Biochar facilitate the dispersion of nanoparticles and improve their adsorption capacity. Herein, we prepared a type of biochar-supported phosphate-doped ferrihydrite (P-FH@BC) for simultaneous uptake of Pb(II) and Ce(Ⅲ). P-FH@BC was prepared by mixing P-FH and biochar at different ratios, and the best ratio is 10:1. Acidic conditions inhibit the adsorption of Pb(Ⅱ) and Ce(Ⅲ) onto P-FH@BC, which was consistent with the result of zeta potential. The adsorption processes of Pb(Ⅱ) and Ce(Ⅲ) are competitive in the binary system. The pseudo-second-order kinetic can explain well the adsorption behavior of Pb(Ⅱ) and Ce(Ⅲ) on P-FH@BC, suggesting a complex chemical adsorption process. The adsorption of Pb(II) and Ce(III) by P-FH@BC included physical and chemical processes. The physical process was mainly contributed by electrostatic attraction and pore filling mechanism. The iron-containing groups, phosphorus-containing groups, oxygen-containing groups on the surface of P-FH@BC, as well as phosphate and iron oxide compounds mainly caused the chemical adsorption. Among them, phosphate, -OH and carbonate could combine with Pb and then form low solubility precipitates, such as Pb₃(PO₄)₂, Pb(OH)₂, etc., and iron-containing groups could adsorb Pb through ion exchange. The surface functional groups of P-FH@BC could also combine Pb through the surface complexation reaction. The chemisorption mechanism of Ce(III) by P-FH@BC is obviously different from that of Pb(Ⅱ). The adsorption of Ce(III) was mainly contributed by the phosphorus-containing groups on the surface of P-FH@BC due to the surface complexation. These results have important environmental implications for the simultaneous uptake of heavy metals and rare earth elements from solution.

生物炭有利于纳米颗粒的分散并提高其吸附能力。在此，我们制备了一种生物炭负载的磷酸盐掺杂水铁矿 (P-FH@BC)，用于同时吸收 Pb(II) 和 Ce(III)。P-FH@BC是将P-FH与生物炭按不同比例混合制备而成，最佳比例为10:1。酸性条件抑制了P-FH@BC对Pb(Ⅱ)和Ce(Ⅲ)的吸附，这与zeta电位结果一致。Pb(Ⅱ)和Ce(Ⅲ)的吸附过程在二元体系中具有竞争性。准二级动力学可以很好地解释Pb(Ⅱ)和Ce(Ⅲ)在P-FH@BC上的吸附行为，表明这是一个复杂的化学吸附过程。P-FH@BC对Pb(II)和Ce(III)的吸附包括物理和化学过程。物理过程主要由静电引力和孔隙填充机制促成。P-FH@BC表面的含铁基团、含磷基团、含氧基团以及磷酸盐和氧化铁化合物主要引起化学吸附。其中磷酸盐、-OH和碳酸盐可以与Pb结合形成低溶解度沉淀物，如Pb₃ (PO ₄ ) ₂、Pb(OH) ₂等，含铁基团可以通过离子交换吸附Pb。P-FH@BC的表面官能团也可以通过表面络合反应结合Pb。P-FH@BC对Ce(III)的化学吸附机理明显不同于Pb(II)。由于表面络合，Ce(III) 的吸附主要由 P-FH@BC 表面的含磷基团贡献。这些结果对于同时从溶液中吸收重金属和稀土元素具有重要的环境意义。