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This paper aims to review and summarize the recent works on the photocatalytic degradation of various organic pollutants in the presence of nano-doped-TiO 2 photocatalysts. In this regard, three main aspects are examined: (a) the presence of various dopants (metal dopants, nonmetal dopants, halogen dopants, metalloid dopants, and codopants) in the formation of nano-doped-TiO 2 photocatalysts, (b) the effect of the presence of dopants on the photocatalytic degradation of organic pollutants, and (c) the effects of various operating parameters on the photocatalytic degradation of organic pollutants in the presence of nano-doped-TiO 2 photocatalysts. Reports resulted suggest that the formation of a high percentage of the anatase phase, small crystallite size, and high specific surface area of the nano-doped-TiO 2 photocatalysts depends on the presence of various dopants in the photocatalysts. The majority of the dopants have the potential to improve the photocatalytic efficiency of nano-doped-TiO 2 in the degradation of organic pollutants. The photocatalytic degradation of organic compounds depends on the calcination temperature of the prepared doped TiO 2 , initial reactant concentration, dosage of doped TiO 2 , and dopant doping concentration.

TiO2nanotubes immobilized on silica gel were used in the photocatalytic degradation of phenol in a batch reactor. The highest rate of photocatalytic activity was observed when the ratios of TiO2nanotubes: silica gel: colloidal silica were 3 : 2 : 20. The optimal air flow rate for phenol degradation was 0.3 L/min while pH 3 was optimal for the reaction medium. Decreasing the initial phenol concentration led to an increase in phenol degradation efficiency due to more hydroxyl radicals being presented on the catalyst surface. Immobilized TiO2nanotubes showed higher photocatalytic activity than that of the pure TiO2which only achieved 87% degradation. Compared with pure TiO2, the immobilized TiO2nanotubes benefited from a larger specific surface area and a low recombination rate of photogenerated electron-hole pairs. After three operating cycles, the decrease in photocatalytic activity of the immobilized TiO2nanotubes was slight, indicating that the immobilized TiO2nanotubes have excellent stability and reusability.

Fluorinated titanium dioxide (F‐TiO2) was synthesized by a simple sonication–hydrothermal method. The effects of dosage of fluoride dopants, hydrothermal durations, and sonication pretreatment were investigated in this paper. F‐TiO2 samples obtained in this manner were characterized by X‐ray diffraction, Brunauer–Emmett–Teller method, transmission electron microscopy, and energy dispersive X‐ray spectroscopy. The photocatalytic activities of F‐TiO2 were evaluated by the phenol degradation in a batch‐mode fluidized bed reactor under ultraviolet irradiation. The results showed that the prepared F‐TiO2 had good crystallinity and a high proportion in the anatase phase. The highest rate of photocatalytic activity was observed when the Ti : F molar ratio (RF) was RF = 0.15 and the hydrothermal duration was 10 h. F‐TiO2 showed better photocatalytic properties than that of pure TiO2. F‐TiO2 prepared by the sonication–hydrothermal treatment showed higher photocatalytic activity as compared with F‐TiO2 prepared similarly, but in the absence of sonication. © 2011 Curtin University of Technology and John Wiley & Sons, Ltd.