Abstract:
Photocatalytic technology has been shown to constitute one of the most promising processes for wastewater treatment. In this work single, binary and ternary systems of photocatalysts have been synthesized by varying the wt% of g-C3N4 (15, 19.84 and 24.15 wt %) and by keeping the amount of CeO2/Ag3PO4 constant with the ratio maintained. The binary photocatalysts were synthesized by precipitation method, while g-C3N4 was prepared by a pyrolysis method. The zeolite supported g-C3N4/CeO2/Ag3PO4 nanocomposite on the other hand synthesized by solid state reaction. The structure, band gap energy and optical properties of the obtained photocatalyst were determined by XRD, UV-Vis and PL, respectively. The photocatalytic activities of all the as synthesized nanomaterials were evaluated using model pollutant methyl orange dye. The photocatalytic efficiency of single and binary photocatalyst was lower than that of the ternary system. For the ternary systems, the one with 15wt% of g-C3N4 in the g-C3N4/CeO2/Ag3PO4 heterojunction relatively shows the highest methyl orange dye degradation (with the value of 83%). Throughout the experiment, the zeolite supported g-C3N4/CeO2/Ag3PO4 photocatalyst demonstrated the highest rate of methyl orange degradation (93.6%). Optimization of parameters was investigated at 30 mg of zeolite supported g-C3N4/CeO2 /Ag3PO4 photocatalyst, 10 ppm of initial dye concentration and pH4 with the highest % degradation values of 91.2%, 91.3% and 90.9%, respectively. The kinetic studies indicated that the degradation of methyl orange follows pseudo first order kinetics. The quenching effects of different scavengers displayed that the reactive hole and electron plays the major role in the methyl orange degradation. A plausible mechanism over zeolite supported g-C3N4/CeO2/Ag3PO4 heterojunction was elucidated based on valence band, conduction band levels, reduction potentials of oxygen and hydroxyl radicals and the role of scavengers. Zeolite supported g-C3N4/CeO2/Ag3PO4 nanocomposite was further tested for the degradation of real sewage sample solution collected from Bahirdar Textile Industry to the extent of 70.2%.
