Development of Ionic Liquids as Green Dual-Function Scale and Corrosion Inhibitor in the Petroleum Industry

In the petroleum industry, it is necessary to control both mineral scale and metal corrosion simultaneously. However, conventional chemical inhibitors are not always effective and can pose environmental concerns. Herein, this study investigates green protic ionic liquids (ILs) with various ethoxy units as dual-functional agents for inhibiting calcium sulfate scale and carbon steel corrosion. The scale inhibition characteristics of these ILs for calcium sulfate were examined using the static bottle test. In this method, a 50:50 mixture of seawater and formation water containing different concentrations of ILs was kept in an oven at 90 °C for 7 days. SEM and EDX were used to evaluate the change in calcium sulfate scale morphology and composition. The quantitative stability of the scale solution was analyzed by the MultiScan MS 20. The corrosion inhibition performance of these eco-friendly ILs was investigated for carbon steel in a 5 wt % HCl medium using the weight loss method. The results showed that the scale and corrosion inhibition performance significantly improved by increasing the number of ethoxy units in the ILs molecular structure. IL₆₉₀ depicted the highest scale inhibition effectiveness (93.72%) at 90 °C among all tested ILs. However, the best corrosion inhibition performance (95.91%) was obtained from IL₇₀₀. The ILs demonstrated significant aerobic biodegradability, with IL₃₆₀ showing the highest BOD₅ values (108.67 mg O₂/L). The results confirmed that ILs act as effective, green, and dual-functional inhibitors for sustainable petroleum application.