According to industrial standards, average particle size can be determined using titration and dynamic light scattering methods. Titration is suitable for silica sol products with an average particle size not exceeding 20 nm, while dynamic light scattering is suitable for silica sol products with an average particle size greater than 20 nm. Industrial silica sols are classified into alkaline sodium type, acidic type, alkaline ammonia type, neutral type, and alkaline potassium type according to different stabilization methods, and their appearance is transparent, translucent, or milky white liquid.
The testing items for the dispersion stability of nano-silica include particle size distribution, zeta potential, sedimentation rate, turbidity, and rheological properties. Commonly used testing instruments include laser particle size analyzers, zeta potential analyzers, UV-Vis spectrophotometers, rheometers, and centrifuges. Laser particle size analyzers measure particle size distribution based on the principles of laser diffraction or dynamic light scattering.