Feasibility of using a rotating packed bed with blade packings to produce ZnO nanoparticles

Abstract

A rotating packed bed with blade packings was used to produce zinc oxide (ZnO) nanoparticles by precipitation. Precursors were firstly produced in a continuous liquid-liquid reaction of zinc chloride (ZnCl2) with sodium hydroxide (NaOH). The effects of the concentrations of ZnCl2 and NaOH, the flow rates of aqueous ZnCl2 and NaOH, and the rotational speed on the size of the precursors were studied. Experimental results indicate that increasing concentrations of ZnCl2 and NaOH, decreasing flow rates of aqueous ZnCl2 and NaOH, and decreasing the rotational speed reduced the size of the precursors. The smallest precursors were produced at a ZnCl2 concentration of 0.4mol/L, an NaOH concentration of 0.8mol/L, flow rates of aqueous ZnCl2 and NaOH of 0.3L/min, and a rotational speed of 600rpm. Then, the precursors were calcined at 400°C for 1h to generate ZnO nanoparticles with a mean size of 43nm and a narrow size distribution. The detailed characterizations revealed that the as-produced ZnO nanoparticles were pure ZnO, which comprised a highly crystalline hexagonal wurtzite phase and exhibited a favorable optical property.