Abstract
The treatment of organic waste from dyes or other industry processes is a crucial issue that requires urgent attention. Photocatalysis is a promising method for tackling this problem, with ZnO being a commonly used photocatalyst material. This study compared the degrading efficiency of ZnO particles and ZnO-Ag composites by utilizing flame and spray pyrolysis techniques. Under UV light, methylene blue (MB) was used as a model organic waste. The generated particles were characterized using Brunauer-Emmett-Teller (BET) surface area, scanning electron microscopy (SEM), X-Ray diffraction (XRD), and a UV-Vis spectrometer. The findings showed that the ZnO and ZnO-Ag obtained using both methods exhibited hexagonal Wurtzite crystal structures, and there was no significant difference in the crystal sizes produced. SEM analysis indicated that the morphology of the resulting particles differed significantly, with flame-synthesized particles being remarkably smaller in size (one-thirtieth the size following spray synthesis) and having smoother surfaces. Furthermore, the addition of Ag particles to ZnO enhanced the MB degradation efficiency by two to three times, achieving a maximum of 64% at 75 min. The BET analysis showed that the surface area of ZnO doped with Ag was larger compared to that of pristine ZnO. On the other hand, the ZnO-Ag particles produced via spray pyrolysis exhibited a total pore volume (determined through nitrogen adsorption-desorption analysis) three times larger than that of the particles produced via the flame method. The particles produced via spray pyrolysis also had better MB degradation performance compared to those synthesized using flame pyrolysis.