scholarly journals Wetting Properties of the CO2–Water–Calcite System via Molecular Simulations: Shape and Size Effects

2019 ◽  
Author(s):  
Alessandro Silvestri ◽  
Evren Ataman ◽  
Akin Budi ◽  
Susan Stipp ◽  
Julian D Gale ◽  
...  
Keyword(s):  
Contact Angle ◽  
Water Contact Angle ◽  
Water Droplet ◽  
Aqueous Fluid ◽  
Water Model ◽  
Correct Prediction ◽  
Mineral Surfaces ◽  
Water Contact ◽  
Local Conditions ◽  
Wetting Properties

<p>Assessment of the risks and environmental impacts of carbon geosequestration requires knowledge about the wetting behavior of mineral surfaces in the presence of CO<sub>2</sub> and the pore fluids. In this context, the interfacial tension (IFT) between CO<sub>2</sub> and the aqueous fluid and the contact angle, theta, with the pore mineral surfaces are the two key parameters that control the capillary pressure in the pores of the candidate host rock. Knowledge of these two parameters and their dependence on the local conditions of pressure, temperature and salinity is essential for the correct prediction of structural and residual trapping. We have performed classical molecular dynamics simulations to predict the CO<sub>2</sub>–water IFT and the CO<sub>2</sub>–water–calcite contact angle. The IFT results are consistent with previous simulations, where simple point charge water models have been shown to underestimate the water surface tension, thus affecting the simulated IFT values. When combined with the EPM2 CO<sub>2</sub> model, the SPC/Fw water model indeed underestimates the IFT in the low pressure region at all temperatures studied. On the other hand, at high pressure and low temperature, the IFT is overestimated by ~5 mN/m. Literature data regarding the water contact angle on calcite are contradictory. Using our new set of force field parameters, we performed NVT simulations at 323 K and 20 MPa to calculate the contact angle of a water droplet on the calcite {10.4} surface in a CO<sub>2</sub> atmosphere. We performed simulations for both spherical and cylindrical droplet configurations for different initial radii, to study the size dependence of the water contact angle on calcite in the presence of CO<sub>2</sub>. Our results suggest that the contact angle of a cylindrical water droplet on calcite {10.4}, in the presence of CO<sub>2</sub>, is independent of droplet size, for droplets with a radius of 50 Å or more. On the contrary, spherical droplets make a contact angle that is strongly influenced by their size. At the largest size explored in this study, both spherical and cylindrical droplets converge to the same contact angle, 38 degrees, indicating that calcite is strongly wetted by water.</p>

scholarly journals Wetting Properties of the CO2–Water–Calcite System via Molecular Simulations: Shape and Size Effects

2019 ◽  
Author(s):  
Alessandro Silvestri ◽  
Evren Ataman ◽  
Akin Budi ◽  
Susan Stipp ◽  
Julian D Gale ◽  
...  
Keyword(s):  
Contact Angle ◽  
Water Contact Angle ◽  
Water Droplet ◽  
Aqueous Fluid ◽  
Water Model ◽  
Correct Prediction ◽  
Mineral Surfaces ◽  
Water Contact ◽  
Local Conditions ◽  
Wetting Properties

<p>Assessment of the risks and environmental impacts of carbon geosequestration requires knowledge about the wetting behavior of mineral surfaces in the presence of CO<sub>2</sub> and the pore fluids. In this context, the interfacial tension (IFT) between CO<sub>2</sub> and the aqueous fluid and the contact angle, theta, with the pore mineral surfaces are the two key parameters that control the capillary pressure in the pores of the candidate host rock. Knowledge of these two parameters and their dependence on the local conditions of pressure, temperature and salinity is essential for the correct prediction of structural and residual trapping. We have performed classical molecular dynamics simulations to predict the CO<sub>2</sub>–water IFT and the CO<sub>2</sub>–water–calcite contact angle. The IFT results are consistent with previous simulations, where simple point charge water models have been shown to underestimate the water surface tension, thus affecting the simulated IFT values. When combined with the EPM2 CO<sub>2</sub> model, the SPC/Fw water model indeed underestimates the IFT in the low pressure region at all temperatures studied. On the other hand, at high pressure and low temperature, the IFT is overestimated by ~5 mN/m. Literature data regarding the water contact angle on calcite are contradictory. Using our new set of force field parameters, we performed NVT simulations at 323 K and 20 MPa to calculate the contact angle of a water droplet on the calcite {10.4} surface in a CO<sub>2</sub> atmosphere. We performed simulations for both spherical and cylindrical droplet configurations for different initial radii, to study the size dependence of the water contact angle on calcite in the presence of CO<sub>2</sub>. Our results suggest that the contact angle of a cylindrical water droplet on calcite {10.4}, in the presence of CO<sub>2</sub>, is independent of droplet size, for droplets with a radius of 50 Å or more. On the contrary, spherical droplets make a contact angle that is strongly influenced by their size. At the largest size explored in this study, both spherical and cylindrical droplets converge to the same contact angle, 38 degrees, indicating that calcite is strongly wetted by water.</p>

