Effect of stearic acid and sodium stearate on hydrophobicity of nano calcium carbonate and mechanism of water vapor adsorption

It is essential to understand the modification mechanism of hydrophobicity nano-CaCO₃ to their potential application in different fields of chemistry. However, the water absorption of hydrophobicity nano-CaCO₃ is seldom studied. In this study, Raman, BET and TGA experiments were performed on nano-CaCO₃ samples to obtain surfactants contents and microstructure characteristics. SEM, TEM and DSL results showed that the nano-CaCO₃ modified by stearic acid and sodium stearate had larger particle size and smaller nanoclusters. In the water vapor adsorption test, the order of saturation adsorption capacity was nano-CaCO₃(PCC) > nano-CaCO₃ modified by sodium stearate(PCC-Sa-Na) > nano-CaCO₃ modified by stearic acid(PCC-Sa), and XPS results showed that PCC-Sa had more hydrophobic groups than PCC-Sa-Na, which also explained that the hydrophobicity of PCC modified by stearic acid and sodium stearate was improved by increasing the hydrophobic bond on the surface of CaCO₃ and reducing the hydrophilic groups. Our analysis provides a path for the design and the prediction of hydrophobicity of nano-CaCO₃, which is the main focus of our work.