Abstract
Zinc white is mainly used as a mild astringent, protectant. and has weak antiseptic action. It is well known that the yield of zinc white produced is greatly affected by the syn thetic conditions such as the reactant concentration, reaction temperature, washing water temperature, mole ratio of reactants, and drying temperature, calcination temperature, etc. The purpose of this study is to investigate the optimal synthesis conditions of zinc white produced. A randomized complete block design suggested by G.E.P. Box and K.B. Wilson was applied for this purpose. Basic zinc carbonate was prepared by reacting zinc sulfate and sod. carbonate solution in this study. Zinc white comes when prepared by calcination of basic zinc carbonate. The optimum synthesis conditions of zinc white obtained from this study is as follows: 1) The reacting temperature range is: 92-100$^{\circ}C$, 2) The concentration of reactant solution is 23.6-27%, 3) The optimum mole-ratio: [ZnSO4]/[Na2CO3] is 1.74~1.96, 4) The washing water temperature is 36$^{\circ}C$, 5) The drying temperature range is 68-74$^{\circ}C$, 6) The calcination temperature is 600$^{\circ}C$. The outcome of DSC indicated a desolvation of basic zinc carbonate occurred at about 133.3$^{\circ}C$. The dehydration of the compound ceased at about 267.9$^{\circ}C$ and the decarboxylation ceased at about 379.9$^{\circ}C$. The physical and chemical properties of zinc white as medicine were studied by use of Volume Test.