Preparation and characterization of self-suspended CaCO3 nanoparticles derived from scallop shells

Abstract

In this study, self-suspended CaCO3 nanoparticles (M-SCC) derived from thermal activated scallop shells were prepared through the hydration–carbonation reaction and surface modification with sodium hexametaphosphate (SHMP). The characterization results proved the successful synthesis and modification of cubic-like CaCO3 particles. Suspension stability of CaCO3 particles was improved greatly after modification. The effects of additive amount of SHMP, modification temperature and time on degradation of SHMP and interaction between SHMP and CaCO3 were discussed using settling height, particle size distribution, zeta potential and viscosity measurements, and the optimum modification sample (M-SCC-OP) with excellent suspension stability was obtained under the condition of 3.0% of SHMP, 55 °C and 40 min. Zeta potential results indicated that surface charge property of CaCO3 was changed from positive to negative, and low viscosity (6.62 mPa·s) for the suspension of M-SCC-OP (23.8 wt.%) further proved strong composite forces among particles. Compared with original CaCO3 particles, suspension rate in a dietary calcium simulation system was improved from 14.2% to 67.6%. This study may help to solve the problem of limited application of CaCO3 in granule products for low solubility and poor suspension stability.