Effects of washing treatments and ashing conditions on <scp> SiO ₂ </scp> crystalline transitions in rice husk ash

Abstract This study investigated the influence of alkali and alkaline earth metals (AAEMs) on the structural transformation of silica (SiO₂) during the ashing of rice husks. It has implications for silicon‐based material development from thermal conversion. Utilizing water/acid‐washed treatments to remove AAEMs, the research assessed the effects of these treatments on the crystallization characteristics of SiO₂ in rice husk ash. The results showed a significant increase in SiO₂ crystallization temperatures under both slow and rapid ashing conditions, with acid washing having a more pronounced effect. The removal of K, a primary AAEM, was identified as a key factor in improving crystallization temperatures. The presence of K during rapid ashing aided the preservation of residual carbon, further influencing SiO₂ crystallization. Washing treatments and lower ashing temperatures also improved the pore structures of the ashes, thus enhancing the functional applicability of rice husk‐derived silicon materials.