New pyrimidothiazine Derivative as Corrosion Inhibitor for Carbon Steel in Acidic Media

摘要

Thiazine-7-carbonitrile(CHPTC) was tested as corrosion inhibitor for carbon steel in 2.0 M H3PO4 by using polarization,electrochemical impedance spectroscopy (EIS) and computational calculations. Potentiodynamicpolarization curves indicated that the pyrimidothiazine derivativeas mixed-type inhibitor. Impedancemeasurements showed that the double-layer capacitance decreased and charge-transfer resistanceincreased with increase in the inhibitor concentration and hence increasing in inhibition efficiency.The effect of temperature on the corrosion behavior of carbon steel in 2.0 M H3PO4 with and withoutaddition of CHPTC was studied in the temperature range 313-333 K. The adsorption of the inhibitormolecules was in accordance with the Langmuir adsorption isotherm. Quantum chemical approachused to calculate electronic properties of the molecule to ascertain the relation betweeninhibitive effect and molecular structure.