Enhanced phenol removal by permanganate with biogas residue biochar: catalytic role of in-situ formation of manganese dioxide and activation of biochar

Increased biogas residue related to the rapid development of anaerobic fermentation has become an urgent environmental problem. The pyrolysis of biogas residue into biochar is one of the most promising treatments. In this study, biochar derived from biogas residue was prepared, and the degradation efficiency of phenol by permanganate (KMnO4) increased from 25.3% to 73.4% in 60 min in the presence of biogas residue biochar (BRB). KMnO4 reacted with BRB to produce intermediate manganese dioxide (MnO2), while BRB was activated. The specific surface area increased by 132.25%, and the oxygen-containing functional groups C=O, C-O, and COOH increased after the reaction. The generated MnO2 complexed with BRB to form MnO2@BRB. The newly formed MnO2@BRB catalyzed KMnO4 to remove phenol, which explains the high removal efficiency of phenol. A significant removal rate was also observed for antibiotics and chlorophenols, which suggested that the KMnO4/BRB system has a relatively high ability to oxidize organic pollutants. In addition, the co-existing metal ions and the natural environment had little influence on the removal efficiency of the KMnO4/BRB system. This work provides a novel technology for the resource utilization of biogas residue and improved organic pollutant removal efficiency of KMnO4 in the presence of BRB. Phenol removal was enhanced by permanganate (KMnO4) with biogas residue biochar (BRB).Manganese dioxide (MnO2) was generated and complexed with BRB to catalyze phenol removal by KMnO4.KMnO4/BRB system can be used for the removal of other organic pollutants.

Automated summary

Increased biogas residue is causing environmental concerns, and the pyrolysis of biogas residue into biochar is a promising solution. This study prepared biochar from biogas residue, which significantly improved the degradation efficiency of phenol when combined with permanganate (KMnO4). The reaction formed manganese dioxide (MnO2) and activated the biochar, resulting in enhanced removal of phenol and other organic pollutants. These findings provide a novel technology for biogas residue utilization and improved organic pollutant removal efficiency.