Department of Geology and Geophysics, University of Utah , Salt Lake City, Utah 84112, United States.
Department of Extractive Metallurgy, Escuela Politécnica Nacional , Quito, Ecuador.
Environ Sci Technol. 2017 Feb 21;51(4):2151-2160. doi: 10.1021/acs.est.6b05911. Epub 2017 Feb 8.
Surface roughness has been reported to both increase as well as decrease colloid retention. In order to better understand the boundaries within which roughness operates, attachment of a range of colloid sizes to glass with three levels of roughness was examined under both favorable (energy barrier absent) and unfavorable (energy barrier present) conditions in an impinging jet system. Smooth glass was found to provide the upper and lower bounds for attachment under favorable and unfavorable conditions, respectively. Surface roughness decreased, or even eliminated, the gap between favorable and unfavorable attachment and did so by two mechanisms: (1) under favorable conditions attachment decreased via increased hydrodynamic slip length and reduced attraction and (2) under unfavorable conditions attachment increased via reduced colloid-collector repulsion (reduced radius of curvature) and increased attraction (multiple points of contact, and possibly increased surface charge heterogeneity). Absence of a gap where these forces most strongly operate for smaller (<200 nm) and larger (>2 μm) colloids was observed and discussed. These observations elucidate the role of roughness in colloid attachment under both favorable and unfavorable conditions.
表面粗糙度已被报道既可以增加也可以减少胶体的保留。为了更好地理解粗糙度作用的范围，在冲击射流系统中，在有利（不存在能垒）和不利（存在能垒）条件下，考察了一系列胶体大小与三种粗糙度水平的玻璃的附着情况。在有利和不利条件下，光滑玻璃分别提供了附着的上限和下限。表面粗糙度降低了（甚至消除了）有利和不利附着之间的差距，其通过两种机制实现：（1）在有利条件下，附着通过增加流体动力滑动长度和降低吸引力而降低，以及（2）在不利条件下，附着通过降低胶体-收集器排斥力（降低曲率半径）和增加吸引力（多点接触，以及可能增加表面电荷异质性）而增加。观察到并讨论了对于较小（<200nm）和较大（>2μm）胶体，这些力最强作用的间隙缺失的情况。这些观察结果阐明了粗糙度在有利和不利条件下对胶体附着的作用。
