Sorptive removal of cadmium from aqueous solution by modified biochar from sycamore wood.

In this study, biochar (BC) was produced from sycamore wood through a typical slow pyrolysis process and modified with sodium hydroxide (SBC), phosphoric acid (PBC), urea (UBC), and thiourea (TBC) at various concentrations. The BCs were characterized with scanning electron microscopy, surface area analysis, and elements analysis. The efficiency and mechanism of cadmium adsorption by SBC, PBC, UBC, and TBC from aqueous solution was investigated through a series of adsorption experiments. Results showed that the adsorption efficiencies of SBC and UBC were greater than those of TBC and PBC. They are also reasonable in terms of treatment costs and are ideal adsorbents. We can infer that chemical modification of BC changed their surface groups and structures and thus enhanced or reduced their adsorption properties.