A new and effective macrocyclic compound as corrosion inhibitor for mild steel in hydrochloric acid solution

Abstract

The inhibition characteristics of a macrocylic compound namely 1, 2, 4, 7, 9, 10-hexaazacyclo-pentadeca-10, 15-dien-3, 5, 6, 8-tetraone (HPTT) has been investigated on acid corrosion of mild steel in 1 M HCl using gravimetric measurement, electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization. The maximum inhibition efficiency (η %) 95.2% of HPTT was obtained at 200 mgL-1. Polarization curves indicate that HPTT acts as a mixed type inhibitor. The adsorption of inhibitor on mild steel surface followed Langmuir isotherm. Thermodynamic adsorption parameters such as adsorption heat (ΔH°ads), adsorption entropy (ΔS°ads) and adsorption free energy (ΔG°ads) have been calculated and discussed.©2012 by ESG.