Retention of Latex Colloids on Calcite as a Function of Surface Roughness and Topography
Retention of Latex Colloids on Calcite as a Function of Surface Roughness and Topography
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DOI：
10.1021/la9033595
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发表时间：
2010-04-06
期刊：
影响因子：
3.9
通讯作者：
Fischer, Cornelius
中科院分区：
文献类型：
--
作者：
Darbha, Gopala Krishna;Schaefer, Thorsten;Fischer, Cornelius
胶体颗粒在矿物和岩石表面的粘附对于环境和工艺过程是重要的。矿物和岩石表面亚微米尺度的表面形貌变化可能对胶体在环境中的滞留起重要作用。在这里，我们基于几平方毫米视场内的表面数据，将方解石上的胶体沉积数据作为亚微米表面粗糙度的函数，足以追踪矿物表面上常见不均匀性的模式。使新劈开的方解石晶体反应，产生轮廓分明的蚀坑密度，其近似于3.4 +/-1.2至8.3 +/-1.6 [10（-3）μ m（-2）]，蚀坑深度范围近似于4至50 nm。该表面在方解石的零电荷点（PZC）处暴露于胶体悬浮液。我们使用了一个双峰粒径分布的非官能化聚苯乙烯乳胶球的平均直径为499和903 nm。垂直扫描干涉法（VSI）被应用于量化方解石表面形貌的变化，以及乳胶胶体的保留。对于这两种颗粒尺寸，实验表明，表面粗糙度（Rq）和吸附颗粒的数量之间的正相关性。与表面台阶相比，蚀坑是胶体沉积的首选部位。与蚀刻坑底部相比，大多数吸附的颗粒被捕获在蚀刻坑壁处。增加凹坑密度（D）和深度（d）导致胶体保留增加。沉积的较小的颗粒超过了较大尺寸的部分的双峰系统在这里调查。结果表明，胶体在粗糙矿物和岩石表面的沉积是一种重要的地球化学过程。有关表面粗糙度依赖的颗粒吸附的结果将促进对胶体保留的理解和可预测性，为众多的自然和技术过程。
Adhesion of colloidal particles to mineral and rock surfaces is important for environmental and technological processes. Surface topography variations of mineral and rock surfaces at the submicrometer scale may play a significant role in colloid retention in the environment. Here, we present colloid deposition data on calcite as a function of submicrometer surface roughness based on surface data over a field of view of several square millimeters, sufficient to trace the pattern of common inhomogeneities on mineral surfaces. A freshly cleaved calcite crystal was reacted to produce a well-defined etch pit density of similar to 3.4 +/- 1.2 to 8.3 +/- 1.6 [10(-3) mu m(-2)] and etch pit depth ranging from similar to 4 to 50 nm. This surface was exposed at the point of zero charge (PZC) of calcite to a colloidal suspension. We used a bimodal particle size distribution of nonfunctionalized polystyrene latex spheres with average diameters of 499 and 903 nm. Vertical scanning interferometry (VSI) was applied to quantify calcite surface topography variations its well as the retention of latex colloids. For both particle sizes, the experiments showed a positive correlation between the surface roughness (Rq) and the number of adsorbed particles. Etch pits were preferred sites for colloidal deposition in contrast to surface steps. The majority of adsorbed particles were trapped at etch pit walls compared to etch pit bottoms. Increasing pit density (D) and depth (d) resulted in an increase of colloidal retention. Deposition of smaller particles exceeded that of the larger-sized fraction of the bimodal system investigated here. Our results show that colloidal deposition at rough mineral and rock surfaces is an important geochemical process. The results about surface roughness dependent particle adsorption will foster the understanding and predictability of colloidal retention for a multitude of natural and technical processes.