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 Fabrication and Characterization of Porous Core–Shell Graphene/SiO2 Nanocomposites for the Removal of Cationic Neutral Red Dye

2020 ◽  
Vol 10 (23) ◽  
pp. 8529
Author(s):  
Junyi Wang ◽  
Tianlu Chen ◽  
Biao Xu ◽  
Yueqiu Chen
Keyword(s):  
Electron Microscopy ◽  
Water Vapor ◽  
Adsorption Capacity ◽  
Photoelectron Spectroscopy ◽  
Neutral Red ◽  
Water Vapor Adsorption ◽  
Core Shell ◽  
X Ray ◽  
Adsorption Sites ◽  
Sio2 Nanocomposites

Porous rGO/SiO2 nanocomposites with a “core-shell” structure were prepared as an efficient adsorbent for the liquid-phase adsorption of cationic neutral red (NR) dye. The samples were characterized with powder X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), thermogravimetric analysis (TG), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, and N2 and water vapor adsorption/desorption methods. The NR removal ability and kinetics of the adsorption process of SiO2 and the rGO/SiO2 nanocomposites were investigated at 298 K. The rGO/SiO2 nanocomposite SG 0.30 showed a superior adsorption of NR dye. In regard to NR at pH 5, we measured a superior adsorption capacity of 66.635 mg/g at an initial NR concentration of 50 mg/L. The experimental adsorption capacity of SG 0.30 was 3.791 times higher than that of SiO2. Then, we compared the results with similar materials used for NR removal. Moreover, the water adsorption sites provided by the nitrogen- and oxygen-containing groups might be one of the reasons for the increased adsorption of water vapor. The broad range of properties of the rGO/SiO2 nanocomposite, including its simple synthesis, ability to be mass prepared, and strong adsorption properties, makes it a truly novel adsorbent that can be industrially produced, and shows potential application in the treatment of wastewater-containing dyes.

The Study on Moisture Adsorption of Oxidized Activated Carbon

2012 ◽  
Vol 581-582 ◽  
pp. 233-237
Author(s):  
Kang Wang ◽  
Wei Long Wang ◽  
Jian Feng Lu ◽  
Jing Ding
Keyword(s):  
Activated Carbon ◽  
Water Vapor ◽  
Specific Surface ◽  
Adsorption Capacity ◽  
Room Temperature ◽  
Specific Area ◽  
Water Vapor Adsorption ◽  
Clean Coal ◽  
Moisture Adsorption ◽  
Oxidized Activated Carbon

Activated carbon made by clean coal and 25% coconut shell was selected to be modified with different concentrations’ HNO3. The productions were characterized by BET, XPS, FTIR and the moisture adsorption of performance is investigated by the DVSA-STD dynamic vapor analyzer. The results show that specific surface area of the activated carbon modified by the 10% concentration of HNO3 is improved 1.3 times than the unmodified one. By comparison the higher concentrations of HNO3 have weaker effects on the specific area of activated carbon. The water vapor adsorption capacity of activated carbon modified by HNO3 at 10% concentration is 1.5 times higher than the unmodified at room temperature at30% RH.

Adsorption Isotherm and Kinetics of Water Vapor Adsorption Using Novel Super-Porous Hydrogel Composites

2020 ◽  
Author(s):  
Hemant Mittal ◽  
Ali Al-Alili ◽  
Saeed M. Alhassan
Keyword(s):  
Water Vapor ◽  
Adsorption Isotherm ◽  
Adsorption Capacity ◽  
Polymer Matrix ◽  
Adsorbed Water ◽  
Water Vapor Adsorption ◽  
Water Molecules ◽  
Vapor Adsorption ◽  
Highly Effective ◽  
Desiccant Material

