Reducing input of phosphorus is the key step for control of eutrophication and algal blooming in freshwater lakes. Adsorption technology is a cost-effective technology for phosphate removal in water for the purpose. Thus, in this study, a novel Fe–Mn–La tri-metal composite sorbent was developed, and then evaluated for phosphate removal. The results showed that the maximum adsorption capacity could be approached to 61.80 mg g−1 at 25°C under pH of 6.03. Adsorption of phosphate by Fe–Mn–La tri-metal composite adsorbent fitted better by pseudo-second-order kinetic equation and Langmuir model, which suggested that the adsorption process was surface chemical reactions and mainly in a monolayer coverage manner. The thermodynamic study indicated that the adsorption reaction was an endothermic process. The phosphate removal gradually decreased with the increasing of pH from 3.02 to 11.00. The sequence of coexisting anions competing with phosphates was that CO32− > Cl− > SO42− > NO3−. Dissolved organic matter, fulvic acid as a representative, would also decrease adsorption capacities of phosphate by Fe–Mn–La tri-metal composite adsorbents. Adsorption capacity would be decreased with increasing addition of adsorbents, while removal efficiency would be increased in this process. The Fe–Mn–La tri-metal composite adsorbent showed a good reusability when applied to removal of dissolved phosphate from aqueous solutions. The Fourier transform infrared spectrometer and X-ray photoelectron spectroscopy analyses indicated that some hydroxyl groups (–OH) on the surface of adsorbent were replaced by the adsorbed PO43−, HPO42−, or H2PO4−. Aggregative results showed that the novel Fe–Mn–La tri-mental composite sorbent is a very promising adsorbent for the removal of phosphate from aqueous solutions.

中文翻译：

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Fe-Mn-La三金属复合吸附剂吸附去除磷酸盐：吸附能力、影响因素和机理

减少磷的输入是控制淡水湖泊富营养化和藻华的关键步骤。吸附技术是一种以去除水中磷酸盐为目的的经济有效的技术。因此，在本研究中，开发了一种新型的 Fe-Mn-La 三金属复合吸附剂，然后评估其去除磷酸盐的能力。结果表明，在 25°C、pH 值为 6.03 的条件下，最大吸附容量可接近 61.80 mg g-1。Fe-Mn-La三金属复合吸附剂对磷酸盐的吸附符合拟二级动力学方程和Langmuir模型，表明吸附过程为表面化学反应，主要以单层覆盖方式吸附。热力学研究表明吸附反应是一个吸热过程。随着pH值从3.02增加到11.00，磷酸盐去除率逐渐降低。共存阴离子与磷酸盐竞争的顺序是 CO32->Cl->SO42->NO3-。以富里酸为代表的溶解有机物也会降低 Fe-Mn-La 三金属复合吸附剂对磷酸盐的吸附能力。随着吸附剂添加量的增加，吸附能力会降低，而在这个过程中去除效率会增加。Fe-Mn-La 三金属复合吸附剂在去除水溶液中溶解的磷酸盐时表现出良好的可重复使用性。傅里叶变换红外光谱仪和 X 射线光电子能谱分析表明，吸附剂表面的一些羟基 (-OH) 被吸附的 PO43-、HPO42- 或 H2PO4- 取代。