Table 4.

CaCO₃ micro- and nanoparticles synthesized by mechano-chemical method

No.	Size (nm)	Nature	Method of synthesis	Results/Observations	References
1	77–142	Amorphous and Crystalline	Mechano-chemical	Vaterite and calcite (ACC) form of CCNPs were synthesized at low and high milling speed in the presence and absence of sodium hexametaphosphate, respectively	Hu et al. (2019a)
2	11.56–180.06	Crystalline	Ball-milling	The energy-dispersive spectroscopy (EDX) data confirmed that the mechano-chemical method helped to obtain CCNPs using Achatina fulica shell. TEM data suggested that CCNPs were in semi-spherical shape. The synthesized CCNPs had potential to modify the mechanical strength and stiffness of the polymer	Gbadeyan et al. (2020)
3	3200–6800	Crystalline	Ball-milling	The synthesized CCNPs’ size was depended on milling speed, number of zirconia balls used, and the collision duration. Using this method, industrial grade CCNPs can be synthesized	Sulimai et al. (2018)
4	19–51	Not specified	Roller ball-milling	The CCNPs was environment friendly as synthesized using biogenic raw material, i.e., cockle–shell (obtained naturally from the molluscs from sea water). The CCNPs can act as good biomaterial for biomedical applications due to stability and ability to act as a nontoxic nanocarrier	(Kiranda et al. 2018)
5	~ 300	Crystalline	Microwave-assisted technique and planetary milling	The synthesized CCNPs was in calcite form. This NPs can be used as polymer filler, pigment, an encapsulation template of bioactive compounds or as an adsorbent to eliminate heavy metals from water	Skubiszewska-Zięba et al. (2017)
6	34	Not specified	Membrane dispersion mini reactor	It was observed that the morphology and size of the CCNPs was dependent on various factors, such as the effect of flow rates of dispersed and continuous phases, amount of CaSt2 surfactant, and the temperature. It was also found that these hydrophobic CCNPs can be produced industrially and their surfaces could be modified	Han et al. (2019)