• 关键词：电吸附  磷酸盐  镧铁羟基氧化物  还原氧化石墨烯  晶格氧

• 基金项目：国家水体污染控制与治理科技重大专项（No.2018ZX07110）；国家自然科学基金项目（No.51778054）

• 于洁
• 河北大学生命科学与绿色发展研究院, 生态与环境治理研究所, 保定 071002

• 王洪杰
• 河北大学生命科学与绿色发展研究院, 生态与环境治理研究所, 保定 071002

• 吉庆华
• 清华大学环境学院, 环境模拟与污染控制国家重点联合实验室, 水质与水生态研究中心, 北京 100084

• 向超
• 河北大学生命科学与绿色发展研究院, 生态与环境治理研究所, 保定 071002

• 摘要：污水处理厂尾水中低浓度PO₄^3-的排放是水体中总磷的主要来源，是导致水体富营养化的重要原因之一，对其开展深度去除的应用基础性研究具有重要的理论意义和实践价值.复合金属氧化物材料表现出较好PO₄^3-吸附能力，但仍然存在吸附速率较慢的问题.本研究采用溶剂热、复合薄膜压片法制备了镧铁羟基氧化物（LaFeO_xH_y）修饰还原氧化石墨烯（rGO）复合电极材料（LaFe-rGO），LaFe-rGO复合电极材料显著提高了对PO₄^3-的吸附速率，5 min可达到吸附平衡，在1.2 V电压下对PO₄^3-的最大吸附量为108.69 mg·g^-1.提出了基于晶格氧提供活性位点及LaFe-rGO双电层电容电促吸附除磷机理，LaFe-rGO复合电极材料中晶格氧La-O与Fe-O同时对PO₄^3-吸附提供吸附位点，PO₄^3-与材料中的La/Fe键合以形成内球表面复合物La/Fe-PO₄，掺杂在rGO表面上的LaFeO_xH_y增加了电极材料电容并提高了其电化学活性，促进了LaFe-rGO复合电极材料对PO₄^3-的吸附.

• Abstract：The discharge of low concentration PO₄^3- in effluent from WWTP is the main source of total phosphorus in water and one of the important causes of eutrophication. It has great theoretical and practical significance for the research on deep PO₄^3- removal. Metal oxide composites exhibit excellent PO₄^3- adsorption capacity, but poor adsorption kinetics. In this work, a LaFe (oxy)hydroxide-decorated rGO (LaFe-rGO) was synthesized by solvothermal-film pressing method. The adsorption kinetics of PO₄^3- by the LaFe-rGO electrode was significantly improved. The equilibrium adsorption can be reached in 5 min and the maximum adsorption capacity of LaFe-rGO for phosphate was 108.69 mg·g^-1 (1.2 V). Mechanism study showed that the electro-promoted adsorption mechanism was due to active sites provided by lattice oxygen of LaFeO_xH_y and double-layer capacitance of LaFe-rGO:PO₄^3- was bonded with La/Fe through the formation inner-sphere surface complexation La/Fe-PO₄. Furthermore, the LaFeO_xH_y on rGO increases the capacitance of the electrode and improves its electrochemical activity, which promotes the PO^3- ₄ adsorption performance.

• Key words：electro-sorption  phosphate  LaFe (oxy)hydroxide  reduced graphene oxide  lattice oxygen

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