Enhanced degradation of organic dyes by peroxymonosulfate with Fe3O4-CoCO3/rGO hybrid activation: a comprehensive study

• Synergistic effects of Fe 3 O 4 , CoCO 3 , and rGO provide excellent PMS activation • 1 O 2 and SO 4 • − were identified as the predominant ROS for RhB degradation • Comprehensive study on the effect of environmental factors on RhB degradation • PMS activation mechanism and RhB degradation pathway were proposed Peroxymonosulfate (PMS) activation emerges as a very promising technology for the decomposition of recalcitrant in wastewater and it is necessary to understand the mechanisms of PMS activation and organic decomposition for the development of effective catalysts. Fe 3 O 4 -CoCO 3 /rGO was synthesized through a one-step solvothermal method, characterized by various surface analyses (e.g., XRD, SEM, EDX, TGA, FTIR, BET, VSM, and Raman), and applied for Rhodamine B (RhB) removal via PMS activation. Several degradation products were identified by mass spectrometry, and the degree of mineralization was estimated through total organic carbon analysis. The Fe 3 O 4 -CoCO 3 /rGO/PMS system exhibits excellent RhB removal efficiency of 98.69% within a short time of 180 s, where the rate constant (1.427 min −1 ) was much higher than that of Fe 3 O 4 (0.0241 min −1 ), CoCO 3 (0.626 min −1 ), and rGO (0.01726 min −1 ). The synergistic effect of Fe 3 O 4 , CoCO 3 , and rGO effectively enhanced the removal of RhB due to its efficient generation of reactive oxygen species (ROS). In which, 1 O 2 and SO 4 • − were identified as the predominant ROS in the Fe 3 O 4 -CoCO 3 /rGO/PMS system via radical quenching experiments. The presence of rGO reduced the leaching of Fe and Co about 2 times (0.38 and 0.54 mg/L, respectively) after 4 consecutive cycling tests with the RhB removal efficiency of above 90%. This study shows that Fe 3 O 4 -CoCO 3 /rGO is an effective catalyst over a wide pH range from 3 - 10 for PMS activation to degrade organic pollutants. Graphical Abstract .