Adsorption and Fenton-like degradation of naphthalene dye intermediate on sewage sludge derived porous carbon

Abstract A sewage sludge derived porous carbon (SC), which was prepared by physicochemical activation and carbonization (600 °C), was applied for the adsorption and degradation of 1-diazo-2-naphthol-4-sulfonic acid (1,2,4-Acid) in the presence of H 2 O 2 and the performance was compared to that of pure Fe 3 O 4 magnetic nanoparticles (MNPs). The prepared SC showed mesoporous structure with magnetic property, which made it favorable for solid–liquid separation application. Further experiments revealed that SC had a higher adsorption capacity and degradation efficiency of 1,2,4-Acid than bare Fe 3 O 4 . The Langmuir and Freundlich model fitted the isotherm data and illustrated that the equilibrium adsorption amount of 1,2,4-Acid onto SC (95.1 mg g −1 ) was quadruple as large as that on Fe 3 O 4 (26.4 mg g −1 ). The subsequent degradation experiments were conducted at conditions (pH 5.0 in the presence of 15 mM H 2 O 2 ) with regard to 1,2,4-Acid degradation efficiency and metal ions leach. The 120 min's treatment in SC/H 2 O 2 system achieved 94% of 1,2,4-Acid (from 150 mg L −1 after adsorption equilibrium to 9 mg L −1 ) and 48.1% TOC reduction, far higher than the efficiency of 46% and 24.3% by using Fe 3 O 4 MNPs. Further analysis evidenced the co-catalytic effect of iron, carbon, silicon and aluminum, which existed in large quantities in sludge derived SC. The carbonaceous phase along with silica contributes to an increase in the dispersion of catalytic centers and an adsorbent to concentrate organic pollutant whereas the iron oxide as well as alumina provides the catalytic centers for a Haber–Weiss initiated reactions.