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Yimyam K, Wongrueng A, Rakruam P. Haloacetonitriles adsorption using a low-cost adsorbent derived from canvas fabric. ENVIRONMENTAL RESEARCH 2023; 234:116539. [PMID: 37414390 DOI: 10.1016/j.envres.2023.116539] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/21/2023] [Revised: 06/29/2023] [Accepted: 07/01/2023] [Indexed: 07/08/2023]
Abstract
The characteristics of canvas fabric-derived adsorbents and their removal efficiency on five haloacetronitriles (HANs) were investigated. In addition, the effect of chemical activation with ferric chloride (FeCl3) and ferric nitrate (Fe(NO3)3) solutions on HANs removal efficiency was determined. The results indicated that the surface area increased from 262.51 m2/g to 577.25 and 370.83 m2/g, respectively, after being activated with FeCl3 and Fe(NO3)3 solutions. Increases in surface area and pore volume had a direct impact on the effectiveness of HANs removal. As compared to the non-activated adsorbent, the activated adsorbent effectively removed five species of HANs. TCAN was highly removed by the Fe(NO3)3-activated adsorbent (94%) due to the presence of mesoporous pore volume after activation with Fe(NO3)3. On the other hand, MBAN had the lowest removal efficiency of all adsorbents in this study. The activation with FeCl3 and Fe(NO3)3 showed equal removal efficiency for DCAN, BCAN, and DBAN, with percent removal higher than 50%. The hydrophilicity of HANs species affected the removal efficiency. The hydrophilicity order of five HANs species was MBAN, DCAN, BCAN, DBAN, and TCAN, respectively, which well corresponded to the obtained removal efficiency. The canvas fabric-derived adsorbents synthesized in this study were proven to be utilized as low-cost adsorbents to efficiently remove HANs from the environment. Future research will focus on the adsorption mechanism and recycling method to realize the potential for large-scale utilization.
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Affiliation(s)
- Kanlayanee Yimyam
- Graduate School, Chiang Mai University, Chiang Mai, 50200, Thailand; Doctor of Engineering Program in Environmental Engineering, Faculty of Engineering, Chiang Mai University, Chiang Mai, 50200, Thailand; Department of Environmental Engineering, Faculty of Engineering, Chiang Mai University, Chiang Mai, 50200, Thailand.
| | - Aunnop Wongrueng
- Department of Environmental Engineering, Faculty of Engineering, Chiang Mai University, Chiang Mai, 50200, Thailand
| | - Pharkphum Rakruam
- Department of Environmental Engineering, Faculty of Engineering, Chiang Mai University, Chiang Mai, 50200, Thailand.
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2
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Pospíšil M, Malijevský A. Phase behavior of fluids in undulated nanopores. Phys Rev E 2022; 106:024801. [PMID: 36109889 DOI: 10.1103/physreve.106.024801] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2022] [Accepted: 07/20/2022] [Indexed: 06/15/2023]
Abstract
The geometry of walls forming a narrow pore may qualitatively affect the phase behavior of the confined fluid. Specifically, the nature of condensation in nanopores formed of sinusoidally shaped walls (with amplitude A and period P) is governed by the wall mean separation L as follows. For L>L_{t}, where L_{t} increases with A, the pores exhibit standard capillary condensation similar to planar slits. In contrast, for L<L_{t}, the condensation occurs in two steps, such that the fluid first condenses locally via bridging transition connecting adjacent crests of the walls, before it condenses globally. For the marginal value of L=L_{t}, all the three phases (gaslike, bridge, and liquidlike) may coexist. We show that the locations of the phase transitions can be described using geometric arguments leading to modified Kelvin equations. However, for completely wet walls, to which we focus on, the phase boundaries are shifted significantly due to the presence of wetting layers. In order to take this into account, mesoscopic corrections to the macroscopic theory are proposed. The resulting predictions are shown to be in a very good agreement with a density-functional theory even for molecularly narrow pores. The limits of stability of the bridge phase, controlled by the pore geometry, is also discussed in some detail.
