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 <0.06 μg/L. The original sludge-derived biochar can only remove at most 58.02% of Pb²⁺. The maximum adsorption capacity of BC3 is six times greater than that of BC1. The ion exchange effect of Ca²⁺ and Mg²⁺ on the biochar surface and the complexation of free -OH or -COOH functional groups lead to an excellent adsorption effect on Pb²⁺. The sludge-derived biochar prepared after the conditioning of K₂FeO₄ can realize efficient removal of Pb²⁺, providing new initiatives for subsequent sludge resource utilization.