Enhanced Cd removal from aqueous solution by biologically modified biochar derived from digestion residue of corn straw silage

Biologically modified biochars derived from digestion residue of corn straw silage at different pyrolysis temperature (300-700 degrees C) were prepared for removing Cd from water. Compared with the pristine biochar derived from corn straw (CB), transabdominal transformation of corn straw silage (TCB) significantly increased surface area (4.24-56.58 m(2) g(-1)), oxygen-containing functional group (C-O-C, Mg-O, Si-O) and mineral components (CaCO3, KCl). The sorption isotherms could be well described by Langmuir model, the kinetic data was best fitted by the Pseudo second order model. The maximum sorption capacity (Qm) obtained from Langmuir model for TCB700 (175.44 mg g(-1)) was 3 times of CB700 (56.82 mg g(-1)). Precipitation with minerals, ion exchange and complexation with oxygen-containing functional groups were the main mechanisms of Cd(II) sorption on TCB. These results imply that biologically modified biochar derived from digestion residue of corn straw silage at >= 600 degrees C is an effective sorbent for Cd removal from water. (C) 2019 Elsevier B.V. All rights reserved.