Amino acid and cinnamaldehyde conjugated Schiff bases as proficient corrosion inhibitors for mild steel in 1 M HCl at higher temperature and prolonged exposure: Detailed electrochemical, adsorption and theoretical study

Three Schiff bases composing of cinnamaldehyde and three different amino acids, namely glycine (CGSB), histidine (CHSB) and tryptophan (CTSB) have been synthesized and investigated for their anti-corrosion propensity on mild steel in 1 M HCl. Both gravimetric and electrochemical experimentation establish the CTSB as superior inhibitor, while the CGSB as the least effective among the three. Effectiveness of the Schiff bases is tested upto 60 degrees C for an exposure of 6 h in HCl. Effect of various exposure times, maximum being 96 h, is also investigated at a fixed temperature of 30 degrees C. All the three inhibitors impart appreciable extent of corrosion inhibition efficiency under these extreme conditions. Thermodynamic adsorption and kinetic parameters ascertain chemisorption of these mixed-type corrosion inhibitors on mild steel. Mode and extent of interaction between Schiff bases and mild steel are evaluated from quantum mechanical calculation and molecular dynamics simulation. (C) 2020 Elsevier B.V. All rights reserved.

Automated summary

The three Schiff bases composed of cinnamaldehyde and different amino acids were synthesized and shown to have anti-corrosion effects on mild steel in hydrochloric acid solution. Among them, the tryptophan Schiff base demonstrated the highest inhibitory effect, while the glycine Schiff base had the least effectiveness. The inhibitors showed significant corrosion inhibition efficiency under different temperatures and exposure times, with their chemisorption on mild steel confirmed by thermodynamic and kinetic parameters as well as molecular dynamics simulations.