Study On Metasequoia Leaves Extract As Corrosion Pickling Inhibitor

In the paper, the inhibition efficiency of fresh or dead Metasequoia leaves extract was respectively studied in 5% H2SO4 solution and in 5% HCl solution by weight loss, electrical impedance spectroscopy and polarization curves methods. And their inhibition mechanisms were analysized with FT-IR, GC-MS and SEM spectrum.The results of weight loss method showed that the inhibition efficiency of fresh or dead Metasequoia leaves extract respectively reached 87.50% and 82.69% in 5% H2SO4 solution, and 89.17% and 85.82% in 5% HCl solution when the concentration is 15 g/L and the temperature is 25℃. Their adsorptions on the carbon steel surface obeyed Langmuir isotherm.The results of electrical impedance spectroscopy method showed that the inhibition efficiency of fresh or dead Metasequoia leaves extract respectively reached 87.89% and 82.56% in 5% H2SO4 solution, and 91.16% and 87.84% in 5% HCl solution when the concentration was 15 g/L and the temperature was 25℃. The results of polarization curves method showed that the inhibition efficiency of fresh or dead Metasequoia leaves extract respectively reached 87.95% and 80.33% in 5% H2SO4 solution, and 91.62% and 84.99% in 5% HCl solution when the concentration was 15 g/L and the temperature was 25℃. Electrical impedance spectroscopy and polarization curves were in good agrement with weight loss method. And the inhibition effect of fresh dead Metasequoia leaves extract was better than that of dead Metasequoia leaves extract in different solutions.Some kinds of main compounds were respectively characterized by GC-MS and FT-IR, and the carbon surface photographs were obtained by SEM. The kinetics and thermodynamic parameters, results of electrical impedance spectroscopy and polarization curves clarified the inhibition mechanisms of fresh and dead Metasequoia leaves extracts.