Abstract:
In the present work, different types of photocatalysts in single, binary, and ternary systems with different molar ratios were prepared. TiO2 was synthesized by sol-gel method from the (Ti (OBut)4); g-C3N4 was synthesized by pyrolysis of urea; g-C3N4/TiO2 was synthesized by facile sonication method; CeO2/TiO2 was synthesized by precipitation method; ternary nanocomposities were synthesized by liquid assisted solid state reactions by varying the amount of g-C3N4. Polyaniline supported g-C3N4/TiO2/CeO2 nanocomposite was also synthesized by “in situ” oxidative polymerization method. Crystal structure, band gap energy, functional groups and optical properties of the assynthesized photocatalysts were characterized by using XRD, UV/Vis, FTIR and PL instruments, respectively. Photocatalytic activities of single, binary, bare and supported ternary nanocomposite were evaluated by using aqueous solution of model pollutant methyl blue dye (MB) as well as a real sewage sample solution collected from Bahirdar Textile Share Company. Photocatalytic activities of ternary g-C3N4/TiO2/CeO2 (1:1, 2:1 and 3:1 Weight ratios) nanocomposite were found to be higher than those of single and binary counterparts. The effect of operational parameters such as pH, initial dye concentration and photocatalyst load in MB dye degradation were investigated by using polyaniline supported g-C3N4/TiO2/CeO2 (PAST) nanocomposite. At optimum operating conditions, photodegradation efficiencies of the bare (T3) and supported (PAST) ternary systems were found to be 81.6 and 92.8%, respectively. The effects of different scavengers suggest that O2- and OH- are the principal species involved in the decolorization of MB. Supported photocatalyst also exhibited a relatively higher efficiency on the photodegradation of MB than real sewage sample solutions which is about 92.6 and 70.4%, respectively. The reusability of supported photocatalyst was tested and only about 22.2% decrement was observed after four successive runs. Photocatalytic degradation of MB dye follows the pseudo first order kinetics for the entire as-synthesized nanocomposite.
