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The photocatalyst sorbic acid (SA)/titanium dioxide (TiO 2) was successfully synthesized by sol-gel method and characterized. The composite exhibited regularly spherical particles with the size of 50 nm and the specific surface area of 90.3 m 2 g −1 , furthermore, it showed mesoporous structure and significantly improved dispersion. SA was grafted on TiO 2 surface by-COOTi and TiO 2 existed as pure anatase phase in the composite. The addition of SA made the band gap of TiO 2 increased from 3.03 to 3.35 eV, which indicting that the composite exhibited a strong response to the ultraviolet light. The optimum preparation parameters of the catalyst were as follows: n(Ti):n(SA) = 1:0.05, ethanol 60 mL, glacial acetic acid 40 mL, hydrothermal temperature 180 °C, hydrothermal time 12 h. The composite could reach the 4.31 log reduction of E. coli, with the optimum catalyst dosage of 0.7 g L −1 , irradiated by UV light for 60 min. SA/TiO 2 was an environmentally friendly, non-toxic and safe sterilized nanocomposite material appropriate for future bactericidal applications, providing a new way to effectively increase the dispersion of TiO 2 particles to achieve superior photocatalytic sterilization efficiency.

Dipropylheterocoerdianthrone (DPHCD) was found to be a potential photo-reactive dispersant of single-walled carbon nanotubes (SWNTs). DPHCD was able to well disperse SWNTs in chloroform. DPHCD is easily photo-oxidized by the irradiation of visible light to form the endoperoxide with a bent structure under oxygen or air atmosphere. Then, SWNTs were photo-precipitated from the DPHCD/SWNTs dispersion. The precipitation was able to disperse again after the photochromic reaction to turn back DPHCD from the endoperoxide and sonication. Such photo-induced precipitation was also observed in DPHCD/SWNTs complex film. The SWNTs precipitates were analyzed by FT-IR and Raman spectra measurements, and discussed about selectivity of DPHCD on chirality, and elimination of the dispersant.