AMORPHOUS SILICA MICROSPHERE FROM OPENLY BURNED RICE HUSK ASH AS AN EFFICIENT ADSORBENT FOR ULTRASOUND-ASSISTED METHYLENE BLUE REMOVAL

In this study, silica (SiO2) was fabricated from a sodium silicate solution derived from an openly burned rice husk using precipitation followed by calcining at 500 oC for five hours. The calcined SiO2 was well-characterized using TGA, XRD, Raman spectroscopy, Nitrogen adsorption-desorption, FTIR, XRF, and FESEM. The results showed that the calcined SiO2 has an amorphous phase, spherical particle shape with micrometer-sized, and belongs to mesoporous material. The fabricated SiO2 was evaluated as an adsorbent for methylene blue removal from an aqueous solution using the ultrasound-assisted adsorption technique. The adsorption parameters including pH of the solution, the dosage of the adsorbent, initial concentration of dye in solution, and adsorption time were evaluated. They revealed the optimum values of 10, 2.5 g/L, 20 ppm, and 10 min, respectively. Under this optimum condition, the adsorption efficiency was found to be 98.43%. The findings implied that the fabrication of SiO2 from openly burned rice husk using a precipitation method is facile and the fabricated SiO2 could be a prospective adsorbent for removing industrial dye waste effluents.