Abstract Deliquescent salts have high water vapor adsorption capacity, but they dissolve in water by forming crystalline hydrates. That restricts their use in different water vapor adsorption applications. However, this limitation can be overcome by incorporating deliquescent salts within a polymer matrix which will keep the salt solution in place. Furthermore, if the polymer matrix used is also capable of adsorbing water vapor, it will further improve the overall performance of desiccant system. Therefore, in this work, we are proposing the synthesis and use of a highly effective new solid polymer desiccant material, i.e. superporous hydrogel (SPHs) of poly(sodium acrylate-co-acrylic acid (P(SA-co-AA)), and subsequently its composite with deliquescent salt, i.e. calcium chloride (CaCl2), to adsorb water vapors from humid air without the dissolution of the salt in the adsorbed water. Parental PAA-SPHs matrix alone exhibited an adsorption capacity of 1.02 gw/gads which increased to 3.35 gw/gads after incorporating CaCl2 salt in the polymer matrix. Both materials exhibited type-III adsorption isotherm and the experimental isotherm data fitted to the Guggenheim, Anderson and Boer (GAB) isotherm model. However, the adsorption kinetics followed linear driving force model which suggested that this extremely high adsorption capacity was due to the diffusion of water molecules into the interconnected pores of SPHs via capillary channels followed by the attachment of adsorbed water molecules to the CaCl2 salt present in the polymer matrix. Furthermore, the adsorbents were used successively for six cycles of adsorption with a very little loss in adsorption capacity. Therefore, the proposed polymer desiccant material overcomes the problem of dissolution of deliquescent salts and opens the doors for a new class of highly effective solid desiccant material.

scholarly journals Water Vapor Adsorption Capacity of Thermally Fluorinated Carbon Molecular Sieves for CO2Capture

2013 ◽  
Vol 2013 ◽  
pp. 1-6 ◽  
Author(s):  
Jin-Young Jung ◽  
Hye-Ryeon Yu ◽  
Se Jin In ◽  
Young Chul Choi ◽  
Young-Seak Lee
Keyword(s):  
Water Vapor ◽  
Specific Surface ◽  
Adsorption Capacity ◽  
Surface Area ◽  
Specific Surface Area ◽  
Molecular Sieves ◽  
Total Pore Volume ◽  
Water Vapor Adsorption ◽  
Carbon Molecular Sieves ◽  
Vapor Adsorption

The surfaces of carbon molecular sieves (CMSs) were thermally fluorinated to adsorb water vapor. The fluorination of the CMSs was performed at various temperatures (100, 200, 300, and 400°C) to investigate the effects of the fluorine gas (F2) content on the surface properties. Fluorine-related functional groups formed were effectively generated on the surface of the CMSs via thermal fluorination process, and the total pore volume and specific surface area of the pores in the CMSs increased during the thermal fluorination process, especially those with diameters ≤ 8 Å. The water vapor adsorption capacity of the thermally fluorinated CMSs increased compared with the as-received CMSs, which is attributable to the increased specific surface area and to the semicovalent bonds of the C–F groups.

scholarly journals An investigation on hygroscopic properties of 15 black carbon (BC) from different carbon sources: Roles of organic and inorganic components

2020 ◽  
Author(s):  
Minli Wang ◽  
Yiqun Chen ◽  
Heyun Fu ◽  
Xiaolei Qu ◽  
Bengang Li ◽  
...  
Keyword(s):  
Water Vapor ◽  
Relative Humidity ◽  
Organic Carbon ◽  
Black Carbon ◽  
Water Uptake ◽  
Carbon Sources ◽  
High Relative Humidity ◽  
Gravimetric Analysis ◽  
Hygroscopic Properties ◽  
Kinetics Of

