Concentration Dependences of Photocatalytic Activity in Green-Synthesized Fe3O4/rGO/TiO2 Composite Nanoparticles for Degradation of Methylene Blue Dye
Hanif Yoma Khoiri (a), Larasati Hayu Regita Salma (a), Hafil Perdana Kusumah (a), Larrisa Jestha Mahardhika (a), Rivaldo Marsel Tumbelaka (a), Nugraheni Puspita Rini (a), Nurul Imani Istiqomah (a), Nining Sumawati Asri (b), and Edi Suharyadi (a*)

(a) Department of Physics, Universitas Gadjah Mada, Yogyakarta, Indonesia
(b) Research Center for Advanced Materials, National Research and Innovation Agency (BRIN), Tangerang Selatan, Indonesia

*Corresponding author: esuharyadi[at]ugm.ac.id

Abstract

The textile industry, printing, dyeing, and other manufacturing are the largest contributors to wastewater, especially organic dyes such as methylene blue (MB). MB has complicated aromatic molecules that are difficult to degrade and cause serious problems for the natural environment. Photocatalysis has gained popularity in wastewater treatment due to its affordability and effectiveness. TiO2 is a semiconductor material that is excellent for photocatalytic activity because of its small bandgap energy and only being excited by UV light, but due to its nanoscale size, TiO2 is difficult to separate from water solutions. Besides, electron-hole pairs have a high recombination rate, so the reactivity will rapidly diminish. Due to high recombination of TiO2, reduced graphene oxide (rGO) is an electron acceptor and promising applications in various fields especially photocatalytic. Fe3O4 is superparamagnetic materials offer a wide range of uses for recovering catalysts and are sensitive to external magnetic fields. This study investigates photocatalytic degradation of Fe3O4/rGO/TiO2 nanoparticles green synthesized utilizing Moringa oleifera and Amaranthus viridis extract. The activity of photodegradation of MB was investigated using Fe3O4/rGO/TiO2 photocatalyst with various concentration. The X ray diffraction showed that Fe3O4 has an inverse cubic structure, TiO2 has a tetragonal structure, and low intensity rGO peaks at around 18 degrees. SEM/EDX confirmed the formation of Fe3O4/rGO/TiO2 with concentration of 5:1:1, which is dominated by Fe and O rather than C and Ti. Uv vis spectroscopy showed the bandgap values of Fe3O4, rGO, Fe3O4/rGO, and Fe3O4/rGO/TiO2 were 3.06, 4.06, 3.19, and 3.23 eV respectively. The highest degradation efficiency reached 98%. The addition of Fe3O4 simplifies the separation process. The presence of rGO and TiO2 makes the photoexcited electron-hole pairs increase and reduce the recombination process. Moreover, because it uses the green synthesis method, it will not be harmful to the environment. Therefore, Fe3O4/rGO/TiO2 has great potential in photocatalysis for water purification.

Keywords: Green-synthesized- Nanoparticles- Photocatalyst- Methylene blue

Topic: Magnetism and Photonics