Agrosphere, ICG 4, Forschungszentrum Jülich GmbH, D-52425 Jülich, Germany.
J Colloid Interface Sci. 2010 Mar 15;343(2):408-14. doi: 10.1016/j.jcis.2009.12.014. Epub 2009 Dec 6.
The goals of the study were to investigate the effects of the soil-water phase ionic strength, mainly monitored by the calcium ion (Ca(2+)) concentration, on the stability behavior of easily dispersed topsoil colloidal clay-sized particles (<2 microm). The aggregation kinetics as a function of the Ca(2+) concentration was monitored by measuring the increase of the particle size over time with photon correlation spectroscopy. The critical coagulation concentrations (CCC) of Ca(2+) were measured. The Hamaker constants (A) characterizing the attractive chemical properties of the topsoil colloid surface were thus scaled according to the Derjaguin, Landau, Verwey, Overbeek (DLVO) theory by taking into account the electrokinetic behavior of the particles, measured by the zeta-potential. Effective values for the Hamaker constants of topsoil clay-sized colloids, clay minerals, and metal oxides were calculated by referring to reported values for crystalline silica or sand (quartz) particles. Potential-energy diagrams of interacting topsoil clay-sized colloids were calculated. The primary energy maximum and secondary energy minimum were used for modeling the aggregation kinetics along the Ca(2+) concentration by employing Marmur's model. Coagulation in the secondary energy minimum can only explain the aggregation efficiency of topsoil colloids at low Ca(2+) concentrations (<2 mM Ca(2+)) under unfavorable electrostatic conditions. The effect of surface-associated organic matter on the colloidal electrosteric stability was also investigated by comparing the topsoil colloid stability after the removal of organic matter.
研究目的是调查土壤-水相离子强度（主要通过钙离子（Ca(2+)）浓度监测）对易分散表土胶体粘土颗粒（<2 微米）稳定性行为的影响。通过光子相关光谱法测量颗粒随时间增加的粒径变化，监测 Ca(2+)浓度下的聚集动力学。测量了 Ca(2+)的临界聚沉浓度（CCC）。因此，根据德加古因、朗道、维韦、奥弗贝克（DLVO）理论，通过考虑颗粒的电动行为（由 ζ 电位测量），对表征表土胶体表面吸引力化学特性的哈默常数（A）进行了缩放。通过参考结晶二氧化硅或沙（石英）颗粒的报告值，计算了表土粘土大小胶体、粘土矿物和金属氧化物的有效哈默常数值。计算了相互作用的表土粘土大小胶体的势能图。利用 Marmur 模型，通过使用主能量最大值和次能量最小值来模拟沿 Ca(2+)浓度的聚集动力学。在不利的静电条件下，只有在低 Ca(2+)浓度（<2 mM Ca(2+)）下，次级能量最小值中的凝聚才能解释表土胶体的聚集效率。还通过比较去除有机质后表土胶体的稳定性，研究了表面结合有机质对胶体电动稳定性的影响。
