A qualitative chemical analysis of three reference clay minerals, Mikawa montmorillonite, synthetic saponite and Nabeyama illite, was performed using a recently developed TEM-EDS set-up built around a microcalorimeter device that has a very high energy resolution. The spectrum obtained by the microcalorimeter EDS showed the small peaks of minor elements present in these clay minerals. It was also used to detect the SKβ peak in saponite and the SiKβ' peak in montmorillonite and saponite whereas by conventional Si(Li) EDS, these peaks disappeared or overlapped. Microcalorimeter EDS with TEM provided us with valuable elemental data of clay minerals in this study, and will considerably contribute to the progress of the study of clay minerals.

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Microbes can significantly influence the precipitation processes of calcium carbonate (CaCO_3) minerals by changing the chemical state of the habitats and by interaction of extracellular polymeric substances with mineral surfaces. To evaluate the effects of bacteria on the precipitation rates and polymorphism, we performed precipitation experiments using 100ml batch systems containing the gram-negative bacterium Pseudomonas fluorescens at 25℃ for 10 days. Two types of reaction systems (i.e., with or without Mg^<2+> ions) were prepared: (1) C system; 5.0mM Ca^<2+>, 20mM HCO_3^-, and P. fluorescens (0, 10^5, 10^6, 10^7, 10^8, or 10^9cells/ml), and (2) CM system; 5.0mM Ca^<2+>, 5.0mM Mg^<2+>, 20mM HCO_3^-, and P. fluorescens (0, 10^5, 10^6, 10^7, 10^8, or 10^9cells/ml). Throughout the reaction period, solution pH, concentrations of Ca^<2+>, Mg^<2+>, and HCO_3^- ions, and dissolved proteins and polysaccharides released from P. fluorescens cells were measured daily. The results indicated that P. fluorescens significantly inhibited the precipitation of CaCO_3 minerals, and the precipitation rates in the C and CM systems decreased with increasing bacterial concentrations with the inhibition factors of 0.18 and 0.28, respectively. Furthermore, P. fluorescens inhibited the formation of aragonite and favored calcite formation as the dominant polymorph despite the presence of Mg^<2+> ions in the CM system. These effects of P. fluorescens on the formation processes of CaCO_3 minerals could likely be attributed to the interaction of dissolved extracellular polymeric substances such as proteins, polysaccharide, and DNA with the surface of CaCO_3 minerals. The ability of these substances to interact and possible interaction mechanisms were discussed.

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A hydrotalcite was subjected to mechanochemical treatment using a vibration mill. The treated samples were characterized using x-ray diffraction (XRD) measurement and thermal analysis. Unlike other clay minerals, the crystal of mechanochemical treated hydrotalcite was reduced parallel to the layer and perpendicular to the layer. The thermal analysis revealed the increasing of surface adsorbed water on the treated samples, which shows the surface areas of the samples were increased. The treated samples show drastic improvement of fluoride adsorption capacity.

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Dioctylviologen (1,1'-dioctyl-4,4'-bipyridinium) modified smectites (Kunipia F and Sumecton SA) were prepared by cation exchange reactions and used as adsorbents of 4-nonylphenol from aqueous solution. Quantitative cation exchanges between smectites and dioctylviologen dibromide were confirmed by the thermal, elemental and XRD analyses. The dioctylviologen-smectites adsorbed 4-nonylphenol from aqueous solution. The adsorbed amount of 4-nonylphenol varied, depending on the nature of smectites, when the adsorption was conducted from lower concentration (less than 0.5ppm) solutions. The adsorption isotherm on dioctylviologen exchanged Sumecton SA was fitted to Langmuir model, while the adsorption on the Kunipia F intercalate is less effective from the low concentration solutions. With increasing the amount of the adsorbed 4-nonylphenol, the basal spacings of the adsorbents decreased, suggesting that the adsorption of 4-nonylphenol was displacement of the intercalated water in the dioctylviologen intercalates.

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Layered double hydroxide (LDH) is widely known as anionic clay and has an anion exchange property. The cellular uptake of LDH has received considerable attention in recent years in view of their potential technological importance as materials for drug delivery due to low cytotoxicity, good biocompatibility and controlled release of drug. To investigate the cellular uptake behaviour of LDH, the stable and labeled highly fluorescent might be required. In this paper, we focused on fluorescein disodium salt (Fluo), as a guest in fluorescence dye, the intercalation of Fluo into Mg-Al LDH by coprecipitation method has been investigated. To define the abilities of LDH as materials for drug delivery, the cellular uptake of the Fluo/LDH for the mammalian cells, L929 and HeLa, has also been studied. The characterization of the Fluo/LDH was carried out by using XRD, FT-IR and element chemical analysis. The Fluo/LDH had a layered structure, which the two kinds of basal spacing (003) was 1.58nm and 0.77nm. These values indicated that the interlayer place of Fluo anion changed for horizontal orientation to vertical orientation with increasing Fluo content. According to the fluorescence, confocal and TEM images of cells, the fluorescence of cellular cytoplasm and the internalized Fluo/LDH particles were observed. We demonstrated that the Fluo/LDH was internalized into the mammalian cells by the cellular endocytosis.

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To develop a novel remediation for Cu- and Zn-bearing wastewater, the natural attenuation process in Dougamaru abandoned mine at Shimane Prefecture, Japan was investigated. In the Dougamaru abandoned mine, Cu- and Zn-bearing mine drainage was naturally attenuated by formation of green precipitate composed of Cu-bearing layered double hydroxide (LDH), hydrowoodwardite (HW) with chemical formula such as Cu_<0.66>Zn_<0.09>Fe_<0.01>Al_<0.23>(OH)_2(SO_4)_<0.15>・mH_2O. This attenuation was achieved at pH 6.0 with aeration and bacterial respiration and without any neutralization process attributed to the mixing with spring or surface water. The formation of the HW at pH 6 is also confirmed by thermodynamic consideration in this study. The formation process of the HW at the Dougamaru abandoned mine teaches us a novel technology for remediation system with addition of Al ion to wastewater and without employing any extensive chemical treatment processes. From the experiment to check applicability of Cu- and Zn-bearing LDHs to wastewater treatment, HW (Cu-bearing LDH) and zincowoodwardite (ZW; Zn-bearing LDH) were obtained by addition of Al ion to the Cu- and Zn-bearing wastewater from lower pH condition. The improvement of removal efficiency by adding Al ion in Cu-bearing wastewater system was not so clear in the experiment because Cu ion is removed from the synthetic wastewater due to Cu-hydroxyl sulfate precipitation at the experimental condition. On the other hand, the removal efficiencies of Zn ion showed the range from 0 to 30% even at pH 6.0 and improved with increasing initial Al ion content. The experimental results in Zn-bearing wastewater system indicate that the safety remediation of Zn ion can be achieved even at lower pH than 6.0-7.0 by selection of the ZW as a candidate of the solubility-limiting solid phase. Moreover, because of high anion exchange capacity of LDH, the method with addition of Al ion source for the wastewater treatment may also be useful for the treatment of wastewater containing Cu and Zn ions and simultaneously with As, Se, and Sb anions, which shows good performance in terms of anion remediation.

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