested yet to trace soil adsorption.<br>    <br>In this contribution we adapt a methodology to derive NRWI from lysimeters data and compare them to EC measurements. We focus mainly on adsorption and evaluate the consistency between adsorption estimated with the lysimeters and negative (downward) latent heat (LE) fluxes from EC. We apply the method to a data set that comprises three years of observations from a semi-arid Spanish tree grass ecosystem. </p><p>Our results show that during the dry season the gradient in water vapour established between the atmosphere (more humid) and the soil pores (more dry) leads to adsorption by the soil. The observations from both instruments suggest that during the dry season, nightly transport of humidity from the atmosphere towards the ground is driven by soil vapor adsorption. This process occurs each night typically in the second half, but begins increasingly earlier in the evening the dryer the conditions are. The amount of water adsorbed is not directly comparable between EC and the lysimeter readings. With the latter, we quantified a yearly mean uptake between 8.8 mm and 25 mm per year. With the lysimeters we measure additionally 23.1 mm of water that condenses as dew and fog in winter, when EC is impeded by stable conditions. We further analyze EC LE measurements from different sites to evaluate if adsorption can be detected from EC data collected at different locations.</p><p>We conclude that the temporal patterns of adsorption estimates from lysimeters match the nighttime negative LE data from the EC technique, although the absolute numbers are uncertain. This might open interesting perspective to fill the knowledge gap of the role of soil water vapor adsorption from the atmosphere at field scale and open the opportunity to broaden the topic across ecosystem research communities. Our results also highlight a potential shortcoming in the interpretation of EC measurements in the case that negative nighttime values, representing physically plausible adsorption, are neglected.</p>

THE HEAT OF WETTING OF SILK FIBROIN BY WATER

1955 ◽  
Vol 33 (5) ◽  
pp. 904-912 ◽  
Author(s):  
H. Brian Dunford ◽  
John L. Morrison
Keyword(s):  
Water Vapor ◽  
Adsorption Isotherm ◽  
Thermodynamic Properties ◽  
Silk Fibroin ◽  
Adsorption Process ◽  
Film Formation ◽  
Adsorbed Water ◽  
Water Vapor Adsorption ◽  
Free Energies ◽  
Heat Of Wetting

The heats of wetting by water of silk fibroin initially containing various amounts of adsorbed and desorbed water have been measured. These measurements along with the water vapor adsorption isotherm of Hutton and Gartside have been used to calculate the integral and differential heats, free energies, and entropies of adsorption. In contrast with cellulose, silk containing desorbed water evolves less heat than that containing adsorbed water. This fact suggests that any contribution by a heat of swelling term is very small for silk fibroin, so that the calculated thermodynamic properties probably can be assigned almost entirely to the adsorption process. The changes in the heats and entropies of adsorption appear to parallel the sequence of changes in film formation as revealed by surface area calculations.

scholarly journals Adsorption Capacities of Hygroscopic Materials Based on NaCl-TiO2 and NaCl-SiO2 Core/Shell Particles

2020 ◽  
Vol 2020 ◽  
pp. 1-16
Author(s):  
Marie Bermeo ◽  
Nabil El Hadri ◽  
Florent Ravaux ◽  
Abdelali Zaki ◽  
Linda Zou ◽  
...  
Keyword(s):  
Water Vapor ◽  
Relative Humidity ◽  
Adsorption Capacity ◽  
High Surface ◽  
Analytical Techniques ◽  
Water Vapor Adsorption ◽  
Environmental Scanning ◽  
Kinetics Of Adsorption ◽  
Hygroscopic Properties ◽  
Shell Particles