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Affiliation(s)
- Martin Pospíšil
- Department of Physical Chemistry, University of Chemical Technology Prague, Praha 6, 166 28, Czech Republic and The Czech Academy of Sciences, Institute of Chemical Process Fundamentals, Department of Molecular Modelling, 165 02 Prague, Czech Republic
| | - Alexandr Malijevský
- Department of Physical Chemistry, University of Chemical Technology Prague, Praha 6, 166 28, Czech Republic and The Czech Academy of Sciences, Institute of Chemical Process Fundamentals, Department of Molecular Modelling, 165 02 Prague, Czech Republic
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3
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Förster C, Veith L, Andrieu-Brunsen A. Visible light induced RAFT for asymmetric functionalization of silica mesopores. RSC Adv 2022; 12:27109-27113. [PMID: 36276013 PMCID: PMC9501659 DOI: 10.1039/d2ra05422a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2022] [Accepted: 09/12/2022] [Indexed: 11/21/2022] Open
Abstract
One key feature for bioinspired transport design through nanoscale pores is nanolocal, asymmetric as well as multifunctional nanopore functionalization. Here, we use a visible-light induced, controlled photo electron/energy transfer-reversible addition–fragmentation chain-transfer (PET-RAFT) polymerization for asymmetric polymer placement into mesoporous silica thin films including asymmetric polymer sequence design. We report the asymmetric silica mesopore functionalization and local polymer sequence control of orthogonally charged stimuli-responsive polymers and their influence on ionic transport.![]()
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Affiliation(s)
- Claire Förster
- Macromolecular Chemistry–Smart Membranes, Technische Universität Darmstadt, 64287 Darmstadt, German
| | - Lothar Veith
- Max Planck Institute for Polymer Research, 55128, Mainz, Germany
| | - Annette Andrieu-Brunsen
- Macromolecular Chemistry–Smart Membranes, Technische Universität Darmstadt, 64287 Darmstadt, German
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Luo Z, Mehraeen S. Molecular View of the Distortion and Pinning Force of a Receding Contact Line: Impact of the Nanocavity Geometry. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2021; 37:7008-7018. [PMID: 34096301 DOI: 10.1021/acs.langmuir.1c00599] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
We present a molecular view using many-body dissipative particle dynamics simulations to unravel the pinning phenomenon of a liquid film receding over a solid substrate with a nanocavity. We find that the pinning force and distortion of the pinned contact line vary across different nanocavity shapes. We show that the mechanism of a caterpillar motion, which has previously been proposed for advancing precursor films, persists in a partially pinned receding contact line. Our results also demonstrate a localized clamping effect, which is originated from the variation of the dynamic contact angle along the pinned contact line. The simulation results suggest that the clamping effect can be controlled by the geometry of the nanocavity and hydrophilicity of the underlying substrate.
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Affiliation(s)
- Zhen Luo
- Department of Chemical Engineering, University of Illinois at Chicago, 929 West Taylor Street, Chicago, Illinois 60607, United States
| | - Shafigh Mehraeen
- Department of Chemical Engineering, University of Illinois at Chicago, 929 West Taylor Street, Chicago, Illinois 60607, United States
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Egorov SA, Binder K. When does Wenzel's extension of Young's equation for the contact angle of droplets apply? A density functional study. J Chem Phys 2020; 152:194707. [PMID: 33687230 DOI: 10.1063/5.0005537] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
The contact angle of a liquid droplet on a surface under partial wetting conditions differs for a nanoscopically rough or periodically corrugated surface from its value for a perfectly flat surface. Wenzel's relation attributes this difference simply to the geometric magnification of the surface area (by a factor rw), but the validity of this idea is controversial. We elucidate this problem by model calculations for a sinusoidal corrugation of the form zwall(y) = Δ cos(2πy/λ), for a potential of short range σw acting from the wall on the fluid particles. When the vapor phase is an ideal gas, the change in the wall-vapor surface tension can be computed exactly, and corrections to Wenzel's equation are typically of the order σwΔ/λ2. For fixed rw and fixed σw, the approach to Wenzel's result with increasing λ may be nonmonotonic and this limit often is only reached for λ/σw > 30. For a non-additive binary mixture, density functional theory is used to work out the density profiles of both coexisting phases for planar and corrugated walls as well as the corresponding surface tensions. Again, deviations from Wenzel's results of similar magnitude as in the above ideal gas case are predicted. Finally, a crudely simplified description based on the interface Hamiltonian concept is used to interpret the corresponding simulation results along similar lines. Wenzel's approach is found to generally hold when λ/σw ≫ 1 and Δ/λ < 1 and under conditions avoiding proximity of wetting or filling transitions.
