scholarly journals Illuminating the Impact of Nanoparticle Size and Surface Chemistry on Interfacial Position

2020 ◽  
Author(s):  
Emma Giakoumatos ◽  
Antonio Aloi ◽  
Ilja Voets
Keyword(s):  
Contact Angle ◽  
Particle Size ◽  
Surface Chemistry ◽  
Particle Surface ◽  
Particle Diameter ◽  
Super Resolution ◽  
Contact Angles ◽  
Pickering Emulsions ◽  
Microscopy Technique ◽  
The Impact

In this manuscript we begin by preparing bulk Pickering emulsions of water:octanol at varying aqueous pH values, using ionizable carboxyl polystyrene nanoparticles of 320 nm and 810 nm diameter. Remarkably we observe two emulsion phase inversions, one resulting from an increase in pH and a second due to an increase in particle size. To illuminate the mechanism of the macroscopic phase inversion, we turn to the super resolution microscopy technique <i>interface Point Accumulation for Imaging and Nanoscale Topography</i> (iPAINT) to measure in-situ the contact angles of single carboxyl polystyrene particles at the water:octanol interface. Importantly, we identify a significant decrease in contact angle over the increase of pH and particle diameter, respectively. Additionally, the non-negligible dependence of contact angle on particle size was shown to hold regardless of particle surface chemistry.

scholarly journals Illuminating the Impact of Nanoparticle Size and Surface Chemistry on Interfacial Position

2020 ◽  
Author(s):  
Emma Giakoumatos ◽  
Antonio Aloi ◽  
Ilja Voets
Keyword(s):  
Contact Angle ◽  
Particle Size ◽  
Surface Chemistry ◽  
Particle Surface ◽  
Particle Diameter ◽  
Super Resolution ◽  
Contact Angles ◽  
Pickering Emulsions ◽  
Microscopy Technique ◽  
The Impact

In this manuscript we begin by preparing bulk Pickering emulsions of water:octanol at varying aqueous pH values, using ionizable carboxyl polystyrene nanoparticles of 320 nm and 810 nm diameter. Remarkably we observe two emulsion phase inversions, one resulting from an increase in pH and a second due to an increase in particle size. To illuminate the mechanism of the macroscopic phase inversion, we turn to the super resolution microscopy technique <i>interface Point Accumulation for Imaging and Nanoscale Topography</i> (iPAINT) to measure in-situ the contact angles of single carboxyl polystyrene particles at the water:octanol interface. Importantly, we identify a significant decrease in contact angle over the increase of pH and particle diameter, respectively. Additionally, the non-negligible dependence of contact angle on particle size was shown to hold regardless of particle surface chemistry.

scholarly journals Ice nucleation abilities of soot particles determined with the Horizontal Ice Nucleation Chamber

2018 ◽  
Vol 18 (18) ◽  
pp. 13363-13392 ◽  
Author(s):  
Fabian Mahrt ◽  
Claudia Marcolli ◽  
Robert O. David ◽  
Philippe Grönquist ◽  
Eszter J. Barthazy Meier ◽  
...  
Keyword(s):  
Particle Size ◽  
Water Saturation ◽  
Particle Surface ◽  
Water Vapor Sorption ◽  
Contact Angles ◽  
Ice Nucleation ◽  
Particle Surface Area ◽  
Soot Particles ◽  
Microphysical Properties ◽  
Homogeneous Freezing

Abstract. Ice nucleation by different types of soot particles is systematically investigated over the temperature range from 218 to 253 K relevant for both mixed-phase (MPCs) and cirrus clouds. Soot types were selected to represent a range of physicochemical properties associated with combustion particles. Their ice nucleation ability was determined as a function of particle size using relative humidity (RH) scans in the Horizontal Ice Nucleation Chamber (HINC). We complement our ice nucleation results by a suite of particle characterization measurements, including determination of particle surface area, fractal dimension, temperature-dependent mass loss (ML), water vapor sorption and inferred porosity measurements. Independent of particle size, all soot types reveal absence of ice nucleation below and at water saturation in the MPC regime (T>235 K). In the cirrus regime (T≤235 K), soot types show different freezing behavior depending on particle size and soot type, but the freezing is closely linked to the soot particle properties. Specifically, our results suggest that if soot aggregates contain mesopores (pore diameters of 2–50 nm) and have sufficiently low water–soot contact angles, they show ice nucleation activity and can contribute to ice formation in the cirrus regime at RH well below homogeneous freezing of solution droplets. We attribute the observed ice nucleation to a pore condensation and freezing (PCF) mechanism. Nevertheless, soot particles without cavities of the right size and/or too-high contact angles nucleate ice only at or well above the RH required for homogeneous freezing conditions of solution droplets. Thus, our results imply that soot particles able to nucleate ice via PCF could impact the microphysical properties of ice clouds.

