Wageningen University, Department of Soil Quality, P.O. Box 47, 6700 AA Wageningen, The Netherlands.
J Phys Chem A. 2012 Jun 28;116(25):6582-9. doi: 10.1021/jp2126448. Epub 2012 Jun 8.
In soil application, o,o-FeEDDHA (iron (3+) ethylene diamine-N,N'-bis(2-hydroxy phenyl acetic acid) complex) is the active ingredient of FeEDDHA chelate-based Fe fertilizers. The effectiveness of o,o-FeEDDHA is potentially compromised by the displacement of Fe from FeEDDHA by Cu. The actual impact of Cu competition is codetermined by the kinetics of the displacement reaction. In this study, the influence of soil parameters on the displacement kinetics has been examined in goethite suspensions. The displacement reaction predominantly takes place on the reactive surface rather than in solution. The rate at which the o,o-FeEDDHA concentration declined depended on the available reactive surface area, the Cu loading, and the FeEDDHA loading. Soil factors reducing FeEDDHA adsorption (high ionic strength, humic acid adsorption onto the goethite surface, and monovalent instead of divalent cations in the electrolyte) decreased the displacement rate. For meso o,o-FeEDDHA, the displacement rate equation was derived, which is first order in FeEDDHA loading and half order in Cu loading. For soil conditions, the equation can be simplified to an exponential decay function in meso o,o-FeEDDHA solution concentration.
在土壤施用中，o,o-FeEDDHA（铁（3+）乙二胺-N,N'-双（2-羟基苯乙酸）配合物）是基于 FeEDDHA 螯合物的铁肥料中的有效成分。Cu 可能会取代 FeEDDHA 中的 Fe，从而降低 o,o-FeEDDHA 的有效性。Cu 竞争的实际影响由取代反应的动力学决定。在这项研究中，在针铁矿悬浮液中检查了土壤参数对取代动力学的影响。取代反应主要发生在反应表面上，而不是在溶液中。o,o-FeEDDHA 浓度下降的速率取决于可用反应表面积、Cu 负载和 FeEDDHA 负载。降低 FeEDDHA 吸附的土壤因素（高离子强度、腐殖酸在针铁矿表面的吸附以及电解质中的单价而不是二价阳离子）降低了取代速率。对于中 o,o-FeEDDHA，推导出了取代速率方程，该方程在 FeEDDHA 负载方面是一级的，在 Cu 负载方面是半级的。对于土壤条件，该方程可以简化为中 o,o-FeEDDHA 溶液浓度的指数衰减函数。
