Gyosik Jun

With increasing amounts of oily water discharged from industrial and domestic sources, purifying oily emulsions using effective and eco-friendly methods is of great significance. Although functional membranes with selective wettabilities have been extensively explored for the efficient purification of oil-in-water emulsions, the development of functional membranes that use green and inexpensive materials, are simple to fabricate, and are easy to scale up remains very challenging. Herein, we report a simple approach that uses biomass to prepare a membrane for the purification of emulsions. A simple top-down approach was used to partially remove lignin and hemicellulose fractions in wood sheets, resulting in a highly porous and flexible wood membrane. The obtained wood membrane shows excellent water-absorbing and underwater anti-oil adhesion properties due to the removal of the hydrophobic lignin. The wood membrane is durable and stable, thereby maintaining its selective wettability in harsh environments. Selective wetting properties along with a porous structure enable the wood membrane to purify surfactant-stabilized oil-in-water emulsions. Such a biomass-derived membrane, which is green, inexpensive, easy to fabricate, and scalable, along with its selective wettability and durability, shows great potential for use as a substitute for existing filter media in diverse industries.

The use of high stiffness plastics to reduce the weight of mechanical systems has been implemented in various industrial fields. As a result, several studies to increase the adhesion strength of metal/polymer joints to improve the mechanical robustness of a system have been reported. In particular, as an alternative to existing adhesive bonding methods, research on the direct molding method has emerged. The direct molding method, which derives from the insert molding method, is based on the fabrication of microstructures on the metal surface to create mechanical interlocking. In this paper a new direct adhesion method is introduced that does not require additional heat management and instead makes use of an organic solvent. This new adhesion method was used to bond micro/nanostructured aluminum and acrylonitrile butadiene styrene (ABS) using chloroform. The bonding strength of the metal/polymer joints was tested by single-lap shear and T-peel tests. The shear strength of the Al-ABS systems showed a positive correlation with the height of the structures created on the Al roughened surfaces. The peel strength increased dramatically for the micro/nano hierarchical Al structures due to additional vertical shear interactions at the surface. Since this method does not require heat control, it improves the adhesion process efficiency, as well as increases the variety of adhesion designs.

In this study, we observed the Geyser phenomenon that occurs in a small-diameter two-phase closed thermosyphon (confinement number of 0.245). This phenomenon interferes with the natural circulation of the internal working fluid and increases the thermal resistance of the system. This study attempts to improve the thermal performance of the system using cellulose nanofiber as the working fluid and hydrophilic surface modification at the inner surface of the evaporator section. As a result, the total thermal resistance showed average reduction rates of 47.51%, 36.69%, and 22.56% at filling ratios of 0.25, 0.5, and 0.75, respectively.