Corrosion Inhibition of Mild Steel Using Plant Extracts of Caesalpinia Pulcherrima Flower, Carica Papaya and Vernonia amygdalina in HCL Acid Solutions

Abstract

Maintaining the integrity of assets and infrastructure is pertinent to the existence of all industries. The oil and gas industry is not left out in this effort, as its entire value chain largely depends on assets made from corrosion-vulnerable mild steel for its operations and the movement or storage of its products. As industries shift towards sustainable and eco-friendly practices, there arises a critical need to explore alternative and environmentally friendly corrosion inhibition approaches that offer comparable or superior effectiveness over traditional corrosion inhibitors, like disodium hydrogen phosphate (DSHP), which poses an environmental hazard despite being widely used. This research aims to investigate the viability of Caesalpinia pulcherrima, Carica papaya (Pawpaw) leaf and Vernonia amygdalina (Bitter leaf) extract as novel eco-friendly corrosion inhibitors for mild steel.  The weight loss method is used to study the performance of Caesalpinia pulcherrima (CPFE), Carica papaya leaf (Pawpaw leaf or CPLE) and Vernonia amygdalina (Bitter leaf or VAE) in inhibiting corrosion. The viability of the novel potential eco-friendly corrosion inhibitor extracts was tested on mild steel in 1M HCl solution over a 24-hour period. Investigations revealed that CPFE, CPLE and VAE demonstrate an increase in inhibition efficiency with increasing concentrations but a decrease with prolonged immersion time. A maximal inhibition efficiency of 91.14%, 89.97% and 88.41% was observed with CPFE, CPLE and VAE, respectively, at a concentration of 1.5g/L after 24 hours of positioning them as green or eco-friendly alternatives for inhibiting corrosion of mild steel.