Tailoring poly(2-ethyl-2-oxazoline) towards effective mitigation of chloride-induced dissolution of S235JR steel: The synergistic contributions of potassium iodide and myristyl trimethylammonium bromide

Organic compounds that exhibit little or no toxicity, have high solubility properties, and are affordable are highly sought after as metal corrosion inhibitors. The key to formulating an effective and economically viable corrosion inhibitor is the identification of compounds with strong synergistic effects. The synergistic inhibition of S235JR carbon steel in 1 M HCl by poly(2-ethyl-2-oxazoline) (PO), KI, and myristyl trimethylammonium bromide (MTAB) is studied. The durability of the PO + KI + MTAB blend is examined for up to 72 h. Results reveal an average inhibition efficiency (η) of 80 % for PO at 1000 mg/L. Adding 5 mg/L KI or MTAB to 1000 mg/L PO raised η to 97 % or 94 % from EIS measurements. PO(1000 mg/L) + KI(5 mg/L) + MTAB(5 mg/L) produced ∼ 99 % inhibition and kept the corrosion rate at 0.09 mm/y for up to 72 h. Spectroscopic and computational studies reveal PO interacted with the steel surface making use of the carbonyl functional group. The DFT calculations and MD simulations confirm the favorable tendency of the PO molecule to adsorb on the metal surface and the synergistic adsorption with KI and MTAB. Furthermore, SEM and AFM results confirm the high inhibitive performance of the blend. PO + KI + MTAB blend is highly recommended for long-term acid pickling of a metal surface and acid cleaning of plants.