玉米须吸附剂去除水溶液中Pb^(2+)的研究

Study on the Adsorption of Heavy Metal Pb^(2+) in Wastewater with Corn Silk

利用废弃物玉米须制备生物质吸附剂,研究其对废水中重金属Pb2+的吸附效果。考察体系pH值、Pb2+初始浓度、吸附剂添加量以及共存离子K+、Na+、Ca2+、Mg2+对吸附率的影响。结果表明:在25℃,玉米须吸附Pb2+的最佳pH值为4.0;吸附剂添加量为0.150g,金属初始浓度为40mg/L时,吸附率高达99%以上。其动力学数据符合准二级动力学模型,Langmuir-Freundlich模型成功拟合了平衡数据,由该模型所得吸附剂的最大吸附容量为68.533mg/g。利用Zeta电位仪、红外光谱仪和扫描电镜进一步探讨玉米须对重金属的吸附机理。结果表明:玉米须外表面遍布墙形褶皱,断面存在孔道,这有利于对Pb2+的吸附;当体系pH>2.0时,玉米须颗粒表面带负电,可以和Pb2+发生静电吸附;-COOH、-OH、-C=O等含氧官能团参与了吸附过程。

Corn silk collected from farmland was used as bio-adsorbents to remove the Pb^2＋ ions in aqueous solution.Effects of initial Pb2＋ ions concentration,solution pH,adsorbent dose and coexisting ions （K^＋,Na^＋,Ca^2＋,Mg^2＋） on the removal process of Pb2＋ were investigated.The peak percentage adsorption （〉99 %） of corn silk were attained at pH 4.0.The Langmuir,Freundlich and Langmuir-Freundlich models have been applied and results showed that the adsorption process was better described by the Langmuir-Freundlich model.The maximum adsorption capacities of corn silk obtained from Langmuir-Freundlich isotherm model were 68.533 mg/g.The adsorption kinetics experiments were carried out,and the obtained data were fitted by the pseudo-first-order equation and pseudo-second-order equation.The adsorption kinetics was studied to conform to the pseudo-second-order equation with a good correlation.FTIR analysis shown the importance of functional groups such as-OH,-COOH and-C=O during lead removal.A large number of folds on the outer wall observed from SEM images.These characteristics of the adsorbents are favorable for the adsorption of Pb2＋.The produced adsorbents present great potential as an inexpensive and easily available alternative for the removal of lead in aqueous solution.