Preparation of magnetically recyclable hierarchical porous sludge-pine needle derived biochar loaded CoFe2O4 nanoparticles for rapid degradation of tetracycline by activated PMS

Porous biochar supported CoFe2O4 nanoparticles (CoFe2O4/BC) was successfully prepared using sludge and pine needle as carbon sources by hydrothermal method for activation of peroxymonosulfate (PMS) and degradation of tetracycline (TC). CoFe2O4/BC had outstanding performance with the TC degradation efficiency of over 90 % in only 5 min under the optimal reaction conditions. The excellent performance was attributed to the macroporous and mesoporous structures of CoFe2O4/BC, which provided a large surface area (101.83 m²/g) and effective dispersion of CoFe2O4 on BC. CoFe2O4/BC also had magnetic recovery (57.40 emu/g) and good stability. The structure and physical and chemical properties of the catalyst remained stable with the degradation efficiency of 96.39 % in 30 min after 5 cycles. Through EPR test, SO4•- was determined to be the decisive active free radical.