Synthesis of silica from rice husk as coating material on magnetic nanoparticle for efficient adsorption of phenol from water samples

Silica (SiO2) from rice husk was coated with magnetic nanoparticles (MNPs) as an adsorbent to adsorb phenol from river water. The structure of SiO2 and SiO2-MNPs were characterized by Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD). Field emission scanning electron microscopy (FESEM) showed a rod shape, with a rough surface area in the range of 2 to 3 µm. Transmission electron microscopy (TEM) and energy dispersive x-ray spectroscopy (EDX) were used to examine the resulting spherical shape of the synthesized SiO2-MNP. The results showed a range of 1.3 to 1.5 nm for SiO2 and 4.2 to 6.4 nm for SiO2-MNP. Vibrating-sample magnetometer (VSM) showed an Fe value of 45.1% in SiO2-MNP (VSM); for MNP, SiO2, SiO2-MNP 104.12, 4.72, and 8.01 emu/g, respectively. Response surface methodology (RSM) was used to study the parameters and responses to obtain an optimized condition in SiO2-MNPs usage. The optimized parameters were extraction time selected at 5 min, pH 8, 8 mL acetonitrile as solvent and 15 min as sonication time. The application of SiO2-MNPs was applied to real water samples, with recovery of 84% of phenol. Thus, the synthesized adsorbent, SiO2-MNPs, was developed successfully for phenol removal from water samples.