Fe3O4@SiO2 nanoflakes synthesized using biogenic silica from Salacca zalacca leaf ash and the mechanistic insight into adsorption and photocatalytic wet peroxidation of dye

Abstract

Abstract Water pollution has become one of the most serious environmental issues recently, especially in relation to chemical-containing wastewater. Uncontrolled industrial waste, including large amounts of dye-containing wastewater from textile industries, needs intensive attention. In this work, the synthesis of Fe3O4@SiO2 nanocomposite biogenic silica from Salacca zalacca leaf ash was conducted for the photo-Fenton-like degradation of dye waste. The use of Salacca zalacca leaf ash and the nanoflake form is the novelty of this work. The physicochemical characterization of the material was conducted using X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), and diffuse reflectance UV-visible spectroscopy (UV-DRS) analyses, and photocatalytic activity of material was investigated in wet peroxidation of rhodamine B and batik wastewater. The results showed homogeneously dispersed Fe3O4 in SiO2 support with a nanoflake form, and a crystallite size of 44.9 nm was obtained. XRD investigation revealed the single phase of Fe3O4, which is consistent with the TEM analysis. The bandgap energy of 2.21 eV was reported from UV-DRS measurements, which influenced the increasing photocatalytic activity and reusability of the nanocomposite compared to pure Fe3O4. The photocatalyst showed the maximum degradation efficiency (DE) of 99.9% after 60 min, and the reusability feature was expressed, as there was an insignificant change in the DE over the fifth cycle of use. The material exhibited photocatalytic oxidation of batik wastewater as the removal of total suspended solids, chemical oxygen demand, and color reached 95.55%, 89.59%, and 90.00%, respectively.