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Scanning Electron Microscopic Study of the Attachment Sstes of Suspenied Particles on the Sand Surface in Rapid Filtration

快速过滤中悬浮颗粒在砂表面附着情况的扫描电镜研究

基本信息

批准号：
01550421
负责人：
EBIE Kunio
金额：
$ 1.34万
依托单位：
Kitami Institute of Technology
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1989
资助国家：
日本
起止时间：
1989 至 1990
项目状态：
已结题

项目摘要

(1) The X-ray analysis has indicated that chemical elements in the sand surface were Si, O, Al, Ca, Mg, Fe and K, in which the predominant elements and compound were Si and O, and SiO2 respectively and each and every element was distributed uniformly over the sand surface.(2) The scanning electron microscopic observation has made clear that the sand surface was composed of several planes divided by edges. On these lanes, there were some kinds of uneven faces such as steps, hollows, cracks, upheavals and so on, which would play the important roles in catching the suspended particles in the water.(3) In the first process of particle deposition in the filter, the existence of deposited particles splashed over the sand surface was observed. After that, these particles continued to catch subsequent particles and grew up rapidly. The masses of the particles contacted with adjoining ones shortly. The surface of the deposits become smoother and smoother as the filtration time passed. These results have indicated that the elucidation of the attachment sites of particles on the sand grain would be important.(4) Filtration experiments have been made by the use of both Au coated and uncoated sands. The efficienies of the particle removal in the experiments with the coated sands were only 1.5-3.0 % higher than that with the uncoated sands. This demonstrates that the chemical effects in the removal of suspended particles would be minor.(5) The surfaces of the sands, which had been used in the upward flow filtration or in the downward flow filtration, were observed by the scanning electron microscope. Most of the deposited particles were caught directly on the uneven faces of the sand surface such as hollows or cracks, or hanging o. These results indicate that the particle removal would depend to a great extent upon the physical effects.

(1)X射线分析表明，砂表面化学元素为Si、O、Al、Ca、Mg、Fe、K，其中主要元素和化合物分别为Si、O和SiO2，各元素在砂表面均匀分布。(2)扫描电镜观察表明，砂表面由多个被边缘分割的平面组成。在这些巷道上，存在着台阶、凹陷、裂缝、隆起等凹凸不平的路面，这些路面对水中悬浮颗粒的捕集起着重要的作用。(3)在过滤器中颗粒沉积的第一个过程中，观察到沉积颗粒飞溅在砂表面上的存在。之后，这些粒子继续捕捉后续粒子，迅速长大。颗粒团与相邻颗粒团接触时间短。随着过滤时间的推移，沉积物的表面变得越来越光滑。这些结果表明，颗粒在砂粒上的附着位点的阐明将是重要的。(4)过滤实验已通过使用Au涂覆和未涂覆的砂。在实验中，用涂层砂去除颗粒的效率仅比用未涂层砂高1.5- 3.0%。这表明去除悬浮颗粒的化学影响很小。(5)通过扫描电子显微镜观察已用于上流式过滤或下流式过滤的砂的表面。大多数沉积颗粒直接被捕获在砂表面的不平坦面上，如凹陷或裂缝，或悬挂在砂表面上。这些结果表明，颗粒的去除将在很大程度上取决于物理效应。