My iron nano particle received strange pattern on Zetasizer intensity result. According to theory, the larger the particle size the result of intensity should received higher result. However, mine showed differently.
I have discussed with my lab mate and we thought it might be the aggregation that led to this kind of result.
Or maybe because the fabricating nano particle process that needed to charge the sample and Electromagnetic effect made the aggregation happened.
Some of the result of small particle intensity was too close to large particle intensity that made us confused.
There were five different environment settings and the results can be seen in the attachment.
Could anyone help me to understand the result?
Thank you so much!
the scattering intensity is larger for larger particles, and therefore the %intensity profile is not a true representation, for a multimodal dispersion. %Number normalises the size dependence of the scattering process and is a better representation of the content of your dispersion.
Several points here:
- The killer word in particle size distribution is the last one and the bane of all sizing techniques. The PDI of 1.0 for all samples shows that your system is probably unsuited to DLS (too large)
- DLS provides an intensity and not a number distribution. Indeed the latter is 'deprecated' by international standards such as ISO22412:2017 and ASTM E2490-09(15)
- It is not true that as size increases, intensity increases. This is a generalization that is not universally true. In certain areas where d ~ lambda then the intensity can actually fall with increasing size (the so-called Mie minima)
- What is the sample being measured? Aggregation and agglomeration invariably complicate nanoparticle measurement. Your materials may be magnetic and thus impossible to overcome van der Waals attraction by charge stabilization routes. The density is also high, so did you observe significant sedimentation? Have you carried out a Stokes' Law calculation to indicate what size particles of your density can stay in suspension?
All your reports say 'Refer to Quality Report'. What does this report actually say? This will give you good clues as to what is happening. I suspect sedimentation will be one of the answers. The sample looks more suited to laser diffraction and not DLS. Indeed it does not appear to meet the definitions of nano (< 100 nm).
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