The effect of the synthesis medium on the photocatalytic efficiency of calcined ZnO nanoparticles

was explicitly noticed by the much higher efficiency of ZnOE than that of ZnOW in the photocatalytic degradation of cyanide ion in the aqueous medium under the same conditions. Table  4 shows that the photocatalytic activity of ZnOE is as approximately 1.5 as that of ZnOW when applying 0.02 wt.% concentration of the ZnO photocatalyst. The higher performance of ZnOE can be attributed to the higher adsorption capability of its particles, owing to its regular, polyhedral surface faces. Table 4 Effect of the synthesis medium on photocatalytic Selleck PF-01367338 activity Sample ZnO loading (wt.%) CN‾ degradation (%) ZnOE 0.02 86 ZnOW 0.02 56 The superiority of ZnOE photocatalytic activity can be correlated to its particle size and shape, as it is reported in the literature [42–45]. However, the effect of ZnO particle shape on the photocatalytic activity is rarely studied in the literature [46]. In this context, the edges and corners of ZnOE hexagonal particles have many coordinatively unsaturated sites, which usually are active in catalysis. On the other hand, the spherical shape of ZnOW find more particles would have much less active sites due to the lack of edges and corners. Aligning with our interpretation

of ZnOE photocatalytic activity, El-sayed and his coworkers, for instance, showed that the influence of the particle shape on the catalytic activity is very important toward better activity N-acetylglucosamine-1-phosphate transferase [42, 45]. In addition, the photocatalytic activity of acetaldehyde decomposition using ZnO powder depended on several factors including the morphology of the particles [46]. Finally, we believe that the morphology of our ZnOE particles is crucial in photocatalytic activity and our present findings will provide a hint about the role of morphology in the ZnOE photocatalytic

performance. Based on the obtained results, ZnOE nanoparticles were used in further investigation for improving the cyanide degradation efficiency. Photocatalytic degradation of CN- using different concentrations wt.% of calcined ZnOE Photocatalytic degradation of cyanide using different weight percent of calcined ZnOE was performed and found to depend on the ZnO concentration wt.%, as shown in Figure  7. It is evident that at the initial reaction stage, the catalyst concentration of ZnO has no notable effect on the catalytic performance, which might due to the high essential activity of the ZnOE catalyst. It is clear from Figure  6 that the smallest concentration of 0.01 wt.% ZnOE resulted in cyanide degradation of 85% after 180 min, while it increased remarkably to 95% with increasing the loading from 0.01 to 0.02 wt.%. However, further increase in the ZnOE concentration from 0.02 to 0.09 wt.% had resulted in almost 100% CN removal efficiency.