Granulometry (english version)

(update February 28th 2023)

Person in charge

Stéphane GROLLEAU - Hélène TERRISSE

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Equipment

• • • Laser Granulomètry :

Malvern  Mastersizer 3000, with an ultrasonic tank in situ, also equipped with a dry powder disperser.
Size range: 20 nm to 1 mm.
Characterization of the size distribution of particles in liquids (syrups, emulsions, suspensions…) and of dry powders.

• • • Dynamic Light Scattering (DLS):

Malvern Zetasizer NanoZS.

Analysis at two angles (13° et 173°) of the size of particles and molecules.

Technology NIBS enabling to better detect aggregates, and to measure small or dilute samples, as well as highly concentrated samples.

Size range: 1 nm to 10 µm.

Incident wavelength: 633 nm.

Volume of cuvettes (polystyrene or quartz): 1 mL.

Temperature range: 10-90°C.
Algorithms for the autocorrelation function analysis: Cumulants, Contin, NNLS.

Possibility to perform static light scattering analyses with Debye model (molecular weight determination).

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Operating principle:

- Laser granulometry:

Granulometry through diffraction and light scattering enables the determination of particles diameter between 20 nm and 1 mm, in suspension in a liquid, or as dry powder (dispersion of particles with compressed air). A laser beam illuminates the particles, which scatter light all around them, with scattering patterns specific to their size. The intensity of scattered light is recorded in a range of angles between 0 and 30°, and after mathematical analysis (MIE equations, which require the knowledge of refractive index of the particles and the dispersion medium), the software gives a histogram indicating the volume fraction of each granulometric class. This method determines the diameter of the sphere with the same volume as the particle.

- Dynamic Light Scattering: (DLS) :

Granulometry through quasi-elastic light scattering enables the measurement of particles with a diameter between 1 nm and a few µm, in suspension in a liquid. This method lies on the determination, by light scattering, of the velocity of colloidal particles when they are subjected to Brownian motion. The instrument records, according to time, the fluctuations of the light scattered by moving particles. This signal is then mathematically analysed to create an autocorrelation function, which enables determination of the translational diffusion coefficient of the particles. The latter is directly proportional to their size through Stokes-Einstein relation. This technique leads to the hydrodynamic diameter of particles, which takes into account the solvation layer around the particles surface. The thickness of this layer depends on various parameters, such as the ionic strength of the dispersion medium.

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Examples

• Granulometric distribution of food-grade titanium dioxide particles (E171) in various pH conditions, obtained through laser granulometry.

Oxy-gallates et oxy-germanates de terre rares conducteurs par ions oxygène, A. Chesnaud, Thèse de doctorat, Université de Nantes (2005).

• • Analysis by DLS of a colloidal suspension of TiDMF.4H₂O obtained by polycondensation of TiOCl₂ in DMF in the presence of water. Figure (a) presents the distribution in intensity of scattered light, figure (b) presents the same distribution, converted in volume fraction.

Monodispersed titanium oxide nanoparticles in N,N-dimethylformamide : water solutions,
H. Terrisse et al., Journal of Sol-Gel Science and Technology, volume 67, 288-296 (2013).