Kinetics Study and Characteristics of Silica Nanoparticles Produced from Biomass-Based Material

Rice husk, a form of biomass material, is a potential source of renewable energy. Recovering silica from rice husk is an important element in manufacturing high value-added products and ensures efficient utilization of a bioresource. This paper describes the kinetics and characteristics of silica prepared from rice husk in an oxidizing atmosphere. Experiments were conducted with rice husk powder under nonisothermal conditions with various gaseous flow rates, sample loadings, reactant grain sizes, oxygen concentrations, and heating rates. Samples were characterized by ICP-MS, XRD, FTIR, HT-DSC, FE-SEM, TEM, and N-2-adsorption analyzer. Experimental results show that the silica yield can be increased by decreasing the grain size of raw husk. Acid-pretreatment of rice husk increases the purity, uniformity, surface area, and porosity of the final silica products. The average size of the silica particles was approximately 60 nm. Two distinct reaction stages were observed for total thermal degradation of the rice husk. This study determines the kinetic parameters of rice husk's combustion reaction, including the activation energy, pre-exponential factor, and reaction order, using thermo-analytical techniques. This study also proposed a mechanism to illustrate the thermal decomposition of the rice husk, which agrees well with the experimental results.