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Affiliation(s)
- Sergei A Egorov
- Department of Chemistry, University of Virginia, Charlottesville, Virginia 22901, USA
| | - Kurt Binder
- Institut für Physik, Johannes Gutenberg Universität Mainz, 55099 Mainz, Germany
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Berim GO, Ruckenstein E. An analog to Bond number for pendant nanodrops. Phys Chem Chem Phys 2019; 21:17314-17322. [DOI: 10.1039/c9cp02994j] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A new dimensionless number is introduced which characterizes the shape and stability of a pendant nanodrop.
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Affiliation(s)
- Gersh O. Berim
- Department of Chemical and Biological Engineering
- State University of New York at Buffalo
- Buffalo
- USA
| | - Eli Ruckenstein
- Department of Chemical and Biological Engineering
- State University of New York at Buffalo
- Buffalo
- USA
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Sauer E, Terzis A, Theiss M, Weigand B, Gross J. Prediction of Contact Angles and Density Profiles of Sessile Droplets Using Classical Density Functional Theory Based on the PCP-SAFT Equation of State. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2018; 34:12519-12531. [PMID: 30247038 DOI: 10.1021/acs.langmuir.8b01985] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
This study demonstrates the capability of the density functional theory (DFT) formalism to predict contact angles and density profiles of model fluids and of real substances in good quantitative agreement with molecular simulations and experimental data. The DFT problem is written in cylindrical coordinates, and the solid-fluid interactions are defined as external potentials toward the fluid phase. Monte Carlo (MC) molecular simulations are conducted in order to assess the density profiles resulting from the Helmholtz energy functional used in the DFT formalism. Good quantitative agreement between DFT predictions and MC results for Lennard-Jones and ethane nanodroplets is observed, both for density profiles and for contact angles. That comparison suggests, first, that the Helmholtz energy functional proposed in a previous study [ Sauer , E. ; Gross , J. Ind. Eng. Chem. Res. 56 , 2017 , 4119 - 4135 ] is suitable for three-phase contact lines and, second, that Lagrange multipliers can be used to constrain the number of molecules, similar to a canonical ensemble. Experiments of sessile droplets on solid surfaces are performed to assess whether a real solid with its microscopic roughness can be described through a simple model potential. Comparison of DFT results to experimental data is done for a Teflon surface because Teflon can be regarded as a substrate exhibiting only attractive interactions of van der Waals type. It is shown that the real solid can be described as a perfectly planar solid with effective solvent-to-solid interactions, defined through a single adjustable parameter for the solid. Subsequent predictions for the contact angle of eight solvents, including polar components such as water, are found in very good agreement to experimental data using simple Berthelot-Lorentz combining rules. For the eight investigated solvents, we find mean absolute deviations of 3.77°.
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Affiliation(s)
- Elmar Sauer
- Institute of Thermodynamics and Thermal Process Engineering , University of Stuttgart , Pfaffenwaldring 9 , 70569 Stuttgart , Germany
| | - Alexandros Terzis
- Institute of Aerospace Thermodynamics , University of Stuttgart , Pfaffenwaldring 31 , 70569 Stuttgart , Germany
| | - Marc Theiss
- Institute of Thermodynamics and Thermal Process Engineering , University of Stuttgart , Pfaffenwaldring 9 , 70569 Stuttgart , Germany
| | - Bernhard Weigand
- Institute of Aerospace Thermodynamics , University of Stuttgart , Pfaffenwaldring 31 , 70569 Stuttgart , Germany
| | - Joachim Gross
- Institute of Thermodynamics and Thermal Process Engineering , University of Stuttgart , Pfaffenwaldring 9 , 70569 Stuttgart , Germany
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Abstract
The shape and stability of a pendant nanodrop attached to a smooth or rough solid surface are considered on the basis of the microscopic density functional theory in the presence of a strong external force normal to the solid surface. The drop profile, width, and height of the drop and the contact angle that a nanodrop makes with the solid surface are calculated and some interesting features of the drop shape and stability are identified. In particular, a linear relationship between the height of the drop and the contact angle, as well as one between the critical external force at which the drop loses its stability and the strength of the fluid-solid interaction, was found. In some cases, a fixed point on the drop profile was observed whose spacial location does not depend on the value of external force. It is also argued that the Bond number that is a characteristic of the pendant macroscopic drop is not applicable to nanodrops.
