Fe3O4/SiO2 composite derived from rice husk ash to enhance methylene blue removal efficiency in wastewater treatment

Abstract

This study addresses the challenging issue of water pollution caused by the non-biodegradable organic compound methylene blue (MB) by synthesizing Fe3O4/SiO2 composite using SiO2 derived from rice husk ash (RHA) for MB photodegradation. The SiO2 was prepared from RHA at various heat treatment temperatures of 750, 800, 850, 900, and 950 °C that resulted in samples A, B, C, D, and E, respectively. The Fe3O4/SiO2 composites were then synthesized using the RHA-derived SiO2 as a precursor, resulting in samples 1 to 5. Various characterizations were conducted, including X-Ray Diffraction (XRD), Scanning Electron Microscopy-Energy Dispersive Spectroscopy (SEM-EDS), Vibrating Sample Magnetometer (VSM), and Fourier Transform Infrared (FTIR). The photodegradation activity of Fe3O4/SiO2 was tested with UV–Visible spectroscopy. XRD pattern of SiO2 derived from RHA revealed a broad diffraction peak at 2θ of 21.52°, confirming the presence of amorphous SiO2. Meanwhile, all of the composite samples showed peaks corresponding to Fe3O4 and SiO2. FTIR analysis of the composite also verified the existence of SiO2 and Fe3O4. SEM images of RHA-derived SiO2 (samples A-E) showed an ununiform shape, while the composite samples showcased a homogeneous morphology. The EDS results showed the RHA-derived SiO2 (samples A-E) consisted of C, O, Si, Zn, and Cl, while Fe3O4/SiO2 composite samples (samples 1–5) comprised elements Fe, O, C, Si, Zn, and Cl. Superparamagnetic properties also showed in Fe3O4/SiO2 samples 1, 3, and 5, according to the VSM analysis with sample 5 exhibiting the highest saturation magnetization. Among the Fe3O4/SiO2 composites, sample 4 exhibited the highest performance as a photocatalyst for degrading MB.

Keywords

• Fe3O4
• Composite
• Rice husk ash
• Photodegradation
• SiO2