Performance of (HEMIM)+ (CN)- and (DMIM)+ (Cl)- as corrosion inhibitor of API 5L X52 steel in HCl medium

摘要

Two ionic liquids, 1-(2-hydroxyethyl)-3-methylimidazolium dicyanamide (HEMIM) + (CN) - and 1,3-didecyl-2-methylimidazolium chloride (DMIM) + (Cl) - , were evaluated as corrosion inhibitors of the API5L X52 in 0.5 M HCl using electrochemical method, weight loss, and surface characterizationtechniques. Gravimetric tests showed that the ILs display high corrosion protection efficiency, % EI, (92% and 97 %) with 100 and 5 ppm of (HEMIM) + (CN) - and (DMIM) + (Cl) - , respectively. Electrochemicaltests showed that the % EI depends on the IL concentration and the temperature. The polarization studiesshowed that the ILs are mixed type inhibitors and the adsorption of the ILs on the API 5L X52 obeyedthe Langmuir adsorption isotherm displaying chemical interaction between the steel and the IL. SEMand AFM verified a considerable reduction of the corrosion process after the addition of the ILs. Uv-visalso confirmed the interaction between ILs and steel. Theoretical quantum chemical calculation studiesagree with experimental results. The adsorption energy of (DMIM) + (Cl) - on Fe (110) surface is higherthan that of (HEMIM) + (CN) - , but both inhibitors are expected to bind strongly to the API 5L X52.