Diatomite has different properties depending on the origin of the deposit and the collection site. In order to obtain a material suitable for silica supply, modification of diatomite using acid leaching after thermal treatment was investigated. Four types of diatomite, white and gray from deposits of marine origin in Takanosu, and white and yellow from lacustrine deposits in Shonai, were used. The samples were calcined at 300-1100℃ for 24h, and then stirred in 5M HCl solution at 80℃ for 1h. There are not notable changes of amorphous phase in diatomite at 300-900℃, while amorphous silica was transformed into cristobalite, which was low solubility in basic solution, after calcining at 1100℃. The removal of Al via acid leaching was the highest at 500-700℃, while those of Fe, Mg and Ca were almost constant at 300-900℃. The removal of Al from lacustrine diatomite was higher than that from marine one. Diatomites via acid leaching after calcination at 700℃ contains higher Si and lower impurities than raw diatomite, and have the almost same solubility of silica into alkali solution.

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The adsorption from water of two model aromatic hydrocarbons, benzene and toluene, by talc has been investigated. Complete adsorption was achieved within five hours of mixing the reactants. Both benzene and toluene gave linear isotherms. The slope of the isotherm for toluene was steeper than that for benzene, indicating that toluene had a greater affinity for talc. The adsorption capacity of talc for benzene and toluene was similar to that of tetramethylphosphonium (TMP)- and tetramethylammonium (TMA)-montmorillonite. However, more benzene and toluene were adsorbed by talc than by a mesoporous silica (FSM-16).

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A unique ecosystem composed of liverworts, diatoms, bacteria and argillaceous sediments is able to thrive in spite of acidic, sulfur and heavy metal contaminated water below the abandoned Ogoya Copper Mine in Ishikawa, Japan. Sample analyses by optical microscope, ED-XRF, XRD, SEM, TEM and FE-TEM revealed that Fe and Cu were taken up by benthic organisms and sediments. Metal uptake and precipitation, including adsorption by clay minerals, improves the water quality for surrounding organisms. Liverworts shelter diatoms and bacteria, also trapping sediments and precipitates that would otherwise be washed away. Meanwhile bacteria are involved in metal accumulation and converting toxic aqueous metals to minerals. Liverworts displayed Cu and occasionally Fe and Zn content. Clay sediments were enriched in Fe and sometimes S, with traces of Ti, Mn, Cu, Zn, and occasionally As, Br, Sr and Zr. Based on XRD analyses, chlorite, mica minerals, feldspar, quartz and chloritoid were predominant in the <2μm fraction of the river sediments, along with traces of the sulfate minerals melanterite, chalcanthite and despujolsite. Mine drainage has compromised the health of surrounding communities and damaged river ecosystems. Clarification and optimization of natural metal uptake processes and the fate of mine-related elements could hold keys to sustainable remediation methods for use in the Ogoya mine area.

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The dynamics of rhodamine B (RB) in D_2O solutions was examined in the absence and presence of a smectite clay mineral, synthetic sodium-saponite (SSA), by ^1H nuclear magnetic resonance (NMR) spectroscopy. Hybridization of RB with the exfoliated SSA particles significantly decreased the intensity of NMR resonance signals of RB protons with the linewidth broadening, compared to RB alone. This indicated that the dynamics of RB molecules adsorbed onto the surface of SSA clay particles was very slower than in free state. The photodegradation profiles of RB in the presence of SSA clay particles were also monitored by ^1H NMR spectroscopy. After visible light irradiation, nine new resonance signals resulting from reaction products were detected in the ^1H NMR spectrum. The analysis of two-dimensional ^1H-^1H COSY and TOCSY spectra of the reaction mixture indicated that the ethyl group(s) of RB molecule adsorbed onto the surface of SSA particles was destroyed in the photodegradation process and that not only N-ethylamine (and/or N,N-diethylamine) as a major product but also other chemical species such as acetoaldehyde, acetic acid and formic acid were also produced. The detection of the minor products by NMR indicated the photodegradation of RB dye under the present experimental conditions involves oxidative reaction processes in which RB itself and/or the N-de-ethylation products react with the dissolved oxygen to produce the minor chemical species.

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The intercalation behavior of various saturated and unsaturated fatty acids into layered double hydroxide (LDH) was investigated by the reconstruction method using Mg-Al-LDH with Mg/Al=3. The fatty acids used were both saturated (butyric acid (number of carbons, NC=4), capric acid, NC=10, lauric acid, NC=12, palmitic acid, NC=16 and stearic acid, NC=18) and unsaturated acids (crotonic acid, NC=4, decenoic acid, NC=10 and oleic acid, NC=18). Intercalation of these fatty acid anions into LDH was confirmed by a shift of the basal reflection at about 2θ=12° toward lower angles, except for crotonic acid. Intercalation became more difficult with fatty acids of smaller NC. At concentrations >1mM the d-spacings of the basal reflections of the saturated fatty acid intercalated samples increased with increasing NC of the fatty acids, from 3.20nm in capric acid to 5.17nm in stearic acid. By contrast, the d-spacings of the unsaturated fatty acid intercalated samples showed no clear trend with the NC values, but were sensitive to the fatty acid concentration, i.e. from 3.55 to 4.85nm in decenoic acid samples and from 3.85 to 4.80nm in oleic acid. The changes in the d-spacings suggest that the fatty acid anions are intercalated as double layers, and then as micelles at higher fatty acid concentrations. The difference in the d-spacing changes between the saturated and unsaturated fatty acids is considered to be resulted from differences in the molecular shape, i.e. the straight configuration of saturated fatty acids compared with the bent configuration of unsaturated fatty acids.

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