Baohong Guan

The fabrication and characterization of novel carbon doped TiO2 nanotubes, nanowires and nanorods with high visible light photocatalytic activity

Novel carbon doped TiO(2) nanotubes, nanowires and nanorods were fabricated by utilizing the nanoconfinement of hollow titanate nanotubes (TNTs). The fabrication process included adsorption of ethanol molecules in the inner space of TNTs and thermal treatment of the complex in inert N(2) atmosphere. The structural morphology of carbon doped TiO(2) nanostructures can be tuned using the calcination temperature. X-ray diffraction, Raman and Brunauer-Emmett-Teller studies proved that the doped carbon promoted the crystallization and phase transition by acting as nucleation seeds. X-ray photoelectron spectroscopy (XPS) showed that O-Ti-C and Ti-O-C bonds were formed in the nanostructures. Additional electronic states from the XPS valence band due to carbon doping were observed. This evidence indicated the electronic origin of the band gap narrowing and visible light absorption. The differences in chemical and electronic states between the surface and bulk of as-prepared samples confirmed that carbon was doped into the lattice of TiO(2) nanostructure through an inner doping process. The as-prepared catalysts exhibited enhanced photocatalytic activity for degradation of toluene in gas phase under both visible and simulated solar light irradiation compared with that of commercial Degussa P25. This novel fabrication approach can valuably contribute to designing nanostructured photocatalytic materials and modifying various nanotube materials.

Adsorption of nitrobenzene from aqueous solution on activated sludge modified by cetyltrimethylammonium bromide.

A novel method was conducted to modify activated sludge with cetyltrimethylammonium bromide (CB) to obtain an adsorbent to remove aqueous nitrobenzene. The adsorption characteristics of nitrobenzene onto modified activated sludge (MAS) were investigated, by contrast with those of unmodified activated sludge (UMAS). Nitrobenzene adsorption onto MAS is more favorable than that of UMAS at initial nitrobenzene concentrations below 150 mg/L, above which they have an equivalent adsorption capacity. pH value has a significant influence on the adsorption capacity, especially from 10.0 to 12.6 for MAS and from 9.0 to 11.0 for UMAS. The modification changes the steady even surface of activated sludge into uneven one, which is better for adsorption. The hydroxyl of activated sludge and hydrophobic group of CB adsorb nitrobenzene molecules, and CB increases the adsorption sites. The nitrobenzene adsorption onto MAS follows Langmuir isotherm, implying the adsorption occurrence tends to be on a homogeneous surface by monolayer adsorption other than multi-layer adsorption which accounts for the adsorption onto UMAS. The maximum adsorption capacity of MAS is 40.6, 25.0 and 25.6 mg/g at 6.0, 25.0 and 40.0°C, respectively. MAS presents to be a good adsorbent to remove nitrobenzene from water, and CB is a successful modifier.