Effect of NTA and temperature on crystal growth and phase transformations of CaCO3

Abstract

A B S T R A C TPhase transition from vaterite to calcite is a general behavior of CaCO 3 materials. The effect of nitrilotriacetic acid disodium salt (NTA) on the crystallization behavior and polymorphism of CaCO 3 was studied at different temperatures between 60 and 230˚C. The morphologies and the structure of the precipitates were characterized using scanning electron microscope, field emission scanning electron microscopy, powder X-ray diffraction, Raman spectroscopy, and Fourier transform infrared spectroscopy. It was observed that NTA could change the morphologies and crystal structures of CaCO 3 with temperature and stabilize least stable vaterite at high temperature. An anomalous conversion of calcite to vaterite in the presence of NTA was observed. The effect of amount of NTA added on the crystallization behavior at selected temperatures is reported.