Evaluation of an ultrasonic-assisted mechanical stirring technique for the synthesis of an efficient nano-photocatalyst

Photocatalysis has emerged as an efficient technique for the removal of contaminants from wastewater. In this work, conventional mechanical stirring was compared with ultrasonic-assisted mechanical stirring for the synthesis of an efficient nano-photocatalyst (Al2O3)(1-x) (ZnO) (x) Fe2O3. The photocatalytic activity of (Al2O3)(1-x) (ZnO) (x) Fe2O3 synthesized by both techniques was compared for the degradation of methyl orange dye (MO) under visible light irradiation. Important process parameters were optimized during the study and the results indicated that the photocatalyst synthesized by ultrasonic-assisted mechanical stirring was more efficient with 93.5% photocatalytic activity for the degradation of MO dye than that synthesized by using a simple mechanical stirring technique which resulted in photocatalytic activity of 83.7%. (Al2O3)(0.75)(ZnO)(0.25)Fe2O3 nano-photocatalysts synthesized by both methods were characterized by X-ray diffraction, scanning electron microscopy, energy dispersive X-ray analysis, dynamic light scattering and BET surface area analysis. The results indicated that the particle size of the (Al2O3)(0.75)(ZnO)(0.25)Fe2O3 catalyst synthesized by ultrasonic-assisted mechanical stirring was significantly smaller and the surface area larger than the particles prepared by the conventional mechanical stirring method. A cyclic study evaluated the reusability of the photocatalyst and found minimal loss in degradation efficiency after seven cycles. The optimal photocatalyst produced in this study can degrade higher concentrations of MO with a higher efficiency using a lower or similar catalyst dose compared to other materials published in the literature.