Synthesis and Characterization of Silica Obtained by Combined Acid-Alkali Treatment of Serpentinite

Serpentinite rocks and their processing waste represent a valuable source of magne-sium and silicon; however, their complex composition complicates efficient component recovery. This study investigates the combined acid–alkali processing of serpentinite waste from the Zhitikara deposit (Kazakhstan). In the acid leaching stage, sulfuric acid enables magnesium extraction, while subsequent treatment with sodium hydroxide facilitates the selective recovery of silica gel formed during acid attack. At the final neutralization step, amorphous silica is precipitated with a yield exceeding 60% of its initial content. The resulting silica was characterized using FTIR spectroscopy, scan-ning electron microscopy (SEM–EDS), and BET adsorption analysis. According to IU-PAC classification, the obtained material corresponds to mesoporous silica gel with a high specific surface area, suitable for adsorption and catalytic applications. It was shown that the dissolution process follows the shrinking core model. The combined acid–alkali method thus offers a promising approach for processing magnesium hy-drosilicates from serpentinite