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首页> 外文期刊>Environmental Science & Technology >Adsorption of Glyphosate on Goethite (α-FeOOH): Surface Complexation Modeling Combining Spectroscopic and Adsorption Data
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Adsorption of Glyphosate on Goethite (α-FeOOH): Surface Complexation Modeling Combining Spectroscopic and Adsorption Data

机译：草甘膦在针铁矿上的吸附（α-FeO​​OH）：结合光谱和吸附数据的表面络合建模

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摘要

N-(phosphonomethyl)glycine (glyphosate, PMG) is the most widely used herbicide, and its adsorption onto soil minerals plays a significant role in its mobility and rate of degradation. In this work, we present the results of the first serious effort to find a realistic surface complexation model that fits both adsorption and total proton concentration data for PMG on the common soil mineral, goethite. Special attention was focused on making sure that the final model was in good semiquantitative agreement with previously reported X-ray photoelectron spectroscopy and Fourier-transform infrared spectroscopic measurements. Electrostatic effects were accounted for using the Basic Stern model, and the charges of the PMG-containing surface complexes were assumed to be distributed across the 0- and β-planes. The reactions for the protonation of the goethite surface were described using the 1 pK model. We optimized on the intrinsic formation constants and the charge distributions of the complexes, as well as the initial total proton concentration (I = 0.1 M Na(NO_3), 25.0 ℃), and the following model was obtained. =FeOH~(0.5-) + H_3L ←→ ≡FeHL~(1.5-) + H~+ + H_2O Log_(10) β = 4.70 ± 0.08, Q_0 = -0.18 ± 0.02 =FeOH~(0.5-) + H_3L ←→ ≡FeL~(2.5-) + 2H~+ + H_2O Log_(10) β = -3.9±0.1, Q_0 = -0.7±0.1 Here, β is the intrinsic formation constant Q_0 is the charge at the 0-plane, and the errors are reported as one standard deviation. The charge distributions of the complexes are rationalized by considering intramolecular hydrogen bonding between the protons of the amine group and both the phosphonate and carboxylate groups.
机译：N-（膦酰基甲基）甘氨酸（草甘膦，PMG）是使用最广泛的除草剂，其吸附到土壤矿物质上对其迁移率和降解速率起着重要作用。在这项工作中，我们提出了第一个认真努力的结果，以找到一个适合于常见土壤矿物针铁矿上PMG的吸附和总质子浓度数据的现实表面络合模型。特别注意的是确保最终模型与先前报道的X射线光电子能谱和傅立叶变换红外光谱法测量值具有良好的半定量一致性。使用Basic Stern模型考虑了静电效应，并假设含PMG的表面复合物的电荷分布在0和β平面上。使用1 pK模型描述针铁矿表面质子化的反应。我们优化了本征形成常数和配合物的电荷分布，以及初始总质子浓度（I = 0.1 M Na（NO_3），25.0℃），并获得了以下模型。 = FeOH〜（0.5-）+ H_3L←→≡FeHL〜（1.5-）+ H〜+ + H_2O Log_（10）β= 4.70±0.08，Q_0 = -0.18±0.02 = FeOH〜（0.5-）+ H_3L← →≡FeL〜（2.5-）+ 2H〜+ + H_2O Log_（10）β= -3.9±0.1，Q_0 = -0.7±0.1这里，β是本征形成常数Q_0是0平面的电荷，并且误差报告为一个标准偏差。通过考虑胺基的质子与膦酸酯基和羧酸酯基两者之间的分子内氢键来合理化配合物的电荷分布。

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