Novel flower-like Fe-Mo composite for peroxydisulfate activation toward efficient degradation of carbamazepine

In this study, novel flower-like Fe-Mo composite material (composed of FeMoO4, FeS2 and Mo2S3, referred to as FMO-FS-MS) with dual active sites and synergistic catalytic effect was designed and successfully synthesized, which could activate peroxydisulfate (PDS) to efficiently degrade carbamazepine (CBZ). Due to Mo(IV) with higher activity could effectively improve the Fe(II)/Fe(III) cycle, the heterogeneous reaction activity was significantly increased. A number of significant affecting elements were explored, including catalyst dose, PDS concentration, pH value, reaction temperature, anion and humic acid (HA). The experimental results declared that FMO-FS-MS/PDS system could degrade 100 % CBZ within 30 min at pH = 6, suggesting excellent catalytic performance. The free radical scavenging experiments and electron paramagnetic resonance (EPR) results confirmed that the activation of PDS by FMO-FS-MS was a multi-reactive oxygen species process with the coexistence of SO4−, 1O2, O2−, and OH. Both Fe(II) and Mo(IV) on the FMO-FS-MS surface could activate PDS to generate ROS. Meanwhile, Mo(IV) could reduce Fe(III) with formation of Mo(VI) and Fe(II) on the FMO-FS-MS surface, eventually leading to an effective redox cycle of Fe(II) and Fe(III). Several CBZ intermediates were found and possible degradation pathways were suggested. Moreover, FMO-FS-MS showed excellent reusability and stability during PDS activation, and it had a high tolerance to background water and was an efficient catalyst for rapid and effective degradation of different organic pollutants. This study provides a new strategy and experimental basis for the development of catalysts for efficient PDS activation.