Surfactant-free synthesis of high surface area silica nanoparticles derived from rice husks by employing the Taguchi approach

Abstract

High surface area biogenic silica nanoparticles extracted from rice husks (RH) were synthesized through a surfactant-free process by employing a design optimization of the Taguchi approach. This approach is a systematic and efficient method to design factorial experiments with a minimum number of experiments. Here, the amount of rice husk ash, pH and aging time were adopted as design parameters to determine the particle size and structural properties including porosity and surface area in the synthetic process. The average particle size of silica nanoparticles ranging 24–87 nm and surface area to ∼740.77 m2/g could be tuned in the factorial optimization, where the degree of parameters that influence the structural properties were investigated, combined with surface characterizations. The surface area, pore volume and pore size of the samples were analyzed by adsorption–desorption characteristics of N2 gas. An amount of silica contents was analyzed by X-ray fluorescence for each step of RH treatment. Scanning electron microscopy and transmission electron microscopy were utilized to show the morphology and primary particle size of the silica nanoparticle. The analysis showed that the optimized experimental parameters calculated based on “signal” to “noise” ratio derived from Taguchi approach shortened the number of experimental variations with a noticeable improvement of surface area, whose individual effects are elucidated. This synthetic technology of biogenic nano silica with high surface area based on the Taguchi approach has potential for efficient time savings and quality control strategies to optimize the synthetic process.