Preparation of a novel sludge-derived biochar by K2FeO4 conditioning to enhance the removal of Pb2+

Abstract In this study, three types of sludge-derived biochars (BC1, BC2 and BC3) were prepared by 1) original sludge, 2) sludge after K2FeO4 conditioning, and 3) sludge after acidification + K2FeO4 conditioning. The results show that the biochar prepared from the conditioned sludge has additional functional groups, and its Pb2+ removal effect is greatly enhanced. The concentration of Pb2+ in the effluent can be reduced to