Terephthalate-based metal-organic frameworks as novel corrosion inhibitors for AM60B magnesium alloy in ethylene glycol solution

A series of metal-organic frameworks (MOFs), including aluminum terephthalate (AlTp), bismuth terephthalate (BiTp), and chromium terephthalate (CrTp), was synthesized for use as inhibitors to protect AM60B magnesium alloy from corrosion in 30% ethylene glycol solution containing 0.5 M NaCl. The prepared MOFs were characterized using the X-ray diffraction (XRD) spectrum, Brunauer, Emmett, and Teller (BET), and scanning electron microscope (SEM) images. Electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization were applied to evaluate the inhibition performance of the MOFs in a concentration range of 50-400 ppm. Inhibition efficiencies of 84.17%, 86.52%, and 89.64% were obtained for BiTp, AlTp, and CrTp at an optimum concentration of 200, 400, and 400 ppm, respectively, indicating high potentials of the proposed inhibitors. Gibbs free energy of adsorption obtained for BiTp, AlTp, and CrTp were as -30.016, -26.725, and -25.792 kJ mol-1, respectively. These results revealed that the inhibitors were adsorbed on the metal surface through both physisorption and chemisorption processes.