Metal-organic framework modified pine needle-derived N, O-doped magnetic porous carbon embedded with Au nanoparticles for adsorption and catalytic degradation of tetracycline

Pine needles (PNs) were used as a biomass precursor to fabricate N, O-doped magnetic porous carbon frameworks (PN−MPC) after modification with metal-organic frameworks (MOFs) and carbonization. And PN−MPC catalysts embedded with Au nanoparticles (Au/PN−MPC) were fabricated by a facile two-step route involving impregnation and subsequent thermal reduction procedures. The crystal structures, morphologies, chemical component, and microstructure of the Au/PN−MPC catalysts were initially investigated through various physicochemical characterization. Au/PN−MPC900 exhibited outstanding catalytic activity toward tetracycline (TC) degradation in the presence of H2O2, with a degradation efficiency and degradation rate constant of 96% and 0.133 min−1 within initial 10 min, respectively. The effects of operating parameters, including initial pH, temperature, catalyst dosage, initial concentrations of TC, and H2O2 concentration on TC degradation were comprehensively investigated. The superior mineralization performance and pH tolerance abilities and catalytic stability of Au/PN−MPC900 were also discussed. After seven consecutive cycles, the removal efficiency of Au/PN−MPC900 for TC degradation was not only greater than 82%, but also exhibited excellent reusability performance. Furthermore, ·OH radicals were confirmed as the dominant reactive species roles for the degradation of antibiotic pollutants through EPR and ·OH−trapping fluorescence spectral tests, and a plausible catalytic degradation mechanism was proposed. Correspondingly, several possible degradation pathways of TC were tentatively proposed on the basis of the degradation intermediates identified by HPLC-MS measurements. Overall, this novel biomass-derived magnetic porous carbon material embedded with Au nanoparticles is highly promising for many applications, especially in the field of environmental remediation.