Valorization of Spent Perlite as a Source of Silicon Dioxide in Vegetable Oil Processing

Abstract This study explores the sustainable valorization of spent perlite, a by-product of vegetable oil winterization, for the synthesis of silicon dioxide. Spent perlite, comprising nearly 70–76% organic residues such as oils and waxes, was regenerated through controlled calcination at 550°C for 120 min, achieving complete removal of the organic fraction. The regenerated material was subjected to alkaline extraction and acid precipitation, enabling the recovery of amorphous SiO2. Increasing the alkali treatment duration from 8 to 24 h enhanced the yield of SiO2 from 39.04 to 54.3%, while the accompanying zeolite by-product decreased from 60.96 to 45.3%. Structural characterization confirmed the transformation into a micro–mesoporous silica network with a high specific surface area, up to 383 m2/g. Comparative analyses with commercial silica demonstrated that regenerated SiO2 exhibits superior sorption properties, underlining its potential for adsorption and catalytic applications. The novelty of this work lies in demonstrating, for the first time, that industrially discarded perlite used in oil purification can be regenerated and converted into high-performance silica-based adsorbents. This approach not only reduces dependence on virgin raw materials but also contributes to waste valorization, resource efficiency, and the development of sustainable silica production routes.

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