Abstract
An effect of associations of high molecular-weight nitrogen-containing inhibitors on their chemisorption to a metal was further investigated. A self-association of these inhibitors in solution was determined with infrared absorption spectra. Corrosion tests were simultaneously carried out in 5% hydrochloric acid with filmed mild steel test coupons which were preliminarily prepared in the solution. The inhibitors used are 2-n-dodecyl pyrrole and N-n-dodecyl pyrrole.
The self-association of inhibitor caused lower inhibition. Therefore, the efficiency increased when effect of the association was removed by following procedure:
1) selecting a solvent which makes the inhibitor free from the association,
2) decreasing the concentration of the solution,
3) elevating the adsorption temperature.
It is concluded that the adsorption of inhibitor is interrupted in such tests since unshared pair of electrons which requires for chemisorption is blocked with hydrogen bond.
Decreases of the inhibition efficiencies were observed in the tests conducted with the pre-filmed coupons in a proton-donating or a proton-accepting solvent. From these results an inter-molecular association of inhibitors with other substances may cause decrease of the inhibition as seen in self-association.
