TiO2 nanoparticles and nanofibres from TiCl4 flocculated sludge: Characterisation and photocatalytic activity

In this study, dye and secondary effluent wastewaters were used to generate a non-hazardous sludge. Anatase TiO2 nanoparticles have been successfully synthesised from the calcination of the TiCl4 flocculated sludge. A conventional hydrothermal method was adopted to produce anatase nanofibres (calcined at 600 °C) from TiO2 nanoparticles. X-ray diffraction, scanning electron microscopy and transmission electron microscopy investigations showed the highly crystalline nanoparticles and nanofibres after calcination. The size of nanofibres was related to the size of their nanoparticles precursors. Nanoparticles had larger surface area than nanofibres, lower pore volume and bigger pore diameter. Energy dispersive X-ray analysis revealed that impurities can be successfully removed by a subsequent hydrothermal/acid wash of nanoparticles. Nanoparticles had better overall photocatalytic activity for the degradation of organics in synthetic wastewater compared to nanofibres. On the other hand, nanofibres had a better adsorption capacity.