Highly cadmium and lead adsorption performances of magnesium-rich nitrogen-self-doped keratin-based biochar

Cadmium (Cd) and lead (Pb) pollution are significant environmental issues. Metal- and heteroatom-co-doped biochar demonstrated enhanced characteristics and adsorption performance compared to the original biochar. Therefore, magnesium-rich nitrogen-self-doped keratin-based biochar (MNBCs) was developed for the adsorption of Cd and Pb in this study. The incorporation of magnesium increased pH levels, specific surface area, and pore volume. The experimental results showed that MNBC3 exhibited maximum adsorption capacities of 295.63 mg·g −1 for Cd and 640.48 mg·g −1 for Pb. The adsorption processes of Cd and Pb on MNBCs followed the pseudo-second-order kinetic model and the Langmuir isotherm model. The formation of Mg 3 (OH) 5 Cl·4H 2 O and MgO in MNBCs enhanced ion exchange and precipitation of Cd(OH) 2 and Pb 3 (CO 3 ) 2 (OH) 2 . FTIR and XPS analyses confirmed the participation of oxygen- and nitrogen-containing functional groups in surface complexation reactions with Cd and Pb. In summary, the adsorption mechanisms of cadmium and lead by MNBCs mainly include pore filling, ion exchange, precipitation, and functional group complexation. The results of this experiment provide references for the resource utilization of waste chicken feathers and the remediation of heavy metal-polluted water.