scholarly journals What Is the Value of Water Contact Angle on Silicon?

Materials ◽  
2020 ◽  
Vol 13 (7) ◽  
pp. 1554 ◽  
Author(s):  
Paweł Bryk ◽  
Emil Korczeniewski ◽  
Grzegorz S. Szymański ◽  
Piotr Kowalczyk ◽  
Konrad Terpiłowski ◽  
...  
Keyword(s):  
Contact Angle ◽  
Water Contact Angle ◽  
Photoelectron Spectroscopy ◽  
Md Simulations ◽  
Surface Cleaning ◽  
Sio2 Layer ◽  
Water Contact ◽  
Pure Silicon ◽  
Wetting Properties ◽  
Cleaning Methods

Silicon is a widely applied material and the wetting of silicon surface is an important phenomenon. However, contradictions in the literature appear considering the value of the water contact angle (WCA). The purpose of this study is to present a holistic experimental and theoretical approach to the WCA determination. To do this, we checked the chemical composition of the silicon (1,0,0) surface by using the X-ray photoelectron spectroscopy (XPS) method, and next this surface was purified using different cleaning methods. As it was proved that airborne hydrocarbons change a solid wetting properties the WCA values were measured in hydrocarbons atmosphere. Next, molecular dynamics (MD) simulations were performed to determine the mechanism of wetting in this atmosphere and to propose the force field parameters for silica wetting simulation. It is concluded that the best method of surface cleaning is the solvent-reinforced de Gennes method, and the WCA value of silicon covered by SiO2 layer is equal to 20.7° (at room temperature). MD simulation results show that the mechanism of pure silicon wetting is similar to that reported for graphene, and the mechanism of silicon covered by SiO2 layer wetting is similar to this observed recently for a MOF.

STICKY AND SLIPPY: TWO HYDROPHOBIC STATES TRANSITION OF ZnO HIERARCHICAL FILMS BY FLUOROALKYLSILANE MODIFICATION

2009 ◽  
Vol 23 (06n07) ◽  
pp. 1867-1872 ◽  
Author(s):  
CHANGSONG LIU ◽  
QIANG ZHANG ◽  
TAO LI ◽  
ZHIWEN LI
Keyword(s):  
Contact Angle ◽  
Water Contact Angle ◽  
Hydrofluoric Acid ◽  
Hierarchical Structures ◽  
Zinc Nitrate ◽  
Zno Films ◽  
Water Droplets ◽  
Water Contact ◽  
Wetting Properties ◽  
Strong Adhesion

ZnO films with hierarchical structures were prepared in an aqueous solution of zinc nitrate, hexamethylenetetramine and hydrofluoric acid. They demonstrated superhydrophobicity and two superhydrophobic states conversion from sticky to slippy after they were modified by fluoroalkylsilane (FAS) self-assemble layers. Before FAS modification, ZnO hierarchical structures, having sphere-like microstructures with nano-petals, showed water contact angle of 151° and a sticky behavior: water droplets rest on such surface did not slide when the surface was tilted to any angle or even upside down, indicating a strong adhesion between water and the surface. However, after FAS modification, ZnO films showed an increase of water contact angle up to 164° and a large difference in dynamic wetting properties: water droplets moved spontaneously and hardly came to rest even on a horizontal surface. The transition from sticky ("Wenzel's state") to slippy ("Cassie's state") resulted from surface free energy change from high to low. The results also confirm that the low enough surface energy, cooperating with surface roughness, is crucial in making Cassie's state superhydrophobicity. The realization of conversion from sticky to slippy is of importance for further understanding wetting properties and applications of ZnO micronanostructures.

