Recycling of rice husk waste to produce nano–silica for fertilization purposes via an easy protocol

Abstract

Recycling agricultural waste is crucial for reducing pollution and gas emission of hazardous gases in the surrounding areas. Two alkaline solutions, NaOH and KOH, were used to extract SiO2 nano particles from rice husk waste. Various examination techniques (Energy-dispersive X-ray spectroscopy (EDS), Fourier transform infrared spectra (FTIR), X-ray diffraction (XRD), transmission electronic microscopy (TEM), and specific surface area (SSA)) were utilized to characterize the nanoparticles which were found to be to be amorphous spherical lumpy nanoparticles (16 nm in size) with a high surface area of 361.92 m2 g-1.However,the amount of silica extracted by KOH was higher than that extracted by Na OH beside avoiding the hazard of Na which is found in the extracted as impurities. Based on previous data, nano-SiO2 produced by KOH was experimentally evaluated using maize grown on a sandy soil of poor levels of bioavailable-Si. In the plant shoots and roots, nano-SiO2 extracted by KOH enhanced the contents of leaf chlorophyll, N, P, K, and Si, and, hence, improved the vegetative growth characteristics. These results suggest that the SiO2 extracted by KOH is still in need for further studies in which higher concentrations of KOH can be used for probably extracting silica than the concentration used in the current study.