物理化学学报 >> 2009, Vol. 25 >> Issue (09): 1737-1742.doi: 10.3866/PKU.WHXB20090815

研究论文 上一篇    下一篇

Zn(II)/α-FeOOH 吸附体系的固体浓度效应

徐丛, 李薇, 潘纲   

  1. 中国科学院生态环境研究中心|环境水质学国家重点实验室, 北京 100085
  • 收稿日期:2009-04-13 修回日期:2009-05-31 发布日期:2009-09-03
  • 通讯作者: 潘纲 E-mail:gpan@rcees.ac.cn

Particle Concentration Effect on Zn(II) Adsorption at Water-Goethite Interfaces

XU Cong, LI Wei, PAN Gang   

  1. State Key Laboratory of Environmental Aquatic Chemistry, Research center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, P. R. China
  • Received:2009-04-13 Revised:2009-05-31 Published:2009-09-03
  • Contact: PAN Gang E-mail:gpan@rcees.ac.cn

摘要:

采用宏观吸附-解吸实验系统地研究了Zn(II)在针铁矿(α-FeOOH)表面吸附的固体浓度(Cp)效应, 并考察了温度对固体浓度效应的影响, 揭示了固体浓度效应产生的机理. 实验结果表明: Zn(II)/α-FeOOH的吸附等温线随固体浓度的增加明显下移, 表现出显著的固体浓度效应; 随着固体浓度的升高, 平衡浓度相近的实验点的解吸滞后角(θ)和热力学不可逆系数(TII)均明显升高, 说明体系的可逆性随固体浓度的增大而显著降低, 这一结果符合亚稳平衡吸附(MEA)理论对固体浓度效应产生机制的预测. 本研究还发现Zn(II)/α-FeOOH体系在低温下的固体浓度效应比在高温下更为显著. 不同温度下的吸附-解吸实验表明,该体系的吸附可逆性随温度的升高而明显增强(θ和TII明显降低), 这再次证明了吸附可逆性对Cp效应的控制作用, 并从另一角度证实了MEA理论对固体浓度效应机制的解释. 实验测得Zn(II)/α-FeOOH体系的吸附热力学参数△H、△S分别为34.07 kJ·mol-1和195.71 J·mol-1·K-1, 表明Zn(II)可在针铁矿表面发生吸热的化学吸附反应.

关键词: 温度, 固体浓度效应, 吸附可逆性, 吸附-解吸, Zn(II), 针铁矿

Abstract:

The adsorption and desorption behaviors of Zn(II) on water-goethite interfaces under various particle concentrations (Cp) and temperatures were studied using traditional batch experiments. The Zn(II)/α-FeOOH adsorption system exhibited a significant particle concentration effect, in other words adsorption isotherms decreased as Cp increased. The adsorption also became less reversible because as the Cp increased which was demonstrated by the hysteresis angle (θ) and thermodynamic index of irreversibility (TII) as derived fromadsorption and desorption isotherms. This agrees with the explanation of the particle concentration effect as postulated in metastable-equilibrium adsorption (MEA) theory. Furthermore, the particle concentration effect became more obvious at lower temperatures. Adsorption of Zn(II) on goethite surfaces was found to increase greatly with the increase of temperature and the adsorption became more reversible. These results further confirmed that the Cp effect is the result of changes in adsorption reversibility. The study also showed that the adsorption was a simultaneous (positive △S value of 195.71 J·mol-1·K-1) and endothermic (positive △H value of 34.07 kJ·mol-1) chemisorption process.

Key words: Temperature, Particle concentration effect, Adsorption reversibility, Adsorption-desorption, Zn(II), Goethite

MSC2000: 

  • O642