The effect of soil organic matters (SOMs) to the uniaxial compressive strength (q_u) of steel slag–dredged soil mixtures was evaluated by partial removing and altering SOM by heat treatment. The effect was also evaluated by dilution of SOMs using a volcanic ash soil. Two dredged soils formed soft mixtures, in which SOM was suspected to be inhibiting the q_u development. Within the studied cases, it was clarified that the dilution of SOMs by the volcanic ash did not improve the q_u, whereas partial removal and alteration of SOMs by heat treatment could improve it significantly. This study demonstrated that moderate heat treatment could modify the structural development of steel slag–dredged soil mixtures. In addition, q_u of the different SOM removal ratios showed that even a slight SOM removal could still increase q_u. From the comparison of the different heat treatments, it was further suggested that a specific type of SOM inhibited the q_u development of the mixtures. Raman microscopy and Emission Excitation Matrices analysis revealed heat treatment did not only remove SOMs but also decreased the aromatic structures and the molecular size of SOMs, which likely depicted the characteristics of SOMs inhibiting the q_u of the mixtures.

Photochemistry of molecules on the surface or in the interlayer space of clay nanosheets has attracted broad attention due to the unique microenvironments provided by the clay. Extensive research has been conducted on dye/clay hybrid systems, including unimolecular, bimolecular, and more complex photochemical reactions. This short review focuses on sequential photochemical reactions involving three types of molecules. The first part presents excitation energy transfer followed by photoinduced electron transfer between molecules assembled on clay nanosheets, facilitated by an organic cavitand to achieve a designed reaction sequence. Excitation of the energy donor resulted in energy transfer efficiencies of 67–73%, sequential electron transfer efficiencies of up to 81%, and less than 5% energy loss. The second part describes a photooxidation reaction mediated by singlet molecular oxygen, generated through energy transfer from a hybrid of cationic phthalocyanine and saponite nanosheets. The effect of phthalocyanine adsorption density on singlet oxygen generation efficiency and the underlying mechanism are also discussed.

Kaolinite, dickite, and pyrophyllite in the CSSJ reference clay samples were investigated using S/TEM, X-ray microanalysis via SEM-EDS and STEM-EDS, and XRD in order to characterize mineral impurities, grain sizes, crystal structures, and other physicochemical properties. The new lot of Kampaku kaolinite (JCSS-1101c) is nearly free of quartz and alunite, both of which were abundant in the previous lot (JCSS-1101b). Svanbergite (SrAl₃(PO₄)(SO₄)(OH)₆) was identified as a minor mineral impurity in both lots through STEM-EDS analysis. The characteristic 02,11 band reflections of well-ordered kaolinite (kaolinite-1A) are more distinct in the new lot, as evidenced by a higher Hinckley Index (1.17), indicating a greater proportion of large, well-crystallized kaolinite grains. Shokozan dickite (JCSS-1301) also contains svanbergite, along with quartz, diaspore, and pyrophyllite as mineral impurities. XRD analysis revealed the presence of kaolin group polymorphs, including significant amounts of nacrite and kaolinite in addition to dickite. S/TEM imaging indicated a bimodal grain-size distribution: smaller grains, with lateral dimensions less than 0.1 µm, likely represent a disordered kaolin phase, while the larger grains correspond to well-ordered dickite or nacrite, exhibiting a two-layer periodicity. Shokozan pyrophyllite (JCSS-2101) was found to contain quartz and diaspore as mineral impurities. HRTEM revealed pronounced stacking disorder, characterized by two alternative interlayer displacements. This structural disorder accounts well for the profile of the 02, 11 band in the XRD pattern.