EFFECT OF ULTRASONIC TREATMENT AND CALCINATION TEMPERATURE OF RICE HUSK ASH ON THE CHARACTERISTICS OF SILICA-CHITOSAN COMPOSITES

Vollständiger Abstract

Worum geht es in dieser Arbeit?

This study investigates the effect of calcination temperature and ultrasonic treatment during the extraction of silica from rice husk ash and its implications for the characteristics of silica-chitosan composites. Rice husk ash was calcined at temperatures of 500, 600, and 700°C, followed by extraction using 2M NaOH solution with and without ultrasonic treatment. The extracted silica was subsequently combined with chitosan to form silica-chitosan composites. Characterization was carried out using X-ray fluorescence (XRF) to determine SiO2 purity, Fourier-transform infrared spectroscopy (FT-IR) for functional group identification, and X-ray diffraction (XRD) for structural analysis. The results showed that increasing the calcination temperature from 500°C to 700°C generally enhanced the silica yield (79.6 - 90.8 %) and purity (92.3 - 97.4 %). Ultrasonic treatment further improved the yield by approximately 2 - 5 % and increased the purity by about 0.5 - 2 % at each calcination temperature. FT-IR and XRD analyses indicated that the obtained silica was predominantly in the amorphous phase with strong Si-O-Si bonds, while the silica-chitosan composites exhibited intermolecular interactions involving -OH, -NH2, and Si-OH functional groups. The combination of calcination temperatures of 600 - 700°C and ultrasonic treatment produced high-quality silica that has strong potential to enhance the performance of silica-chitosan composites for dye adsorption and heavy metal ion removal applications.