Ni/Al2O3 waste catalyst loaded with pomegranate peel extract and Ce3+ ions as a sustainable active/barrier pigment for epoxy anti-corrosion coating

Abstract

Nickel-containing alumina (Ni/Al2O3) is a commercially available catalyst that is widely used for desulfurizing crude oil components. However, the accumulation of carbon and sulfur on the catalyst surface can lead to its deactivation, making its disposal environmentally hazardous. Additionally, extracting nickel from waste catalysts is not economically feasible. The high specific surface area of Ni/Al2O3 waste catalyst (Cat), which can exceed 100 m2/g, makes it a promising material for repurposing as nanocontainers for anti-corrosive coatings. In this study, an intelligent epoxy (EP) anti-corrosion coating incorporating Cat for encapsulating a green hybrid corrosion inhibitor based on pomegranate peel extract (PPE) and Ce3+ ions was developed. Brunauer-Emmett-Teller (BET) analysis revealed that Cat nanopigment possessed a mesoporous structure and a surface area of 127 m2/g, rendering it a suitable candidate for encapsulating corrosion inhibitors. Fourier-transform infrared spectroscopy (FTIR), BET, and thermogravimetric analysis (TGA) were employed to confirm inhibitor loading in the Cat nanopigment. The self-healing and protective properties of the prepared EP-based composite coatings were evaluated using salt spray and electrochemical impedance spectroscopy (EIS) tests. The findings demonstrated a 440% improvement in the overall corrosion resistance (RT) of Ce-PPE@Cat/EP coating compared to blank/EP coatings.