Preparation of sludge derived magnetic porous carbon and their application in Fenton-like degradation of 1-diazo-2-naphthol-4-sulfonic acid

A magnetic porous carbon containing Fe3O4 (FPC) has been synthesized by a novel activation and carbonization process of sewage sludge without extra addition of ferric ions. Properties of FPC carbonized at 600, 800 and 1000 °C were studied using N2 adsorption and desorption isotherms, X-ray diffraction (XRD), scanning electron microscopy (SEM) and vibrating sample magnetometer. The results indicate that FPC carbonized at 600 °C has a superior porous structure and high pore volume (0.504 mL/g). Further study found that Fe3O4 is dominating in the presence of iron in FPC carbonized at 600 °C. The resulting chars shows higher catalytic activity in 1-diazo-2-naphthol-4-sulfonic acid (1,2,4-Acid) oxidation than commercial Fe3O4 MNPs. The 1,2,4-Acid and TOC removal efficiency can reach 96.6% and 87.2% after 260 min Fenton-like treatment. The mechanism in FPC-H2O2 system may include a Haber–Weiss type reaction between the active sites (e.g. Fe3O4) in FPC and hydrogen peroxide.