Ferric nitrate/dopamine/melamine-derived nitrogen doped carbon material as the activator of peroxymonosulfate to degrade sulfamethoxazole

Nitrogen-doped carbon materials can effectively activate peroxymonosulfate (PMS) to degrade organic pollutants. In this study, one or more of the following raw ingredients, ferric nitrate, dopamine hydrochloride and melamine, were used as raw materials to prepare different carbon-based catalysts. The different effects of each raw ingredient on the performance of the catalyst were studied. Characterization by X-ray diffract grams spectra, Raman spectroscopy and X-ray photoelectron spectroscopy found that Fe(NO3)3·9H2O in the catalyst is beneficial to promote the degree of graphitization, and melamine can increase the nitrogen content in the catalyst. The prepared Fe-DA-CN catalyst, prepared with three materials has the highest activity. When the catalyst dose was 50 mg/L and the PMS concentration was 0.25 mM, the removal rate of 5 mg/L sulfamethoxazole (SMX) reached more than 99% after 30 min of reaction; furthermore, the pH, presence of inorganic anions (HPO42-, NO3–, CO32–, Cl-) and presence of humic acid had little effect on the SMX removal rate. Repeated use experiments show that the catalyst has good stability. Through electron paramagnetic resonance and quenching tests, it is found that the main active substances that activate PMS to degrade SMX are free radicals (·OH, SO4·-) bound on the catalyst surface and a small part of singlet oxygen (1O2).