Modeling of Transport During Droplet Deposition and Spreading on Smooth and Microstructured Superhydrophilic Surfaces

2016 ◽  
Author(s):  
Jordan P. Mizerak ◽  
Van P. Carey
Keyword(s):  
Contact Angle ◽  
Contact Angles ◽  
Ansys Fluent ◽  
Effective Contact ◽  
Microstructured Surfaces ◽  
Static Contact ◽  
Droplet Behavior ◽  
Contact Line Pinning ◽  
The Impact ◽  
Superhydrophilic Surfaces

The dynamic behavior of impinging water droplets is studied in the context of varying surface morphologies on smooth and microstructured superhydrophilic surfaces. The goal of this study is to evaluate the capability of contact angle wall adhesion models to accurately produce spreading phenomena seen on a variety of surface types. We analyze macroscale droplet behavior, specifically spreading extent and impinging regime, in situations of varying microscale wetting character and surface morphology. Axisymmetric, volume of fluid (VOF) simulations with static contact angle wall adhesion are conducted in ANSYS Fluent. Simulations are performed on water for low Weber numbers (We<20) on surfaces with features of length scale 5–10μm. Advanced microstructured surfaces consisting of unique wetting characteristics and lengths on each face are also tested. Results show that while the contact angle wall adhesion model shows fair agreement for conventional surfaces, the model underestimates spreading by over 60% for surfaces exhibiting estimated contact angles below approximately 0.5°. Microstructured surfaces adapt the wetting behavior of smooth surfaces with higher effective contact angles based on contact line pinning on morphology features. The propensity of the model to produce Wenzel and Cassie-Baxter states is linked to the spreading radius, introducing an interdependency of microscale wetting and macroscale spreading behavior. Conclusions describing the impact of results on evaporative cooling are also discussed.

A numerical study of particle migration in porous media during produced water reinjection

2021 ◽  
pp. 1-34
Author(s):  
Tian Xia ◽  
Qihong Feng ◽  
Sen Wang ◽  
Qinglin Shu ◽  
Yigen Zhang ◽  
...  
Keyword(s):  
Particle Size ◽  
Porous Media ◽  
Oil Recovery ◽  
Produced Water ◽  
Numerical Study ◽  
Particle Diameter ◽  
Particle Migration ◽  
Critical Ratio ◽  
Clear Understanding ◽  
The Impact

Abstract The clogging phenomenon often occurs during the reinjection of produced water due to the suspended particles, which will deteriorate the development efficiency. Many experimental and analytical methods have been introduced to solve this problem; however, few numerical approaches have been proposed to investigate the particle migration in the produced water reinjection process. Moreover, it is hard to obtain a clear understanding directly from the particle scale when the injected particles have different sizes. This paper employs a coupled lattice Boltzmann method and discrete element method (LBM-DEM) to study the aforementioned process. The method was validated by reproducing the Drafting-Kissing-Tumbling (DKT) process. Simulations of migration of injected particles with different sizes through porous media were conducted and three clogging scenarios had been identified. We investigated the impact of injected particle size distribution and porous media on particle migration and concluded the results in the polydisperse aspect. From the simulation, we can conclude that mix clogging is the scenario we should try to avoid. Besides, both critical ratio of particle diameter of porous media to median particle diameter of injected particles (D/d50) and critical standard deviation value exist. The particle size range should be as small as possible in economical limits and the D/d50 value should be larger than the critical value. Our results can provide a good guide for the produced water pretreatment, which can improve oil recovery.

Study on Rebound Characteristics of Fine Spherical Particles Impacting an AISI 403 Steel With High Velocity

2015 ◽  
Author(s):  
Juan Di ◽  
Shun-sen Wang ◽  
Liu-xi Cai ◽  
Shang-fang Cheng ◽  
Chuang Wu
Keyword(s):  
Particle Size ◽  
High Velocity ◽  
Particle Diameter ◽  
Impact Angle ◽  
Spherical Particles ◽  
Dissipated Energy ◽  
Normal Velocity ◽  
Relative Impact ◽  
Restitution Coefficient ◽  
The Impact

