Department of Natural Resources and Environmental Sciences, University of Illinois at Urbana-Champaign, 61801, USA.
Department of Natural Resources and Environmental Sciences, University of Illinois at Urbana-Champaign, 61801, USA.
Sci Total Environ. 2022 Sep 1;837:155525. doi: 10.1016/j.scitotenv.2022.155525. Epub 2022 Apr 28.
Myo-inositol hexakisphosphate (myo-IHP) is one of the most common soil organic phosphorus (P) species in soil. Its retention in soil is often competed by phosphate, making bioavailability of P species difficult. In this study, the adsorption mechanism of myo-IHP at the amorphous aluminum (oxyhydr)oxide (AAH)-water interface was investigated at pH 6.5 in the presence of phosphate using batch adsorption experiments and solution P NMR spectroscopy. The ratio of [myo-IHP]/[phosphate] (Ri) was kept 0.33-3 while ligand addition was varied. In the absence of phosphate, myo-IHP forms inner-sphere surface complexes in AAH via P1,3, P2, P4,6, and P5 functional group coordination. When two ligands were simultaneously added, fewer P functional groups of myo-IHP coordinated to AAH and the surface complexes were altered with the coordination of mainly P1,3 and P2 functional groups. When phosphate was pre-adsorbed, myo-IHP adsorption decreased by 8.0-44% compared to the respective simultaneous addition system. P2 or P5 functional group was predominantly coordinated to the AAH surfaces at Ri = 0.33. Myo-IHP pre-adsorption resulted in an increase in the final myo-IHP adsorption compared to that in the simultaneous addition system under the respective Ri values (0.33-3). In this system, P1,3, P2, P4,6, and P5 functional groups were coordinated to form inner-sphere surface complexes regardless of Ri. The study revealed that the functional group specific adsorption mechanism of myo-IHP at the AAH-water interface was affected by addition sequence and Ri of two ligands. The competitive adsorption between organic P and phosphate plays an important role in the fate of P in soils.
肌醇六磷酸（myo-IHP）是土壤中最常见的有机磷（P）物种之一。由于其在土壤中的保留常常受到磷酸盐的竞争，因此 P 物种的生物可利用性变得困难。在这项研究中，使用批处理吸附实验和溶液 P NMR 光谱法，在 pH 6.5 下研究了磷酸盐存在时 myo-IHP 在无定形铝（氧氢）氧化物（AAH）-水界面上的吸附机制。保持 [myo-IHP]/[phosphate]（Ri）的比值在 0.33-3 之间，同时改变配体的添加量。在没有磷酸盐的情况下，myo-IHP 通过 P1,3、P2、P4,6 和 P5 官能团配位在 AAH 上形成内圈表面配合物。当同时添加两种配体时，myo-IHP 的更少 P 官能团与 AAH 配位，并且表面配合物发生变化，主要通过 P1,3 和 P2 官能团配位。当预吸附磷酸盐时，与各自的同时添加体系相比，myo-IHP 的吸附减少了 8.0-44%。在 Ri = 0.33 时，主要配位 P2 或 P5 官能团到 AAH 表面。与各自的 Ri 值（0.33-3）下的同时添加体系相比，myo-IHP 预吸附导致最终 myo-IHP 吸附增加。在该体系中，无论 Ri 如何，都通过 P1,3、P2、P4,6 和 P5 官能团配位形成内圈表面配合物。该研究表明，myo-IHP 在 AAH-水界面上的特定官能团吸附机制受两种配体的添加顺序和 Ri 的影响。有机磷和磷酸盐之间的竞争吸附在土壤中 P 的命运中起着重要作用。
