A newly synthesized sulphated 8-hydroxyquinoline derivative to effectively control aluminum corrosion in perchloric acid: Electrochemical and positron annihilation studies

The corrosion of aluminum in 1.0 M HClO4 was effectively controlled by a newly synthesized sulphated 8-hydroxy-quinoline derivative (8HQD), namely 2-(2-(quinolin-8-yloxy)acetamido)ethyl hydrogen sulfate. Rates of corrosion were monitored as a function of C8HQD (C8HQD: 10− 4-10− 2 M) using Tafel extrapolation method and linear polarization resistance (LPR) measurements. The electron density and corrosion-related defects in corroded and inhibited Al samples were probed using the positron annihilation lifetime (PAL) and positron annihilation Doppler broadening (PADB) techniques. Results were compared with 8-hydroxyquinoline (8HQ) itself. Polarization studies indicated that 8HQD acted as a mixed-type inhibitor with anodic predominance. PAS measurements demonstrated that the PAL components (τi) and their corresponding intensities (Ii) as well as PADB line-shape parameters (S and W) can be used to assess the inhibition performance of the tested materials. Results obtained from the different corrosion evaluation techniques were in good agreement and went parallel with those of PAS measurements. 8HQD was much better than 8HQ in inhibiting Al corrosion in these solutions.