Removal of some types of polyphenols and aromatic amines in textile industry wastewaters by nanocerium-dioxide-doped titanium dioxide

The interfacial and surface structures of CeO2-doped TiO2 prepared under laboratory conditions have been investigated in detail by means of X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET) surface area measurement, a high-resolution transmission electron microscope, X-ray photoelectron spectroscopy (XPS) and energy-dispersive spectroscopy (EDS). TiO2 and CeO2 are in the anatase phase and the cubic-fluorite phase in CeO2-TiO2 mixed oxides, respectively. The mixed CeO2-TiO2 nanocomposite exhibits much higher surface areas than the individual oxides. Field-emission scanning electron microscope analysis showed that TiO2 exhibited aggregated spherical particles while a flake-like shape was observed for CeO2. The peak locations and relative intensities in XRD showed cubic-fluorite crystalline structure for CeO2. BET analysis results showed that the maximum surface area and pore volume were obtained at a CeO2 ratio of 15 mg/L CeO2-doped TiO2 nanocomposite. The energy dispersive spectrum of the CeO2-doped TiO2 nanocomposite showed that only Ti, Ce and O elements are detected in the CeO2-doped TiO2 nanocomposite and Ce is mixed with TiO2. Maximum color, polyphenols (quercetin, fisetin, ellagic acid, carminic acid, luteolin and curcumin) and polyaromatics (2,6-dimethylaniline, 2-aminoanisole, 2,4-toluenediamine, 4,40-thiobisbenzenamine and 3,3-dichlorobenzidine) removal efficiencies were observed between 97% and 99% in a textile industry wastewater (TI ww) treatment plant located in Izmir, Turkey, during photodegradation experiments, under 130 W UV light, at 15% CeO2 containing 15 mg/L CeO2-doped TiO2 nanocomposite, at 21 degrees C, after 30 min irradiation time. The results show that the CeO2/TiO2 nanocomposite produced has a high photocatalytic activity to remove pollutants from TI ww.