Electrical Sheet Resistance and Wetting Properties of TiO2 Nanoparticle Thin Films Prepared by Sparking Process

2017 ◽  
Vol 866 ◽  
pp. 313-317
Author(s):  
Buppachat Toboonsung
Keyword(s):  
Electron Microscopy ◽  
Thin Films ◽  
Contact Angle ◽  
Sheet Resistance ◽  
Water Contact Angle ◽  
Annealing Temperature ◽  
Water Contact ◽  
Titanium Dioxide Nanoparticle ◽  
Wetting Properties ◽  
Scanning Electron

An electrical sheet resistance and water contact angle of titanium dioxide nanoparticle thin films were prepared by sparking process. The experiments were carried out by the titanium wires as electrodes of sparking process and varied the sparking time of 1-4 h and the annealing temperature of 200-400 OC for 2 h. The as-deposited and as-annealed of thin films on glass substrate were measured a water contact angle and a sheet resistance whereas a surface was analyzed by a scanning electron microscopy. The results found that the optimum as-deposited TiO2 NP thin films was shown the homogeneity surface, the minimum sheet resistance and the duplicate water contact at the sparking time of 3 h. The optimum as-deposited TiO2 NP thin films was annealed which the water contact angle and the sheet resistance of the as-annealed TiO2 NP thin films decreased with increasing the annealing temperature. However, the hydrophilic property was shown optimum at the annealing temperature of 400 OC.

Long-Term Stable Metal Organic Framework (MOF) Based Mixed Matrix Membranes for Ultrafiltration

2020 ◽  
Author(s):  
Muayad Al-shaeli ◽  
Stefan J. D. Smith ◽  
Shanxue Jiang ◽  
Huanting Wang ◽  
Kaisong Zhang ◽  
...  
Keyword(s):  
Contact Angle ◽  
Water Contact Angle ◽  
Mixed Matrix Membranes ◽  
Recovery Ratio ◽  
Mixed Matrix ◽  
Water Contact ◽  
Membrane Performance ◽  
Metal Organic ◽  
Matrix Membranes

<p>In this study, novel <a>mixed matrix polyethersulfone (PES) membranes</a> were synthesized by using two different kinds of metal organic frameworks (MOFs), namely UiO-66 and UiO-66-NH<sub>2</sub>. The composite membranes were characterised by SEM, EDX, FTIR, PXRD, water contact angle, porosity, pore size, etc. Membrane performance was investigated by water permeation flux, flux recovery ratio, fouling resistance and anti-fouling performance. The stability test was also conducted for the prepared mixed matrix membranes. A higher reduction in the water contact angle was observed after adding both MOFs to the PES and sulfonated PES membranes compared to pristine PES membranes. An enhancement in membrane performance was observed by embedding the MOF into PES membrane matrix, which may be attributed to the super-hydrophilic porous structure of UiO-66-NH<sub>2</sub> nanoparticles and hydrophilic structure of UiO-66 nanoparticles that could accelerate the exchange rate between solvent and non-solvent during the phase inversion process. By adding the MOFs into PES matrix, the flux recovery ratio was increased greatly (more than 99% for most mixed matrix membranes). The mixed matrix membranes showed higher resistance to protein adsorption compared to pristine PES membranes. After immersing the membranes in water for 3 months, 6 months and 12 months, both MOFs were stable and retained their structure. This study indicates that UiO-66 and UiO-66-NH<sub>2</sub> are great candidates for designing long-term stable mixed matrix membranes with higher anti-fouling performance.</p>

scholarly journals Surface modification of PMMA polymer and its composites with PC61BM fullerene derivative using an atmospheric pressure microwave argon plasma sheet

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Andrzej Sikora ◽  
Dariusz Czylkowski ◽  
Bartosz Hrycak ◽  
Magdalena Moczała-Dusanowska ◽  
Marcin Łapiński ◽  
...  
Keyword(s):  
Contact Angle ◽  
Surface Modification ◽  
Chemical Composition ◽  
Water Contact Angle ◽  
Plasma Sheet ◽  
Atmospheric Pressure ◽  
Argon Plasma ◽  
Fullerene Derivative ◽  
Water Contact ◽  
Pmma Polymer

