FeCu-biochar enhances the removal of antibacterial sulfapyridine from groundwater by activation of persulfate

Waters are often polluted by antibacterial drugs such as sulfonamides, which are widely used in animal husbandry, aquaculture and other sectors. Actual decontamination methods are limited, thus requiring the development of alternative treatments. Here, we hypothesized that a composite of biochar-supported Fe/Cu (FeCu-biochar) would activate persulfate to remove the antibiotic sulfapyridine from aqueous solutions using batch experiments. FeCu-biochar was characterized by scanning electron microscopy with energy-dispersive spectroscopy (SEM-EDS) and X-ray diffraction (XRD). We tested the effect of catalyst type, initial pH and reusability runs. Results show that, compared to Fe-biochar, 1 g/L FeCu-biochar activated 4 mM persulfate better, removing 97.6% of 20 mg/L sulfapyridine in 5 min at pH 8.2. Such enhancement is attributed to the strong oxidization of (SO4-)-S-center dot, the high catalytic ability of CuO and synergistic effects between Fe and Cu. The removal of sulfapyridine by FeCu-biochar was pH-dependent, and the best catalytic performance occurred in alkaline conditions. FeCu-biochar also displayed excellent stability, easy separation and good recyclability.