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研究报告

The adsorption of phosphate on a novel Fe-Cu-Al trimetal oxide: Behavior and mechanism

摘要：采用共沉淀法制备了一种新型铁铜铝三元复合氧化物吸附剂，系统研究了其对磷的吸附行为，并对吸附磷前后的吸附剂进行了表征.吸附实验结果表明，铁铜铝三元复合氧化物对磷具有优异的吸附去除效能，Freundlich吸附等温线模型能更好地拟合其对磷的吸附，最大吸附量为62.6 mg·g^-1（pH=7.0），显著高于多数文献报道的磷吸附剂；吸附速率较快，吸附动力学更符合Elovich模型；溶液pH对磷吸附有一定影响，随着pH的升高，磷吸附量降低，离子强度则影响不大；共存阴离子对磷吸附具有抑制作用，影响的大小顺序为SiO₃^2- > SO₄^2- > CO₃^2- > Cl^-，而共存阳离子Ca²⁺和Mg²⁺则对磷吸附略有促进作用.Zeta电位、红外谱图（FTIR）和X射线光电子能谱（XPS）表征分析表明，磷在铁铜铝三元复合氧化物表面发生了特性吸附，磷酸根主要通过取代复合氧化物表面的羟基形成内表面络合物而被吸附去除.溶出实验结果表明，当pH在5.0~8.5范围内，Fe³⁺、Cu²⁺、Al³⁺的溶出量均较低.由此可知，铁铜铝三元复合氧化物是一种具有良好应用前景的除磷吸附剂.

Abstract：A novel Fe-Cu-Al trimetal oxide adsorbent was fabricated via a facile co-precipitation process, assessed for effective phosphate adsorption, and was characterized by multiple techniques. The isotherm data was well fitted by the Freundlich model and the maximal adsorption capacity was 62.6 mg·g^-1 at pH 7.0, which outperformed the majority of phosphate adsorbents reported. The adsorption of phosphate was very fast and the Elovich model was more suitable for describing the kinetic data. The adsorption of P was pH-depended and the efficiency decreased with increasing pH; whereas ionic strength had little influence on the adsorption. Further, coexisting anion inhibited phosphate adsorption and the effects decreased in the order of SiO₃^2- > SO₄^2- > CO₃^2- > Cl^-. In contrast, coexisting cations Ca²⁺ and Mg²⁺ slightly enhanced phosphate adsorption. Results of Zeta potential, FTIR and XPS analysis indicate specific adsorption occurred at the aqueous phosphate/adsorbent interface. Phosphate was probably removed by replacing the hydroxyl groups on the surface of the adsorbent and forming inner-sphere complex. Leaching of Fe³⁺, Cu²⁺ and Al³⁺ was low at the pH range of 5.0~8.5. This further makes Fe-Cu-Al trimetal oxide a promising adsorbent for phosphate removal from water.