Fractal analysis of polyferric chloride-humic acid (PFC-HA) flocs in different topological spaces.
Fractal analysis of polyferric chloride-humic acid (PFC-HA) flocs in different topological spaces.
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DOI：
10.1016/s1001-0742(09)60009-7
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发表时间：
2009
影响因子：
6.9
通讯作者：
Yili Wang;Jia Lu;Du Baiyu;Baoyou Shi;Dongsheng Wang
中科院分区：
文献类型：
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作者：
Yili Wang;Jia Lu;Du Baiyu;Baoyou Shi;Dongsheng Wang
采用有效密度-最大直径法、图像分析法和N2吸附-脱附法分别计算了不同初始pH值（9.0、7.0、5.0）和不同投加量的不同种类腐殖酸（HA）水溶液中聚合氯化铁-HA（PFC-HA）絮体在不同拓扑空间中的分形维数。利用有效密度与最大粒径的双对数关系和Logan经验公式计算了PFC-HA絮体的质量分形维数。在初始pH为7.0时，Df值大于2.0，比pH为9.0和5.0时分别提高了11%和13%，表明在初始pH为7.0时形成的絮体最致密。图像分析表明，在初始pH大于7.0的HA水中，PFC絮凝剂处理后，PFC-HA絮体的分形维数D2（logA vs. logdL）和D3（logVsphere vs. logdL）随着PFC投加量的增加而减小，絮体结构逐渐疏松。在PFC最佳投加量下，絮体的D2（logA vs. logdL）值与相应的Df值相差14%~ 43%，且随初始pH值的变化趋势也不同。而在3种不同初始pH条件下形成的絮体的D2值与相应的Df值变化趋势相同。基于分形的Frenkel-Halsey-Hill（FHH）吸附和解吸方程，在pH为9.0和7.0的HA水中形成的PFC-HA絮体的孔表面分形维数（Ds）均接近2.9421，而在pH为5.0时形成的絮体的Ds值小于2.3746。表明PFC-HA絮体干粉的孔表面分形维数主要表现为中孔尺寸分布和大孔尺寸分布的不规则性。
The fractal dimensions in different topological spaces of polyferric chloride-humic acid (PFC-HA) flocs, formed in flocculating different kinds of humic acids (HA) water at different initial pH (9.0, 7.0, 5.0) and PFC dosages, were calculated by effective density-maximum diameter, image analysis, and N2absorption-desorption methods, respectively. The mass fractal dimensions (Df) of PFC-HA flocs were calculated by bi-logarithm relation of effective density with maximum diameter and Logan empirical equation. The Dfvalue was more than 2.0 at initial pH of 7.0, which was 11% and 13% higher than those at pH 9.0 and 5.0, respecively, indicating the most compact flocs formed in flocculated HA water at initial pH of 7.0. The image analysis for those flocs indicates that after flocculating the HA water at initial pH greater than 7.0 with PFC flocculant, the fractal dimensions of D2(logA vs. logdL) and D3(logVsphere vs. logdL) of PFC-HA flocs decreased with the increase of PFC dosages, and PFC-HA flocs showed a gradually looser structure. At the optimum dosage of PFC, the D2(logA vs. logdL) values of the flocs show 14%–43% difference with their corresponding Df, and they even had different tendency with the change of initial pH values. However, the D2values of the flocs formed at three different initial pH in HA solution had a same tendency with the corresponding Df. Based on fractal Frenkel-Halsey-Hill (FHH) adsorption and desorption equations, the pore surface fractal dimensions (Ds) for dried powders of PFC-HA flocs formed in HA water with initial pH 9.0 and 7.0 were all close to 2.9421, and the Dsvalues of flocs formed at initial pH 5.0 were less than 2.3746. It indicated that the pore surface fractal dimensions of PFC-HA flocs dried powder mainly show the irregularity from the mesopore-size distribution and marcopore-size distribution.