Synergistic Inhibition Effect of Chitosan and L-Cysteine for the Protection of Copper-Based Alloys against Atmospheric Chloride-Induced Indoor Corrosion.

Elena Messina,Monica Albini,Chiara Giuliani,Cristina Riccucci,Maria Paola Staccioli,Marianna Pascucci,Gabriella Di Carlo

doi:10.3390/ijms221910321

Abstract

The protection of metals from atmospheric corrosion is a task of primary importance for many applications and many different products have been used, sometimes being toxic and harmful for health and the environment. In order to overcome drawbacks due to toxicity of the corrosion inhibitors and harmful organic solvents and to ensure long-lasting protection, new organic compounds have been proposed and their corrosion inhibition properties have been investigated. In this work, we describe the use of a new environment-friendly anticorrosive coating that takes advantage of the synergism between an eco-friendly bio-polymer matrix and an amino acid. The corrosion inhibition of a largely used Copper-based (Cu-based) alloy against the chloride-induced indoor atmospheric attack was studied using chitosan (CH) as a biopolymer and l-Cysteine (Cy) as an amino acid. To evaluate the protective efficacy of the coatings, tailored accelerated corrosion tests were carried out on bare and coated Cu-based alloys, further, the nature of the protective film formed on the Cu-based alloy surface was analyzed by Fourier-transformed infrared spectroscopy (FTIR) while the surface modifications due to the corrosion treatments were investigated by optical microscopy (OM). The evaluation tests reveal that the Chitosan/l-Cysteine (CH/Cy) coatings exhibit good anti-corrosion properties against chloride attack whose efficiency increases with a minimum amount of Cy of 0.25 mg/mL.

Highlights

These studies have shown that molecules containing both nitrogen and sulfur atoms such as the mercapto-functionalized thiadiazole derivatives [5,6,7,8,9] and amino acids [10], among others, provide better inhibition efficiency compared to organic inhibitors containing only sulfur or nitrogen
All the coatings were prepared by drop-casting solutions onto ontobronze bronze disks a prepared by drop-casting μLchitosan-based chitosan-based solutions disks withwith a diameter diameter of
The variation of the cysteine content has been investigated and the results reveal its key role on the inhibition effect of the active coating

Summary

Introduction

A large effort has been devoted to replace the toxic or low-toxic organic and inorganic inhibitors with green compounds characterized by a good anti-corrosion efficiency and which do not pose health or ecological hazards [1,2,3,4,5,6] These studies have shown that molecules containing both nitrogen and sulfur atoms such as the mercapto-functionalized thiadiazole derivatives [5,6,7,8,9] and amino acids [10], among others, provide better inhibition efficiency compared to organic inhibitors containing only sulfur or nitrogen. By using potentiodynamic and spectrophotometric techniques, the positive effect of Trp was evidenced especially at the highest concentrations and temperature as well as after six months of specimen immersion in concentrated Trp solution (10−2 M) in H2 SO4 0.5 M

Methods

Results

Conclusion