جواد صاین

Abstract: In this research, nitrogen doped TiO2 (N-TiO2) nanoparticles and hybrid nanocomposites based on N-TiO2 and hematoporphyrin pigment (HP/N-TiO2) were synthesized with the goal of TiO2 band gap modification. The N-TiO2 nanoparticle (initial N/Ti molar ratio: 2) was synthesized with sol-gel method and calcined at 550°C. The hybrid nanocomposite HP/2N-TiO2 was synthesized by precipitation method. The prepared NTiO2 nanoparticles and hybrid nanocomposite HP/2N-TiO2 were characterized by XRD, UV-Vis spectroscopy, TG-DTA, FT-IR, SEM and BET surface area. The results confirmed the purity of synthesized N-TiO2 nanoparticles and hybrid nanocomposites HP/N-TiO2. N-TiO2 nanoparticles have anatase phase and the absorption edge of hybrid nanocomposite HP/N-TiO2 has been shifted significantly into visible region. The photocatalytic activity of the prepared hybrid nanocomposite was evaluated by the photocatalytic degradation of methyl orange in a slurry reactor under visible light. The observed high visible light activity of HP/2N-TiO2 can be attributed to the synergistic effect of titania nitrogen doping and sensitization with HP. In the next step, the hybrid nanocomposites HP/zN-TiO2 with different nitrogen doping (z: 0, 2, 5, 8 and 10) with the goal of evaluation of the amount of nitrogen were synthesized. The prepared hybrid nanocomposites were employed for degradation MO in a novel helical flow photoreactor. The effects of important influencing parameters (initial N/Ti molar ratio hybrid nanocomposites, photocatalyst dosage and solution pH) were investigated and optimized using the response surface methodology (RSM). A maximum degradation efficiency of 89.2% was attainable after 60 min treatment under the optimum conditions of initial N/Ti molar ratio of 4.97 (5), photocatalyst dosage of 0.73 g/L and pH of 4.8. Different thin film layers of N-TiO2, sensitized with different HP dosages (concentrations of 0, 1, 3 and 6 mM), were synthesized on wire gauze structured pac