The sedimentationofdiluteironsuspensionswithdifferent
concentrations ofsurfactantswascheckedbystudyingtheevo-
lution withtimeofthenormalizedopticalabsorbance(A/A0, A is
the absorbanceattimet,andA0 is thevaluecorrespondingtothe
initial conditions).Asshownin Fig. 7(a), thereisasimilarten-
dency ofA/A0 to decreasewithtimeforCI/OAsuspensionsinthe
concentration rangestudied(alsoobservedinRef. [16]). Itseems
that stericrepulsiondoesnotplayanyimportantroleonthese-
dimentation behaviorofironsuspensions.Fordilutesuspension,