Akane Miyazaki

Airborne microplastics (AMPs) on konara oak (Quercus serrata Murray) leaves collected at a small forest in the Tokyo metropolitan area were analyzed. The leaves underwent a three-step treatment process: (i) washing with Milli-Q water, (ii) sonication in Milli-Q water, and (iii) extraction with a 10% KOH solution. The average number of AMPs found in solutions (i), (ii), and (iii) were 0.01, 0.05, and 0.07 microplastics (MP) /cm² leaf, respectively. More than 50% of the total AMPs recovered from the aqueous samples were detected in the KOH solution. Scanning electron microscopy (SEM) observation revealed that the KOH solution significantly altered the leaf surfaces, while rinsing and ultrasonication with Milli-Q water had little effect. These results emphasize the strong adsorption of AMPs to epidermal waxes and the importance of using KOH solutions in addition to conventional water washing methods to prevent underestimation of AMPs intercepted by forest canopy leaves. Using data from the growing season, it was estimated that a small forest in the metropolitan area captures approximately 2.2 billion AMP particles per year. This indicates that forests may play an important role as sinks for AMPs in the terrestrial environment.

A multi-step ion-exchange methodology was developed for the fabrication of Cu(LaTa₂O₇)₂ lamellar architectures capable of wastewater depollution. The (001) diffraction line of RbLaTa₂O₇ depended on the guest species hosted by the starting material. SEM and TEM images confirmed the well-preserved lamellar structure for all intercalated layered perovskites. The UV–Vis, XPS, and photocurrent spectroscopies proved that Cu intercalation induces a red-shift band gap compared to the perovskite host. Moreover, the UV–Vis spectroscopy elucidated the copper ions environment in the Cu-modified layered perovskites. H₂-TPR results confirmed that Cu species located on the surface are reduced at a lower temperature while those from the interlayer occur at higher temperature ranges. The photocatalytic degradation of phenol under simulated solar irradiation was used as a model reaction to assess the performances of the studied catalysts. Increased photocatalytic activity was observed for Cu-modified layered perovskites compared to RbLaTa₂O₇ pristine. This behavior resulted from the efficient separation of photogenerated charge carriers and light absorption induced by copper spacer insertion.

Morphological development from nanowire to hexagonal platelet was observed for hydrolysis products of Cd(NO₃)₂ aqueous solution. ¹¹³Cd cross-polarization magic-angle spinning nuclear magnetic resonance spectroscopy and X-ray diffraction revealed that the morphological development corresponds to the change of coordination environment around Cd²⁺ from double salts containing nitrate ions to β-Cd(OH)₂.

The adsorption sites of active carbon were found to promote efficiently the catalytic reduction of concentrated HNO₃ by HCOOH at low temperature.