Electrochemical Studies on the Corrosion Behavior of Common Metals in Eutectic Ionic Liquids

Abstract

Recently, new green novel solvents called Deep Eutectic Solvents (DES) were investigated as substitute for none environmentally friendly organic solvents and ionic liquids that are used in many applications such as metal processing, organic synthesis, extraction and adsorption processes, and in medical and pharmaceutical researches. DES are biodegradable and eco-friendly solvents. However, their corrosivity is not well studied. Corrosion of metals is a major problem in the chemical, oil and gas industries. In this work, several DES were synthesized and their corrosivity towards mild steel, stainless steel and copper was investigated using electrochemical techniques such as electrochemical impedance spectroscopy (EIS) and Cyclic Sweep (CS). DES were synthesized by mixing choline chloride with a hydrogen bond donor at 70oC for about an hour. The corrosivity of DES at three different temperatures (25 oC, 50 oC and 75 oC) and as a function moisture content (0%, 5% and 10%) was determined. In most of the observations, corrosion rate increases as temperature and moisture content increase. Moreover, the corrosion rate of stainless steel was found to be the lowest of the tested metals at all conditions which makes it a good material for different applications. It was concluded that urea and glycol based DES are good candidates as green solvents due to their low and resilient corrosion rate values.