Electrokinetics of polar liquids in contact with nonpolar surfaces

Gold-nanoparticle-embedded microchannel array for enhanced power generation

A high streaming potential and current were generated using a gold-nanoparticle-embedded patterned PDMS microchannel array. Gold nanoparticles with dimensions of ∼70 nm were prepared inside a hydrophobic patterned PDMS microchannel. The channel array was developed on a ridge-shaped patterned surface by performing soft lithography using UV-laser micromachining with a ridge spacing of 27.0 μm, width of 22.0 μm, and height of 16.0 μm. Subsequently, tests were conducted in which ultrapure water, solutions of 0.1 M NaCl, 0.1 M HCl and 40% H₂O₂ were passed through the patterned channel array at various flow rates and pressures using a microfluidic pump wherein the channel inlet and outlet acted as collector electrodes. A maximum streaming potential of 2.6 V, a current of 1.3 μA, and a maximum power density of 4.3 μW cm^-2 were obtained for this gold-nanoparticle-embedded PDMS channel with ultrapure water as the working fluid at an inlet pressure of 1 bar. The generated power density here was ∼256 times higher than that for the PDMS channel array without gold nanoparticles using ultrapure water as the working fluid, confirming the benefit of gold nanoparticles in the channel array, which may have potential applications in microwatt-powered lab-on-chip devices.

Identification and characterization of bilgewater emulsions

Literature on bilgewater focuses on empirically determined treatment methods and lacks specific information on emulsion characteristics. Therefore, this review discusses potential emulsion stabilization mechanisms that occur in bilgewater and evaluates common approaches to study their behavior. Current knowledge on emulsion formation, stabilization, and destabilization is outlined to provide researchers and bilgewater treatment operators with the knowledge needed to determine emulsion prevention and treatment strategies. Furthermore, a broad assessment of bilgewater emulsion characterization techniques, from general water quality analysis to advanced droplet stability characterization methods are discussed in detail. Lastly, a survey of typical bilgewater characteristics and information on standard synthetic bilgewater mixtures used in the testing of oil pollution abatement equipment are presented. Overall, the goal of this article is to provide a better understanding of physical and thermodynamic properties of emulsions to help improve bilgewater treatment and management.