Appraisal of corrosion inhibiting ability of new 5-N-((alkylamino)methyl)quinolin-8-ol analogs for C40E steel in sulfuric acid

Abstract

Two new 5-N-((alkylamino)methyl)quinolin-8-ol analogs, namely 5,5'-(azanediylbis(methylene))bisquinolin-8-ol (ABMQ), 5-(((4-hydroxybenzyl)amino) methyl)quinolin-8-ol (HAMQ) were synthesized in moderate yields via the N-alkylation of 5-Aminomethyl-quinolin-8-ol with benzyl alcohol derivatives. Their structures were determined on the basis of elemental analysis, NMR, and FT-IR. The corrosion inhibiting ability of 5-N-((alkylamino)methyl)quinolin-8-ol analogs was assessed on C40E steel in 0.5 M H2SO4 media via multiples approaches such that the weight reduction, electrochemical measurements, UV–Visible spectroscopy, scanning electron microscopy (SEM), and computational techniques. All achievements are underscored that ABMQ and HAMQ behave as good corrosion inhibitors of C40E steel in sulfuric acid and their performances follow the sequence, ABMQ (97.3) > HAMQ (94.6) at 0.001 M. Both 5-N-((alkylamino)methyl)quinolin-8-ol analogs revealed mixed-type inhibitory activity. Two loops; one in high-frequency and another in low-frequency were observed in EIS plots. A substantial reduction of corrosive attack on the surface exposed to ABMQ or HAMQ solution was upheld by SEM. The 5-N-((alkylamino)methyl)quinolin-8-ol analogs were chemisorbed on the C40E steel surface and followed the Langmuir isotherm model. Quantum chemical calculations using the Density Functional Theory (DFT) method and molecular dynamics simulations suggest a good agreement with the experimental results.