The methylene-blue adsorption-test, which measures the amount of methylene-blue adsorbed on minerals in bentonite, is one of the most important methods to estimate a quality of the bentonite. This test is conducted by mining companies of bentonite, general construction companies and foundries. The detail procedures of the test, however, vary among different companies, which results in different adsorption values even if the sample is the same. Therefore, some companies request the standard procedures of the test. This paper reports the difference in procedures conducted in companies in Japan, which is helpful to make the standard procedures of the test. We have gathered the information on the procedures of the test in 13 companies in Japan. Among the 13 companies, 10 companies are conducting the spot method, 4 companies conducting the colorimetric method, and one company conducting both methods. The spot method conducted in the 10 companies is based on JBAS-107-91 established by Japan Bentonite Manufacturers Association Standard (JBAS) in the 1970s. However, some of the procedures are different among the companies. The difference are found in the temperature and time for drying bentonite samples, the preparation method of methylene blue solution, the amount of the samples, the method of dispersion of bentonite in solution, the first additive amount of methylene blue solution, the method of stirring, the kind of filter paper, the kind of instrument for making spots on a filter paper, and the size of halo at the end point. The difference in the procedures are attributed to ambiguous description of the procedures in the JBAS-107-91 and to the presence of other descriptions on spot methods (JBAS-107-77, TJFS-205 and TIKS-415), which are similar to but different from the JBAS-107-91. Among the 4 companies conducting the colorimetric method, 3 companies were conducting the colorimetric method after conducting the spot method. The colorimetric method can determine the adsorbed amount of methylene blue without making the difficult decision of the end point in the spot method. Therefore, the colorimetric method can produce the precise result, and is a promising candidate for a standard method. We have asked 5 companies to measure the adsorbed amounts of methylene blue of two bentonite samples, JCSS-3102 Montmorillonite (Mikawa) provided by the Clay Science Society of Japan (JCSS) and Kunigel-V1 provided by Kunimine Industries Co., Ltd.. The adsorbed amounts of methylene blue by 3 companies were about 10 mmol/100g larger than the value by other 2 companies. The difference is attributed to the difference in procedures among the companies, which confirms that we need to standardize the procedures of the spot method.

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The Research Group of Photofunctional Systems on Clay Minerals, the Clay Science Society of Japan was established in April 2011, and continued its activity to March 2014. The research group held a special session in the 55th Annual Meeting of the Clay Science Society of Japan, and published a special issue in Clay Science.

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Recent studies on the crystal growth of inorganic layered solids and zeolites on solid surfaces are reviewed. The growth has been conduced through contact of solids (e.g. silica and alumina) with aqueous solutions dissolving starting chemicals of the crystals, followed by a heat-treatment of the mixtures. The fine crystals of layered silicates, layered titanosilicates, and silicalite-1 have grown on silica substrates, and Mg/Al, Ni/Al, Zn/Al-LDHs crystals have been formed on the aluminas. These crystals have been firmly immobilized on the solids without any pretreatment including surface modifications.

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High-density intercalation of cationic free base porphyrin into interlayer space of synthetic saponite and the photochemical behavior of intercalated porphyrin were investigated. Porphyrin molecules were successfully intercalated into the interlayer space of saponite densely without an aggregation. It is turned out that intercalated porphyrin keeps the photo-activity by fluorescence quantum yields measurement. In addition, photo-functionality of the intercalated magnesium porphyrin was demonstrated, and it exhibited the reversible chromism depending on relative humidity

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Smectite-type clay minerals have been investigated as heterogeneous media of photochemical reactions for more than 30 years. In such studies, recognition of the clay structures has been limited to nanoscopic scales, which has yield various precise molecular-level organization of the reaction species by using the clay surfaces and interlayer spaces. However, macroscopic structures based on interparticle interactions between the clay particles can also contribute to the intermolecular reactions on the clay surfaces. This short review describes our recent studies of photoinduced electron transfer from ruthenium-bipyridine complex to methylviologen controlled by the aggregation of clay particles. Although the reaction is suppressed by seggregative adsorption of the reaction species onto the clay surfaces, it becomes allowed if enough small clay particles are aggregated in disordered manners.

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Diacetylene derivatives, 1-methyl-4-[biphenyl-4-(1,3butadiyn4-yl)] pyridinium triflate (monoBBP) and 4,4'-[biphenyl-4,4'-bis(1,3-butadiyn-4-yl)]bis(1-methylpyridinium) ditriflate (bisBBP) were synthesized. We fabricated composites consisting of the diacetylene derivatives and synthetic saponite. The two-photon absorption (TPA) characteristics of the diacetylene derivatives confined in the interlayer space of synthetic saponite were compared to those in dimethylsulfoxide (DMSO). The maximum values of TPA cross-section of monoBBP and bisBBP confined in the interlayer space of synthetic saponite were 7.3 and 13.5 times larger than that in DMSO, respectively.

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