Biochar-Supported FeCo-MOF derivative catalyzes PDS-Mediated degradation of tetracycline

Bimetallic metal–organic framework (MOF) has gained wide attention in the field of advanced oxidative processes (AOPs), however, the agglomeration problem severely limits its active sites and its activation mechanism still needs to be further explored. This study developed the BC@CoFe composite material, utilizing biochar (BC) to support FeCo-MOF derivatives, effectively alleviating their agglomeration and structural collapse. The results of the BC@CoFe activated peroxydisulfate (PDS) system for the degradation of tetracycline (TC) revealed an excellent degradation efficiency up to 97.7 % in 2 h for TC solution (20 mg/L, degradation rate constants k = 7.066 mM-1min−1). Furthermore, the BC@CoFe/PDS system exhibits exceptionally high cyclic stability (73.23 % degradation efficiency after 12 h continuous degradation), a wide range of pH (3–11) and temperature tolerance (20-60℃), resistance to background ion interference (SO42-, H2PO4-, NO3– and HA), and reduced toxicity of the degradation products. X-ray photoelectron spectroscopy (XPS) and density functional theory (DFT) analyses show that the exceptional catalytic performance of BC@CoFe primarily stems from the synergistic effect between Fe(II)/Co(III) and Fe(III)/Co(II). Regarding the reactive active species involved in TC degradation, the contribution rates of 1O2, SO4•- and ·OH were measured and calculated to be 73.6 %, 14.9 %, and 11.5 %, respectively. Thus, the BC@CoFe/PDS system exhibits outstanding catalytic activity and has broad practical applications in water treatment.