Investigation of inhibitive property of hydroxypropyl methylcellulose on acid corrosion of copper using experimental and computational simulation techniques

Abstract

The inhibitive property of hydroxypropyl methylcellulose (HPC) on acid (1.0 M HCl and 0.5 M H₂SO₄) corrosion of copper was investigated using gravimetric, electrochemical impedance spectroscopy (EIS), potentiodynamic polarization and computational simulation techniques. Gravimetric results showed decrease in weight loss in the presence of HPC at room temperature of 25°C. With increase in temperature from 30–60°C, weight gain was observed which indicates that HPC film was adsorbed on the Cu surface. According to impedance measurement results, HPC displayed better inhibition in the presence of HCl (I.E._Rct% = 23.99) than in the presence of H₂SO₄ with 19.98 inhibition efficiency. Potentiodynamic polarization tests showed HPC inhibited HCl solution with I.E.% of 43.69 whereas 19.05 I.E.% was obtained for HPC in H₂SO₄ acid solution. Nonetheless, HPC acted as a mixed-type inhibitor with predominant cathodic effect. The DFT calculations showed that E_Homo is − 5.504 eV, while E_Lumo is 0.859 eV and energy gap is 6.363 eV. These values indicate that HPC inhibitor molecules are highly reactive and can readily transfer as well as accept electrons during copper surface-inhibitor interactions. Molecular dynamics simulation showed the adsorption energy (E_ads) for HPC on copper in the presence of 0.5 M H₂SO₄ solution was determined to be − 1.277 kcal/mol (− 5.108 kJ/mol), while E_ads for HPC on copper in the presence of 1.0 M HCl solution was − 1.55 kcal/mol (− 6.485 kJ/mol). The higher negative value of E_ads for HPC in the presence of HCl indicates stronger adsorption. Based on the observed results, HPC could be used as corrosion inhibitor for protection against corrosion of copper in 0.5 M H₂SO₄ acid solution but better in 1.0 M HCl acid solution.