CaCO₃-derived from eggshell waste for improving the corrosion resistance of zinc composite coating on mild steel for biodiesel storage tank

Sustainability of energy does not end in the generation of biofuels, but as well encompasses proper mitigation of the metallic equipment used in the plant from corrosion degradation. Corrosion of metallic equipment in biodiesel plants limits the storage and distribution of biodiesel to the end-users. Carbon steel of Mild steel type/grade is one of the major metallic materials used in the construction of biodiesel storage tanks. The major setback of using mild steel for biodiesel storage is the high corrosion rate. This research aims to develop a novel coating of mild steel using CaCO₃ derived from eggshell waste (ESP). The Codeposition method was used to develop Zn-10%CaCO₃-ESP (single and double layer). The corrosion of the samples was tested in a Jatropha curcas biodiesel (JBD) environment. Microstructure, hardness values, viscosity, and density of the oil were determined. A corrosion protection efficiency of 68.87% was obtained using the Zn-10%CaCO₃-ESP double layer. High corrosion damage as a result of localized pitting corrosion mechanism was observed for the mild steel without coating. This novel coating can be used in the industrial fabrication of storage tanks for biodiesel since the CaCO₃-ESP is prepared by a simple method.