Hygroscopic materials which possess high moisture adsorption capacity were successfully upgraded by the functionalization of sodium chloride (NaCl) using two nuances of oxides. A procedure was developed to first prepare submicron-sized NaCl crystals; thereafter, these crystals were coated by choice of either titanium dioxide (TiO2) or silica (SiO2) to enhance the hygroscopic properties of NaCl and prevent its premature deliquescence. After coating, several analytical techniques were employed to evaluate the obtained composite materials. Our findings revealed that both composites NaCl-TiO2 and NaCl-SiO2 gave excellent performances by exhibiting interesting hydrophilic properties, compared to the sole NaCl. This was demonstrated by both environmental scanning electron microscope (ESEM) and water vapor adsorption experiments. In particular, NaCl-TiO2 composite showed the highest water adsorption capacity at low relative humidity and at a faster adsorption rate, induced by the high surface energy owing to the presence of TiO2. This result was also confirmed by the kinetics of adsorption, which revealed that not only does NaCl-TiO2 adsorb more water vapor than NaCl-SiO2 or sole NaCl but also the adsorption occurred at a much higher rate. While at room temperature and high relative humidity, the NaCl-SiO2 composite showed the best adsorption properties making it ideal to be used as a hygroscopic material, showing maximum adsorption performance compared to NaCl-TiO2 or sole NaCl. Therefore, NaCl-TiO2 and NaCl-SiO2 composites could be considered as promising hygroscopic materials and potential candidates to replace the existing salt seeding agents.

scholarly journals Vapor isotopic evidence for the worsening of winter air quality by anthropogenic combustion-derived water

2020 ◽  
Vol 117 (52) ◽  
pp. 33005-33010
Author(s):  
Meng Xing ◽  
Weiguo Liu ◽  
Xia Li ◽  
Weijian Zhou ◽  
Qiyuan Wang ◽  
...  
Keyword(s):  
Water Vapor ◽  
Air Quality ◽  
Relative Humidity ◽  
Isotope Composition ◽  
Winter Season ◽  
Energy Structure ◽  
Particulate Pollution ◽  
Guanzhong Basin ◽  
Physical And Chemical

Anthropogenic combustion-derived water (CDW) may accumulate in an airshed due to stagnant air, which may further enhance the formation of secondary aerosols and worsen air quality. Here we collected three-winter-season, hourly resolution, water-vapor stable H and O isotope compositions together with atmospheric physical and chemical data from the city of Xi’an, located in the Guanzhong Basin (GZB) in northwestern China, to elucidate the role of CDW in particulate pollution. Based on our experimentally determined water vapor isotope composition of the CDW for individual and weighted fuels in the basin, we found that CDW constitutes 6.2% of the atmospheric moisture on average and its fraction is positively correlated with [PM2.5] (concentration of particulate matter with an aerodynamic diameter less than 2.5 μm) as well as relative humidity during the periods of rising [PM2.5]. Our modeling results showed that CDW added additional average 4.6 μg m−3 PM2.5 during severely polluted conditions in the GZB, which corresponded to an average 5.1% of local anthropogenic [PM2.5] (average at ∼91.0 μg m−3). Our result is consistent with the proposed positive feedback between the relative humidity and a moisture sensitive air-pollution condition, alerting to the nontrivial role of CDW when considering change of energy structure such as a massive coal-to-gas switch in household heating in winter.

scholarly journals Investigation on Water Vapor Adsorption of Silica-Phosphonium Ionic Liquids Hybrid Material

Materials ◽  
2019 ◽  
Vol 12 (11) ◽  
pp. 1782
Author(s):  
Cancan Li ◽  
Jiamei Zhu ◽  
Min Zhou ◽  
Shuangquan Zhang ◽  
Xiaodong He
Keyword(s):  
Ionic Liquids ◽  
Water Vapor ◽  
Silica Gel ◽  
Photoelectron Spectroscopy ◽  
Sorption Isotherms ◽  
Effective Diffusivity ◽  
Water Vapor Adsorption ◽  
Modified Silica ◽  
Modified Silica Gel ◽  
Vapor Adsorption

Adsorption and diffusion of water vapor in phosphonium ionic liquid modified silica gel were studied, aiming to reduce the loading of water vapor in porous materials. The modified silica gel was prepared through a grafting method and characterized by FTIR, thermal gravity analysis and X-ray photoelectron spectroscopy. N2 sorption isotherms at −196 °C and CO2 sorption isotherms at 0 °C were also measured to analyzee the porosity. Water vapor adsorption equilibriums at 25 °C up to 30 mbar were tested. The results indicate that the ionic liquids (ILs) phase acts as a protecting film which decreases water vapor adsorption. The improvement of water-resistant performance is also attributed to the decrease of micro-porosity and silanol groups on the silica surface. Diffusion behavior of water vapor on modified silica was determined on the basis of the adsorption equilibrium. The effective diffusivity of water vapor in modified silica is almost the same as in bare silica and decreases with the increasing of water vapor loading.

