MAGNESIOTHERMIC REDUCTION OF RICE HUSK-DERIVED SILICA FOR HIGH-PURITY SILICON SYNTHESIS

This research paper presents a comprehensive study of the magnesiothermic reduction (MTR) process of amorphous silica derived from rice husks of the Kyzylorda region, aimed at synthesizing high-purity nanoporous silicon. Silica was extracted via alkaline leaching followed by precipitation, yielding a precursor with a highly developed specific surface area. During the experimental study conducted at temperatures of 650–700 °C in an inert argon atmosphere, the thermodynamic patterns of the process were analyzed. Special attention was paid to the role of sodium chloride (NaCl) as a heat-absorbing agent, which prevents structural sintering by controlling the exothermic reaction effect. For the efficient removal of by-products such as magnesium oxide (MgO) and residual SiO2, a multi-stage hydrometallurgical purification in the HCl–H₂O–EtOH system was utilized. The phase composition and morphological features of the synthesized samples were characterized in detail using X-ray diffraction (XRD) and scanning electron microscopy (SEM). The results confirmed the formation of polycrystalline silicon with a unique hierarchical porous morphology, entirely inherited from the biogenic precursor structure. The proposed methodology demonstrates high efficiency and environmental significance in utilizing renewable agro-industrial waste for the production of advanced nanomaterials.

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