Synergistic inhibition effect of L-Phenylalanine and zinc salts on chloride-induced corrosion of magnesium alloy: Experimental and theoretical investigation

L-Phenylalanine (L-Phe) is a promising eco-friendly alternative to replace the conventional toxic inhibitors for magnesium alloys in NaCl solution. However, its inhibitory performance is not satisfied. The addition of slight amount Zn(NO3)2 would greatly refine the inhibitory efficiency. The inhibitory performance of hybrid inhibitor is explored by scanning electron microscopy (SEM) along with energy dispersive X-ray spectroscopy (EDS), X-ray diffractometer (XRD), X-ray photoelectron spectroscopy (XPS), and various electrochemical measurements. The highest inhibitory efficiency of 93.2% is achieved for 0.30 mM L-Phe + 0.07 mM Zn(NO3)2. The amount of each inhibitor and the suitable match of two inhibitors are carefully determined, which are both critical items for the final performance. The possible inhibitory mechanism is conjectured by the XRD and XPS measurements along with the quantum chemical calculations. (c) 2021 Taiwan Institute of Chemical Engineers. Published by Elsevier B.V. All rights reserved.

Automated summary

The study demonstrates that L-phenylalanine is a promising eco-friendly alternative to replace conventional toxic inhibitors for magnesium alloys. The addition of a slight amount of Zn(NO3)2 greatly improves the inhibitory efficiency, with the highest inhibitory efficiency achieved at 93.2%.