An enhancement of singlet oxygen generation from dissolved oxygen activated by three-dimensional graphene wrapped nZVI-doped amorphous Al species for chloramphenicol removal in the Fenton-like system

Abstract

Three-dimensional graphene wrapped nZVI-doped amorphous Al species (3D-GN@Fe/a-Al) was fabricated as a novel Fenton-like catalyst for efficient removal of chloramphenicol (CAP) within a wide pH range. The mechanism of singlet oxygen (1O2) generation from dissolved oxygen (DO) activated by 3D-GN@Fe/a-Al was discovered. 3D-GN@Fe/a-Al was characterized by field emission scanning electron microscopy combined with an energy dispersive spectrometer (SEM-EDS), Brunner–Emmet–Teller (BET) measurement, X-ray diffraction (XRD) pattern and Raman spectroscopy to investigate the morphological and physicochemical properties. The catalytic performance of 3D-GN@Fe/a-Al for DO activation was estimated by the factor experiments of CAP degradation, including CAP concentration, catalyst dose, reaction temperature and pH value. Based on the evolution of the ultraviolet spectrum during the reaction and the results of high performance liquid chromatography-mass spectrometry (HPLC-MS) detection, the degradation pathway of CAP in the 3D-GN@Fe/a-Al–DO system was proposed. More importantly, the generation of singlet oxygen from DO activation mediated by the Al3+-promoted single electron delivery was further explored by the experiments of scavengers, electron spin resonance spectroscopy (ESR), X-ray photoelectron spectroscopy (XPS) analysis and electrochemical tests. The mechanism of 1O2 generation provides a new strategy for improving the degradation of organic pollutants in water by Fenton-like systems.