Oil shale semi-coke (OSSC) was produced by low-temperature retorting of oil shale. We demonstrate that OSSC transition metal element iron and organic functional groups synergistically activate persulfate oxidation and degrade phenolics. Firstly, the acidified OSSC (OSSC-N) was characterized by SEM, XRF, XRD, EA, Raman, BET, XPS and FTIR. The results show that OSSC-N has a porous structure, and its surface contains transition metal (Fe) and organic matter composed of C, N and O. Secondly, the catalytic performance of OSSC-N was influenced by pH, Persulfate (PS) dosage, catalyst dosage, temperature, and inorganic ions. Under the optimized conditions of initial pH= 10, 1 g/L PS, and 3 g/L OSSC-N catalyst, the highest removal rates of phenol, o-cresol, and m-cresol reached 99.24 %, 98.56 %, and 99.38 % after 30 min of reaction, respectively. Through electron paramagnetic resonance (EPR) and quenching experiments, it was found that Fe and surface oxygen-containing functional groups in OSSC-N act as active sites to synergistically produce SO4 center dot-, center dot OH, singlet oxygen (1O2) and superoxide radical(center dot O2- ), in which electron transfer and 1O2 are the primary mechanisms for the degradation of volatile phenols in OSSC-N/PDS system. Finally, a heterogeneous activation mechanism through surface reaction was proposed. Volatile phenols was first adsorbed on the surface of OSSC-N and then oxidized by free radicals and non-radical substances. This work provides a new idea for reusing OSSC resources.
