Erratum: Surface Energy of Filtration Media Influencing the Filtration Performance against Solid Particles, Oily Aerosol, and Bacterial Aerosol. Polymers 2019, 11, 935

Particulate airborne pollutants are a big concern to public health, and it brings growing attention about effective filtration devices. Especially, particulate matters smaller than 2.5 µm can reach the thoracic region and the blood stream, and the associated health risk can be exacerbated when pathogenic microbials are present in the air. This study aims at understanding the surface characteristics of nonwoven media that influence filtration performance against solid particles (sodium chloride, NaCl), oily aerosol (dioctyl phthalate, DOP), and Staphylococcus aureus (S. aureus) bacteria. Nonwoven media of polystyrene (PS) fibers were fabricated by electrospinning and its pristine surface energy (38.5 mN/m) was modified to decrease (12.3 mN/m) by the plasma enhanced chemical vapor deposition (PECVD) of octafluorocyclobutane (C4F8) or to increase (68.5 mN/m) by the oxygen (O2) plasma treatment. For NaCl particles and S. aureus aerosol, PS electrospun web showed higher quality factor than polypropylene (PP) meltblown electret that is readily available for commercial products. The O2 plasma treatment of PS media significantly deteriorated the filtration efficiency, presumably due to the quick dissipation of static charges by the O2 plasma treatment. The C4F8 treated, fluorinated PS media resisted quick wetting of DOP, and its filtration efficiency for DOP and S. aureus remained similar while its efficiency for NaCl decreased. The findings of this study will impact on determining relevant surface treatments for effective particulate filtration. As this study examined the instantaneous performance within 1–2 min of particulate exposure, and the further study with the extended exposure is suggested.

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Facile Functionalization via Plasma-Enhanced Chemical Vapor Deposition for the Effective Filtration of Oily Aerosol

Polymers ◽

10.3390/polym11091490 ◽

2019 ◽

Vol 11 (9) ◽

pp. 1490 ◽

Cited By ~ 10

Author(s):

Sanghyun Roh ◽

Sungmin Kim ◽

Jooyoun Kim

Keyword(s):

Chemical Vapor Deposition ◽

Vapor Deposition ◽

Filter Design ◽

Chemical Vapor ◽

Surface Modifications ◽

Solid Particles ◽

Oxygen Species ◽

Plasma Process ◽

Filter Performance ◽

Filtration Performance

With the growing concern about the health impacts associated with airborne particles, there is a pressing need to design an effective filter device. The objective of this study is to investigate the effect of plasma-based surface modifications on static charges of electrospun filter media and their resulting filtration performance. Polystyrene (PS) electrospun web (ES) had inherent static charges of ~3.7 kV due to its electric field-driven process, displaying effective filtration performance. When oxygen species were created on the surface by the oxygen plasma process, static charges of electret media decreased, deteriorating the filter performance. When the web surface was fluorinated by the plasma-enhanced chemical vapor deposition (PECVD), the filtration efficiency against oily aerosol significantly increased due to the combined effect of decreased wettability and strong static charges (~−3.9 kV). Solid particles on the charged media formed dendrites as particles were attracted to other layers of particles, building up a pressure drop. The PECVD process is suggested as a facile functionalization method for effective filter design, particularly for capturing oily aerosol.

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Rate Equations for Material Transport Driven by Excess Free Energy in Solid

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.352.1 ◽

2007 ◽

Vol 352 ◽

pp. 1-4

Author(s):

Hidehiko Tanaka

Keyword(s):

Free Energy ◽

Surface Energy ◽

Shape Change ◽

Excess Free Energy ◽

Boundary Energy ◽

Solid Particles ◽

Rate Equations ◽

Material Transport ◽

Key Factor ◽

Diffusion Phenomena

Diffusion phenomena in solid particles were analyzed with the new material transport concept. It was assumed that total excess free energy in a system acted as a driving force for material transport so that the system changed to an equilibrium state. The new rate equation was adopted to analyze shape change, sintering and growth of grains. It was found that surface energy or ratio of grain boundary energy to surface energy was key factor for shape changes in these processes.

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General approach to describing the properties of solid particles defined by the surface energy

Tsvetnye Metally ◽

10.17580/tsm.2019.01.08 ◽

2019 ◽

pp. 51-57

Author(s):

G. M. Voldman

Keyword(s):

Surface Energy ◽

Solid Particles

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Numerical Investigation of the Influence of Fiber Geometry on Filtration Performance With a Coupled Lattice Boltzmann–Discrete Element Method

Journal of Applied Mechanics ◽

10.1115/1.4044928 ◽

2019 ◽

Vol 87 (1) ◽

Author(s):

Jianhua Fan ◽

Franck Lominé ◽

Mustapha Hellou

Keyword(s):

Reynolds Number ◽

Pressure Drop ◽

Lattice Boltzmann ◽

Density Ratio ◽

Discrete Element ◽

Solid Particles ◽

Capture Efficiency ◽

Fibrous Filter ◽

Cross Sectional ◽

Filtration Performance

Abstract Motion and deposition of solid particles in fibrous filter with circular, diamond, and square fibers are numerically investigated. A coupled Lattice Boltzmann (LB) and discrete element (DE) method is presented and applied to simulate the filtration process in particulate flow, taking into account the mutual interaction between fluid and particle. The influence of pertinent parameters such as the Reynolds number, the particle-to-fiber diameter ratio, and the particle-to-fluid density ratio on filtration performance (pressure drop and capture efficiency) is analyzed for fibrous filter with different fiber cross-sectional shapes. The simulation results indicate that both the pressure drop and the capture efficiency of filter are considerably affected by the fiber’s shape. Dimensionless drag force increases with the Reynolds number when Re > 1. The filter with diamond fiber has a lower pressure drop than that of the circular and square cases. Meanwhile, the deposition of particles on the surface of square fiber is more favorable. From the filter quality factor standpoint, filter with diamond fiber exhibits a better filtration performance.

