School of Resources and Environment, Northeast Agricultural University, Harbin 150030, PR China.
School of Resources and Environment, Northeast Agricultural University, Harbin 150030, PR China.
Ecotoxicol Environ Saf. 2018 Nov 30;164:484-492. doi: 10.1016/j.ecoenv.2018.08.026. Epub 2018 Aug 23.
This study investigated the competitive sorption of black soil to adsorb Pb(II) and methylene blue (MB) from multi-contaminated soils. According to the experimental data, the process of adsorption can be clearly explained by pseudo-second-order kinetic equation. Both single and binary systems of the adsorption isotherms had a good fit with Langmuir models. The maximal adsorption abilities of Pb(II) and MB acquired from binary systems sorption were attenuated compared to those from the single system (Pb(II): 77.70 > 65.96 mg g; MB: 242.31 > 222.36 mg g). Pb(II) and MB can inhibit each other's sorption ability. A combination of three-dimensional excitation-emission matrix (3D-EEM), synchronous fluorescence spectra as well as two-dimensional correlation spectroscopy (2D-COS) were employed to determine the binding of dissolved organic matter (DOM) for Pb(II) and MB during soil sorption process. As a result, 3D-EEM implicated that the two main composes of DOM were humic acid-like substances and the fluorescence of DOM specimens were gradually diminished with increasing concentrations of Pb(II) and MB. According to synchronous fluorescence spectra, static quenching of Pb(II) and MB mainly led to fluorescence quenching. Specifically, fluorescence-2D-COS implicated that Pb(II) and MB bound to fluorescence in the following sequence: the earlier occurrence of the humic-like fraction compared to that of protein-like fraction. FTIR-2D-COS results concluded that the structural change sequence of DOM by Pb(II) binding followed the order: 1700＞863＞1332＞1529＞1200＞1086 cm and the sequence of the MB binding affinities followed the order: 1520＞1399＞1345＞1152＞1602＞993＞881 cm. These findings would be beneficial to understand the mechanism of adsorb multi-component systems and have the potential to contribute significance to the interaction mechanism of multi-component with soil DOM at the molecular level.
本研究考察了黑土对多污染土壤中 Pb(II)和亚甲基蓝（MB）的竞争吸附。根据实验数据，吸附过程可以用准二级动力学方程清楚地解释。单一组分和二元体系的吸附等温线均与 Langmuir 模型拟合良好。从二元体系吸附中获得的 Pb(II)和 MB 的最大吸附能力与从单一组分吸附中获得的相比有所减弱（Pb(II)：77.70>65.96mg g；MB：242.31>222.36mg g）。Pb(II)和 MB 可以抑制彼此的吸附能力。采用三维激发-发射矩阵（3D-EEM）、同步荧光光谱和二维相关光谱（2D-COS）相结合的方法，确定了在土壤吸附过程中溶解有机质（DOM）与 Pb(II)和 MB 的结合情况。结果表明，3D-EEM 表明 DOM 的两个主要成分是腐殖酸类物质，随着 Pb(II)和 MB 浓度的增加，DOM 样品的荧光逐渐减弱。根据同步荧光光谱，Pb(II)和 MB 的静态猝灭主要导致荧光猝灭。具体来说，荧光 2D-COS 表明 Pb(II)和 MB 与荧光的结合顺序为：腐殖酸样部分比蛋白质样部分更早发生。FTIR-2D-COS 结果表明，Pb(II)结合引起 DOM 结构变化的顺序为：1700>863>1332>1529>1200>1086 cm，MB 结合亲和力的顺序为：1520>1399>1345>1152>1602>993>881 cm。这些发现有助于理解吸附多组分体系的机制，并有可能为多组分与土壤 DOM 分子水平上的相互作用机制提供重要贡献。