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Affiliation(s)
- Gersh O Berim
- Department of Chemical and Biological Engineering , State University of New York at Buffalo , Buffalo , New York 14260 , United States
| | - Eli Ruckenstein
- Department of Chemical and Biological Engineering , State University of New York at Buffalo , Buffalo , New York 14260 , United States
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9
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Song F, Ma L, Fan J, Chen Q, Zhang L, Li BQ. Wetting Behaviors of a Nano-Droplet on a Rough Solid Substrate under Perpendicular Electric Field. NANOMATERIALS (BASEL, SWITZERLAND) 2018; 8:E340. [PMID: 29772828 PMCID: PMC5977354 DOI: 10.3390/nano8050340] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/27/2018] [Revised: 05/14/2018] [Accepted: 05/15/2018] [Indexed: 12/27/2022]
Abstract
Molecular dynamic simulations were adopted to study the wetting properties of nanoscale droplets on rough silicon solid substrate subject to perpendicular electric fields. The effect of roughness factor and electric field strength on the static and dynamic wetting behaviors of a nano-droplet on a solid surface was investigated at the molecular level. Results show that the static contact angle tends to decrease slightly and show small difference with the increase of roughness factor, while it shows an obvious increase for the ramp-shaped surface because the appearing bottom space reduces the wettability of solid surface. Additionally, under the electric field, a nano-droplet was elongated in the field direction and the equilibrium contact angle increases with the increase of electric field strength. The nano-droplet was completely stretched to be column-shaped at a threshold value of the field. Besides, accompanied by the shape variation of water droplets, the molecular dipole orientations of water molecules experience a remarkable change from a random disordered distribution to an ordered profile because of the realignment of water molecules induced by electric fields.
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Affiliation(s)
- Fenhong Song
- School of Energy and Power Engineering, Northeast Electric Power University, Jilin 132012, China.
| | - Long Ma
- School of Energy and Power Engineering, Northeast Electric Power University, Jilin 132012, China.
| | - Jing Fan
- School of Energy and Power Engineering, Northeast Electric Power University, Jilin 132012, China.
| | - Qicheng Chen
- School of Energy and Power Engineering, Northeast Electric Power University, Jilin 132012, China.
| | - Lihui Zhang
- Key Laboratory of Special Purpose Equipment and Advanced Processing Technology, Ministry of Education, Zhejiang University of Technology, Hangzhou 310014, China.
| | - Ben Q Li
- Department of Mechanical Engineering, University of Michigan, Dearborn, MI 48128, USA.
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10
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Chang CC, Sheng YJ, Tsao HK. Wetting hysteresis of nanodrops on nanorough surfaces. Phys Rev E 2016; 94:042807. [PMID: 27841480 DOI: 10.1103/physreve.94.042807] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2016] [Indexed: 06/06/2023]
Abstract
Nanodrops on smooth or patterned rough surfaces are explored by many-body dissipative particle dynamics to demonstrate the influence of surface roughness on droplet wetting. On a smooth surface, nanodrops exhibit the random motion and contact angle hysteresis is absent. The diffusivity decays as the intrinsic contact angle (θ_{Y}) decreases. On a rough surface, the contact line is pinned and the most stable contact angle (θ_{Y}^{'}) is acquired. The extent of contact angle hysteresis (Δθ) is determined by two approaches, which resemble the inflation-deflation method and inclined plane method for experiments. The hysteresis loop is acquired and both approaches yield consistent results. The influences of wettability and surface roughness on θ_{Y}^{'} and Δθ are examined. θ_{Y}^{'} deviates from that estimated by the Wenzel or Cassie-Baxter models. This consequence can be explained by the extent of impregnation, which varies with the groove position and wettability. Moreover, contact angle hysteresis depends more on the groove width than the depth.
