Pyrazole derivatives as environmental benign acid corrosion inhibitors for mild steel: Experimental and computational studies

Four industrially relevant pyrazole derivatives (PYRs) differing in their nature of substituents were synthesized by an eco-friendly one-pot multicomponent reaction (MCR), and their acid corrosion inhibition was studied for mild steel using experimental and computational approaches. Results revealed that the inhibition capability of PYRs was substituent-and concentration-dependent. Even though the efficiency increases in the existence of both the electron-withdrawing and the electron-releasing substituents, the best inhibition efficiency was achieved in the presence of electron releasing (-OH, -OHOCH3) groups. The inhibition efficiency of the studied PYRs followed the order: PYR-OHOCH3 (94.88%) > PYR-OH (91.47%) > PYR-NO2 (90.90%) > PYR-H (89.77%). Electrochemical studies suggested that PYRs functioned as mixed-type inhibitors and their adsorption obeyed the Langmuir isotherm. The interactions between PYRs and metallic surface were explained using DFT and MD simulations, and correlated with the experimental results. (C) 2019 Elsevier B.V. All rights reserved.