Fe@Fe2O3-loaded biochar as an efficient heterogeneous Fenton catalyst for organic pollutants removal

With increased demand for various chemical raw materials, sudden pollution incidents are more prone to occur during their transportation and usage, threatening the environment and human health. In this study, discarded tea stalks were recycled into composite materials (FSC-X00: X represents the calcination temperature) by impregnating tea stalks in Fe2+ solution combined with subsequent calcination. X-ray diffractometer (XRD) and X-ray photoelectron spectroscopy (XPS) patterns verified the existence of Fe-0 and Fe2O3, and Fe2O3 was gradually reduced to Fe-0 when the calcination temperature was raised from 700 degrees C to 900 degrees C. FSC-X00 was adopted as a heterogeneous catalyst for activating H2O2 to quickly degrade phenol in water system. The degradation experiments indicated that FSC-600 exhibited superior degradation performance for phenol (20 mg/L) within 5 min and 80% total organic carbon (TOC) removal rate at pH = 3 within 30 min. The effects of the calcination temperature, the pH value and the amount of H2O2 on the degradation efficiency were investigated. Competing experiments showed that fulvic acid (FA) and inorganic salts Na+ had little effect on the degradation performance. The FSC-600 catalyst can be reused by thermal reduction. In addition, it was found that FSC-600 has a good degradation effect on ciprofloxacin (CIP), norfloxacin (NOR) and enrofloxacin (ENR), indicating that FSC-600 catalysts are a promising candidate for quick degradation of organic pollutants by Fenton reaction. Electron paramagnetic resonance (EPR) spectra analysis indicated that center dot OH is the dominant reactive oxygen species (ROS) and part O-1(2) from O-2 also participated in the degradation. This study provides an example of creating catalysts from organic solid waste for use in emergency treatment for phenol.