Our study synthesized La(OH)₃ decorated co-graft tannin and polyethyleneimine (PEI) co-coating magnetic composites (La@TP@Fe₃O₄). Dual organic modification with co-grafted tannin and PEI can significantly enhance the material's charge density, allowing La@TP@Fe₃O₄ to maintain a high phosphate adsorbability at a wide pH range (3.0–11.0). La@TP@Fe₃O₄ achieved a maximum theoretical phosphate adsorption capacity of 363.64 mg/g at 25 °C under pH 3.0 and was consistent with the Langmuir model, reaching adsorption equilibrium in 20 min. Phosphate adsorption was less affected by various coexisting ions with >90% of phosphate removal maintained after five cycles. La@TP@Fe₃O₄ could be quickly separated by magnetic force with negligible La and Fe leakages. Besides electrostatic attraction, inner-sphere complexation and weak precipitation contributed to phosphate uptake on La@TP@Fe₃O₄, as demonstrated by X-ray absorption near edge structure (XANES) analysis. Importantly, low La@TP@Fe₃O₄ doses could quickly decrease phosphate concentrations in natural water and wastewater to meet regulatory requirements, thus highlighting the potential applicability of La@TP@Fe₃O₄ for phosphate removal.

我们的研究合成了La(OH) ₃修饰的共接枝单宁和聚乙烯亚胺(PEI)共涂层磁性复合材料(La@TP@Fe ₃ O ₄ )。共接枝单宁和PEI的双重有机改性可以显着提高材料的电荷密度，使La@TP@Fe ₃ O ₄在较宽的pH值范围（3.0-11.0）下保持较高的磷酸盐吸附能力。La@TP@Fe ₃ O ₄在 25 ℃、pH 3.0 条件下的最大理论磷酸盐吸附容量为 363.64 mg/g，与 Langmuir 模型一致，在 20 min 内达到吸附平衡。磷酸盐吸附受各种共存离子的影响较小，>90%五次循环后保持磷酸盐去除。La@TP@Fe ₃ O ₄可以通过磁力快速分离，La和Fe泄漏可忽略不计。X射线吸收近边缘结构（XANES）分析表明，除了静电吸引外，内球络合和弱沉淀有助于La@TP@Fe ₃ O _{4对磷酸盐的吸收。}重要的是，低剂量的 La@TP@Fe ₃ O ₄可以快速降低天然水和废水中的磷酸盐浓度以满足法规要求，从而突出了 La@TP@Fe ₃ O ₄在去除磷酸盐方面的潜在适用性。