Biochar loaded on MnFe2O4 as Fenton catalyst for Rhodamine B removal: Characterizations, catalytic performance, process optimization and mechanism

In order to reduce the adverse environmental and health-related effects of dye, a series of MnFe 2 O 4 -wood flour biochar (MFO-WFB) carbonic materials was prepared by a simple one-step hydrothermal process for effective heterogeneous photo-Fenton degradation of Rhodamine B (RhB). Compared with MFO, MFO-WFB presented higher catalytic activity for the degradation of RhB. The enhanced catalytic activity of MFO-WFB was attributed to the introduction of WFB, which increased the specific surface area and reduced the aggregation of magnetic nanoparticles. The MFO-WFB catalytic performance was evaluated by varying the amount of WFB in the catalyst, the MFO-WFB catalytic dose, H 2 O 2 concentration, and pH. According to the results of a response surface methodology based on central composite design, the optimal conditions for RhB removal were 0.6 g/L MFO-WFB-1.0, 115 mM H 2 O 2 , and pH = 4.8. Through quenching experiments and electron spin resonance spectroscopy, hydroxyl radicals and superoxide radicals were shown to be the main active radicals for the catalyzed photo-Fenton degradation of RhB. A possible photo-Fenton catalysis mechanism was proposed based on the radical capture experiments and electron spin resonance (ESR) analysis. • Waste wood powder was used as a low-cost, environmentally friendly supports of heterogeneous catalysts. • MnFe 2 O 4 -WFB was used as a heterogeneous Fenton-like catalyst to efficiently degrade RhB. • Fe 2+ / Fe 3+ and Mn 2+ / Mn 3+ redox cycles contributed to the activity of MnFe 2 O 4 -WFB. • ESR experiments revealed hydroxyl radical and peroxide radicals as the main oxidative species. • The degradation of RhB was optimized by RSM based on CCD.