Effect of the Surface Tension of an Intrapore Liquid on the Structural-Surface Properties of the Silicon Dioxide Produced from Nepheline-Containing Raw Materials

Abstract—This work presents the results of studying the effect of the intrapore fluid surface tension on the structural and surface properties (the specific surface area, the pore volume, and the diameter distribution) of the silicon oxide (SiO2) synthesized by the acid decomposition of a mineral raw material (nepheline). Synthesized samples are studied by chemical and X-ray diffraction analyses, Brunauer–Emmett–Teller (BET), and Barrett–Joyner–Halenda (BJH) methods. Equations connecting the specific surface and the pore volume and the pore diameter of the synthesized SiO2 samples with the surface tension of the intrapore medium have been obtained. The substitution of an organic medium for an aqueous one in the pore space before drying the synthesized SiO2 is shown to allow us not to only significant (by a factor of two) increase the capacity of the adsorption monolayer of the products, but also to influence the distribution of the pore volume along the pore diameter. Based on the specific surface capacitance of the SiO2 and the change in the Gibbs energy (ΔG°) during sorption, it is concluded that the method of their preparation weakly affects the physicochemical properties of their surfaces (type and number of sorption centers per surface unit) and the nitrogen sorption mechanism.