四种植物材料对废水中铅离子的吸附特征

为解决重金属废水处理问题，寻找高效低成本的生物吸附剂，本文选用了野菊杆（Dendranthema indicum， DI）、艾杆（Artemisia argyi， AA）、薄荷杆（Mentha haplocalyx， MH）和柠檬皮（Citrus limon， CL）四种植物材料对水中铅离子进行吸附研究。并利用SEM、BET和FTIR对材料进行表征，探讨了吸附剂投加量、溶液初始pH和共存阳离子对吸附量的影响。结果表明，四种材料对模拟废水中铅的吸附量随投加量的增加呈对数下降（P<0.05）；随初始pH的升高，四种材料呈现先增加后逐渐趋于稳定的趋势。准一级动力学能更好地描述野菊杆对Pb²⁺的动力学吸附过程，准二级动力学能更好描述艾杆、薄荷杆和柠檬皮对Pb²⁺的动力学吸附过程。野菊杆和艾杆对铅的吸附是以化学吸附为主的单层吸附，符合Langmuir模型；薄荷杆和柠檬皮对铅的吸附过程主要为不规则的多分子层吸附，更符合Freundlich模型。共存阳离子Mg²⁺、Cu²⁺、Al³⁺与Pb²⁺产生竞争吸附，显著降低材料对Pb²⁺的吸附量（P<0.05）。四种植物材料吸附性能大小顺序为薄荷杆 > 艾杆 > 柠檬皮 > 野菊杆。因此，四种植物材料是吸附废水中铅离子的潜在材料。

Adsorption Characteristics of Lead Ions in Wastewater by Four Plant Derived Materials

In order to solve the problem of wastewater treatment with respect to heavy metals and find high-efficiency and low-cost biosorbent, four materials derived from the stems of Dendranthema indicum (DI), Artemisia argyi (AA), and Mentha haplocalyx (MH), and the peel of Citrus limon (CL), were selected to study the adsorption of lead ions in water. SEM, BET, and FTIR were used to characterize the materials, and the effects of absorbent dosage, initial pH and coexisting cations on the adsorption quantity were discussed. The lead adsorption capacities of four materials in simulated wastewater decreased logarithmically with increasing dosages (P<0.05), and increased firstly and then stabilized gradually with increasing solution pH. Pseudo first order kinetic described the dynamic adsorption process of Pb²⁺ by the stem of Dendranthema indicum more suitable than other models, while pseudo second order kinetic described such process more better for the stems of Artemisia argyi and Mentha haplocalyx, and the peel of Citrus limon. The adsorption of Pb²⁺ by the stems of Dendranthema indicum and Artemisia argyi is a single-layer adsorption mainly based on chemical adsorption, which follows by the Langmuir model. The adsorption of Pb²⁺ by the stem of Mentha haplocalyx and the peel of Citrus limon, is mainly irregular multi-molecular layer adsorption, that suitable with the Freundlich model. Coexisting cations, including Mg²⁺, Cu²⁺, and Al³⁺, generated competitive adsorption with Pb²⁺ in the adsorption process, thus significantly reduced the adsorption amount of Pb²⁺ on the materials (P<0.05). The adsorption capacity of the four plant materials is MH > AA > CL >DI. Therefore, four plant materials have the potential for adsorbing lead ions in wastewater.