Eggshell waste extract as potential natural corrosion inhibitor for AISI 1020 steel in acidic environment

Using natural corrosion inhibitors from calcium carbonate has gained attention in corrosion prevention approaches as it offers comparable and significant benefits compared to other corrosion inhibitors. Consequently, eggshells with a high amount of calcium carbonate were proposed as a corrosion inhibitor to evaluate the effect on the corrosion behaviour of AISI 1020 steel. In this study, the eggshell waste was extracted in ethanol solution using a Soxhlet extractor and thickened through the rotary evaporator to produce the proposed natural corrosion inhibitor with 10%, 20%, and 30%. The characteristics of the inhibitor were then examined and verified through FTIR and XRD analysis. The corrosion performance was then evaluated through the weight loss method in 1.0 molar hydrochloric acid in different durations, which are 7, 14, and 21 days. The corrosion rate and inhibiting efficiency were also performed to analyse the effect of eggshell concentration on the AISI 1020 steel. In addition, macrostructure observations were executed to assess the physical appearances of the samples. The results show that the proposed eggshell inhibitor successfully helped improve the inhibiting efficiency of AISI 1020 steel by 88.37%. Additionally, increasing the eggshell concentration decreases the corrosion rate and increases the inhibitor efficiency. This is due to CaCO3 in eggshells, a barrier to metal surfaces. Results indicate that selecting eggshell as a natural corrosion inhibitor successfully and confirmably protected the surface. Thus, this study is a viable utilisation of sustainable use from eggshell waste in reducing the corrosion occurrence of AISI 1020 steel in an acidic environment.