Glycerol and malonic acid as corrosion inhibitors as seen through the density functional theory perspective

Abstract

Glycerol (G) is the major co-product in the transesterification process of biodiesel. As clean energy demand increases, the production of G also increases and new ways of re-using it are needed. In the last decade, some experimental studies claimed that G and its derivative, malonic acid (MA), could be used as corrosion inhibitors. Yet, presently, there is little evidence of it and more studies are needed to confirm that G and MA could have a good performance in metal protection. The present work aims to study the reactivity of G and MA, since reactivity and inhibition are intimately linked. The density functional theory (DFT) at the B3YLP/6-31G** level of theory was used to study the reactivity of both molecules. The global and local quantum parameters derived were used to assess the reactivity of both molecules. Analysis of the calculated reactivity descriptors suggest that G and MA should exhibit an acceptable corrosion efficiency, but MA showed have a greater potential as a corrosion inhibitor.