Adsorption and desorption behaviour of Pb(II) on a natural kaolin: equilibrium, kinetic and thermodynamic studies
Adsorption and desorption behaviour of Pb(II) on a natural kaolin: equilibrium, kinetic and thermodynamic studies
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DOI：
10.1002/jctb.2192
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发表时间：
2009-09
影响因子：
3.4
通讯作者：
Q. Tang;Xiaowu Tang;Zhenze Li;Yun-min Chen;Nai-Yu Kou;Zufeng Sun
中科院分区：
文献类型：
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作者：
Q. Tang;Xiaowu Tang;Zhenze Li;Yun-min Chen;Nai-Yu Kou;Zufeng Sun
背景：Pb(II) 在废水和气体排放中都很常见。在发展中国家，有关Pb(II)污染的公共卫生问题已有报道，因此需要采取严格的措施来应对。主要结果：研究了 Pb(II) 在天然中国高岭土上的吸附和解吸行为。包括初始浓度、pH、平衡时间、剂量和温度在内的几个因素与 Pb(II) 吸附呈正相关。天然高岭土对 Pb(II) 的吸附量为 165.117 mg g−1。动力学研究表明，纯化高岭土上的 Pb(II) 吸附在 35 分钟内达到平衡。对于含有 50、100 和 200 mg L−1 Pb(II) 的溶液，Pb(II) 在纯化高岭土上的吸附焓变分别为 63.683、20.488 和 21.371 kJ mol−1，熵变分别为 262.250、112.210 和 105.120 J mol−1 K−1，表明吸热和自发吸附过程。高岭土中 Pb(II) 的解吸困难，Pb(II) 去除率超过 85%。基于 X 射线衍射 (XRD) 分析，天然和纯化高岭土上的 Pb(II) 吸附主要归因于菱镁矿成分和与矿物表面的络合。结论：天然高岭土对水溶液中的 Pb(II) 具有良好的吸附性能。最佳吸附条件为：离子强度=0.01 mol·L−1； pH值≥7.2；剂量 = 10 g L−1;温度=25℃；持续时间 ≥ 16 小时（Ci = 80 mg L−1）；最佳解吸条件为离子强度= 0.1 mol L−1、pH ≤ 5.0。版权所有© 2009 中国化工学会
BACKGROUND: Pb(II) is common in both waste-waters and gas emissions. In developing countries, public health problems have been reported concerning Pb(II) pollution, so that stringent measures are required to deal with it. MAJOR RESULTS: The adsorption and desorption behaviour of Pb(II) has been investigated on a natural Chinese kaolin. Several factors, including initial concentration, pH, equilibration time, dosage and temperature correlated positively with Pb(II) adsorption. The Pb(II) adsorption capacity of natural kaolin was 165.117 mg g−1. A kinetic study shows that Pb(II) adsorption on purified kaolin equilibrates within 35 min. The enthalpy changes of Pb(II) adsorption on purified kaolin were 63.683, 20.488 and 21.371 kJ mol−1 with entropy changes 262.250, 112.210 and 105.120 J mol−1 K−1 for solutions containing 50, 100 and 200 mg L−1 Pb(II) respectively, indicating an endothermic and spontaneous adsorption process. The desorption of Pb(II) from kaolin was difficult with more than 85% Pb(II) removal. Based on X-ray diffraction (XRD) analysis, the Pb(II) adsorption on natural and purified kaolin was attributed mainly to the magnesite component and complexation with the mineral surface. CONCLUSIONS: Natural kaolin exhibits a satisfactory performance for adsorption of Pb(II) from aqueous solution. The optimum conditions for adsorption were: ionic strength = 0.01 mol L−1; pH ≥ 7.2; dosage = 10 g L−1; temperature = 25 °C; duration ≥ 16 h (Ci = 80 mg L−1); and the optimum conditions for desorption were ionic strength = 0.1 mol L−1 and pH ≤ 5.0. Copyright © 2009 Society of Chemical Industry