scholarly journals Liquid-Liquid Interfacial Transport of Nanoparticles

2007 ◽  
Vol 2007 ◽  
pp. 1-7 ◽  
Author(s):  
Stefanie Machunsky ◽  
Urs Alexander Peuker
Keyword(s):  
Particle Size ◽  
Liquid Phase ◽  
High Efficiency ◽  
Phase Transfer ◽  
Organic Liquid ◽  
Particle Surface ◽  
Aqueous Dispersion ◽  
Polymer Nanocomposite ◽  
Liquid Interface ◽  
Interfacial Transport

The study presents the transfer of nanoparticles from the aqueous phase to the second nonmiscible nonaqueous liquid phase. The transfer is based on the sedimentation of the dispersed particles through a liquid-liquid interface. First, the colloidal aqueous dispersion is destabilised to flocculate the particles. The agglomeration is reversible and the flocs are large enough to sediment in a centrifugal field. The aqueous dispersion is laminated above the receiving organic liquid phase. When the particles start to penetrate into the liquid-liquid interface, the particle surface is covered with the stabilising surfactant. The sorption of the surfactant onto the surface of the primary particles leads to the disintegration of the flocs. This phase transfer process allows for a very low surfactant concentration within the receiving organic liquid, which is important for further application, that is, synthesis for polymer-nanocomposite materials. Furthermore, the phase transfer of the nanoparticles shows a high efficiency up to 100% yield. The particle size within the organosol corresponds to the primary particle size of the nanoparticles.

Effect of Crystal Modifiers and Dispersants on Paraffin-Wax Particles in Petroleum Fluids

SPE Journal ◽  
2018 ◽  
Vol 24 (01) ◽  
pp. 32-43 ◽  
Author(s):  
Minwei Sun ◽  
Khosrow Naderi ◽  
Abbas Firoozabadi
Keyword(s):  
Particle Size ◽  
High Efficiency ◽  
Particle Surface ◽  
Molecular Structures ◽  
Paraffin Wax ◽  
Intensity Increase ◽  
Chemical Additives ◽  
Submicron Scale ◽  
Wax Crystal ◽  
Crystal Particle

Summary Petroleum fluids from shale light-oil and gas/condensate reservoirs generally have a high content of normal paraffins. Paraffin-wax deposition is among the challenges in shale gas and oil production and in offshore flow assurance. Low-dosage chemical additives can be effective in paraffin-wax mitigation because of their high efficiency and economics. These additives are divided into broad categories of crystal modifiers and dispersants with vastly different molecular structures and mechanisms in wax-crystal-particle stabilization and wetting. This investigation focuses on the understanding of the differences in the aggregate size and morphology of chemical additives, and it centers on (1) wax-particle sedimentation from diluted petroleum fluids in vial tests, (2) wax-crystal-particle-size distributions and morphology by dynamic light scattering (DLS) and polarized-light microscopy, and (3) the wetting state from the effect of water. In two of the three petroleum-fluid samples used in this work, there is no visible precipitation at the bottom of the vials at temperatures below the wax-appearance temperature (WAT). The microscopic image of fluids along the length of the tube shows that the wax-particle size and intensity increase from top to bottom. To observe precipitation, we dilute the crude with a hydrocarbon such as n-heptane. The sedimentation of wax is then observed. The petroleum fluids used in this work have very low asphaltene content, and there is no complication from asphaltene precipitation. Our study shows that a small amount of crystal modifier and dispersant can reduce crystal-particle size to the submicron scale, and change the crystal morphology. We investigate the differences in the mechanisms of dispersants and crystal modifiers in bulk. Water, which is often coproduced with petroleum fluids, can increase the effectiveness of dispersants significantly by altering the wetting state of the wax-particle surface. Such enhancement is not found in crystal modifiers. Both additives affect the rheology of petroleum fluids.

Theoretical analysis of counter-current absorption of a poorly soluble gas based on the PDE-AD model

1986 ◽  
Vol 51 (6) ◽  
pp. 1222-1239 ◽  
Author(s):  
Pavel Moravec ◽  
Vladimír Staněk
Keyword(s):  
Experimental Data ◽  
Liquid Phase ◽  
Gas Phase ◽  
Transfer Functions ◽  
Packed Bed ◽  
Packed Bed Column ◽  
Interfacial Transport ◽  
Gaseous Component ◽  
Poorly Soluble ◽  
Counter Current

Expression have been derived in the paper for all four possible transfer functions between the inlet and the outlet gas and liquid steams under the counter-current absorption of a poorly soluble gas in a packed bed column. The transfer functions have been derived for the axially dispersed model with stagnant zone in the liquid phase and the axially dispersed model for the gas phase with interfacial transport of a gaseous component (PDE - AD). calculations with practical values of parameters suggest that only two of these transfer functions are applicable for experimental data evaluation.

scholarly journals Awareness of aerosol-related transmission of COVID-19 among the dentists of Nepal

BDJ Open ◽  
2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Nashib Pandey ◽  
Buddha Bahadur Basnet ◽  
Sushmit Koju ◽  
Anju Khapung ◽  
Alka Gupta
Keyword(s):  
Social Sciences ◽  
Particle Size ◽  
High Efficiency ◽  
Emergency Services ◽  
Uv Light ◽  
Ventilation System ◽  
Age Groups ◽  
Air Filtration ◽  
Online Questionnaire ◽  
Dental Practitioners

