Design and synthesis of uniform defective carbon nanosheets via CoAl-layered double hydroxide interlayer confinement for boosting peroxymonosulfate activation with highly efficient degradation of antibiotics contaminants

The Carbon-catalyzed persulfate oxidation has recently obtained extensive attention owing to the economical, eco-friendly and continuable nature of carbon materials. However, the essence of active site, precise control of microstructure and defect sites as well as related catalytic degradation mechanism still remain mystery, impeding advancements of advanced oxidation process for wastewater treatment practice. Herein, the defective carbon nanosheets were fabricated by one-step confined pyrolysis of sodium benzoate intercalated CoAl-layered double hydroxide (SB-CoAl-LDH), which were used to activate peroxymonosulfate (PMS) for tetracycline (TC) oxidation in water. As a result, the optimized defective carbon nanosheets (SLC-700) catalysts with appropriate defect sites exhibited superior catalytic activity in SLC-700/PMS activation system, achieving 94.96 % of TC elimination within 60 min, which might be due to the larger specific surface area, abundant defect sites and rich oxygen-containing functional groups. Besides, the SLC-700/PMS activation system also possessed good catalytic stability under different degradation conditions (PMS dosage, pH, interference ions, actual water sample), evidencing its bright feasibility for practical applications. In addition, the reusability and biotoxicology of SLC-700 catalysts were investigated. At last, based on the radical quenching experiments and EPR results, the related degradation pathways, catalytic process mechanism and quantitative structure-activity relationship between specific surface area (defect sites) and TC removal efficiency were discussed. Overall, this work develops a novel method for preparing defective carbon-based materials, which provides a practical as well as high-efficiency way for antibiotic-polluted water remediation.