Abstract

One of the most important metal oxide nanoparticles, zinc oxide (ZnO) nanoparticles, were synthesized by a simple hydrothermal method. The synthesis ZnO nanorods were carried out using an organic solvent (methanol) and in the presence of hexadecyltrimethylammonium bromide (CTAB) as an organic additive. The size of the synthesized ZnO nanorods (around 100 nm in length and 10-15nm diameter). The main point of this study is to investigate the influence of the ZnO nanocatalysts on the photocatalytic degradation of methylene blue (MB) dye. As-synthesized ZnO nanorods were characterized utilizing Transmission Electron Microscope (TEM), X-ray diffraction (XRD), Brunauer, Emmett, and Teller, (BET) and UV-Visible spectroscopic techniques. The XRD data analyses provide that ZnO nanorods have hexagonal crystalline structure. ZnO nanorods provide high photocatalytic activity on the degradation process of MB, a widespread water contaminant. The photocatalytic process was carried out under UV radiation. The influences of significant parameters as the adsorption efficiency of nanorods to MB molecules in dark, the nanocatalysts load, the initial concentration load of MB, calcination of the nanocatalysts, and stirring the solution were studied. The degradation of methylene blue decrease within dye concentration range of 10 to 50mg/L, the maximum efficiency of the photocatalytic degradation process of the dye achieved with nanocatalyst load of 100mg/L in order to reach 98.28% of dye degradation after one hour. Moreover, the kinetics of photocatalytic reaction process based on ZnO nanorods follow pseudo-first-order with a rate constant of 58.6 x10-3 min-1.

Keywords: Metal oxide; ZnO; Nanorods; Photocatalysts; Methylene blue; Photo-degradation