Surfactants And Admixtures; Surfactants - Malvern Mastersizer Series Getting Started

Surfactants and admixtures

If you are experiencing problems such as the sample floating on the surface of the
dispersant then the addition of a surfactant or an admixture may be helpful. The
next section briefly explains the use of these additives.

Surfactants

The addition of a surfactant may assist the preparation of the sample by removing
the surface charge effects on the sample that cause it to float on the surface or
clump together.
Surfactants have to be added in minute quantities, typically one drop per litre of
dispersant. If too much surfactant is added to the dispersion tank then the action
of stirring and pumping the sample may cause it to froth, entering bubbles into
the system. Bubbles are measured by the system as particles which can bias the
results. Anti-foaming agents may be added to prevent the formation of bubbles.
Try adding a drop of surfactant to a quantity of sample and dispersant mixed in a
small beaker. If the sample sinks to the bottom of the beaker in large clumps then
discard the sample and start again. Try again, this time adding the sample to a dry
beaker and adding a drop of surfactant and mixing thoroughly. Add the dispersant
and mix well. This usually avoids the agglomeration caused by adding the
dispersant first.
A list of recommended surfactants in order of common use is given below:
Surfactant
Nonidet P40
Teepol L
Synperonic N
Aerosol OT
Sodium dodecyl sulphate
Hyamine 2389
C H A P T E R 9
Nature
Non-ionic
Non-ionic
Non-ionic
Anionic (solid)
Anionic
Cationic
G E T T I N G S T A R T E D
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