Seul-Yi Lee

Surface treatment is crucial for enhancing the performance of carbon fibers (CFs) within a matrix, necessitating a detailed examination of varying treatment effects on surface energetics. In this study, high-strength CFs (Toray T-300, 3 K fibers) underwent electrochemical treatment in a sodium hydroxide solution, applying increasing current densities to modify surface properties. The surface properties, including surface free energy and acid–base characteristics, were analyzed using inverse gas chromatography at infinite dilution. The results showed that weak acidic probes, such as carbon tetrachloride or chloroform, are ineffective for accurate assessment of acid–base properties of solid surfaces. Experimental data showed that all CF surfaces exhibited amphoteric behavior, with increased basicity under the experimental conditions. Increased current intensity of the electrochemical treatment from 90 to 300 mA enhanced surface acidity and basicity; however, no significant changes were observed beyond 300 mA. This suggested that a moderate treatment at 90 mA is optimal for achieving the desired acid–base properties, improving the integration of CFs into polar organic matrices and potentially enhancing efficient fiber-resin bonding.

Biochar, a carbon‐rich material produced from the partial combustion of biomass wastes is often termed “black gold” for its potential in water pollution mitigation and carbon sequestration. By customizing biomass feedstock and optimizing preparation strategies, biochar can be engineered with specific physicochemical properties to enhance its effectiveness in removing contaminants from wastewater. Recent studies demonstrate that biochar can achieve > 90% removal efficiency for heavy metals such as lead and cadmium, > 85% adsorption capacity for organic pollutants such as dyes and phenols, and > 80% reduction in microplastics and nanoplastics. This review explores recent advancements in biochar preparation technologies, such as pyrolysis, carbonization, gasification, torrefaction, and rectification, along with physical, chemical, and biological modifications that are crucial for efficient pollutant removal. The core of this review focuses on biochar's applications in removing a wide range of pollutants from wastewater, detailing mechanisms for organic pollutants, inorganic salts, pharmaceutical contaminants, microplastics, nanoplastics, and volatile organic compounds. In addition, the review introduces machine learning as a key technique for optimizing biochar production and functionality, showcasing its potential in advancing biochar technology. The conclusion provides a comprehensive outlook on biochar's future, emphasizing ongoing research and its role in sustainable environmental management.

Epoxy-based nanocomposites can be ideal electromagnetic interference (EMI)-shielding materials owing to their lightness, chemical inertness, and mechanical durability. However, poor conductivity and brittleness of the epoxy resin are challenges for fast-growing portable and flexible EMI-shielding applications, such as smart wristband, medical cloth, aerospace, and military equipment. In this study, we explored hybrid nanofillers of single-walled carbon nanotubes (SWCNT)/reduced graphene oxide (rGO) as conductive inks and polyester fabrics (PFs) as a substrate for flexible EMI-shielding composites. The highest electrical conductivity and fracture toughness of the SWCNT/rGO/PF/epoxy composites were 30.2 S m⁻¹ and 38.5 MPa m^1/2, which are ~ 270 and 65% enhancement over those of the composites without SWCNTs, respectively. Excellent mechanical durability was demonstrated by stable electrical conductivity retention during 1000 cycles of bending test. An EMI-shielding effectiveness of ~ 41 dB in the X-band frequency of 8.2–12.4 GHz with a thickness of 0.6 mm was obtained with an EM absorption-dominant behavior over a 0.7 absorption coefficient. These results are attributed to the hierarchical architecture of the macroscale PF skeleton and nanoscale SWCNT/rGO networks, leading to superior EMI-shielding performance. We believe that this approach provides highly flexible and robust EMI-shielding composites for next-generation wearable electronic devices.