scholarly journals Multiple air-bubble enhanced oil rupture on nanostructured cellulose fabric for easy-oil cleaning fouled in a dry state

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Min-Sung Kim ◽  
Tae-Jun Ko ◽  
Seong Jin Kim ◽  
Young-A. Lee ◽  
Kyu Hwan Oh ◽  
...  
Keyword(s):  
Aspect Ratio ◽  
Solid Fraction ◽  
High Aspect Ratio ◽  
Air Bubbles ◽  
Oil Droplets ◽  
Water Contact ◽  
Air Bubble ◽  
Cellulose Fabric ◽  
Oily Water ◽  
Oil Fouling

Abstract Nanostructured cellulose fabric with an air-bubble-enhanced anti-oil fouling property is introduced for quick oil-cleaning by water even with the surface fouled by oil before water contact under a dry state. It is very challenging to recover the super-hydrophilicity because once the surface is oil-fouled, it is hard to be re-wetted by water. Anti-oil-fouling under a dry state was realized through two main features of the nanostructured, porous fabric: a low solid fraction with high-aspect-ratio nanostructures significantly increasing the retracting forces, and trapped multiscale air bubbles increasing the buoyancy and backpressure for an oil-layer rupture. The nanostructures were formed on cellulose-based rayon microfibers through selective etching with oxygen plasma, forming a nanoscale open-pore structure. Viscous crude oil fouled on a fabric under a dry state was cleaned by immersion into water owing to a higher water affinity of the rayon material and low solid fraction of the high-aspect-ratio nanostructures. Air bubbles trapped in dry porous fibers and nanostructures promote oil detachment from the fouled sites. The macroscale bubbles add buoyancy on top of the oil droplets, enhancing the oil receding at the oil-water-solid interface, whereas the relatively smaller microscale bubbles induce a backpressure underneath the oil droplets. The oil-proofing fabric was used for protecting underwater conductive sensors, allowing a robot fish to swim freely in oily water.

Effect of morphology on interactions between nanoparticle-stabilised air bubbles and oil droplets

Soft Matter ◽  
2018 ◽  
Vol 14 (17) ◽  
pp. 3246-3253 ◽  
Author(s):  
Victoria J. Cunningham ◽  
Emma C. Giakoumatos ◽  
Melissa Marks ◽  
Steven P. Armes ◽  
Erica J. Wanless
Keyword(s):  
Air Bubbles ◽  
Oil Droplets ◽  
Oil Droplet ◽  
Air Bubble ◽  
Multiphase Systems

Adsorbed copolymer nanoparticle spheres and worms can stabilise oil droplet or air bubble pairs, or indeed multiphase systems.

Fabrication of High Aspect Ratio Silicon Nanostructure with Sphere Lithography and Metal-Assisted Chemical Etching and its Wettability

2016 ◽  
Vol 10 (6) ◽  
pp. 971-976 ◽  
Author(s):  
Nobuyuki Moronuki ◽  
◽  
Nguyen Phan ◽  
Norito Keyaki ◽  
◽  
...  
Keyword(s):  
Contact Angle ◽  
Aspect Ratio ◽  
High Aspect Ratio ◽  
Chemical Etching ◽  
Ion Bombardment ◽  
Water Contact ◽  
Cross Sectional ◽  
Practical Applications ◽  
Metal Assisted Chemical Etching ◽  
Si Nanostructures

Metal-assisted chemical etching (MACE) is a site-selective etching process produced by a catalyst reaction at the interface between noble metal and silicon. This paper aims to make clear the applicability of sphere lithography and MACE to the fabrication of high aspect ratio Si nanostructures. The capacity to control the etched profiles and the scale extension are investigated. First, silica particles (e.g. φ1 μm) were self-assembled on a Si substrate. After the reduction of particle size via argon ion bombardment, a gold layer was deposited using the particles as a mask. The substrate was then etched with a mixture of hydrofluoric acid and hydrogen peroxide. It was found that an array of nanopillars with a regular pitch, good separation, and an aspect ratio of about 52 was produced. The effects of MACE conditions on final profiles were clarified. A limitation of this approach is the small (several millimeters) area fabricated due to the dependence on the vacuum technique (ion bombardment, Au deposition), and the size of the area limits its practical applications. Thus, Ag nanoparticles (e.g. φ150 nm) were applied. The relationship between the concentration of the Ag suspension, the Ag assembled layer, and the morphology of MACE structures was made clear. A spray method was applied to extend the deposited area of Ag particles up to φ100 mm. Finally, the effects of the cross-sectional profile on the contact angle of a water droplet were examined. By applying a high aspect ratio nanostructure on the substrate, the water contact angle increased up to 153 degrees while that without the structure is 58 degrees.

Boehmite Nanofibers as a Dispersant for Nanotubes in an Aqueous Sol

2018 ◽  
Author(s):  
Gen Hayase
Keyword(s):  
Carbon Nanotubes ◽  
Aspect Ratio ◽  
Aqueous Solutions ◽  
High Aspect Ratio ◽  
Multiwall Carbon Nanotubes ◽  
Multiwall Carbon ◽  
Nanotube Films

By exploiting the dispersibility and rigidity of boehmite nanofibers (BNFs) with a high aspect ratio of 4 nm in diameter and several micrometers in length, multiwall-carbon nanotubes (MWCNTs) were successfully dispersed in aqueous solutions. In these sols, the MWCNTs were dispersed at a ratio of about 5–8% relative to BNFs. Self-standing BNF–nanotube films were also obtained by filtering these dispersions and showing their functionality. These films can be expected to be applied to sensing materials.

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