No abstract

For combining the properties of organoclays and pillared clays, inorganic-organic clays have attracted much attention in recent years. In this study, Al Keggin cation pillared montmorillonites (Al-Mts) were first prepared and parts of Al-Mts were calcined at different temperatures (C-Al-Mts). The inorganic-organic montmorillonites were synthesized by intercalating Al-Mts and C-Al-Mts with the cationic surfactant, hexadecyltrimethyl ammonium bromide (HDTMAB). The products were characterized by X-ray diffraction, X-ray fluorescence, and simultaneous thermogravimetric analysis. For HDTMAB-modified uncalcined Al Keggin cation pillared montmorillonites (H-Al-Mts), the basal spacing increased with the increment of surfactant loading level, but the Al content of H-Al-Mts decreased simultaneously, indicating that the intercalated surfactant replaced some Al Keggin cations in the interlayer space. However, in the case of C-Al-Mts, the interlayer spaces could not be further expanded after surfactant modification, implying that the neighboring montmorillonite layers were ''locked'' by the aluminum pillars which were formed by dehydroxylation of Al Keggin cation pillars during thermal treatment. The thermal stability of HDTMAB-modified C-Al-Mts (H-C-Al-Mts) was much better than that of H-AlMts. The major mass loss of H-C-Al-Mts occurred at ca. 410°C, corresponding to decomposition of intercalated surfactant cations. In contrast, H-Al-Mts displayed two mass loss temperatures at ca. 270 and 410°C, corresponding to the evaporation of surfactant molecules and the decomposition of surfactant cations in the interlayer space, respectively.

Silver vanadate nanoribbons were synthesized via a hydrothermal process, which exhibited surface-enhanced Raman scattering effect. This surface-enhanced substrate was stable and reproducible for identifying human serum transferrin and human serum apotransferrin in the concentration of 1×10−5 M, which further exhibited significant sensitivity in monitoring the conversion of these two proteins in turn. This result showed that the silver vanadate nanoribbon might be employed as biomonitor in such systems.

No abstract

No abstract