Department of Chemistry, Umeå University, SE-901 87 Umeå, Sweden.
Langmuir. 2010 Dec 21;26(24):18760-70. doi: 10.1021/la1026152. Epub 2010 Nov 18.
Adsorption, desorption, and precipitation reactions at environmental interfaces govern the fate of phosphorus in terrestrial and aquatic environments. Typically, a substantial part of the total pool of phosphorus consists of organophosphate, and in this study we have focused on the interactions between glucose-1-phosphate (G1P) and goethite (α-FeOOH) particles. The adsorption and surface-promoted hydrolysis reactions have been studied at room temperature as a function of pH, time, and total concentration of G1P by means of quantitative batch experiments in combination with infrared spectroscopy. A novel simultaneous infrared and potentiometric titration (SIPT) technique has also been used to study the rates and mechanisms of desorption of the surface complexes. The results have shown that G1P adsorption occurs over a wide pH interval and at pH values above the isoelectric point of goethite (IEP(goethite) = 9.4), indicating a comparatively strong interaction with the particle surfaces. As evidenced by IR spectroscopy, G1P formed pH-dependent surface complexes on goethite, and investigations of both adsorption and desorption processes were consistent with a model including three types of surface complexes. These complexes interact monodentately with surface Fe but differ in hydrogen bonding interactions via the auxiliary oxygens of the phosphate group. The apparent desorption rates were shown to be influenced by reaction pathways that include interconversion of surface species, which highlights the difficulty in determining the intrinsic desorption rates of individual surface complexes. Desorption results have also indicated that the molecular structures of surface complexes and the surface charge are two important determinants of G1P desorption rates. Finally, this study has shown that surface-promoted hydrolysis of G1P by goethite is base-catalyzed but that the extent of hydrolysis was small.
环境界面上的吸附、解吸和沉淀反应控制着磷在陆地和水生环境中的归宿。通常，总磷库的很大一部分由有机磷酸盐组成，在本研究中，我们专注于葡萄糖-1-磷酸（G1P）和针铁矿（α-FeOOH）颗粒之间的相互作用。通过定量批量实验与红外光谱相结合，研究了吸附和表面促进水解反应在室温下随 pH 值、时间和 G1P 总浓度的变化规律。还使用了一种新的同时红外和电位滴定（SIPT）技术来研究表面配合物的解吸速率和机制。结果表明，G1P 在很宽的 pH 范围内吸附，并且在针铁矿等电点（IEP(goethite) = 9.4）以上的 pH 值下吸附，表明与颗粒表面的相互作用比较强。如红外光谱所示，G1P 在针铁矿上形成了依赖 pH 的表面配合物，对吸附和解吸过程的研究都与包括三种类型的表面配合物的模型一致。这些配合物通过磷酸基团的辅助氧以单齿方式与表面 Fe 相互作用，但氢键相互作用不同。明显的解吸速率受包括表面物种相互转化的反应途径的影响，这突出了确定单个表面配合物的固有解吸速率的困难。解吸结果还表明，表面配合物的分子结构和表面电荷是 G1P 解吸速率的两个重要决定因素。最后，本研究表明，针铁矿对 G1P 的表面促进水解是碱催化的，但水解程度很小。
