H. Ebeltoft et J. Sjoblom, LANGMUIR FILMS OF CORROSION MODEL INHIBITORS IN PRESENCE OF OTHER PRODUCTION CHEMICALS IN OIL INDUSTRY, Journal of dispersion science and technology, 15(4), 1994, pp. 487-511
Interactions between monolayers of trilaurylamine (TLA) and various wa
ter-soluble corrosion, hydrate and scale inhibitors, as well as acetic
acid and FeCl2, have been studied by means of the Langmuir technique.
The water-soluble compounds were present in the subphase before TLA w
as spread. Their influence on the monolayer properties were measured b
y means of surface pressure-area (pi-A) isotherms and constant surface
pressure-area relaxation measurements. All the added water soluble sp
ecies gave rise to monolayer expansion. The monolayer expansion observ
ed for TLA at pH 1, increased when FeCl2 was added to the subphase at
the same pH. Polyethyleneglycols with molecular weight higher than 200
destabilized totally the TLA-monolayer, probably due to bending and f
olding into multilayers. Monolayer expansion and film instability incr
eased with increased acetic acid concentrations. The destabilization m
echanism in this case was most likely due to a combination of nucleati
on and dissolution of film components into the subphase. The corrosion
inhibitor Dyno KI 384 had a higher surface activity than TLA. Hence t
he monolayer became unstable already at an addition of 0.7 ppm due to
a high penetration into the film. Monolayer penetration of the scale i
nhibitor by Dyno SI 427 seems to be concentration independent, but the
monolayer rigidity increases upon penetration.