Highly efficient corrosion inhibitor for C1020 carbon steel during acid cleaning in multistage flash (MSF) desalination plant

Abstract

A new environmentally friendly and cost effective molecule, thiabendazole (TBZ), was evaluated as a potential acid corrosion inhibitor for a typical carbon steel (C1020 grade) used as construction material in MSF desalination plant using electrochemical and (weight loss) immersion techniques. Electrochemical measurements after 1, 4 and 8h immersion in 1.0M HCl at 25°C showed that TBZ is an excellent corrosion inhibitor for C1020 grade steel and its inhibition efficiency reaches ≈90% at 4mM concentration with no substantial increase at 10mM. In the presence of iodide ions, TBZ showed improved corrosion inhibition attaining inhibition efficiency of 94.3% with 4mM concentration after 4h of testing with no increase in inhibition efficiency after 8h. However, weight loss measurements indicate that the corrosion inhibition performance of TBZ, and TBZ in combination with KI decreased with immersion time up to 24h and temperature up to 60°C. SEM-EDX and ATR-IR spectroscopy confirm that the inhibition process was due to the formation of an adsorbed film that protects the steel surface against corrosive medium. DFT and Monte Carlo simulation results gave further molecular and atomic level insight on mechanism of interaction between the inhibitor and the steel surface.