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

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.