Fe3O4 nanoparticles (NPs) with a continuous and mesoporous silica (m-SiO2) shell were synthesized using a one-step method. sourcing silica from rice husk ash (RHA). The rice husk was thermally treated to obtain ash. from which silica was extracted as sodium silicate and precipitated by pH reduction. https://www.thegreensjunglebeautyshops.shop/product-category/pencil-sharpener/