光谱学与光谱分析, 2018, 38 (6): 1889, 网络出版: 2018-06-29  

ICP-MS研究太湖表层沉积物对Cd2+和Zn2+的吸附-解吸特性

Study on Adsorption and Desorption Characteristics of Cd2+ and Zn2+ on the Surface Sediments of Taihu Lake by Using ICP-MS
作者单位
1 中央民族大学生命与环境科学学院, 北京 100081
2 中央民族大学北京市食品环境与健康工程技术研究中心, 北京 100081
摘要
前期研究发现太湖过滤水和表层沉积物中Zn含量最高, 且表层沉积物中Cd存在强生态危害。 因此, 在优化实验条件下, 以电感耦合等离子体质谱(ICP-MS)为分析手段研究了太湖苏州湾大桥东表层沉积物(标记为SES)对Cd2+和Zn2+的吸附-解吸特性。 吸附动力学结果表明: SES对Cd2+和Zn2+的吸附能力相差不大, 在吸附时间t<120 min时, 吸附是一个快速阶段, 而当t≥120 min时则相反, 吸附趋于动态平衡; Cd2+和Zn2+的吸附更符合伪二级动力学模型。 吸附热力学实验表明, 沉积物对Cd2+的吸附更符合Freundlich模型, 而对Cd2+的吸附更符合Langmuir模型。 沉积物中Cd2+和Zn2+的解吸动力学研究发现, 二者均更符合Elovich方程, 为非均相扩散过程。 且当pH值增大时, 沉积物中Cd2+和Zn2+的解吸量逐渐减小, 并在pH=9时趋于稳定。 结合Cd2+和Zn2+的吸附-解吸特性发现, SES对Cd2+和Zn2+的吸附速率远远大于其解吸速率, 与作者前期研究结果一致。 揭示了太湖表层沉积物对Cd2+和Zn2+的吸附-解吸作用机理及不同因素对吸附-解吸行为的影响。 对研究太湖固-液两相界面重金属的分配和污染水体修复具有重要指导意义。
Abstract
In our experiment, studies have found that the content of Zn is the highest in the filtered water and surface sediments of Taihu Lake, and Cd has the strongest ecological hazards on surface sediments. Therefore, in this paper, the adsorption and desorption characteristics of Cd2+ and Zn2+ on the surface sediments of Suzhou Bay Bridge East (marked as SES) of Taihu Lake were investigated by using inductively coupled plasma mass spectrometry (ICP-MS) under the optimized experimental conditions. Adsorption kinetics results showed that the adsorption capacity of Cd2+ was similar to that of Zn2+, adsorption was a rapid process within 120 min, and when t≥120 min, the result was the opposite and the adsorption reached to dynamic balance. In addition, the adsorption of Cd2+ and Zn2+ were corresponding to the pseudo-second-order kinetics model. Adsorption thermodynamics experiments showed that the adsorption of Cd2+ on the sediments was in accordance with the Freundlich model, while the adsorption of Zn2+ on the sediments were conformed to the Langmuir model. The assay of desorption kinetics of Cd2+ and Zn2+ in sediments found, both of which were more in accordance with the Elovich equation and belonged to the heterogeneous diffusion. When the pH increased, the desorption of Cd2+ and Zn2+ in the sediments decreased gradually, and tended to stabiliz at pH=9. Combination with the adsorption-desorption characteristics of Cd2+ and Zn2+, the adsorption rates of Cd2+ and Zn2+ were much larger than desorption rates of Cd2+ and Zn2+, which was consistent with the results of our previous studies. This study revealed the mechanism of adsorption and desorption of Cd2+ and Zn2+ on surface sediments of Taihu Lake and the effect of different factors on the adsorption-desorption behavior. It is of great significance to study the distribution of heavy metals and the remediation of polluted water in the solid-liquid interface of Taihu Lake.

方芳, 季雨珊, 柏娜, 李想, 刘颖. ICP-MS研究太湖表层沉积物对Cd2+和Zn2+的吸附-解吸特性[J]. 光谱学与光谱分析, 2018, 38(6): 1889. FANG Fang, JI Yu-shan, BAI Na, LI Xiang, LIU Ying. Study on Adsorption and Desorption Characteristics of Cd2+ and Zn2+ on the Surface Sediments of Taihu Lake by Using ICP-MS[J]. Spectroscopy and Spectral Analysis, 2018, 38(6): 1889.

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