Although, glyphosate (N-(phosphonomethyl) glycine) is one of the most widely used herbicides in the world, its interaction with poorly crystalline iron oxides, such as ferrihydrite, is not well studied. In this research, we examined the adsorption of glyphosate onto ferrihydrite using infrared spectroscopy (FT-IR), electron paramagnetic resonance spectroscopy (EPR), adsorption kinetic models and adsorption isotherm models. The effect of pH and sodium chloride concentration on the adsorption of glyphosate onto ferrihydrite as well as the effect of extractors (CaCl2 0.010 mol L-1 and Mehlich) on the desorption of glyphosate were also evaluated. There are two important findings described in this work. First, 84% of adsorbed glyphosate strongly interacted to ferrihydrite as an inner-sphere complex and phosphate and amine groups are involved in this interaction. Second, an increase of sodium chloride salt concentration increased the adsorption of glyphosate onto ferrihydrite. The non-linear Langmuir model and pseudo second order model showed a good agreement of theoretical limit of glyphosate adsorbed onto ferrihydrite, 54.88 µg mg-1 and 48.8 µg mg-1, respectively. The adsorption of glyphosate onto ferrihydrite decreased when the pH increased. Under the conditions used in this work, EPR spectra did not show dissolution of ferrihydrite. Surface area, pore volume and pHpzc of ferrihydrite decreased after adsorption of glyphosate.

中文翻译：

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pH和离子强度对草甘膦吸附到三水铝石上的影响。

尽管草甘膦（N-（膦酰基甲基）甘氨酸）是世界上使用最广泛的除草剂之一，但尚未很好地研究其与结晶性较弱的氧化铁（如亚铁酸盐）的相互作用。在这项研究中，我们使用红外光谱（FT-IR），电子顺磁共振光谱（EPR），吸附动力学模型和吸附等温线模型研究了草甘膦在三水铝石上的吸附。还评估了pH和氯化钠浓度对草甘膦在亚铁酸盐上吸附的影响以及萃取剂（CaCl2 0.010 mol L-1和Mehlich）对草甘膦解吸的影响。这项工作描述了两个重要发现。第一，84％的被吸收的草甘膦作为内球络合物与水铁矿强烈相互作用，并且磷酸盐和胺基团参与该相互作用。其次，氯化钠盐浓度的增加增加了草甘膦在三水铁矿上的吸附。非线性Langmuir模型和伪二阶模型显示草甘膦吸附到三水铝石上的理论极限值分别为54.88 µg mg-1和48.8 µg mg-1很好地吻合。当pH值升高时，草甘膦在亚铁酸盐上的吸附降低。在这项工作中使用的条件下，EPR光谱没有显示出水铁矿的溶解。草甘膦吸附后，水铁矿的表面积，孔体积和pHpzc降低。非线性Langmuir模型和伪二阶模型显示草甘膦吸附到三水铝石上的理论极限值分别为54.88 µg mg-1和48.8 µg mg-1很好地吻合。当pH值升高时，草甘膦在亚铁酸盐上的吸附降低。在这项工作中使用的条件下，EPR光谱没有显示出水铁矿的溶解。草甘膦吸附后，水铁矿的表面积，孔体积和pHpzc降低。非线性Langmuir模型和伪二阶模型显示草甘膦吸附到三水铝石上的理论极限值分别为54.88 µg mg-1和48.8 µg mg-1很好地吻合。当pH值升高时，草甘膦在亚铁酸盐上的吸附降低。在这项工作中使用的条件下，EPR光谱没有显示出水铁矿的溶解。草甘膦吸附后，水铁矿的表面积，孔体积和pHpzc降低。