Highly efficient degradation and detoxification of antibiotics over C–Dots/siderite heteroaggregates in photo-Fenton systems: The crucial role of C–Dots

Abstract

The substantial presence of antibiotics in aquatic environments remains as a critical environmental issue that needs to be urgently addressed. In this study, mimetics of C–Dots/siderite heteroaggregates (CSI) were studied in a visible-light-responsive Fenton system as a platform for the degradation of antibiotics in contaminated water. By virtue of the excellent electron transfer of C–Dots, the sustained conversion cycles of Fe(II) → Fe(III) → Fe(II) in CSI were greatly accelerated, and meanwhile the H2O2 utilization was enhanced. The optimized CSI–3 nanocomposite displayed a prominent degradation efficiency towards a series of tetracycline analogs at ppb levels. Density functional theory (DFT) calculations indicated the excellent photo-Fenton catalytic performance of CSI originated from the increased d-band center and electron density, which considerably improves the utilization of H2O2. Both experimental and theoretical studies revealed that the correlated toxicity of degradation intermediates was significantly decreased. Additionally, a continuous flow device integrating the CSI photo-Fenton system maintained a high degradation efficiency after long-term treatment of simulated chlortetracycline wastewater. The presented work thereby confirms a spontaneous remediation process for the decontamination and detoxification of persistent organic pollutants under the action of heteroaggregates formed by engineered nanoparticles and natural minerals.