高效镧铝双金属吸附剂的制备及其除磷机制研究

Preparation and phosphorus removal mechanism of a high-efficiency Lanthanum-Aluminum bimetallic adsorbent

摘要

【目的】磷是引起水体富营养化的关键限制性因子，高效除磷是治理富营养化的核心环节。针对现有吸附材料吸附容量低、再生困难等，本研究制备新型改性吸附剂，系统考察其对水中磷酸盐的去除效果及吸附机理。【方法】采用化学沉淀法，以氧化铝为载体、氢氧化镧为活性组分，制备了镧铝双金属吸附剂（La-Al）。通过静态吸附试验，系统比较了La-Al、氢氧化镧及氧化铝对水中磷酸盐的去除性能，并探究了La-Al吸附磷酸盐的动力学、等温线、热力学特征，以及pH和共存离子的影响。此外，评估了La-Al的循环使用性能及其在实际水体中的除磷效果。【结果】La-Al对磷酸盐的吸附行为符合准二级动力学模型和Langmuir等温模型，最大吸附容量可达122.73 mg·g^-1，远高于商业氧化铝。该材料在pH 3~9范围内均保持高效吸附，且对常见阴离子表现出良好的抗干扰能力。经过6次NaOH再生循环后，La-Al仍能维持初始吸附容量的100%，显示出优异的再生稳定性。表征分析表明，其吸附机制主要包括静电吸引与配体交换。【结论】La-Al对磷酸盐具有强亲和力且具备优异的应用性能，为水体中磷污染控制提供了一种具有潜力的技术途径。

Abstract

[Objective] Phosphorus is the key limiting factor driving water eutrophication, and this makes efficient phosphorus removal a critical requirement for eutrophication control. To address the limitations of conventional adsorbents, including low adsorption capacity and poor regenerability, this study synthesized a novel modified adsorbent and systematically evaluated its phosphate removal performance in aqueous media and the underlying adsorption mechanism. [Method] A Lanthanum-Aluminum bimetallic adsorbent (La-Al) was prepared via chemical precipitation, using alumina as the carrier and lanthanum hydroxide as the active component. Static adsorption experiments were conducted to systematically compare the phosphorus removal performances of La-Al, lanthanum hydroxide, and alumina. Furthermore, the kinetic, isothermal, and thermodynamic characteristics of phosphate adsorption by La-Al were investigated, along with the effects of pH and coexisting ions. In addition, the cyclic reusability of La-Al and its phosphorus removal efficiency in actual water bodies were evaluated. [Result] The phosphate adsorption behavior of La-Al conformed to the pseudo-second-order kinetic model and Langmuir isotherm model, with a maximum adsorption capacity of 122.73 mg·g^-1, which was much higher than that of commercial alumina. The adsorbent maintains high adsorption efficiency over a pH range of 3-9 and exhibited excellent resistance to interference from common anions. After six regeneration cycles with NaOH, La-Al retained 100% of its initial adsorption capacity, demonstrating outstanding regeneration stability. Characterization analysis indicated that the adsorption mechanism mainly involves electrostatic attraction and ligand exchange. [Conclusion] La-Al possesses strong affinity for phosphate and excellent application performance, providing a promising technical approach for phosphorus pollution control in water bodies.

关键词

富营养化 / 双金属 / 磷酸盐 / 吸附 / 改性材料

Key words

eutrophication / bimetallic adsorbent / phosphate / adsorption / modified material

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基金资助

国家自然基金青年科学基金项目(42207067)

安徽农业大学 2022 教学研究基金项目(auxxkc005)