Abstract. The hygroscopic behavior of black carbon (BC) has a significant impact on global and regional climate change. However, the mechanism and factors controlling the hygroscopicity of BC from different carbon sources are not well understood. Here, we systematically measured the equilibrium and kinetics of water uptake by 15 different BC (10 herb-derived BC, 2 wood-derived BC, and 3 soot) using gravimetric water vapor sorption method combined with in-situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS). In the gravimetric analysis, the sorption/desorption equilibrium isotherms were measured under continuous-stepwise water vapor pressure conditions, while the kinetics was measured at a variety of humidity levels obtained by different saturated aqueous salt solutions. The equilibrium water uptake of the BC pool at high relative humidity (> 80 %) positively correlated to the dissolved mineral content (0.01–13.0 wt %) (R2 = 0.86, P = 0.0001) as well as the content of the thermogravimetrically analyzed organic carbon (OCTGA, 4.48–15.25 wt %) (R2 = 0.52, P = 0.002) and the alkali-extracted organic carbon (OCAE, 0.14–8.39 wt %) (R2 = 0.80, P = 0.0001). In contrast, no positive correlation was obtained with the content of total organic carbon or elemental carbon. Among the major soluble ionic constituents, chloride and ammonium were each correlated with the equilibrium water uptake at high relative humidity. Compared with the herbal BC and soot, the woody BC had much lower equilibrium water uptake, especially at high relative humidity, likely due to the very low dissolved material content and OC content. The DRIFTS analysis provided generally consistent results at low relative humidity. The kinetics of water uptake (measured by pseudo-second order rate constant) correlated to the content of OCTGA and OCAE as well as the content of chloride and ammonium at low relative humidity (33 %), but to the porosity of bulk BC at high relative humidity (94 %). This was the first study to show that BC of different types and sources has greatly varying hygroscopic properties.

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.

scholarly journals An investigation on hygroscopic properties of 15 black carbon (BC)-containing particles from different carbon sources: roles of organic and inorganic components

2020 ◽  
Vol 20 (13) ◽  
pp. 7941-7954
Author(s):  
Minli Wang ◽  
Yiqun Chen ◽  
Heyun Fu ◽  
Xiaolei Qu ◽  
Bengang Li ◽  
...  
Keyword(s):  
Water Vapor ◽  
Relative Humidity ◽  
Organic Carbon ◽  
Black Carbon ◽  
Water Uptake ◽  
Mineral Content ◽  
Carbon Sources ◽  
High Relative Humidity ◽  
Hygroscopic Properties ◽  
Kinetics Of

Abstract. The hygroscopic behavior of black carbon (BC)-containing particles (BCPs) has a significant impact on global and regional climate change. However, the mechanism and factors controlling the hygroscopicity of BCPs from different carbon sources are not well understood. Here, we systematically measured the equilibrium and kinetics of water uptake by 15 different BCPs (10 herb-derived BCPs, 2 wood-derived BCPs, and 3 soot-type BCPs) using a gravimetric water vapor sorption method combined with in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS). In the gravimetric analysis, the sorption–desorption equilibrium isotherms were measured under continuous-stepwise water vapor pressure conditions, while the kinetics was measured at a variety of humidity levels obtained by different saturated aqueous salt solutions. The equilibrium water uptake of the tested group of BCPs at high relative humidity (>80 %) positively correlated to the dissolved mineral content (0.01–13.0 wt %) (R2=0.86, P=0.0001), the content of the thermogravimetrically analyzed organic carbon (OCTGA, 4.48–15.25 wt %) (R2=0.52, P=0.002), and the content of the alkali-extracted organic carbon (OCAE, 0.14–8.39 wt %) (R2=0.80, P=0.0001). In contrast, no positive correlation was obtained with the content of total organic carbon or elemental carbon. Among the major soluble ionic constituents, chloride and ammonium were each correlated with the equilibrium water uptake at high relative humidity. Compared with the herbal BCPs and soot, the woody BCPs had much lower equilibrium water uptake, especially at high relative humidity, likely due to the very low dissolved mineral content and OC content. The DRIFTS analysis provided generally consistent results at low relative humidity. The kinetics of water uptake (measured by pseudo-second-order rate constant) correlated to the content of OCTGA and OCAE as well as the content of chloride and ammonium at low relative humidity (33 %) but to the porosity of BCPs at high relative humidity (94 %). This was the first study to show that BCPs of different types and sources had greatly varying hygroscopic properties.

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