I am measuring the size distribution of PbO particles with glycerine as solvent with Malvern zetasizer. Is it ok to use glycerine as solvent. I am also adding dispersant in it.
Hi Afza
Addition of glycerine is indeed possible, and this is something that may typically be done to help stabilise large particles by density matching to reduce sedimentation. The refractive index and viscosity of the dispersion will change with the addition of glycerine, so this should be accounted for when setting up the measurement. The Malvern Zetasizer software has a tool under the Calculators option whereby you can calculate the viscosity of mixtures of known solvents.
Good luck with your measurements.
Hi Afza
Addition of glycerine is indeed possible, and this is something that may typically be done to help stabilise large particles by density matching to reduce sedimentation. The refractive index and viscosity of the dispersion will change with the addition of glycerine, so this should be accounted for when setting up the measurement. The Malvern Zetasizer software has a tool under the Calculators option whereby you can calculate the viscosity of mixtures of known solvents.
Good luck with your measurements.
In addition to the excellent answer from Alexander above, remember that although the settling is reduced by using a thicker solvent such as glycerol, the Brownian motion of the particles is also reduced correspondingly. PbO has a relatively high density and if the material begins in powder form, then laser diffraction could be an alternative measurement technique as dispersion to the nano (< 100 nm) size could prove problematical. Carry out a Stokes' Law calculation (as in ASTM E2490-09(15)) to determine the maximum size of PbO that would allow it to remain in suspension for a considerable period of time.
@Muhammad - optical properties/refractive index are not required for the intensity distribution in a DLS experiment. See for example: https://www.researchgate.net/post/Can_anyone_help_me_in_providing_physical_properties_of_the_sample_required_for_DLS_Measurement
In my opinion so far I have following answer for your question:
As DLS (Dynamic Light Scattering) measures the hydrodynamic size of particles and gives the surfactant stabilized size of particle i.e how deep or effective solvation of your surfactant is it is directly related to that, if it solvates deeper then size will be smaller relative to that size of particle in which surfactant solvates not much effectively. If Glycerine is stabilizing the particle like surfactant then it will certainly effect the size of particle...Further I suggest you that you should google the hydrodynamic size as well....
As stated above, glycerine or glycerol may be used as a solvent in the Zetasizer, and it may also be used as an additive in a complex solvent mixture. As long as the cuvette material is compatible with the sample, this is OK and a wide range of solvents are used for DLS. As an example, polystyrene cuvettes will not hold up to toluene overnight.
When using additives such as glycerol, there may be an unexpected side effect: for samples with low scattering from the nanoparticles (due to low concentration or low refractive index difference) the additive may also appear as an additional peak in the size distribution.
http://www.materials-talks.com/blog/2016/06/15/solvent-peaks-how-to-get-rid-of-the-buffersaltadditive-dls-contribution/
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