Mixing ratio of zinc nitrate and phosphoric acid for preparation of zinc phosphate white pigments

Abstract

In this work, zinc phosphates were prepared from zinc nitrate and phosphoric acid at various Zn/P ratios as a novel white pigment for use in cosmetics. The chemical composition, powder properties, photocatalytic activity, color phase, moisture retention, and smoothness of the zinc phosphates were studied. Samples prepared at Zn/P = 2/1, 3/2, and 1/1 indicated XRD pattern of Zn3(PO4)2•4H2O. The plane particles were observed in SEM images of sample prepared at Zn/P = 2/1, 3/2 and 1/1. The photocatalytic activity of these zinc phosphate particles was too less to protect the sebum on the skin. The materials prepared at Zn/P = 2/1, 3/2 and 1/1 and their thermal products at 100 °C showed a high reflectance within the range of visible light. Samples prepared at high Zn/P ratio indicated small MIU value.