posted on 2012-12-04, 00:00authored byY. Mikal van Leeuwen, Krassimir
P. Velikov, Willem K. Kegel
Repeptization (redispersion) from
an aggregated state is usually
only possible in charge-stabilized colloidal systems if the system
is either coagulated in the secondary minimum of the interaction potential
or if the system cannot settle completely into the primary minimum.
In this work, we analyze the zeta potential, conductivity, and long-term
stability of colloidal systems of iron(III) pyrophosphate and surprisingly
find that the system seems to defy conventional wisdom as it can be
repeptized from its coagulated state regardless of aging time and
background ions. Moreover, after having been stored for up to a month
in 2 M NaCl, dialysis of iron pyrophosphate will yield a colloidal
dispersion that is actually stable for a longer period of time than
a fresh system with background electrolyte removed.