Measurement of Fractal Aggregates of Polydisperse Particles Using Small-Angle Light Scattering

Aggregation Kinetics and Fractal Structure of γ-Alumina Assemblages

“…Results of studies on alumina suspensions (γ -alumina, boehmite, and gibbsite) (15) indicate that while gibbsite suspensions display a critical coagulation concentration of chloride ion in the expected region of around 50 mM, the other alumina suspensions display a resistance to aggregation in high-concentration chloride and nitrate solutions and are only aggregated at anion concentrations greater than 0.5 M. Van Bruggen et al (16) report similar stability for boehmite suspensions after addition of aluminum chlorohydrate. This stability has been hypothesized to be due to the presence of the aluminum tridecamer Al 13 O 4 (OH) 24 (H 2 O) 7+ 12 , which is proposed to adsorb to the alumina surface, generating powerful repulsive forces that are operative at small interparticle separations (<5 nm). Interestingly, all alumina suspensions investigated by Beattie et al (15) aggregated rapidly in the presence of less than 1 mM sulfate, a specifically binding anion apparently able to negate the powerful repulsive forces operating between Al 13 polymer coated particles.…”

Observations of a Correlation Between Primary Particle and Aggregate Size for Soot Particles

“…In most previous work, it was assumed that the average primary particle diameter is similar in all soot aggregates generated by a specific combustion source or at a specific operating condition (Dobbins and Megaridis 1991;Dobbins et al 1994;Farias et al 1996;Köylü 1997;Bushell and Amal 1998;Bushell and Amal 2000;Charalampopoulos and Shu 2002;Bond and Bergstrom 2006;Liu and Smallwood 2010). In other words, aggregates were assumed to be produced from equal-sized primary particles regardless of the size of the aggregates.…”

Flocculation of kaolin particles by two typical polyelectrolytes: A comparative study on the kinetics and floc structures

“…For example, the aggregation kinetics of hematite and aluminum oxides was studied using dynamic light scattering commonly referred to as photo correlation spectroscopy (PSC) [4][5][6]21]. Recently, static light scattering, such as small-angle laser light scattering (SALLS), has also been employed to determine on-line floc size of the alum-polystyrene flocculation [22], the sludge flocculation [23][24], the salt-latex flocculation [25][26], and the coagulation of raw water with rich natural organic matter [27][28]. Furthermore, SALLS has also been extensively utilized in acquiring information on the aggregate structures in terms of the mass fractal dimension.…”

“…Furthermore, SALLS has also been extensively utilized in acquiring information on the aggregate structures in terms of the mass fractal dimension. This method has been successfully used to rapidly determine the fractal dimension of the sludge floc structure [24,[29][30][31]], the salt-particle floc structure [25,26,32,33], and the polymer-alumina floc structure [9][10][11][15][16][17]. In addition, the traditional technique of image analysis was also used to determine the floc structure by fractal method [34][35][36].…”