纳米羟基磷灰石纳米管的一种简便制备方法及其对溶液中重金属离子的吸附

采用简便的方法合成了20~40 nm长、56 m^2·g^-1的比表面积的羟基磷灰石纳米管(HAP)。然后用制备的HAP纳米管在水溶液中同时吸附Pb^2+、Cd^2+、Cu^2+、Co^2+、Ni^2+、Zn^2+和Hg^2+,其具有高的吸附能力,并能实现快速去除。此外,制备的HAP纳米管对7种重金属离子的脱附率均小于1%,表现出较强的稳定性。实验数据采用Langmuir等温线模型和Freundlich等温线模型进行分析。2个方程的应用结果表明,吸附平衡最适合Langmuir模型,单层饱和吸附能力为958.28 mg·g^-1,具有较好的吸附性能。通过能量色散X射线光谱(EDS)和X射线衍射(XRD)图进一步研究了吸附机理,结果表明,当溶液中Pb^2+离子数量足够时,吸附机理为Pb取代了HAP中的Ca,形成了更稳定的Pb5(PO4)3(OH)。上述实验研究预测了利用HAP纳米管处理含铅废水在环境污染治理中的可行性。

A Facile Method to Prepare Hydroxyapatite Nanotubes and Immobilization Activities Against Heavy Metal Ions in Solutions

Hydroxyapatite nanotubes (HAP NTs) were synthesized by a facile method, which were 20~40 nm in length and had a large surface area of 56 m²·g^-1. Then the prepared HAP NTs were employed to immobilize Pb²⁺, Cd²⁺, Cu²⁺, Co²⁺, Ni²⁺, Zn²⁺, and Hg²⁺ in aqueous solution and the as-prepared HAP NTs showed a high immobilization capacity. In addition, the desorption rate of the prepared HAP NTs on seven heavy metal ions were all less than 1%, which showed a strong stability. The experimental data was analyzed by the Langmuir and Freundlich isotherm models. The obtained results from the application of the two equations showed that the adsorption equilibrium was best fitted with a Langmuir model and monolayer adsorption capacity was 958.28 mg·g^-1, which showed a perfect immobilization property. The adsorption mechanisms were further studied by energy dispersive X-ray spectrum (EDS) and X-ray diffraction (XRD) patterns and the results showed that the adsorption mechanism was the dissolution of HAP NTs and the precipitation of a more stable Pb₅(PO₄)₃(OH) when the amount of Pb²⁺ ions in solution was sufficient. Our study confirmed the possibilities of using HAP NTs to treat Pb-contaminated wastewater in the environmental pollution management.