Theoretical and Experimental Researches of Size-Dependent Surface Thermodynamic Properties of Nanovaterite

Considerable unique chemical properties of nanoparticles are related to their surface thermodynamic properties which mainly depend on their sizes. Herein, the theoretical relationships between partial molar surface thermodynamic properties as well as molar surface thermodynamic properties and size were derived, respectively. It was found that the ratio of molar surface thermodynamic properties to the corresponding partial molar surface thermodynamic properties for spherical nanoparticles is 3:2 during the dissolution process. In experiment, the standard dissolution equilibrium constants and the thermodynamic properties of nanovaterite with different sizes were obtained by determining the equilibrium conductivities in distilled water at different temperatures. Then, the surface thermodynamic properties were calculated, and the size dependence of the surface thermodynamic properties were discussed eventually. The results show that particle size has remarkable influence on the surface thermodynamic properties; the molar surface Gibbs energy, the molar surface enthalpy, and the molar surface entropy increase with decreasing size and are linearly related to the reciprocal of particle radius, respectively, when the radius is close to or exceeds 10 nm. The relationships between the surface thermodynamic properties and particle size together with the quantitative influence regularities of particle size on these properties are valuable to understand some unique chemical processes involving nanoparticles.