Corrosion inhibition of mild carbon steel in well water medium L-TRYPTOPHAN - Zn2+ System

Abstract

The environmentally friendly inhibitor system, L-Tryptophan-Zn²⁺, was investigated using the weight loss method. A synergistic effect was observed between L-Tryptophan and Zn²⁺ system. The formulation comprising 250 ppm of L-Serine and 50 ppm of Zn²⁺ demonstrated an impressive inhibition efficiency of 91%. UV-Visible spectroscopy revealed the formation of a protective film on the metal surface. FTIR analysis suggested that the Zn²⁺-L-Tryptophan complex formed at the anodic sites of the metal surface, which inhibited the anodic reaction, while Zn(OH)₂ formed at the cathodic sites, controlling the cathodic reaction. A corrosion inhibition mechanism was proposed based on the results from weight loss studies and surface analysis techniques. Synergism parameters were calculated and found to be greater than 1, confirming the synergistic effect between L-Tryptophan and Zn²⁺. The surface morphology of the compound was examined using SEM and EDAX