Development of a structure-activity relationship for oil field corrosion inhibitors

Corrosion rare data for mild steel corrosion inhibitors in carbonated brine media were fitted to the Temkin adsorption isotherm. The fundamental const ants of the Temkin adsorption isotherm, i.e., molecular interaction and ads orption equilibrium constants, were used to glean important information abo ut the behavior of adsorbed corrosion inhibitors. Adsorption data were also used to calculate Delta(ad)H, Delta(ad)G, and Delta(ad)S, and the results demonstrated that some compounds are chemisorbed onto the electrode. Signif icantly, it has been found that chemisorption of corrosion inhibitors can y ield very good film persistency (i.e., corrosion protection even when the i nhibitor is no longer present). Molecular modeling using the quantum mechan ical program PCSpartan plus, along with a comparative analysis of adsorptio n data for a broad range of inhibitor molecules, has been used to derive a tentative structure/activity relationship for some oil field corrosion inhi bitors. (C) 1999 The Electrochemical Society. S0013-4651(98)07-066-9. All r ights reserved.