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Affiliation(s)
- Cheng-Chung Chang
- Department of Chemical Engineering, National Taiwan University, Taipei 106, Taiwan
| | - Yu-Jane Sheng
- Department of Chemical Engineering, National Taiwan University, Taipei 106, Taiwan
| | - Heng-Kwong Tsao
- Department of Chemical and Materials Engineering, National Central University, Jhongli 320, Taiwan
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11
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de Alvarenga Pinto Cotrim M, Mottin AC, Ayres E. Preparation and Characterization of Okra Mucilage (Abelmoschus esculentus) Edible Films. ACTA ACUST UNITED AC 2016. [DOI: 10.1002/masy.201600019] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Affiliation(s)
- Monique de Alvarenga Pinto Cotrim
- Department of Materials, Technologies and Processes, School of Design; Minas Gerais State University - UEMG, Avenida Antônio Carlos; 7545 - CEP: 31.270-010 - Belo Horizonte MG Brazil
| | - Artur Caron Mottin
- Department of Materials, Technologies and Processes, School of Design; Minas Gerais State University - UEMG, Avenida Antônio Carlos; 7545 - CEP: 31.270-010 - Belo Horizonte MG Brazil
| | - Eliane Ayres
- Department of Materials, Technologies and Processes, School of Design; Minas Gerais State University - UEMG, Avenida Antônio Carlos; 7545 - CEP: 31.270-010 - Belo Horizonte MG Brazil
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12
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Ramiasa-MacGregor M, Mierczynska A, Sedev R, Vasilev K. Tuning and predicting the wetting of nanoengineered material surface. NANOSCALE 2016; 8:4635-4642. [PMID: 26854095 DOI: 10.1039/c5nr08329j] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
The wetting of a material can be tuned by changing the roughness on its surface. Recent advances in the field of nanotechnology open exciting opportunities to control macroscopic wetting behaviour. Yet, the benchmark theories used to describe the wettability of macroscopically rough surfaces fail to fully describe the wetting behaviour of systems with topographical features at the nanoscale. To shed light on the events occurring at the nanoscale we have utilised model gradient substrata where surface nanotopography was tailored in a controlled and robust manner. The intrinsic wettability of the coatings was varied from hydrophilic to hydrophobic. The measured water contact angle could not be described by the classical theories. We developed an empirical model that effectively captures the experimental data, and further enables us to predict the wetting of surfaces with nanoscale roughness by considering the physical and chemical properties of the material. The fundamental insights presented here are important for the rational design of advanced materials having tailored surface nanotopography with predictable wettability.
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Affiliation(s)
- M Ramiasa-MacGregor
- Future Industries Institute, University of South Australia, Mawson Lakes, SA 5095, Australia
| | - A Mierczynska
- Australian Wine Research Institute, Waite Precinct, Hartley Grove Corner Paratoo Road, Urrbrae, SA 5064, Australia
| | - R Sedev
- Future Industries Institute, University of South Australia, Mawson Lakes, SA 5095, Australia
| | - K Vasilev
- School of Engineering, University of South Australia, Mawson Lakes, SA 5095, Australia.
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13
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Svoboda M, Malijevský A, Lísal M. Wetting properties of molecularly rough surfaces. J Chem Phys 2015; 143:104701. [DOI: 10.1063/1.4930084] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
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Wang Y, Wang X, Du Z, Zhang C, Tian M, Mi J. Evaluation of macroscale wetting equations on a microrough surface. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2015; 31:2342-2350. [PMID: 25654557 DOI: 10.1021/la505035k] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
The wettability of critical droplets on microscale geometric rough surfaces has been investigated using a density functional theory approach. In order to analyze the effect of roughness on nucleation free-energy barriers, the local density fluctuations at liquid-solid interfaces induced by the multi-interactions of a corner substrate are presented to interpret the interfacial free-energy variations, and the vapor-liquid-solid contact line tensions are derived from the contact angles of nuclei to account for the three-phase contact energies. The corresponding wetting diagrams have been constructed in Cassie, Wenzel, and impregnation regions. It is shown that, under the same condition, modest deviations between the microscale and the macroscale models can be observed within the Cassie region, whereas these deviations have been enlarged in the Wenzel and impregnation regions as well as the Cassie-Wenzel transition region. These deviations are also correlated to the roughness of the surface. The reason can be attributed to the cooperative effect of the liquid-solid interfacial free energy and line tension. This study offers a fundamental understanding of wettability of ultrasmall droplets on a microscale geometric rough surface.
