Electrodeposited Zn and Zn–CaCO3 composite on mild steel for biodiesel storage tanks: Corrosion resistance evaluation

Biofuels' sustainable energy necessitates using corrosion-resistant steels in plant equipment and storage tanks. However, the availability of locally sourced PCC (precipitated calcium carbonate) from Buton asphalt-recovered solid wastes ( ashbuton ) promises technically and economically for Zn-PCC composites coated on mild carbon steel grade in biodiesel storage tank construction. This study was to investigate electrodeposited mild steel with Zn and Zn-PCC composites followed by corrosion testing on uncoated and coated steel samples in a simulated biodiesel environment employing the electrochemical impedance spectroscopy (EIS) technique. The results indicated that Zn-PCC ( ashbuton ) coated to the mild steel greatly enhanced the substrate's corrosion performance in terms of polarization resistance (4204.6 Ω), lowest corrosion rate (2.1557E-7 mm/year), and through EIS analysis shows the corrosion rates in the following sequence: Zn-PCC (commercial) > Zn > Zn-PCC ( ashbuton ). Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray spectroscopy (EDX) results of selected produced coatings revealed the presence of homogeneous calcium carbonates and a lesser amount of iron oxide in the mild steel coating. The Zn-PCC coating is ideal for industrial biodiesel storage tanks and uses the low-cost value of PCC-derived industrial wastes to improve corrosion resistance.