Copper corrosion inhibition by 2-Thiobenzylbenzothiazole in 2M nitric acid

2-Thiobenzylbenzothiazole (2TBBT) has been used as corrosion inhibitor for copper corrosion in 2.0 M nitric acid. The studies were conducted, using mass loss and a quantum chemical method based on Density Functional Theory (DFT). The corrosion rate was found to be concentration and temperature dependent. Information on adsorption of the molecule on the copper surface was assessed through isotherms, including Langmuir, Freundlich and Flory Huggins. The best fit was obtained with the modified Langmuir adsorption isotherm. Thermodynamic adsorption functions and activation ones were determined and analysed. They show a spontaneous adsorption and a chemisorption process. Quantum chemical calculations at B3LYP level with 6-31G (d) basis set lead to molecular descriptors such as EHOMO (energy of the highest occupied molecular orbital), ELUMO (energy of the lowest unoccupied molecular orbital), Δ (energy gap) and  (dipole moment). The global reactivity descriptors such as  (electronegativity),  (hardness), (softness) and  (electrophilicity index) were derived using Koopman’s theorem and analysed. The local reactivity parameters, including Fukui functions  and local softness were determined and discussed. Furthermore, the relative electrophilicity  /   and relative nucleophylicity  /  were also determined and analysed. Experimental and theoretical data are in good agreement.