In a previous study published in Chemical Engineering Research and Design (Ota et al., 2018), a theoretical model for predicting the solubility of solid solutes in supercritical carbon dioxide was proposed. In this work, the model was extended to predict the solubility of organically modified inorganic nanoparticles (HNPs) in organic solvents at atmospheric pressure. The results showed that the solubility of decanoic-acid-modified ceria particles (C10CeO₂) were successfully predicted using the reduced critical properties of the pure solvent.

In this study, polyurea microcapsules immobilizing aluminum nitrate were prepared and characterized with the aim of applying them as materials that impart self-healing functionality to anticorrosion coatings. During the corrosion process of metals, anodes and cathodes are generated, causing localized pH changes on the surface of the metal substrate. Therefore, the sustained-release behavior of aluminum nitrate in response to environmental pH changes was evaluated. Examination of the theoretical loading of aluminum nitrate revealed that a theoretical loading of 2.36% resulted in the highest encapsulation efficiency. Furthermore, the prepared microcapsules exhibited different sustained-release behaviors of aluminum nitrate depending on changes in environmental pH.

In this study, a microporous carbon electrode with polyvinyl alcohol (PVA), a hydrophilic binder, was prepared as enzyme immobilization electrodes of biofuel cells. Furthermore, the effect of PVA content on the electrode structure and its performance was evaluated based on electrochemical measurements. According to the analysis of particle-size distribution, the PVA content in the electrode slurry is preferably set more than 10 wt% to improve the dispersibility of carbon particles. The authors investigated the impregnation of electrolytic solution and the reaction characteristics of the microporous carbon electrode using cyclic voltammetry. It was found that an increase in PVA content induces its coverage on the electrode surface, resulting in inhibiting the reactant supply to reaction sites. When used as enzyme-immobilized electrode of lactate biofuel cells, the addition of 15 wt% PVA derives the optimum electrode performance.

Phosphorus is an essential nutrient for plant growth, and Japan’s agriculture relies entirely on imports for its supply. Then the security of domestic phosphorus resource becomes the critical issue. This study aimed to recover phosphorus efficiently from sewage sludge ash, and to develop liquid fertilizer by the recovered phosphorus for cultivating plants. By employing two-step elution process that combines acid and alkali leaching methods, high phosphorus recovery efficiency was achieved while effectively removing heavy metals. The final precipitate obtained was primarily composed of high-purity hydroxyapatite, which was suitable for use as a fertilizer component. Furthermore, hydroponic cultivation experiments using the produced liquid fertilizer demonstrated growth-promoting effects on Komatsuna (Brassica rapa var. perviridis) comparable to those of commercial fertilizers. This technology is expected to contribute to the sustainable utilization of phosphorus resources in Japan and provide solutions to waste management issues, offering potential applications in the future.