N, O co-doping enhanced the ability of carbon/Fe composites for peroxymonosulfate activation to degrade sulfadiazine: The advantages of nitrate saturated MOFs as precursors

Using nitrate saturated metal–organic frameworks (MOFs) MIL-101-NH2(Fe) as precursors, N, O co-doped carbon/Fe composites (NOC/Fe-MIL) were synthesized by carbonization for activating peroxymonosulfate (PMS) to degrade sulfadiazine (SDZ). N and O species were doped into the carbon matrix by adsorbed nitrate, increasing the degradation rate of SDZ by 2.80 times compared to the original materials (NC/Fe-MIL). N, O co-doping not only increased the charge transfer rate on the materials surface, but also provided more pyridine N, CO groups and defects as main active sites for enhancing the adsorption to PMS indicated by DFT calculations, thus promoting the generation of O2− and 1O2 to degrade SDZ. More importantly, the NOC/Fe-MIL/PMS system still exhibited stable degradation performance in a wide pH range and in the presence of background anions, which can be used in a variety of complex water matrices and regenerated by heating, enabling it to be applied to practical wastewater treatment. This work will provide a general approach for preparing heteroatom modified materials and new insights for exploring critical roles of N and O species in PMS activation.