Activated biochar from Co-hydrothermal carbonization of municipal sludge and enteromorpha for high-efficiency Pb(II) removal: Activation optimization and adsorption mechanism - Xinyuan Zhu; Youwei Zhi; Yue Zhang; Tonggui Liu; Snabal Ashraf; Donghai Xu; Guanyu Jiang; Yang Guo (Biomass and Bioenergy, 2026)