A novel porous biochar-supported Fe-Mn composite as a persulfate activator for the removal of acid red 88

Abstract

In this study, a novel porous biochar-supported Fe-Mn composite (Fe-Mn@BC) was prepared as an effective persulfate (PS) activator for the removal of acid red 88 (AR88). Bimetallic Fe-Mn oxides was supported by biochar to prevent agglomeration of metal oxides nanoparticles and provide more active sites for PS activation. The results showed that bimetallic Fe-Mn oxides were evenly dispersed on the surface of biochar (BC), due to its high specific surface area (1570 m2/g) and hierarchical porous structure. Fe-Mn@BC + PS showed a high removal rate of 98.84% for AR88, compared with that of Fe-Mn + PS (80.4%) and BC + PS (78.6%). The synergistic mechanism in Fe-Mn@BC for the enhanced PS activation was studied. Moreover, the reaction rate constant of Fe-Mn@BC + PS for the removal of AR88 was 0.03814 min−1, indicating a fast reaction rate for AR88 removal. The optimal dosages of Fe-Mn@BC and PS were 1 g/L and 2 g/L, respectively. The possible degradation pathways of AR88 were also proposed under the optimal conditions in the Fe-Mn@BC + PS system. The results demonstrate that Fe-Mn@BC is a promising catalyst for PS activation to remove AR88 with high stability and reusability.