Photocatalytic activity of the novel triazine-based magnetic core–shell Cu nanocomposite for degradation of RhB and MB via air oxidation and Cr(VI) reduction

Abstract

This study examines the degradation of methylene blue (MB) and Rhodamine B (RhB) and also reduction of Cr(VI) from water via novel thiol-functionalized magnetic core–shell Fe3O4/MPTMS/Ligand and Fe3O4/MPTM/Ligand-Cu nanoparticles as recyclable photocatalysts. The structure and morphology of the synthesized compounds were confirmed by different techniques. Nanospherical particles were identified through FE-SEM, TEM and HR-TEM analysis. The oxidation states and also bonding type of different elements of nano compounds were recognized by XPS spectra. According to the PL spectra, the electron/hole recombination of Fe3O4/MPTMS/Ligand-Cu decreased in comparison with Fe3O4/MPTMS/Ligand. The investigation of the optical properties of the synthesized samples showed that optical band gap value decreased at each stage and was about 2.09 eV for Fe3O4/MPTMS/Ligand-Cu nanoparticles, which sufficiently absorbed visible light. The Fe3O4/MPTMS/Ligand and Fe3O4/MPTMS/Ligand-Cu nanoparticles were used to degrade MB and RhB dyes under sun and visible light irradiation without using external oxidation agent. According to the TOC results, more than 80 percent of dyes were decomposed to CO2. Based on the results of the scavenger tests, the hydroxyl radical could play a significant part in MB and RhB photocatalytic degradation and also reduction of Cr(VI) by Fe3O4/MPTMS/Ligand-Cu and Fe3O4/MPTMS/Ligand nanoparticles under visible and sun light irradiation. The excellent photoelectrochemical properties of Fe3O4/MPTMS/Ligand-Cu compared with Fe3O4/MPTMS/Ligand are in agreement with its higher photocatalytic activity for RhB and MB degradation and Cr(VI) reduction. Generally, the advantage of Fe3O4/MPTMS/Ligand-Cu and Fe3O4/MPTMS/Ligand nanoparticles is that they can be separated using an external magnet and used for subsequent reactions.