Microstructure and Spectroscopic Characteristics of Shell and Pearl Powder from Hyriopsis Cumingii

Scanning electron microscopy (SEM),thermal gravimetric (TG) analysis,Fourier transformation infrared spectra (FTIR) and whiteness test were employed to comparatively investigate the differences between shell powder and the corresponding pearl powder from bivalve shell,Hyriopsis cumingii. It was found that:① the frequency of υ2 band of aragonite in pearl powder was greater than that in shell powder,and the blue shift of υ2 band was about 1~3 cm-1. But the frequencies of υ1 and υ4 bands of aragonite were not altered. ② based on SEM images,the particle side and morphology of shell powder and pearl powder could not be taken as the standard for discriminating shell powder and pearl powder. ③ with increasing calcining temperature,the whiteness of pearl powder and shell powder gradually decreased first and then increased. The decreasing rate of pearl′s whiteness was faster than shell′s. Meanwhile,the lowest whiteness of pearl powder calcinated was lower than shell′s.