Enabling capillary wicking on bulk metal alloys is challenging due to processing complexity at different size scales. This work presents a laser-chemical surface treatment to fabricate superwicking patterns guided by a superhydrophobic region over a large-area metal alloy surface. The laser-chemical surface treatment generates surface micro/nanostructures and desirable surface chemistry simultaneously. The superhydrophobic surface was first fabricated over the whole surface by laser treatment under water confinement and fluorosilane treatment; subsequently, superwicking stripes were processed by a second laser treatment in air and cyanosilane treatment. The resultant surface shows superwicking regions surrounded by superhydrophobic regions. During the process, superwicking regions possess dual-scale structures and polar nitrile surface chemistry. In contrast, random nanoscale structures and fluorocarbon chemistry are generated on the superhydrophobic region of the aluminum alloy 6061 substrates. The resultant superwicking region demonstrates self-propelling anti-gravity liquid transport for methanol and water. The combination of the capillary effect of the dual-scale surface microgrooves and the water affinitive nitrile group contributes toward the self-propelling movement of water and methanol at the superwicking region. The initial phase of wicking followed Washburn dynamics, whereas it entered a non-linear regime in the later phase. The wicking height and rate are regulated by microgroove geometry and spacing.

Due to the impact of fossil fuel use on the environment, renewable jet fuel has been pursued as an alternative fuel for aircraft engines. Several renewable jet fuels are developed with minimal carbon footprint and pollutants emission to replace petroleum jet fuels. To modify certain combustion behaviors such as combustion rate, ignition delay and total combustion time, colloidal suspension of carbon-based nanoparticles to liquid fuels has proven to be an effective mechanism. But the influence of carbon-based nanoparticles on the combustion behaviors of renewable jet fuels at different concentrations has not yet been investigated. Researchers have been exploring ways to modify the combustion performances of renewable jet fuel, and in this work, the addition of carbon-based nanoparticles (Graphene Nano Particles) is examined as a potential performance enhancing additive for fuel transport safety. The effects of Graphene Nano Particles (GNP) on the ignition and combustion characteristics of soy oil and canola oil based renewable jet fuel at different mass concentrations (1%, 2% & 3%) loading are investigated in this manuscript. The impact of different mass concentrations loading of GNP on the combustion behavior is analyzed by post-processing the high-speed images. It is observed that the ignition delay decreased by 8.52% and combustion rate decreased by 7.26% for renewable jet fuel at 3% GNP loading. GNP also caused a maximum decrease of total combustion time by 13.61% at 3% loading. It is expected that this study will drive further interest in fuel characteristics improvement of renewable jet fuel and will provide experimental data for future computational modeling.

This manuscript investigates an improvised gasification process for capturing and recycling rare earth metals (REMs) from consumer and industrial electronic wastes, often termed “e-waste”. The proposed procedure is based on the formation of coalesced and aggregated metal nodules on biochar surfaces through the gasification of e-waste mixed with gasifier feedstocks. A preliminary understanding of metal nodule formation based on different atmospheric conditions (inert, oxidizing, and oxidizing followed by reducing atmospheres) was examined in both pilot-scale gasifier and tube furnace experiments using iron powder mixed with corn. Iron powder is representative of the REM in the e-waste. Metal nodule sizes, morphology, and composition are analyzed and compared via scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), and X-ray fluorescence spectroscopy (XRF) techniques. We conclude that sintering is the key mechanism responsible for metal nodule growth through metal particle coalescence and aggregation by migration and diffusion of metal particles on biochar surfaces at elevated temperatures. Oxidizing atmosphere followed by a reducing atmosphere facilitates larger metal nodule growth compared to only an inert or oxidizing atmosphere. Additionally, the effect of adding NaCl salt is investigated on lowering the metal nodules’ surface energy and enhancing both metal particle and metal nodule agglomeration characteristics. Salt addition facilitates spherical metal nodule formation without any significant effect on the nodule composition and localized formation of nodules.

Highly photoluminescent gel-like carbon dots (G-CDs) have interesting applications in the fields of bio-sensing, thermofluids, and as photocatalysts to reduce water contaminants. G-CDs have been shown to be nontoxic and environmentally benign while exhibiting interesting characteristics as fluid additives. For additives like G-CDs to be effective, they need to stay suspended in the liquid medium. If they settle to the bottom, the positive benefits are lost, and the high-density lower region can experience adverse effects due to excessive particle loading. Many existing techniques are available to analyze suspension stability. However, most of these techniques are expensive and/or require specialized equipment. Moreover, these methods can be invasive and ultimately end up disturbing the suspension. Furthermore, these methods often focus on understanding the relation between colloidal stability and surface charge development through measuring the zeta potential, an indicator which is reported to be unsuitable while working with higher concentrations of nanomaterial in the colloidal suspension. To overcome the deficiencies of the traditional zetametry experiments, a novel, non-contact, non-invasive, quantitative, and economical experimental setup was deployed in this work to investigate the stability of G-CD nanofluids. The G-CD concentration is kept constant at 3wt%. Decane and small amount of water is used as dispersion media for the nanofluid in this study. Four different water concentrations of 1.5 wt%, 1 wt%, 0.75 wt% and 0.375 wt% are tested in this work. The results show the technique is both effective and inexpensive.

The emulsification of water with liquid fuels to modify combustion characteristics has been of great interest to the combustion research community for some time. The emulsions are usually comprised of only water combined via ultrasonification (or other mechanical methods) with a base hydrocarbon fuel. These emulsions show improved combustion characteristics, such as lower combustion temperatures, and lower emissions. One of the main issues with these emulsions, however, is that these emulsions are not stable and are prone to phase separation over time, which inhibit the economic viability and practical application of these fuels. There are a multitude of ways being researched to improve fluid stability, including new mixing techniques, the addition of nanoparticles, as well as the addition of other fluids. The addition of ethanol to water-based emulsions has been shown to decrease the size of water droplets in the emulsion, allowing for a more homogenous mixture. With the aviation industry being a sizeable source of the global emissions caused by transportation, methods of lowering the emissions of aviation fuels as well as greener alternatives are needed. Present research quantitatively studies how the addition of ethanol to water and jet fuel emulsions affects the stability of the emulsion. A non-invasive, quantitative, and economical method for determining phase separation is used to study the stability of these multi-component mixtures. The system periodically measures the phase separation of the fluid column by automatically shining light through the fluid and detecting how much interference is created by the fluid. The system does this at five different depths of the fluid so the phase separation of the emulsion can be tracked in more detail. Ethanol and water are studied at mixtures of 5%, 10%, 15%, and 20% ethanol by weight and 5% and 10% water by weight emulsified with jet fuel. It is expected that the present research will lay additional foundation for the future study of fuel emulsion stability, as well as spark additional interest in utilizing emulsions to improve fuels.