High selectivity and removal efficiency of lotus root-based activated carbon towards Fe(III) in La(III) solution

Rare earth elements are an important strategic resource. However, a trace of Fe(III) impurity has serious adverse impact on the performance of rare earth materials. We synthesized a novel nitrogen-containing carbon material, AC_LR-400, using lotus root as raw materials. The AC_LR-400 was characterized by surface area analyzer, elemental analysis and FT-IR. The selectivity and removal efficiency of AC_LR-400 towards Fe(III) were also investigated. The BET specific surface area of AC_LR-400 was 68.44 m²·g⁻¹, and the average pore diameter was 12.54 nm. With abundant nitrogen- containing functional groups and well-developed internal pore structure, AC_LR-400 possesses strong adsorption affinity, excellent selectivity and removal efficiency for Fe(III). The adsorption capacity of AC_LR-400 towards Fe(III) could reach to 0.46 mmol·g⁻¹, selectivity coefficient with respect to La(III) was 8.9, and removal efficiency was 99.61%. The adsorption isotherm data greatly obey the Freundlich isotherm. In addition, AC_LR-400 can be regenerated easily and possesses better regeneration ability and reusability.