Enhanced persulfate degradation of PAH-contaminated sediments using magnetic carbon microspheres as the catalyst substrate

The advanced oxidation process (AOP) is a promising remediation technology for persistent organic pollutants in the environment. We herein investigated the ability of a magnetic carbon microsphere (CM)-based composite catalyst (Fe3O4-CM) to catalyze sodium persulfate (Na2S2O8, SPS) for the remediation of marine sediments contaminated with polycyclic aromatic hydrocarbons (PAHs). The effectiveness of the process parameters, catalyst dose, and initial pH were investigated. Using the optimized conditions, 87% of the PAHs were removed in the Fe3O4-CM/PS system within 24 h, compared with 59% and 41% in the case of persulfate (PS) and CM/PS (PS concentration = 1.3 x 10(-5) M, catalyst concentration = 5.0 g/L, pH = 6.0) alone. The PAH reduction rate can be attributed to the uniform graphitic structure of Fe3O-CM, which serves as an effective matrix for PAH degradation by providing additional active sites. The degradation of the PAHs was related to the number of rings in their structure, as confirmed by the higher degradation efficiency observed for high aromatic ring PAHs (HPAHs). Thus, we herein demonstrated the CM-mediated electron transfer catalysis of the surface functional groups at circumneutral pH values in the Fe3O4-CM/PS system to the highly efficient removal of PAHs from contaminated sediments. (C) 2019 Published by Elsevier B.V. on behalf of Institution of Chemical Engineers.