Effect of molecular scale roughness of glass beads on colloidal and bacterial deposition.
Effect of molecular scale roughness of glass beads on colloidal and bacterial deposition.
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DOI：
10.1021/es015515k
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发表时间：
2002-01
影响因子：
11.4
通讯作者：
K. Shellenberger;B. Logan
中科院分区：
文献类型：
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作者：
K. Shellenberger;B. Logan
分子尺度的表面粗糙度和电荷不均匀被认为是影响胶体在多孔介质中传输过程中沉积速度的因素。为了测试它们的相对重要性，将一批清洁的玻璃珠子一分为二，并用酸或碱进行化学处理，以改变表面粗糙度。用原子力显微镜(AFM)对20个玻璃微珠的表面形貌进行了分析，结果表明，经铬酸处理(粗)的微珠表面均方根粗糙度为38.1+/-3.9 nm，而经氢氧化钠处理(光滑)的微珠表面均方根粗糙度为15.0+/-1.9 nm。玻璃微珠表面的AFM力体积成像没有显示表面电荷的不均匀。无机胶体(乳胶微球，直径1微米)的过滤实验始终表明，乳胶微球在粗糙表面上的保留率高于悬浮在低离子强度(10(-5)M)或高离子强度(10(-1)M)溶液中的光滑玻璃微珠。粗糙珠子的碰撞效率比光滑珠子高30-50%。使用粗糙玻璃微珠的细菌碰撞效率也等于或高于使用光滑微珠测得的效率。在使用高氯酸盐还原细菌分离物KJ的实验中，对于两种不同的离子强度溶液(IS=0.05或1M)，粗糙珠的碰撞效率明显高于光滑珠。在另一种情况下(IS=0.1M)，对于KJ，在与大肠杆菌的过滤实验中，粗珠和光珠之间的碰撞效率没有显著差异。我们假设，微球在粗糙的珠子而不是光滑的珠子上持续较高的沉积速度，部分原因是细菌表面存在聚合物。
Molecular-scale surface roughness and charge heterogeneity have been hypothesized as factors that can affect the deposition rates of colloids during their transport in porous media. To test their relative importance, a single batch of cleaned glass beads was divided in half and chemically treated with acid or base to alter surface roughness. Analysis of the topography of 20 glass beads with an atomic force microscope (AFM) indicated that the chromic acid-treated (rough) beads had a root-mean-square roughness of 38.1 +/- 3.9 nm, while the sodium hydroxide-treated (smooth) beads had root-mean-square surface roughness of 15.0 +/- 1.9 nm. AFM force volume imaging of glass bead surfaces did not reveal surface charge heterogeneity. Filtration experiments with inorganic colloids (latex microspheres, 1 microm diameter) consistently demonstrated that there was a greater retention of latex microspheres on rough than smooth glass beads suspended in either low (10(-5) M) or higher (10(-1) M) ionic strength (IS) solutions. Collision efficiencies for rough beads were 30-50% larger than for smooth beads. Collision efficiencies of bacteria using rough glass beads were also equal to or greater than those measured for smooth beads. In experiments with the perchlorate-reducing bacterial isolate KJ, collision efficiencies were significantly greater on rough rather than smooth beads for two different ionic strength solutions (IS = 0.05 or 1 M). In another case (IS = 0.1 M) for KJ, and in filtration experiments with E coli, collision efficiencies were not significantly different between the rough and smooth beads. We hypothesize that the consistently greater deposition rates of microspheres, but not bacteria, on rough rather than smooth beads are due in part to the presence of polymers on the surfaces of bacteria.