Experimental and quantum chemical studies on corrosion inhibition performance of some Schiff bases for mild steel in 4M HCl

262-271The inhibiting action of three synthesized&nbsp; Schiff bases, namely&nbsp; 4,4'-bis(benzalideneimino) diphenylether (BBDE); 4,4'-bis(anisalideneimino)diphenylether (BADE); and 4,4'-bis(2-Hydroxy-3-methoxybenzalideneimino)diphenylether (BHBDE) towards the corrosion behavior of mild steel in 4M HCl solution has been studied by using weight loss, potentiodynamic polarization and electrochemical impedance spectroscopy techniques. Corrosion inhibition efficiency of all the three inhibitors increases with increasing the concentration of inhibitors. <span style="mso-fareast-font-family:AdvGulliv-R; mso-ansi-language:EN-IN">The inhibitors BBDE, BADE and BHBDE<span style="mso-bidi-font-weight: bold"> show corrosion inhibition efficiency of 82.48, 96.01 and 99.20% at 500 ppm concentration respectively at 323 K. Polarization studies show that all the three studied inhibitors act as mixed inhibitors. Scanning electron microscopy and infrared spectroscopy have been performed for surface study of uninhibited and inhibited mild steel samples. All the three inhibitors follow Langmuir adsorption isotherm and the adsorption mechanism of inhibition is proposed. The semi-empirical AM1 method is employed for theoretical calculations.