Abstract

The corrosion inhibition of inhibitor tris(hydroxymethyl)amino methane (THAM) and 1-hydroxyethylidenediphosphonic acid (HEDP) in
combination with a bivalent cation like Zn2+ in controlling corrosion of carbon steel immersed in aqueous solution containing 60 ppm Clwas investigated using weight loss method and electrochemical impedance spectroscopy .The combined corrosion inhibition efficiency
offered by 50 ppm of THAM, 250 ppm of HEDP, 50 ppm of Zn2+ has 86%. The synergistic effect of the inhibiting compound was
calculated. The corrosion inhibition was observed due to the formation of more stable and compact protective film on the metal surface.
Fluorescence spectral analysis was used in detecting the presence of iron-inhibitor complex and the coordination sites of the metal inhibitor
with iron were determined by the FTIR spectra. The surface morphology of the protective film on the metal surface was characterized by
using Scanning Electron Microscope (SEM)

Key words: Corrosion inhibition, Carbon steel, Scanning Electron Microscope, Fluorescence spectra, Nano film