Impingement on blade surface by fine particles with high velocity is commonly seen in steam turbines, gas turbines and compressors, which affect the service life and reliability of the equipment. Study on particles’ rebound characteristics is of great significance to reduce the blade erosion and to control particle trajectory. Based on the nonlinear explicit dynamics analysis software ANSYS/LS-DYNA, the impacts of fine spherical particles with different diameters (20 to 500μm) on a typical martensitic stainless steel (AISI 403) target with high velocity (50 to 250m/s) have been systematically studied. The influences of incident velocities, impact angles, particles sizes on its rebound characteristics, relative impact depth, and relative dissipated energy have been analyzed. Results show that velocity restitution coefficient e decreased with the impact angle β1, the incident velocity V1, and the particle size dp. However, the role of particle size on the velocity restitution coefficient seemed to be far less than that of the other two factors. Both of particle’s tangential and normal velocity coefficient of restitution declined with the increasing impact angle in most cases. However, when the incident velocity V1 = 200m / s and the impact angle β1 > 45°, the tangential velocity restitution coefficient et of 100 μm and 200 μm particles increased with the increase in the impact angle β1. The reason might be that the relative impact depth drel was located a zone ranged from 0.1515 to 0.1677, where the tangential rebound behavior could be enhanced. Most of the variation of the tangential and normal velocity restitution coefficient along β1 decreased with the increase in the particle diameter. However, when V1 = 200m/s and β1 > 15°, the tangential reflected velocity of the larger particles was enhanced gradually. In addition, the values of the relative impact depth drel increased with the increasing impact angle and incident velocity, and it increased with the increasing particle diameter in most cases. The relative dissipated energy of particles steadily increased with the impact angle and incident velocity, respectively. Particle diameter had little effect on energy dissipation in comparison with the impact angle and incident velocity.

scholarly journals PRELIMINARY STUDY ON THE IMPACT OF POLYMER-LIPID TYPES AND RATIO TO POLYMERIC-LIPID HYBRID NANOPARTICLE

2021 ◽  
pp. 150-153
Author(s):  
OKTAVIA EKA PUSPITA ◽  
FERRI WIDODO ◽  
MONICA ANDIKA PUTRI ◽  
ISWA ROSSARIZA ◽  
AVIOLA FADHILLA ◽  
...  
Keyword(s):  
Particle Size ◽  
Zeta Potential ◽  
Particle Surface ◽  
Surface Characteristics ◽  
Lipid Nanoparticles ◽  
Polydispersity Index ◽  
Lipid Nanoparticle ◽  
Nanoprecipitation Method ◽  
One Step ◽  
The Impact

Objective: This study aims to determine the best lipid to polymer ratios in polymeric-lipid nanoparticles using various types and ratios of polymers and lipids. Method: Polymeric-lipid nanoparticle was prepared using the modified one-step nanoprecipitation method. This study used chitosan and Na alginate as polymers and lecithin and egg phosphatidylcholine as lipids. The lipid was crossed-combined with polymer in various ratios, i. e 12.5%, 25.0%, and 37.5%. On its preparation, Cinnamomum burmanii extract was loaded into the resulted polymeric-lipid nanoparticle as an active substance model. The results were assessed its particle surface characteristics including particle size, polydispersity index, and zeta potential. Results: Twelve formulas resulted from crossed-combination between the lipid and polymer were used in this study. Polymeric-lipid nanoparticles resulted from the combination of egg phosphatidylcholine/Na alginate has particle size, polydispersity index, and zeta potential of 380.07±3.52 nm, 0.66±002, and-30.6±1.15 mV, respectively. Conclusions: The best lipid to polymer ratio and type was observed in egg phosphatidylcholine: Na alginate. The particle surface characteristics were better compared to other combinations.

The Study on the Synthesis of Polyfluoroacrylate

2013 ◽  
Vol 395-396 ◽  
pp. 351-354
Author(s):  
Qin Huan Yang
Keyword(s):  
Contact Angle ◽  
Particle Size ◽  
Polymer Film ◽  
Water Contact Angle ◽  
Film Surface ◽  
Contact Angles ◽  
Fluoride Content ◽  
Water Contact ◽  
Copolymer Films ◽  
High Fluoride

Cationic polyfluoroacrylate has been synthesized in the dual presence of cationic and non-ionic emulsifiers. Optimization studies indicated that the optimal proportions of cationic emulsifier 1631 and non-ionic emulsifiers FSA and AEO-9 were 1.75%, 1.25%, and 0.08%, respectively. Under these conditions, the conversion to the polymer was 92.5%, the particle size was 142 nm, and the water contact angle on a polymer film surface was 94.0°. With increasing dosage of hydrocarbon emulsifier, the water contact angles of copolymer films decreased dramatically. The magnitude of this decrease for a polymer with low fluoride content was greater than that for a polymer with high fluoride content. The fluorinated emulsifier FSA behaved similarly to the hydrocarbon emulsifier.

