Surfaces which possess extraordinary water attraction or repellency depend on surface energy, surface chemistry, and nano-and microscale surface roughness. Synergistic superhydrophilic-underwater superoleophobic surfaces were fabricated... more
Surfaces which possess extraordinary water attraction or repellency depend on surface energy, surface chemistry, and nano-and microscale surface roughness. Synergistic superhydrophilic-underwater superoleophobic surfaces were fabricated by spray deposition of nanostructured TiO 2 on stainless steel mesh substrates. The coated meshes were then used to study gravity driven oil−water separation, where only the water from the oil−water mixture is allowed to permeate through the mesh. Oil−water separation efficiencies of up to 99% could be achieved through the coated mesh of pore sizes 50 and 100 μm, compared to no separation at all, that was observed in the case of uncoated meshes of the same material and pore sizes. An adsorbed water on the TiO 2 coated surface, formation of a water-film between the wires that form the mesh and the underwater superoleophobicity of the structured surface are the key factors that contribute to the enhanced efficiency observed in oil−water separation. The nature of the oil−water separation process using this coated mesh (in which the mesh allows water to pass through the porous structure but resists wetting by the oil phase) minimizes the fouling of mesh so that the need for frequent replacement of the separating medium is reduced. The fabrication approach presented here can be applied for coating large surface areas and to develop a large-scale oil−water separation facility for oilfield applications and petroleum industries.
Surfaces which possess extraordinary water attraction or repellency depend on surface energy, surface chemistry and nanoand microscale surface roughness. Synergistic superhydrophilic-underwater superoleophobic surfaces were fabricated by... more
Surfaces which possess extraordinary water attraction or repellency depend on surface energy, surface chemistry and nanoand microscale surface roughness. Synergistic superhydrophilic-underwater superoleophobic surfaces were fabricated by a spray deposition of nanostructured TiO2 on stainless steel mesh substrates. The coated meshes were then used to study gravity driven oil-water separation, where only the water from the oil-water mixture is allowed to permeate through the mesh. Oil-water separation efficiencies of up to 99 % could be achieved through the coated mesh of pore sizes 50 and 100 micron, compared to no separation at all, that was observed in the case of uncoated meshes of the same material and pore sizes. An adsorbed water on the TiO2 coated surface, formation of a water-film between
Two-dimensional diffusion of a rhodamine 6G fluorescent tracer molecule at the n-decane–water interface was studied with all-atom molecular dynamics simulations. In agreement with experimental data, we find increased mobility of the... more
Two-dimensional diffusion of a rhodamine 6G fluorescent tracer molecule at the n-decane–water interface was studied with all-atom molecular dynamics simulations. In agreement with experimental data, we find increased mobility of the tracer at the n-decane–water interfaces in comparison to its mobility in bulk water. Orientational ordering of water and n-decane molecules near the interface is observed, and may change the interfacial viscosity as suggested to explain the experimental data. However, the restricted rotational motion of the rhodamine molecule at the interface suggests that the Saffman-Delbrück model may be a more appropriate approximation of rhodamine diffusion at n-decane–water interfaces, and, without any decrease in interfacial viscosity, suggests faster diffusion consistent with both experimental and simulation values.
