Structural and Acid-Base Properties of Aluminosilicon Compounds Obtained by Acid Processing of Nepheline.

The work is devoted to research on obtaining materials based on silicon and aluminum oxides from nepheline concentrate, the main component of which is the mineral nepheline. The obtained samples were studied by XRD, SEM, porosimetry, chemical analysis, etc. It has been established that all of them are X-ray amorphous substances with particle sizes from 40 to 300 nm, in which, according to chemical analysis, the mass ratio of Al2O3 : SiO2 is ≈ 1 : 1.2. The structural and acid-base properties of the surface of the synthesized samples have been studied. According to the porosimetry data, all samples are predominantly mesoporous substances with a developed specific surface area (Ssp = 380–450 m2/g). There is a directly proportional relationship between H2SO4 concentration used in the decomposition of the nepheline concentrate and the specific surface area of the synthesized compounds. Data are presented on the dependence of the specific surface charge of the obtained samples on the pH of the medium, which indicate that the point of zero charge for the synthesized substances shifts to a more acidic region with an increase in the concentration of H2SO4 taken for the decomposition of nepheline. [ABSTRACT FROM AUTHOR]