Effect of L (+) ascorbic acid and monosodium glutamate concentration on the morphology of calcium carbonate

• Interactions between Ca2+ and both ascorbic acid and monosodium glutamate were observed.
• Using ascorbicascorbic acid, vaterite can be formed and is stable compared to the crystals formed in the presence of monosodium glutamate.
• The ascorbic acid results in the formation of cauliflower aggregates that are composed of nanoparticles.
• The monosodium glutamate results in a mixture of rhombohedral and spherical crystals.

In this study, monosodium glutamate and ascorbic acid were used as crystal and growth modifiers to control the crystallization of CaCO3. Calcium carbonate prepared by reacting a mixed solution of Na2CO3 with CaCl2 at ambient temperature, (25 °C), constant Ca++/CO3-- molar ratio and pH with stirring. The polymorph and morphology of the crystals were characterized using scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), transmission electron microscopy (TEM) and differential scanning calorimetry (DSC). The results indicate that rhombohedral calcite was only formed in water without organic additives, and both calcite and spherical vaterite with various morphologies were produced in the presence of monosodium glutamate. The content of vaterite increased as the monosodium glutamate increased. In addition, spherical vaterite was obtained in the presence of different concentrations of ascorbic acid. The spherical vaterite posses an aggregate shape composed of nano-particles, ranging from 30 to 50 nm as demonstrated by the SEM and TEM analyses. Therefore, the ascorbic stabilizes vaterite and result in nano-particles compared to monosodium glutamate.

Graphic abstract shows that agglomerates of nano vaterite calcium carbonate were formed in the presence of SCOB acid while in the presence of MSG mixture of vaterite and calcite were formed.Figure optionsDownload as PowerPoint slide