Effects of PAA and PBTCA on CaCO_3 Micro-Structure

The effects of two dispersant, polyacrylic acid (PAA) and 2-phosphonobutane-l,2, 4-tricarboxylic acid (PBTCA), on the calcium carbonate microstructure were studied by using SEM and AFM. XRD analysis demonstrates that the content of vaterite increases with the increase in inhibition effects. The metastable crystal forms of vaterite and aragonite are stabilized kinetically in the presence of dispersants. The fractal analysis result shows that the fractal dimension is higher in the presence of dispersants. The better the inhibition effect, the higher the fractal dimension. The step morphology observed by AFM images shows that the step space on the CaCO3 surface increases in the presence of dispersants. Moreover, with the increase of inhibition effect, both the step space and fractal dimension increase. Step bunching was found on the CaCO3 crystal surfaces by AFM and discussed.