Abstract Objective To access the awareness of dental practitioners of Nepal towards COVID-19 transmission through aerosols. Materials and methods The study involved 384 dentists from all over Nepal and was conducted for a period of 3 months. A self-reported online questionnaire was developed using Google forms and the link was shared. It emphasized the awareness related to the aerosol and ventilation system in their daily practices was prepared. The data were analyzed in Statistical Package for Social Sciences version 20.0 software. Results The majority of participants were female 52.9% (n = 203) and within the age groups of <30 years 57% (n = 219). Participants from Bagmati Province were 60.4% (n = 232), with least from Sudurpaschim Province 0.5% (n = 2). 60% of participants provided only emergency services during the COVID-19 pandemic and few (7%) provided consultations via telephone. The current ventilation system used was a well-ventilated room with open windows 65.4% (n = 251). However, 52.8% (n = 203) preferred specialized operatory incorporating high-efficiency particulate air (HEPA) filters and ultraviolet (UV) light. More than 60% of respondents were unaware of the particle size of the aerosol. Conclusions The obtained results signify the need for the proper ventilation system with appropriate air filtration systems in dental clinical setups.

Enrichment of a Nigerian chromite ore for metallurgical application by dense medium flotation and magnetic separation

2019 ◽  
Vol 116 (3) ◽  
pp. 324 ◽  
Author(s):  
Kuranga Ibrahim Ayinla ◽  
Alafara Abdullahi Baba ◽  
Bankim Chandra Tripathy ◽  
Malay Kumar Ghosh ◽  
Rajan Kumar Dwari ◽  
...  
Keyword(s):  
Particle Size ◽  
Magnetic Separation ◽  
Organic Liquid ◽  
Size Fraction ◽  
Dense Medium ◽  
Chromium Alloy ◽  
Magnetic Separator ◽  
Electro Deposition ◽  
Chromite Ore ◽  
Wet Chemical

This study, focused on the beneficiation of a Nigerian complex chromite ore sourced from Tunga-Kaduka, Anka Local Government of Zamfara State, Nigeria, assaying 45.85% Cr2O4 and 54.15% mineral impurities, was enriched concurrently through sink floatation and magnetic separation techniques. The chromite ore initially analyzed to contain silicate impurities was found not suitable for metallurgical purposes. Thus, enrichment was examined through gravity separation studies using organic liquid with different specific gravities at 2.8, 3.3, and 4.0. The separation of chromite ore with lowest particle size fraction was done using Mozley mineral separator followed by the magnetic separation of the sink product by magnetic separator. The results obtained revealed about 77% of the total material containing 300 μm particle size, 52% ˂ 212 μm and 17% below 75 μm. Subsequent analysis of the beneficiated ore was carried out by wet chemical analysis and atomic absorption spectrophotometer. The results showed that Cr2O4 content increased to 78.34% from initial 45.83% with maximum Cr:Fe ratio of 3.2:1, representing 84.27% of chromium metal present in the ore. The enrichment of Cr2O4 obtained in this study could be found metallurgically applicable in the electro-deposition and ferro-chromium alloy production practices.

A Selective Synthesis of Unsymmetrical 1,1'-Methylenebisdiazoles by Solid-liquid Phase Transfer Catalysis

Heterocycles ◽  
1986 ◽  
Vol 24 (8) ◽  
pp. 2233 ◽  
Author(s):  
Jos� Elguero ◽  
Sebastian Juli� ◽  
Carlos Mart地ez-Martorell
Keyword(s):  
Liquid Phase ◽  
Phase Transfer Catalysis ◽  
Phase Transfer ◽  
Selective Synthesis ◽  
Solid Liquid

Solid-liquid phase-transfer catalysis reactions without solvent; very mild conditions for .beta.-eliminations

1984 ◽  
Vol 49 (6) ◽  
pp. 1138-1140 ◽  
Author(s):  
Jean Barry ◽  
Georges Bram ◽  
Guy Decodts ◽  
Andre Loupy ◽  
Philippe Pigeon ◽  
...  
Keyword(s):  
Liquid Phase ◽  
Phase Transfer Catalysis ◽  
Phase Transfer ◽  
Mild Conditions ◽  
Solid Liquid

The Research of Silica-Coated Chromium Oxide Green Pigment Prepared by Liquid Phase Method

2011 ◽  
Vol 84-85 ◽  
pp. 514-518
Author(s):  
Hong Yan Zhang ◽  
Jin Hua Wang ◽  
Li Fang Zhang ◽  
Li Li Wang
Keyword(s):  
Liquid Phase ◽  
Experimental Method ◽  
Chromium Oxide ◽  
Particle Surface ◽  
Tetraethyl Orthosilicate ◽  
Hydrolysis Reaction ◽  
Phase Method ◽  
Green Pigment ◽  
Coated Particle ◽  
Liquid Phase Method

This paper is researched on SiO2-coated Cr2O3 for the hydrolysis reaction of tetraethyl orthosilicate. The influences of precursors, solid contents of suspension and Si ratio of water on coated particle surface are investigated. The products are characterized and the conclusion shows that the experimental method is feasible.

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