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Affiliation(s)
- Yang Wang
- State Key Laboratory of Organic-Inorganic Composites and ‡The Key Laboratory of Carbon Fiber and Functional Polymers, Ministry of Education, Beijing University of Chemical Technology , Beijing 100029, China
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15
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Berim GO, Ruckenstein E. Contact angle of a nanodrop on a nanorough solid surface. NANOSCALE 2015; 7:3088-3099. [PMID: 25608234 DOI: 10.1039/c4nr06591c] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
The contact angle of a cylindrical nanodrop on a nanorough solid surface is calculated, for both hydrophobic and hydrophilic surfaces, using the density functional theory. The emphasis of the paper is on the dependence of the contact angle on roughness. The roughness is modeled by rectangular pillars of infinite length located on the smooth surface of a substrate, with fluid-pillar interactions different in strength from the fluid-substrate ones. It is shown that for hydrophobic substrates the trend of the contact angle to increase with increasing roughness, which was noted in all previous studies, is not universally valid, but depends on the fluid-pillar interactions, pillar height, interpillar distance, as well as on the size of the drop. For hydrophilic substrate, an unusual kink-like dependence of the contact angle on the nanodrop size is found which is caused by the change in the location of the leading edges of the nanodrop on the surface. It is also shown that the Wenzel and Cassie-Baxter equations can not explain all the peculiarities of the contact angle of a nanodrop on a nanorough surface.
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Affiliation(s)
- Gersh O Berim
- Department of Chemical and Biological Engineering, State University of New York at Buffalo, Buffalo, New York 14260, USA.
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16
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Berim GO, Ruckenstein E. Adsorption isoterms and capillary condensation in a nanoslit with rough walls: a density functional theory. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2012; 28:11384-11390. [PMID: 22738325 DOI: 10.1021/la3014464] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Adsorption isoterms and capillary condensation in an open slit with walls decorated with arrays of pillars are examined using the density functional theory. Compared with the main substrate, the pillars can have the same or different parameters in the Lennard-Jones interaction potential between them and the fluid in the slit. The roughness of the solid surface, defined as the ratio between the area of the actual surface and the area of the surface free of pillars, is controlled by the height of the pillars. It is shown that the capillary condensation pressure first increases with increasing roughness, passes through a maximum, and then decreases. The amount of adsorbed fluid at constant volume of the slit has, in general, a nonmonotonic dependence on roughness. These features of adsorption and capillary condensation are results of increased surface area and changes in the fluid-solid potential energy due to changes in roughness.
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Affiliation(s)
- Gersh O Berim
- Department of Physics, Canisius College, Buffalo, New York 14208, United States
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17
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Berim GO, Ruckenstein E. Sorption on deformable solids. Density functional theory approach. J Phys Chem B 2011; 115:13271-4. [PMID: 21985615 DOI: 10.1021/jp206863c] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A modified density functional theory is proposed to describe fluid adsorption and absorption by a solid, the density of which is nonhomogeneous near the interface. The density distribution of the solid is not provided by apriori assumptions, but is obtained via the minimization of an appropriate thermodynamic potential. The theory considers a mixture of two components in a slitlike pore. One of them, the fluid, is in contact with a reservoir containing the same kind of molecules and can be described through a grand canonical ensemble. The other component has strong interactions between its molecules. As a consequence, it forms a solid in the slit which can be treated as a canonical ensemble of a fixed number of molecules. The theory predicts both an intrinsic (in the absence of fluid) change in the solid density near the interface and a solid density variation as the fluid density in the reservoir is changed. In addition, it reveals that the oscillations that occur in the fluid density when the solid density is uniform are damped by the nonuniform solid. The theory provides the amounts of fluid adsorbed as well as absorbed by the solid.
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Affiliation(s)
- Gersh O Berim
- Department of Chemical and Biological Engineering, State University of New York at Buffalo, Buffalo, New York 14260, United States
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