Synthesis of ZnO Pigment by Hydrothermal Process and Evaluation of Different Factors Effects on Its Properties by Taguchi Method

One of the most ZnO applications is in paint industry as pigment, specially in white thermal control coatings used on satellites. In this paper, the effects of the process variables on ZnO size and morphology is studied. The experiments were carried out based on the design of experiments using Taguchi method. The parameters were zinc nitrate solution concentration, potassium hydroxide solution concentration, the pH of initial solution, temperature and reaction time. The ZnO structures were characterized by X-ray diffraction (XRD) and field-emission scanning electron microscopy (FE-SEM). The analysis of variance showed that among the parameters studied, temperature and potassium hydroxide solution concentration have the most significant effects on ZnO properties and amount of produced powder. The zinc nitrate solution concentraton should be always lower than potassium hydroxide solution concentration. The optimum sample was prepared according to the best levels of each factor, 1m zinc nitrate solution, 4m potassium hydroxide solution, the pH equals to 12.5, temperature of 170 ºC and reaction time of 14 h. The powder yield from a 100 mL autoclave was about 3.1 g and its purity was about 97%. The yield of ZnO powder by hydrothermal method was 94%. J. Color Sci. Tech. 7(2014), 281-296©. Institute for Color Science and Technology.