AbstractThis paper presents the results of experimental investigations of the plasma surface modification of a poly(methyl methacrylate) (PMMA) polymer and PMMA composites with a [6,6]-phenyl-C61-butyric acid methyl ester fullerene derivative (PC61BM). An atmospheric pressure microwave (2.45 GHz) argon plasma sheet was used. The experimental parameters were: an argon (Ar) flow rate (up to 20 NL/min), microwave power (up to 530 W), number of plasma scans (up to 3) and, the kind of treated material. In order to assess the plasma effect, the possible changes in the wettability, roughness, chemical composition, and mechanical properties of the plasma-treated samples’ surfaces were evaluated by water contact angle goniometry (WCA), atomic force microscopy (AFM), attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) and X-ray photoelectron spectroscopy (XPS). The best result concerning the water contact angle reduction was from 83° to 29.7° for the PMMA material. The ageing studies of the PMMA plasma-modified surface showed long term (100 h) improved wettability. As a result of plasma treating, changes in the samples surface roughness parameters were observed, however their dependence on the number of plasma scans is irregular. The ATR-FTIR spectra of the PMMA plasma-treated surfaces showed only slight changes in comparison with the spectra of an untreated sample. The more significant differences were demonstrated by XPS measurements indicating the surface chemical composition changes after plasma treatment and revealing the oxygen to carbon ratio increase from 0.1 to 0.4.

scholarly journals Physicochemical Properties and Biocompatibility of Electrospun Polycaprolactone/Gelatin Nanofibers

2021 ◽  
Vol 18 (9) ◽  
pp. 4764
Author(s):  
Wei Lee Lim ◽  
Shiplu Roy Chowdhury ◽  
Min Hwei Ng ◽  
Jia Xian Law
Keyword(s):  
Contact Angle ◽  
Physicochemical Properties ◽  
Water Contact Angle ◽  
Ligament Injury ◽  
Great Promise ◽  
Composition Analysis ◽  
Water Contact ◽  
Tenogenic Differentiation ◽  
Good Biocompatibility ◽  
Tissue Grafts

Tissue-engineered substitutes have shown great promise as a potential replacement for current tissue grafts to treat tendon/ligament injury. Herein, we have fabricated aligned polycaprolactone (PCL) and gelatin (GT) nanofibers and further evaluated their physicochemical properties and biocompatibility. PCL and GT were mixed at a ratio of 100:0, 70:30, 50:50, 30:70, 0:100, and electrospun to generate aligned nanofibers. The PCL/GT nanofibers were assessed to determine the diameter, alignment, water contact angle, degradation, and surface chemical analysis. The effects on cells were evaluated through Wharton’s jelly-derived mesenchymal stem cell (WJ-MSC) viability, alignment and tenogenic differentiation. The PCL/GT nanofibers were aligned and had a mean fiber diameter within 200–800 nm. Increasing the GT concentration reduced the water contact angle of the nanofibers. GT nanofibers alone degraded fastest, observed only within 2 days. Chemical composition analysis confirmed the presence of PCL and GT in the nanofibers. The WJ-MSCs were aligned and remained viable after 7 days with the PCL/GT nanofibers. Additionally, the PCL/GT nanofibers supported tenogenic differentiation of WJ-MSCs. The fabricated PCL/GT nanofibers have a diameter that closely resembles the native tissue’s collagen fibrils and have good biocompatibility. Thus, our study demonstrated the suitability of PCL/GT nanofibers for tendon/ligament tissue engineering applications.

Osteoconductivity of Superhydrophilic Ti- and Zr-Alloy for Biomedical Application

2016 ◽  
Vol 879 ◽  
pp. 2524-2527
Author(s):  
Masazumi Okido ◽  
Kensuke Kuroda
Keyword(s):  
Contact Angle ◽  
Water Contact Angle ◽  
Strong Influence ◽  
Biomedical Application ◽  
Hydrophobic Surface ◽  
Hydrophilic Surface ◽  
Water Contact ◽  
Zr Alloy ◽  
Zr Alloys

Surface hydrophilicity is considered to have a strong influence on the biological reactions of bone-substituting materials. However, the influence of a hydrophilic or hydrophobic surface on the osteoconductivity is not completely clear. In this study, we produced super-hydrophilic and hydrophobic surface on Ti-and Zr-alloys. Hydrothermal treatment at 180 oC for 180 min. in the distilled water and immersion in x5 PBS(-) brought the super-hydrophilic surface (water contact angle < 10 (deg.)) and heat treatment of as-hydrothermaled the hydrophobic surface. The osteoconductivity of the surface treated samples with several water contact angle was evaluated by in vivo testing. The surface properties, especially water contact angle, strongly affected the osteoconductivity and protein adsorbability, and not the surface substance.

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