Photodegradation of organic contamination in wastewaters by bonding TiO2/single-walled carbon nanotube composites with enhanced photocatalytic activity

Bonding TiO2/single-walled carbon nanotube (SWCNT) composites have been successfully synthesized through a facile sol-solvothermal technique. The obtained materials were characterized in detail by XRD, FT-IR, Raman and TEM. The results revealed that TiO2 and SWNCT linked compactly through ester bonds and thus improved their interfaces. Therefore, the recombination of photogenerated electron-hole pairs was inhibited efficiently, which improved the photocatalytic activity. A reasonable mechanism was proposed to explain its formation. The photocatalytic activity was investigated utilizing rhodamine B and nitrobenzene (NB) as models for organic contamination in wastewaters. Experimental results indicated that this bonding composite exhibited higher photocatalytic activity than that of Degussa P25. The excellent photocatalytic activity could be attributed to larger surface area, smaller crystalline size, and especially the ester bonds, which was further confirmed by surface photovoltage spectroscopy. Furthermore, by adding OH scavenger tert-butanol, the obvious decrease of NB photodegradation indicated that NB was oxidized primarily by OH. The photodegradation products were identified by GC/MS, further indicating that the degradation proceeded via OH oxidation. A possible reaction pathway for the degradation of NB was suggested by the evidence presented in this study.