Cinnamaldehyde-modified chitosan as a bio-derived corrosion inhibitor for acid pickling of copper: Microwave synthesis, experimental and computational study.

Chitosan (CS) was cross-linked using cinnamaldehyde (Cinn) in a single step procedure following microwave irradiation to produce cinnamaldehyde-modified chitosan (Cinn-CS). The synthesized Cinn-CS was used as a novel corrosion inhibitor for copper in 1 M hydrochloric acid. A comprehensive electrochemical investigation using the impedance measurements, and potentiodynamic polarization was undertaken, supported with surface analysis and computational studies. The inhibitor Cinn-CS functioned by adsorption on the copper surface and showed an inhibition efficiency of >89% at a dose of 1000 mgL-1. The charge transfer resistance showed a rise with increase in inhibitor dosage to the corrosive medium, and the corrosion currents showed a significant decrease with the addition of the inhibitor. The Cinn-CS displayed a mixed type of inhibition performance with cathodic nature. The study of the copper surface using scanning electron microscopy depicted a considerably smooth morphology in the presence of the adsorbed Cinn-CS. The computational studies indicated that the Cinn-CS Schiff base shows better adsorption behavior compared to the parent molecules of chitosan and cinnamaldehyde and can show an inhibition performance in the neutral, and the protonated form.

Chitosan polymer as a green corrosion inhibitor for copper in sulfide-containing synthetic seawater.

The influence of chitosan on the copper corrosion in sulfide polluted synthetic seawater (SSW) containing 20 ppm of sulfide has been investigated for the first time. Potentiodynamic polarization measurements, electrochemical impedance spectroscopy at the open circuit potential and weight loss measurements were employed to assess the corrosion inhibition ability of chitosan. The impedance studies revealed that in the presence of chitosan at various concentrations, the charge transfer resistance increases. At a concentration of 800 ppm, chitosan exhibited a corrosion inhibition efficiency of 89% following physical adsorption. The influence of temperature and immersion time was studied in sulfide-contaminated synthetic seawater and significant inhibition was observed even after 90 days. SEM-EDS studies confirm the absence of the deterioration products on copper surface.