Fabrication of large-diameter tube-like mesoporous TiO2 via homogeneous precipitation and photocatalytic decomposition of papermaking wastewater

• Large-diameter tube-like mesoporous TiO2 was synthesized using CTAB and urea.
• A possible mechanism for the formation of tube-like mesoporous TiO2 was proposed.
• Tube-like TiO2 was suitable for photodegradation of papermaking wastewater.
• Tube-like TiO2 showed much higher photocatalytic activities than Degussa P25.

Large-diameter tube-like mesoporous TiO2 nanotubes were synthesized via homogeneous precipitation from aqueous solutions containing titanium oxysulfate (TiOSO4) using urea. The cationic surfactant cetyltrimethylammonium bromide was used as a structure-directing agent. Prepared samples were characterized by X-ray diffraction, transmission electron microscopy (TEM), field emission scanning electron microscopy, energy-dispersive X-ray spectroscopy, and N2 adsorption–desorption isotherms. Experimental results indicated that the samples exhibit tube-like structures with lengths of approximately 6 μm to 8 μm, large tube diameters of approximately 500 nm to 600 nm, and a wall thickness of approximately 450 nm. TEM images and N2 adsorption–desorption isotherms showed that the tube walls of the samples have a uniform mesoporous structure. A possible mechanism for the formation of tube-like mesoporous TiO2 was proposed. The photocatalytic activities of the large-diameter tube-like mesoporous TiO2 were assessed via the photocatalytic decomposition of papermaking wastewater under ultraviolet light irradiation. The effects of different parameters such as UV light irradiation, catalyst dosage and solution pH on photocatalytic activities of tube-like mesoporous TiO2 were studied. The as-synthesized tube-like TiO2 showed higher photocatalytic activities than Degussa P25. MTS3 exhibited the highest photocatalytic activity. The chemical oxygen demand and chroma percent degradations of papermaking wastewater were approximately 73.0% and 99.5%, respectively, at MTS3 dosage of 1.0 g/L and pH value of 3.0 after 12 h of photodegradation.

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