Physicochemical, Structural, and Surface Properties of Silicon Dioxide Produced from Mineral Raw Materials

Samples of amorphous silicon dioxide (SiO2) were obtained by acid decomposition of mineral raw materials (nepheline). Their physicochemical, acid-base, structural, and surface properties were studied by chemical analysis, potentiometric titration, and by the methods of Parks, Brunauer-Emmett-Taylor (BET), Barrett-Joyner-Halenda (BJH), and others. It was determined that the obtained SiO2 samples are almost identical to pyrogenic amorphous silicon dioxide produced from reactive raw materials (pharmaceutical drug Polisorb MP) in content of impurities, pH of the aqueous extract, and pH values of the isoionic point and the zero-charge point and have larger values of specific external surface area and specific pore volume (by a factor of 1.1-1.9 and similar to 1.4, respectively). Based on the found values of the specific capacity of the adsorption monolayer of the surface of the SiO2 samples and the Gibbs free energy change of sorption (Delta G(0)), it was concluded that the method of their preparation does not significantly affect the physicochemical properties of their surfaces and the mechanism of nitrogen sorption. On the basis of the results obtained, it was assumed that silicon dioxide produced by acid processing of mineral raw materials is promising as an enterosorbent in therapeutic practice.