Polyethylene glycol (PEG) as corrosion inhibitor for steel in an acidic environment

Corrosion of stainless steel in acidic environments remains a critical issue in industry, where exposure to hydrochloric acid (HCl) can cause severe damage to the function of equipment and machinery used in the industry. The use of polyethylene glycol (PEG) as corrosion inhibitor in an acidic media has a limitation in an adsorptivity that may result in low inhibition efficiency. The addition of other chemicals such as imidazoline and zinc (II) ion (Zn2+) is a good approach in enhancing the inhibition. However, it may raise environmental concerns and economical aspect. Thus, in this study a specific concentration range of PEG 2000 is used to investigate its capability in inhibiting corrosion in acid. This study investigates PEG as a low-toxicity corrosion inhibitor for SUS304 stainless steel in acidic environments (HCl) solutions. This investigation has focused on immersion tests using PEG 2000 concentrations ranging from 0.015 M to 0.2 M in 1 M and 0.5 M HCl. Inhibition behaviour was evaluated through weight loss measurements which were used to evaluate the inhibition efficiency of PEG on stainless steel in HCl solutions. Surface analysis was performed using optical microscope to identify inhibited and uninhibited steel surface. Fourier Transform Infrared Spectroscopy (FTIR) was used to confirm the presence of functional groups important in the corrosion inhibitor for adsorption on the steel surface. The results showed a significant reduction in corrosion rate with increasing PEG concentration. At the highest concentration tested, 0.2 M PEG, the inhibition efficiency reached 83.02% in 0.5 M HCl and 70.60% in 1 M HCl. In the absence of PEG, the corrosion rate values were in the poor range, while the PEG treated samples shifted to fair and good classifications. The results from the observation of the samples under optical microscopy were evident that the smoother surface in the PEG inhibited specimens confirmed the formation of a protective film on the steel surface. This study highlights the potential of PEG as a sustainable corrosion inhibitor condition, offering a safer and more environmentally friendly solution for industrial applications involving acidic conditions and provides valuable insights for designing green corrosion protection strategies.