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Prevention of Barite Sag in Oil-Based Drilling Fluids Using a Mixture of Barite and Ilmenite as Weighting Material

Sustainability ◽

10.3390/su11205617 ◽

2019 ◽

Vol 11 (20) ◽

pp. 5617 ◽

Cited By ~ 7

Author(s):

Abdelmjeed Mohamed ◽

Salem Basfar ◽

Salaheldin Elkatatny ◽

Abdulaziz Al-Majed

Keyword(s):

High Pressure ◽

Viscoelastic Properties ◽

Elevated Temperatures ◽

Drilling Fluid ◽

Solid Particles ◽

Electrical Stability ◽

Dynamic Conditions ◽

Filtration Performance ◽

Static Conditions ◽

The Impact

Drilling high-pressure high-temperature (HPHT) wells requires a special fluid formulation that is capable of controlling the high pressure and is stable under the high downhole temperature. Barite-weighted fluids are common for such purpose because of the good properties of barite, its low cost, and its availability. However, solids settlement is a major problem encountered with this type of fluids, especially at elevated downhole temperatures. This phenomenon is known as barite sag, and it is encountered in vertical and directional wells under static or dynamic conditions leading to serious well control issues. This study aims to evaluate the use of barite-ilmenite mixture as a weighting agent to prevent solids sag in oil-based muds at elevated temperatures. Sag test was conducted under static conditions (vertical and inclined) at 350 °F and under dynamic conditions at 120 °F to determine the optimum ilmenite concentration. Afterward, a complete evaluation of the drilling fluid was performed by monitoring density, electrical stability, rheological and viscoelastic properties, and filtration performance to study the impact of adding ilmenite on drilling fluid performance. The results of this study showed that adding ilmenite reduces sag tendency, and only 40 wt.% ilmenite (from the total weighting material) was adequate to eliminate barite sag under both static and dynamic conditions with a sag factor of around 0.51. Adding ilmenite enhanced the rheological and viscoelastic properties and the suspension of solid particles in the drilling fluid, which confirmed sag test results. Adding ilmenite slightly increased the density of the drilling fluid, with a slight decrease in the electrical stability within the acceptable range of field applications. Moreover, a minor improvement in the filtration performance of the drilling fluid and filter cake sealing properties was observed with the combined weighting agent. The findings of this study provide a practical solution to the barite sag issue in oil-based fluids using a combination of barite and ilmenite powder as a weighting agent to drill HPHT oil and gas wells safely and efficiently with such type of fluids.

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The annealed (0001) α-alumina surface and its influence on thin-film growth

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100138051 ◽

1995 ◽

Vol 53 ◽

pp. 336-337

Author(s):

Michael W. Bench ◽

Paul G. Kotula ◽

C. Barry Carter

Keyword(s):

Electron Microscopy ◽

Surface Energy ◽

Film Growth ◽

Thin Film Growth ◽

Energy Calculations ◽

Transmission Electron ◽

Reflection Electron Microscopy ◽

Low Energy Electron ◽

Surface Nature

The growth of semiconductors, superconductors, metals, and other insulators has been investigated using alumina substrates in a variety of orientations. The surface state of the alumina (for example surface reconstruction and step nature) can be expected to affect the growth nature and quality of the epilayers. As such, the surface nature has been studied using a number of techniques including low energy electron diffraction (LEED), reflection electron microscopy (REM), transmission electron microscopy (TEM), molecular dynamics computer simulations, and also by theoretical surface energy calculations. In the (0001) orientation, the bulk alumina lattice can be thought of as a layered structure with A1-A1-O stacking. This gives three possible terminations of the bulk alumina lattice, with theoretical surface energy calculations suggesting that termination should occur between the Al layers. Thus, the lattice often has been described as being made up of layers of (Al-O-Al) unit stacking sequences. There is a 180° rotation in the surface symmetry of successive layers and a total of six layers are required to form the alumina unit cell.

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The nucleation of cavities at grain boundaries

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100126299 ◽

1987 ◽

Vol 45 ◽

pp. 288-291

Author(s):

P. J. Goodhew

Keyword(s):

Surface Tension ◽

Surface Energy ◽

Grain Boundaries ◽

Radiation Damage ◽

Impurity Concentration ◽

Driving Force ◽

Nucleation And Growth ◽

Phase Boundaries ◽

Cavity Nucleation ◽

Spherical Bubble

Cavity nucleation and growth at grain and phase boundaries is of concern because it can lead to failure during creep and can lead to embrittlement as a result of radiation damage. Two major types of cavity are usually distinguished: The term bubble is applied to a cavity which contains gas at a pressure which is at least sufficient to support the surface tension (2g/r for a spherical bubble of radius r and surface energy g). The term void is generally applied to any cavity which contains less gas than this, but is not necessarily empty of gas. A void would therefore tend to shrink in the absence of any imposed driving force for growth, whereas a bubble would be stable or would tend to grow. It is widely considered that cavity nucleation always requires the presence of one or more gas atoms. However since it is extremely difficult to prepare experimental materials with a gas impurity concentration lower than their eventual cavity concentration there is little to be gained by debating this point.

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