Corrosion inhibition by amitriptyline and amitriptyline based formulations for steels in simulated pickling and acidizing media

Investigation into amitriptyline (AMI) as a corrosion inhibitor for different grades of pipeline steels (X80, J55 and mild steel) was undertaken under static conditions in 3.7% and 15% HCl solution and temperature ranging from 30 to 90 degrees C using electrochemical, gravimetric, and surface screening approaches. AMI is adjudged an effective steel corrosion inhibitor in 3.7% HCl at 30 degrees C but poor inhibitor at high temperatures and in 15% HCl. The values of enthalpy of adsorption and variation of protection efficacy with temperature point to physical interaction between AMI molecules and the steel surface. Evidence of formation of adsorbed film on the specimen surface has been found via Scanning electron microscope (SEM) and energy dispersive spectroscopy (EDAX) screening. Various formulations consisting of AMI as the base component and other additives (potassium iodide, glutathione and N-acetyl cysteine) have been developed. The formulations were tested at different experimental conditions and inhibition performance compared with that of a commercial corrosion inhibitor. Results obtained show that AMI based formulations can compete favorably with commercial inhibitor even at severe conditions. In 15% HCl solution and temperature of 90 degrees C, inhibition efficiency of 94% is recorded for commercial inhibitor and 92% for AMI based formulation. AMI based formulation can be utilized as effective corrosion inhibitor in oil and gas production.