摘要
通过显微摄影分析研究了腐殖酸铝盐絮凝体成长的动态过程以及在混凝过程中絮凝体构造 (分形维数 )的变化规律 .结果表明 ,在腐殖酸混凝过程中 ,随搅拌历时延长 ,絮凝体粒径不断成长变大 ,最终达到平衡状态 .随着絮凝体的成长 ,其构造呈现由密实逐渐向疏松过渡的过程 ,空隙率变大 ,二维分形维数由初期的 1 8左右下降到1 4左右 .絮凝体分形维数Df 和粒径df 之间具有Df=Ad-nf 的幂函数关系 .理论分析结果说明了Df 随df 增大而减小是随机碰撞结合的必然结果 .铝盐混凝剂投量直接影响了腐殖酸絮凝体的成长速度和平衡粒径 .
Using a microscopic technique, the dynamic properties of Al humic flocs were studied and the regularity of the variation of floc structure, i.e. fractal dimension, was discussed. The results show that during coagulation floc size increased with agitation time and finally reacheds an equilibrium state. As flocs grow their structure gradually become looser with an increase of void ratio, and results in a substantial decrease of their fractal dimension from the initial value of 1 8 to about 1 4. There exist an exponential relation between the fractal dimension D f and the floc size d f as D f= Ad - n f. It was explained by theoretical analysis that the decrease of D f with increase of d f as was the result of random collision and agglomeration of primary particles. The alum dosage directly affected the rate of floc growth and its equilibrium size. Overdosing may bring about an apparent decrease of the fractal dimension of the flocs.
出处
《环境科学》
EI
CAS
CSCD
北大核心
2002年第4期71-75,共5页
Environmental Science
基金
国家自然科学基金国际合作项目 (5 0 0 10 130 4 6 0 )
