Ultrasound assisted AgO/ZnO doped g-C3N4 synthesis and investigation of its photocatalytic effects

Nowadays, minimizing the serious environmental damage caused by waste dyes of various sectors especially textiles, is economically costly. For this reason, intensive studies are carried out to remove dyes from waters containing textile waste dyes. With these efforts, it is aimed to minimize the damage to nature. In the scope of this thesis, the synthesis of ultrasound assisted AgO/ZnO doped g-C3N4 photocatalysts was carried out and the removal efficiencies of these catalysts were investigated. For this purpose, pure graphitic carbon nitride was synthesized from melanin in the laboratory environment in a tube furnace. Then, two different methods were used for the preparation of Ag/Zn/g-CN composite. One of these methods is the ultrasound based co-precipitation method and the other is the co-precipitation method synthesized without ultrasound support. The g-C3N4/AgO/ZnO solutions containing different ratios of Zn and Ag were synthesized by reduction in the presence of NaOH solution in a semi-batch system maintained at constant temperature. Then, filtration, drying and calcination steps were carried out. Photocatalytic reactions were then initiated in batch reactors with a constant concentration of methylene blue solution. The effect of five different parameters on the removal performance of the prepared solution was investigated. The effect of time-dependent removal, the ratio of metal oxide in the catalyst, the amount of catalyst, different methods used in synthesizing the catalyst, different types of light used for photocatalytic reaction; are the parameters investigated in this thesis. The synthesized catalysts were characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction method (XRD) and their surface morphologies and structures were investigated. It was observed that there was an increase in removal with the increase in the amount of ZnO and AgO added to graphitic carbon nitride. Using g-C3N4 hetero photocatalyst with 25% ZnO-2% AgO and minimum metal oxide added, 91% removal after 1 hour and 96% removal after 3 hours were obtained. As a result of the study, it was concluded that the synthesized catalyst can perform well in visible light as well as UV light. In the presence of visible light, 44% removal in the first 1 hour and 75% removal was observed at the end of the 3rd hour. Keywords: Photocatalyst, Graphitic Carbon Nitride, AgO, ZnO, UV, Methylene Blue