Synergistic adsorption of Cd(II) with sulfate/phosphate on ferrihydrite: An in situ ATR-FTIR/2D-COS study
Synergistic adsorption of Cd(II) with sulfate/phosphate on ferrihydrite: An in situ ATR-FTIR/2D-COS study
复制标题
Cd(II) 与硫酸盐/磷酸盐在水铁矿上的协同吸附：原位 ATR-FTIR/2D-COS 研究
DOI：
10.1016/j.chemgeo.2017.12.004
复制
发表时间：
2018-01
期刊：
影响因子：
3.9
通讯作者：
Molinari Marco
中科院分区：
文献类型：
--
作者：
Liu Jing;Zhu Runliang;Liang Xiaoliang;Ma Lingya;Lin Xiaoju;Zhu Jianxi;He Hongping;Parker Stephen C.;Molinari Marco
阐明重金属阳离子和含氧阴离子在(含氧)氧化物上的共吸附特性有助于更好地了解它们在许多地质环境中的分布和转化。本文采用间歇吸附实验结合原位衰减全反射傅里叶变换红外光谱(ATR-FTIR)研究了Cd(II)与硫酸盐或磷酸盐在水界面的相互作用机理，并利用二维相关光谱分析(2D-COS)提高了ATR-FTIR谱带的分辨率和分析精度。间歇吸附实验表明，与Cd(II)共吸附时，FH对硫酸盐(S)和磷酸盐(P)的吸附均有增强，且P+Cd吸附体系中Cd(II)的解吸率远低于S Cd+Cd吸附体系中的解吸率。光谱结果表明，在单一吸附体系中，硫酸盐主要以外球络合物的形式被吸附，并有少量的双齿内球络合物，而磷酸盐的主要吸附物种是双齿非质子化的内球络合物，尽管存在明显的pH依赖性。在共吸附体系中，Cd(II)和硫酸盐的协同吸附主要归因于静电相互作用以及Fe-Cd-S(即Cd桥联)三元络合物的形成。相反，在磷酸盐和Cd(II)的所有共吸附体系中都发现了Fe-P-Cd(即磷酸盐桥联的)三元络合物；此外，静电相互作用也有助于共吸附过程。结果表明，原位ATR-FTIR结合2D-COS可以有效地分析三元吸附体系中铁(氧)氧化物对阴离子和重金属离子的共吸附机理。Cd(II)与硫酸盐或磷酸盐共存有利于Cd(II)在FH上的积累，而磷酸盐对Cd(II)的长期固定比硫酸盐更有效。
Elucidation of the co-adsorption characteristics of heavy metal cations and oxyanions on (oxyhydr)oxides can help to better understand their distribution and transformation in many geological settings. In this work, batch adsorption experiments in combination with in situ attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) were applied to explore the interaction mechanisms of Cd(II) with sulfate or phosphate at the ferrihydrite (Fh)–water interface, and the two-dimensional correlation spectroscopic analysis (2D–COS) was used to enhance the resolution of ATR-FTIR bands and the accuracy of analysis. The batch adsorption experiments showed enhanced adsorption of both sulfate (S) and phosphate (P) on Fh when co-adsorbed with Cd(II); additionally, the desorbed percentages of Cd(II) were much lower in the P + Cd adsorption systems than those in the S + Cd adsorption systems. The spectroscopic results suggested that in the single adsorption systems, sulfate primarily adsorbed as outer-sphere complexes with a small amount of bidentate inner-sphere complexes, while the dominant adsorbed species of phosphate were largely the bidentate nonprotonated inner-sphere complexes, although there was significant pH-dependence. In the co-adsorption systems, the synergistic adsorption of Cd(II) and sulfate was dominantly attributed to the electrostatic interaction, as well as the formation of Fe–Cd–S (i.e., Cd-bridged) ternary complexes. In contrast, Fe–P–Cd (i.e., phosphate-bridged) ternary complexes were found in all of the co-adsorption systems of phosphate and Cd(II); furthermore, electrostatic interaction should also contribute to the co-adsorption process. Our results show that in situ ATR-FTIR in combination with 2D–COS can be an efficient tool in analyzing the co-adsorption mechanisms of anions and heavy metal cations on iron (oxyhydr)oxides in ternary adsorption systems. The co-existence of Cd(II) with sulfate or phosphate can be beneficial for their accumulations on Fh, and phosphate is more efficient than sulfate for the long-term immobilization of Cd(II).
登录
查看更多内容
影响因子：
11.4
作者：
Li, Wei;Livi, Kenneth J. T.;Sparks, Donald L.
通讯作者：
Sparks, Donald L.
影响因子：
12.8
作者：
P. Swedlund
通讯作者：
P. Swedlund
影响因子：
3.7
作者：
G. Lefèvre;M. Fédoroff
通讯作者：
G. Lefèvre;M. Fédoroff
影响因子：
9.9
作者：
H. Wijnja;C. P. Schulthess
通讯作者：
H. Wijnja;C. P. Schulthess
影响因子：
3.4
作者：
P. Swedlund;J. Webster;G. Miskelly
通讯作者：
P. Swedlund;J. Webster;G. Miskelly