Corrosion inhibitive properties and electrochemical adsorption behaviour of some piperidine derivatives on brass in natural sea water

The piperidine derivatives, namely (4-Hydrazono-2,6-diphenyl-piperidin-1-yl)-ethanoic acid hydrazide; 5-(2,6-diphenyl-4-hydrazono-piperidin-1-ylmethyl)-3H-1, 3, 4]oxadiazole-2-thione; 4-amino-5-(2,6-diphenyl-4-hydrazono-piperidin-1-ylmethyl)-4H-1, 2, 4]triazole-3-thiol were synthesised and characterised by Fourier transform-infrared spectroscopic studies to confirm the purity of compounds. The corrosion inhibition effect of these compounds on brass in natural sea water was studied using potentiodynamic polarisation studies and electrochemical impedance spectroscopic measurements. The presence of these inhibitors in sea water suppresses both anodic and cathodic processes, and it is enhanced by the increase in the concentration of the inhibitors. The surface morphology of the brass after its exposure to natural sea water with and without inhibitors was examined by scanning electron microscopy. Inductively Coupled Plasma Atomic Emission Spectroscopic analysis were carried out after the polarisation studies showed minimum leached out of metal ions from the brass specimen in the presence of inhibitors. The structural and electronic parameters of these piperidine derivatives were calculated using computational methodologies.