Photocatalytic Degradation of Malachite Green in Simulated Textile Dyeing Wastewater Using Fe₃O₄/SiO₂/ZnO

¹ Department of Chemistry, Faculty of Mathematics and Natural Science, Universitas Negeri Malang, Malang, Indonesia
² Centre of Advance Material for Renewable Energy, Universitas Negeri Malang, Malang, Indonesia

^* Corresponding author: This email address is being protected from spambots. You need JavaScript enabled to view it.

Abstract

Malachite Green (MG) is a triphenylmethane-based textile dye that is toxic and difficult to degrade. Various methods for textile wastewater treatment contaiing textile dyes have been developed, one of which involves using composites based on magnetite (Fe₃O₄) coated with silica (SiO₂) and ZnO as a photocatalyst. This study aims to synthesize and characterize the Fe₃O₄/SiO₂/ZnO composite, test its ability to reduce MG concentration in a textile wastewater simulator, and evaluate the reusability of the composite. FTIR spectra showed absorption peaks at 651.94 cm⁻¹ and 941.26 cm⁻¹, corresponding to Zn-O and Si-O-Zn bonds, confirming the presence of ZnO and SiO₂ in the synthesized composite. The XRD diffractogram showed diffraction patterns consistent with Fe₃O₄/SiO₂/ZnO, with diffraction peaks observed at 31.89°, 34.53°, 36.25°, 47.65°, 57.45°, and 67.85°, measured at 2θ angles. SEM-EDX analysis identified the presence of Fe, O, Si, and Zn elements, the average of composite particle size is 67.636 nm. Performance tests for MG removal demonstrated that the Fe₃O₄/SiO₂/ZnO composite effectively reduced MG concentration of textile waste simulated sample, under UV irradiation at 366 nm for 8 hours, with a removal capacity of 0.5084 mg MG/g composite. Reusability tests showed that in the first cycle, the composite reduced MG concentration by 0.4880 mg/g, while in the second and third cycles, the removal capacities were 0.4863 mg/g and 0.4809 mg/g, respectively. The synthesized Fe₃O₄/SiO₂/ZnO composite successfully degraded Malachite Green (MG) in the textile wastewater simulation under UV 366 nm irradiation. The composite was able to degrade MG over multiple reuse cycles, the performance decline is 2%