title: [Dynamic properties of Al-humic flocs].
abstract: 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 reached 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 Df and the floc size df as Df = Adf-n. It was explained by theoretical analysis that the decrease of Df with increase of df 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.
authors.affiliation: School of Environmental and Municipal Engineering, Xi'an University of Architecture & Technology, Xi'an 710055, China.
authors.forename: Xiaochang
authors.initials: X
authors.lastname: Wang
authors.forename: Pengkang
authors.initials: P
authors.lastname: Jin
mesh_terms: D000535:Aluminum / Q000737:chemistry*; D005427:Flocculation; D006812:Humic Substances / Q000737:chemistry*
chemical_list: D006812:Humic Substances; D000535:Aluminum