Relation between aggregation kinetics and the structure of kaolinite aggregates

Area of Science:

• Colloid and Surface Science
• Materials Science
• Physical Chemistry

Background:

• Understanding colloidal particle aggregation is crucial for various applications.
• Kaolinite's aggregation behavior influences its properties in suspensions.
• Characterizing aggregation dynamics requires precise measurement techniques.

Purpose of the Study:

• To determine the stability ratio (W) and fractal dimension (D(f)) of kaolinite (KGa-2).
• To investigate kaolinite aggregation kinetics under varying concentrations and pH 9.5.
• To explore the universality classes and scaling relations in kaolinite aggregation.

Main Methods:

• Dynamic Light Scattering (DLS) for aggregation kinetics and stability ratio (W).
• Static Light Scattering (SLS) for fractal dimension (D(f)) determination.
• Controlled variations in kaolinite and electrolyte concentrations at pH 9.5.

Main Results:

• Kaolinite aggregation fits diffusion-limited and reaction-limited universality classes at W ≈ 1 and W > 100, respectively.
• An intermediate aggregation regime (5 < W < 100) exhibits power-law aggregate radius growth.
• A scaling relation between fractal dimension and stability ratio was demonstrated, indicating increased packing density with reduced sticking probability.

Conclusions:

• Colloidal kaolinite aggregation exhibits universal characteristics under specific conditions.
• The stability ratio (W) is a key parameter governing kaolinite aggregation regimes.
• A continuous relationship exists between fractal dimension and stability ratio in intermediate aggregation.