Evaluation of effective parameters to describe wetting, adhesion and, sorption phenomena on biogeochemical interfaces

土壤中几乎所有的过程都发生在生物地球化学界面上。到目前为止，能够将化学表面结构与液相中的物理相互作用（润湿性，吸附性）联系起来的特定界面参数仍然缺失。我们的假设是，热力学定义的表面参数，如接触角和表面自由能成分（色散和酸碱成分）可能是适当的有效参数，补充土壤特性，如pH值，质地或阳离子交换能力。为了将有效参数与化学结构联系起来，将用x射线光电子能谱分析与界面相相关的接触角。有效参数的知识应该允许检测界面的相关修改或解释表面与孔隙水（液体渗透动力学），溶质（农药）或分散颗粒（胶体）之间的相互作用。我们将应用基于热力学的概念来量化从亲水到疏水的润湿系统的转变。这种转变的意义，即孔液分布和几何（膜厚度和破碎），将分析与共聚焦激光扫描显微镜。通过化学处理和阳离子交换对自然土壤和模型土壤进行修改将确保参数的大范围变化。

Nearly all processes in soils take place at biogeochemical interfaces. Until now, specific interfacial parameters which are able to link the chemical surface structure with physical interactions in the liquid phase (wettability, sorption) are still missing. Our hypothesis is that thermodynamically defined surface parameters like the contact angle and surface free energy components (dispersive and acid-base components) may be appropriate as effective parameters, complementary to soil properties like pH, texture or cation exchange capacity. To relate effective parameters to chemical structure, the contact angle relevant interphase will be analyzed by X-ray photoelectron spectroscopy. Knowledge of effective parameters should allow to detect relevant modifications of the interfaces or to explain interactions between surfaces and pore water (liquid penetration dynamics), solutes (pesticides) or dispersed particles (colloids). We will apply a thermodynamically-based concept to quantify the transition from hydrophilic to hydrophobic wetting systems. The significance of this transition i.e. on pore liquid distribution and geometry (film thickness and fragmentation), will be analyzed with confocal laser scanning microscopy. Modification of natural and model soils by chemical treatment and cation exchange will ensure a wide range of parameter variation.