Characterization of a Ceramic Powder Surface by Contact Angle Measurements and Infrared Spectroscopy

2012 ◽  
Vol 507 ◽  
pp. 233-238 ◽  
Author(s):  
Bram Neirinck ◽  
Dimitri Soccol ◽  
Jan Fransaer ◽  
Omer Van der Biest ◽  
Jef Vleugels
Keyword(s):  
Contact Angle ◽  
Infrared Spectroscopy ◽  
Surface Chemistry ◽  
Suspended Particle ◽  
Ceramic Powder ◽  
Contact Angles ◽  
Alumina Powder ◽  
Surface Groups ◽  
Angle Measurements ◽  
Contact Angle Measurements

The surface chemistry of a suspended particle greatly affects it behavior during electrophoretic deposition. The type and amount of surface groups determines whether the particles can be charged by interaction with the solvent. Furthermore, it is suspected that the surface chemistry plays a prominent role in the mechanisms governing the actual deposition of the particles. In the present work the surface chemistry of as-received and surface modified alumina powder is characterized by means of contact angle measurements and Diffuse Reflectance Infrared Fourier Transform spectroscopy. The wetting is measured using a modified Washburn method which yields quantitative contact angle values. The acid-base and dispersive surface energy components are calculated from these values using the surface tension component theory. Infrared spectroscopy was used to compare the surface groups of the treated and untreated powders and confirm the trends in surface properties as calculated from the contact angles.

scholarly journals Wettability in complex porous materials, the mixed-wet state, and its relationship to surface roughness

2018 ◽  
Vol 115 (36) ◽  
pp. 8901-8906 ◽  
Author(s):  
Ahmed AlRatrout ◽  
Martin J. Blunt ◽  
Branko Bijeljic
Keyword(s):  
Surface Roughness ◽  
Contact Angle ◽  
Pore Space ◽  
Contact Angles ◽  
Wettability Alteration ◽  
Water Repellent ◽  
Local Degree ◽  
Wide Range ◽  
Mixed Wettability ◽  
The Impact

A quantitative in situ characterization of the impact of surface roughness on wettability in porous media is currently lacking. We use reservoir condition micrometer-resolution X-ray tomography combined with automated methods for the measurement of contact angle, interfacial curvature, and surface roughness to examine fluid/fluid and fluid/solid interfaces inside a porous material. We study oil and water in the pore space of limestone from a giant producing oilfield, acquiring millions of measurements of curvature and contact angle on three millimeter-sized samples. We identify a distinct wetting state with a broad distribution of contact angle at the submillimeter scale with a mix of water-wet and water-repellent regions. Importantly, this state allows both fluid phases to flow simultaneously over a wide range of saturation. We establish that, in media that are largely water wet, the interfacial curvature does not depend on solid surface roughness, quantified as the local deviation from a plane. However, where there has been a significant wettability alteration, rougher surfaces are associated with lower contact angles and higher interfacial curvature. The variation of both contact angle and interfacial curvature increases with the local degree of roughness. We hypothesize that this mixed wettability may also be seen in biological systems to facilitate the simultaneous flow of water and gases; furthermore, wettability-altering agents could be used in both geological systems and material science to design a mixed-wetting state with optimal process performance.

scholarly journals Ice nucleation abilities of soot particles determined with the Horizontal Ice Nucleation Chamber

2018 ◽  
Author(s):  
Fabian Mahrt ◽  
Claudia Marcolli ◽  
Robert O. David ◽  
Philippe Grönquist ◽  
Eszter J. Barthazy Meier ◽  
...  
Keyword(s):  
Particle Size ◽  
Water Saturation ◽  
Particle Surface ◽  
Water Vapor Sorption ◽  
Contact Angles ◽  
Ice Nucleation ◽  
Particle Surface Area ◽  
Soot Particles ◽  
Microphysical Properties ◽  
Homogeneous Freezing

Abstract. Ice nucleation by different types of soot particles is systematically investigated over the temperature range from 218 to 253 K relevant for both mixed-phase (MPCs) and cirrus clouds. Soot types were selected to represent a range of physicochemical properties associated with combustion particles. Their ice nucleation ability was determined as a function of particle size using relative humidity (RH) scans in the Horizontal Ice Nucleation Chamber (HINC). We complement our ice nucleation results by a suite of particle characterization measurements, including determination of particle surface area, fractal dimension, temperature dependent mass loss, water vapor sorption and inferred porosity measurements. Independent of particle size, all soot types reveal absence of ice nucleation below and at water saturation in the MPC regime (T > 235 K). In the cirrus regime (T ≤ 235 K), soot types show different freezing behaviour depending on particle size and soot type, but the freezing is closely linked to the soot particle properties. Specifically, our results suggest that if soot aggregates contain mesopores (pore diameters of 2–50 nm) and have sufficiently low water-soot contact angles, they show ice nucleation activity and can contribute to ice formation in the cirrus regime at RH well below homogeneous freezing of solution droplets. We attribute the observed ice nucleation to a pore condensation and freezing (PCF) mechanism. Nevertheless, soot particles without cavities of the right size and/or too high contact angles nucleate ice only at or well above the RH required for homogeneous freezing conditions of solution droplets. Thus, our results imply that soot particles able to nucleate ice via PCF, could impact the microphysical properties of ice clouds.

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