scholarly journals Tribological Properties of Ionic Liquids

2020 ◽  
Author(s):  
Sumit Kumar Panja
Keyword(s):  
Ionic Liquids ◽  
Metal Surface ◽  
Tribological Properties ◽  
Tribological Property ◽  
Film Formation ◽  
Tribological Performance ◽  
Additive Property ◽  
Thin Film Formation ◽  
Performance Structure

Our main focus is to report the tribological properties of ionic liquids (ILs). Mainly, lubricating of ILs has been reported to understand the applicability of ionic liquids (ILs) in petroleum-based lubricant industry and energy conversion process as oil additive. The influence of counter parts of ILs on tribological property has been reported for designing efficient lubricating and oil-additive property of ILs. The effect of halogenated and nonhalogenated ILs on corrosion is also reported during tribological studies at different metal surface. Further, role of ILs as oil-additive has been discussed in terms of better tribological performance. Structure modification and role of anion on better performance of tribological property have been mentioned for enhancing effectiveness of lubricant and oil-additive properties. Origin of corrosion and thin film formation on metal surface are also discussed in detailed using different types of ILs and metal surfaces.

Preparation of Humidity Control Ceramics from Selectively Leached Kaolin

2007 ◽  
Vol 280-283 ◽  
pp. 333-336
Author(s):  
Shang Feng Du ◽  
Yun Fa Chen ◽  
Yun Liang
Keyword(s):  
Water Vapor ◽  
Relative Humidity ◽  
Sharp Increase ◽  
Sintering Temperature ◽  
Water Vapor Adsorption ◽  
Kaolin Clay ◽  
Selective Leaching ◽  
Liquid Ratio ◽  
Humidity Control ◽  
Solid Liquid

The humidity control ceramics were prepared by selective leaching and sintering of Suzhou kaolin clay. Effects of sintering temperature and solid/liquid ratio of selecting leaching of the kaolin clay on the humidity controlling properties of ceramics were analyzed. It was found that the ceramic had the best properties when the kaolin clay was sintered at 1000oC for 2 hours and leached with the solid/liquid ratio being 1:50. Water vapor adsorption isotherms of the ceramic possessed a sharp increase in the relative humidity between 45 and 85%.

scholarly journals Features of water vapor adsorption and desorption on the surface of non-stoichiometric tin dioxide films

2020 ◽  
Vol 56 (1) ◽  
pp. 102-113
Author(s):  
D. V. Adamchuck ◽  
V. K. Ksenevich ◽  
N. A. Poklonski ◽  
A. I. Kavaleu
Keyword(s):  
Electrical Conductivity ◽  
Water Vapor ◽  
Relative Humidity ◽  
Room Temperature ◽  
Oxygen Vacancies ◽  
Water Vapor Adsorption ◽  
Nanocrystalline Films ◽  
Adsorption And Desorption ◽  
Vapor Adsorption ◽  
Adsorption Of Water

Herein, the influence of water vapor adsorption and desorption processes on the surface of SnO2−δ nanocrystalline films with different concentrations of oxygen vacancies on their electrical conductivity at room temperature was studied. SnO2−δ films were synthesized by means of reactive magnetron sputtering of tin in an argon-oxygen plasma followed by 2-stage oxidative annealing. The concentration of oxygen vacancies in the films was varied by changing the 2nd stage annealing temperature within the range 350–400 °C. It was found that in the films with the highest concentration of oxygen vacancies (~1020 cm−3) in the region of low relative humidity (less than ~30 %), an increase in electrical conductivity was observed due to the dissociative adsorption of water molecules with the formation of hydroxyl groups. The adsorption of water vapor on the surface of SnO2−δ films at room temperature at relative humidity values higher than ~30 % was found to induce a decrease in the electrical conductivity of the samples. The generation of positive and negative EMF pulses between the open surface of SnO2−δ nanocrystalline films and the one covered by waterproof materials under the adsorption and desorption of water vapor, respectively, was detected. The change of resistance and the generated EMF value under the adsorption-desorption processes was found to increase with the concentration of free charge carriers in the films.

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