Biopolymer Xylan as a novel green corrosion inhibitor for AISI 5140 steel and copper in H₂SO₄ medium

Background: AISI 5140 steel and copper, widely used in water cooling and desalination systems, are prone to corrosion in harsh environments. To address this, Xylan (XL) was studied as a novel green corrosion inhibitor in H₂SO₄ medium. Methods: A custom design approach of Design of Experiments (DoE) was introduced to optimize key parameters. The inhibition performance was evaluated using electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization (PDP), while surface morphology was examined through SEM and EDX analysis. The mechanism of inhibition of XL was explained using DFT studies. Significant Findings: The developed model demonstrated the significance of medium concentration and temperature on inhibition efficiency. Experimental validation confirmed the model's accuracy. For AISI 5140 steel, a maximum inhibition efficiency of 84.05 % was achieved at 0.1 M H₂SO₄, 0.25 g/L XL, and 50 °C. For copper, the highest efficiency of 77.15 % was observed at 0.1 M H₂SO₄, 0.25 g/L XL, and 50 °C. The results confirm XL's potential as a sustainable corrosion inhibitor and highlight the effectiveness of the DoE approach in predicting inhibitor performance. This study underscores the viability of XL for corrosion protection in industrial applications.