Comparative study of corrosion inhibition by three anionic surfactants in an acidic environment

Corrosion in carbon steel units of chemical, petrochemical and oil and gas plants poses safety and economic concerns. The goal of our study is to investigate the corrosion inhibition effectiveness of an environmentally benign surfactant, namely sodium lauroyl lactylate (SLL), in comparison to sodium cocoyl glutamate (SCG) and sodium dodecyl sulfate (SDS). The corrosion of carbon steel in 1 M HCl was markedly inhibited by 0.05 and 0.1 M of the anionic surfactant SLL, as determined from weight loss over 96 h, at ambient conditions. X-ray photoelectron spectroscopy (XPS) showed that SLL adsorbed at the carbon steel surface, forming a protective film that decreased corrosion. Scanning electron microscopy (SEM) showed that carbon steel surfaces immersed in 1 M HCl for 96 h had an etched appearance without SLL, whereas they retained their smoothness with 0.1 M SLL. Electrochemical impedance spectroscopy (EIS) measurements confirmed that SLL passivated carbon steel surfaces, markedly increasing the polarization resistance R-p from approximate to 95 to approximate to 20,694 omega cm(2) over a 12 h period. In contrast, without SLL, R-p decreased from approximate to 92 to approximate to 12 omega cm(2). These results demonstrate for the first time that the environmentally friendly surfactant SLL is an efficient corrosion inhibitor in extreme environments such as 1 M HCl solutions. Dissimilar to SLL, SCG and SDS were not effective in inhibiting corrosion.

Automated summary

The study showed that the environmentally friendly surfactant SLL effectively inhibits corrosion of carbon steel in 1 M HCl solutions by forming a protective film on the surface, while SCG and SDS were less effective in inhibiting corrosion.