Rapid removal of high-concentration Rhodamine B by peroxymonosulfate activated with CoO-FeO composite loaded on rice straw biochar.

In this study, rice straw biochar modified with CoO-FeO (RSBC@CoO-FeO) was successfully prepared via calcinating oxalate coprecipitation precursor and employed as a catalyst to activate peroxymonosulfate (PMS) for the treatment of Rhodamine B (RhB)-simulated wastewater. The results indicated that RSBC@CoO-FeO exhibited high catalytic performance due to the synergy between CoO and FeO doping into RSBC. Approximately 98% of RhB (180 mg/L) was degraded in the RSBC@CoO-FeO/PMS system at initial pH 7 within 15 min. The degradation efficiency of RhB maintained over 90% after the fourth cycle, illustrating that RSBC@CoO-FeO displayed excellent stability and reusability. The primary reactive oxygen species (ROS) answerable for the degradation of RhB were O, •OH, and SO. Moreover, the intermediates involved in the degradation of RhB were identified and the possible degradation pathways were deduced. This work can provide a new approach to explore Co-based and BC-based catalysts for the degradation of organic pollutants.