Search

This study explores the conversion of agricultural waste into valuable industrial precursors, specifically focusing on the production of silica nanoparticles from rice husk (RH) via calcination and sol–gel processes. The synthesized particles underwent detailed analysis to assess their chemical composition, structural features, morphological characteristics, and size distribution. This comparative analysis evaluates the effectiveness of various methods in generating silica from RH and examines the impact of different drying techniques, including freeze-drying and conventional thermal drying, on the properties of the resulting silica nanoparticles. Utilizing a combination of sol–gel and freeze-drying techniques produced spherical nanoparticles with diameters of 10 to 20 nm, characterized by size uniformity, clear contours, and minimal aggregation. X-ray diffraction (XRD) analysis identified the amorphous nature of the silica, as evidenced by diffraction peaks typical of amorphous silica in the RH-derived samples processed via different methods. Significantly, the XRD patterns of the calcination-derived silica showed no foreign peaks, indicating a purer amorphous state. The findings of this study are anticipated to contribute to the development of innovative and efficient silica nanomaterials, fostering the sustainable use of agricultural waste. [ABSTRACT FROM AUTHOR]

The rice husk (RH) combustion pretreatment method plays a crucial role in the extraction of nanoscale SiO2 from RH as a silicon source. This study examined the effects of diverse pretreatment methods and combustion temperatures on the particle size distribution of nanoscale high-purity amorphous SiO2 extracted from rice husk ash (RHA) post RH combustion. The experiment was structured using the Taguchi method, employing an L9 (21 × 33) orthogonal mixing table. The median diameter (D50) served as the output response parameter, with the drying method (A), combustion temperature (B), torrefaction temperature (C), and pretreatment method (D) as the input parameters. The results showed the torrefaction temperature (C) as being the predominant factor affecting the D50, which decreased with an increasing torrefaction temperature (C). The optimal parameter combination was identified as A2B2C3D2. The verification test revealed that roasting could improve the abrasiveness of Rh-based silica and reduce the average particle size. Torrefaction at medium temperatures might narrow the size distribution range of RHA-SiO2. We discovered that the purity of silica increased with an increasing roasting temperature by evaluating the concentration of silica in the sample. The production of RHA with silica concentrations up to 92.3% was investigated. X-ray diffraction analysis affirmed that SiO2's crystal structure remained unaltered across different treatment methods, consistently presenting as amorphous. These results provide a reference for extracting high-value products through RH combustion. [ABSTRACT FROM AUTHOR]