Synergistic impact of rice husk biomass derived carbon supports on the performance of biogenic Fe0-catalyzed advanced oxidation processes for oxytetracycline remediation†

Abstract

This study explores the use of rice husk biomass and its derived carbon materials—hydrochar (HC) and biochar (BC)—as supports for biogenic zerovalent iron (ZVI) nanocomposites (ZVI@RH, ZVI@HC, and ZVI@BC) in advanced oxidation processes (AOPs) for the degradation of oxytetracycline (OTC). The catalysts were characterized using FTIR, XRD, FESEM, and XPS techniques, and their performance in activating peroxymonosulfate (PMS) for OTC degradation was assessed. Results showed that the ZVI@BC nanocomposite outperformed ZVI@RH and ZVI@HC in OTC removal through heterogeneous Fenton-like processes. The addition of PMS further enhanced OTC degradation by generating more reactive oxygen species (ROS), making the process more efficient than the Fenton process alone. The higher surface defects in BC, resulting from pyrolysis, improved OTC adsorption and degradation, and facilitated more effective ZVI-mediated PMS activation in ZVI@BC, achieving nearly 98.3% OTC removal from the aqueous solution. The involvement of various ROS in OTC degradation was examined using radical scavengers, and DFT calculations proposed a degradation pathway by identifying ROS attack sites on the OTC chromophore. High-resolution mass spectrometry (HRMS) analysis was used to identify reaction intermediates. This study emphasizes the potential of using agricultural waste-derived materials in AOPs, presenting a sustainable and cost-effective method for environmental remediation and OTC antibiotic degradation.