Amorphous Microstructural Evolution and Impurity Removal in Acid-Leached Rice Husk

Abstract

This study investigates the microstructural transformations of rice husk, with a focus on the amorphous-to-crystalline phase transition and the impact of acid leaching treatments. Recognizing rice husk’s potential as a source for high-purity silica materials, the research explores the influence of treatment sequences and citric acid concentrations on microstructure and impurity removal. Utilizing X-ray Diffraction (XRD) and Scanning Electron Microscopy (SEM), the study analyzes leached rice husk samples subjected to varied acid leaching conditions. Notably, XRD reveals a consistent amorphous phase in both leached rice husk (LRH) and leached rice husk ash (LRHA), independent of pre-treatment methods. SEM images demonstrate enhanced SiO2 particle morphology at different citric acid concentrations compared to raw rice husk particles. The nuanced interplay between treatment sequences, acid concentrations, and resulting microstructures is highlighted, indicating the potential for tailored high-purity silica materials from rice husk. The presence of pores in rice husk ash further underscores the efficacy of acid leaching in impurity removal. In conclusion, the study offers a comprehensive understanding of amorphous microstructural evolution in rice husks, presenting opportunities for controlled microstructure development in the production of high-purity silica materials.