Potential of water-soluble chitosan Schiff bases extracted from Metapenaeus dobsoni shells as effective corrosion inhibitors

Corrosion causes significant economic losses and structural failures in industries, highlighting the need for eco-friendly inhibitors. Chitosan (CS), a biodegradable and non-toxic biopolymer, shows potential, though its limited water solubility restricts its applications. To overcome this challenge, this study presents the synthesis of two water-soluble chitosan Schiff bases (CSBs) derived from the shells of Metapenaeus dobsoni (M. dobsoni). The extracted CS exhibits a remarkable degree of deacetylation exceeding 95 %, which was subsequently modified through reactions with o-vanillin (2-hydroxy-3-methoxybenzaldehyde) (CSB I) and 2,3-dihydroxybenzaldehyde (CSB II). Structural characterization using spectroscopic techniques confirmed the successful formation of CSBs. Electrochemical measurements were employed to assess the corrosion resistance of mild steel in 0.5 M HCl with varying concentrations of CSB I and CSB II. The results revealed superior corrosion inhibition by CSB II (% IE = 94.48 %) compared to CSB I (% IE = 88.80 %). The methoxy group in CSB II contributed to its higher electron density and enhanced adsorption, leading to better surface coverage and corrosion resistance. Both inhibitors followed the Langmuir isotherm, suggesting a mix of physisorption and chemisorption. These CSBs are promising for corrosion control in industries like pipelines, storage tanks, construction materials, and acid pickling.