Photocatalytic Activity of ZnO-SnO2 Ceramic Nanofibers for RhB Dye Degradation: Experimental Design, Modeling, and Process Optimization

Photocatalytic degradation of rhodamine B (RhB) dye in aqueous solution is evaluated using ZnO-SnO2 nanofibers under visible- and UV-light irradiation. The ceramic nanofibers are characterized by X-ray diffractometry (XRD) and TEM technique. The results of XRD disclose the wurtzite phase for the inorganic structures. In turn, the microscopy analysis by TEM reveals the formation of the ultrathin ceramic fibers with 500nm in diameter. The influence of the irradiation time, temperature, and pH on the color removal efficiency is investigated. UV-vis spectral analysis is used to measure the photocatalytic activity of metal oxide composites. The optimal conditions for the efficient RhB dye degradation under visible-light are found to be: irradiation time *t=13.3h; temperature *T=42 degrees C, and *pH=9.5. In these conditions, a color removal efficiency of 94.20% is observed under visible-light irradiation. In addition, a photocatalytic test under UV-light irradiation is performed revealing a pseudo-first-order rate constant of 0.0166min(-1) and a color removal efficiency of 99.35%.