Anticorrosive activity of 2-hydroxybenzaldehyde-thiosemicarbazone for AISI 1020 carbon steel in acid medium

Abstract

Thiosemicarbazones belong to a widely pharmacologically and technologically used class of compounds. The heteroatoms (N and S) and double bond in their structure enable them to act as inhibitory agents - an alternative to corrosion control. This work synthesised 2-hydroxybenzaldehyde-thiosemicarbazone (THIO-6) aiming at its anticorrosive activity against AISI 1020 carbon steel in acid medium; the electrochemical methods Potentiodynamic Polarization and Impedance Electrochemical Spectroscopy were used to investigate it. Results showed great anticorrosive efficiency (94%), even at low concentration (40.10-5 mol L-1). This effect was confirmed by the determination of the double-layer capacitance (Cdl), which provided information about the protective film formed on the metal surface. The adsorption process obeyed the Langmuir adsorption isotherm and the Kads value from the investigation of THIO-6 adsorption mechanisms on metal surfaces indicated that corrosion inhibition occurred through chemisorption, which identifies it as an effective corrosion inhibitor agent.