Aggregation of nano-sized alum-humic primary particles
Aggregation of nano-sized alum-humic primary particles
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纳米级铝腐殖初级颗粒的聚集
DOI：
10.1016/j.seppur.2012.08.017
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发表时间：
2012-10
影响因子：
8.6
通讯作者：
Jiu-hui Qu
中科院分区：
文献类型：
--
作者：
Wen-zheng Yu;Ting Liu;John Gregory;Gui-bai Li;Hui-juan Liu;Jiu-hui Qu
为了了解混凝过程中絮体形成和生长的机理，本研究通过腐植酸与明矾混凝，研究了纳米级一次颗粒的zeta电位和表面特性对混凝效率的影响。结果表明，只需1分钟的快速混合就足以将腐植酸吸附到明矾沉淀上，而15分钟的絮凝（缓慢混合）仅诱导絮凝体的形成和生长。明矾-腐植絮体的初级粒径接近50nm，呈球形。由Derjaguin-Landau-Verwey-Overbeek (DLVO)理论推导出的数学模型表明，微絮凝体的形成(或滞后时间)由纳米级初级粒子的zeta电位的平方值和布朗运动的强度决定，与水温密切相关。本研究存在一个绝对临界zeta电位，即13.5mV，确定两个纳米粒子能否克服范德华力和双电层排斥力组成的能垒，在一定温度下形成絮体。布朗运动决定了纳米级初级颗粒（氢氧化铝与腐殖酸沉淀）是否有机会克服排斥力而相互胶结。冬季高纬度地区混凝效率低是由于碰撞频率低造成的，这主要是由于低温下布朗运动强度低所致。此外，结果表明，如果絮凝体的尺寸大于某个值，则当扫掠絮凝主导混凝机制时，微絮凝体或其簇的聚集显着取决于初级颗粒上的活化位点，而不是初级颗粒的 zeta 电位。
In order to understand the mechanism of floc formation and growth in coagulation process, effect of zeta potential and surface characteristic of nano sized primary particles on coagulation efficiency were investigated by coagulation of humic acid with alum in this study. It was demonstrated that only 1min rapid mixing was enough for adsorption of humic acid onto the precipitates of alum, and 15min flocculation (slow mixing) only induced the formation and growth of flocs. The primary particle size of alum–humic flocs was near 50nm and spherical. Mathematical model deduced from Derjaguin–Landau–Verwey–Overbeek (DLVO) theory showed that the formation of micro-flocs (or lag time) was determined by the square value of zeta potential of nano-sized primary particles and intensity of Brownian motion, which is closely related to water temperature. There was an absolute critical zeta potential, i.e. 13.5mV in this study, determining whether two nano-sized particles could overcome the energy barrier consisted of Van der Waals force and electrical double layer repulsion force to allow floc formation to occur at a certain temperature. The Brownian motion determined whether the nano-sized primary particles (aluminum hydroxide precipitates with humic acid) had the opportunity to overcome the repulsive force and cement with each other. Low coagulation efficiency at high latitude area in winter is caused by low collision frequency, which is mainly attributed to the low intensity of Brownian motion at a low temperature. Furthermore, it was demonstrated that aggregation of micro-flocs or their clusters significantly depended on activated sites on the primary particles rather than the zeta potential of primary particles when sweep flocculation dominated the coagulation mechanism if the size of flocs was larger than some value.
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DOI：
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发表时间：
1997
期刊：
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影响因子：
--
作者：
通讯作者：
--
影响因子：
11.4
作者：
Xiao-yan Li;B. Logan
通讯作者：
Xiao-yan Li;B. Logan
DOI：
--
发表时间：
1987
期刊：
Journal of Water Pollution Control Federation
影响因子：
--
作者：
S. Dentel;J. Gossett
通讯作者：
S. Dentel;J. Gossett
影响因子：
12.8
作者：
W. Snodgrass;M. Clark;C. R. O'melia
通讯作者：
W. Snodgrass;M. Clark;C. R. O'melia
DOI：
10.2166/ws.2002.0051
发表时间：
2002-04
期刊：
Water Science & Technology: Water Supply
影响因子：
--
作者：
Xu-dong Wang;P. Jin;J. Gregory
通讯作者：
Xu-dong Wang;P. Jin;J. Gregory