3D network structure graphene hydrogel-Fe3O4@SnO2/Ag via an adsorption/photocatalysis synergy for removal of 2,4 dichlorophenol

Abstract

In this study, a core-shell design of Fe3O4@SnO2 was prepared, doped with silver nanoparticles (Fe3O4@SnO2/Ag) and later laden into three-dimensional graphene oxide hydrogel (rGH) forming 10% rGH-Fe3O4@SnO2/Ag, which was synthesized using chemical reduction methods and utilized in the degradation of 2,4 dichlorophenol as a target pollutant in the solution. Fourier Transform Infrared Spectroscopy/FTIR spectra, Raman spectroscopy, Brunauer-Emmett-Teller, X-ray photoelectron spectroscopy, X-ray diffraction, Photoluminescence spectra, Field Emission Scanning Electron Microscopy and Transmission Electron Microscopy were some of the standardized characterization techniques utilized. 2,4 dichlorophenol (2,4-DCP) was quickly adsorbed by three-dimensional 10% rGH-Fe3O4@SnO2/Ag composite and rapidly degraded by Fe3O4@SnO2/Ag nanoparticles under sunlight irradiation, indicating that superb synergies between adsorption-photocatalysis degradation could significantly improve the pollutant degradation performance. The maximum adsorption capacity of 10% rGH-Fe3O4@SnO2/Ag was 14.90 mg/g after 30 min. According to the results, the percent degradation efficiency of 2,4-DCP in Fe3O4@SnO2/Ag-rGH was not only high i.e. 93.8% via the synergy amongst adsorption-photocatalytic degradation, but also the percent degradation efficiency of 2,4-DCP was 85% after 5 repetitive cycles, which signified a high synergistic effect between Fe3O4@SnO2/Ag nanoparticles and 3D graphene. A corresponding pathway for 2,4-DCP photodegradation was suggested, such as 2,4 -dichlorophenol, formic, acetic, or oxalic acid as the main intermediate compounds. The experimental results of radical species trapping showed the photo-generated holes exhibiting an important role in promoting both direct oxidation of 2,4-DCP and production of ·O2 radicals. Therefore, 10% rGH-Fe3O4@SnO2/Ag composite revealed that it has a photocatalyst with high degradation activity, facile recyclability and easy magnetic separation for its potential wide application in the water treatment.