Comparison of a bio-based corrosion inhibitor versus benzotriazole on corroded copper surfaces

Abstract

This research aims to characterize and compare the protective behaviour of a bio-based treatment versus benzotriazole (BTA) for the preservation of copper-based artefacts affected by active corrosion induced by copper chlorides. For this, the treatments were applied on artificial copper hydroxychlorides produced on copper sample. Their inhibition performance was then investigated by Scanning Electron Microscopy, Infrared Spectroscopy and Electrochemical Impedance Spectroscopy. Results showed few BTA-Cu complexes formed and poor protectiveness of the BTA treatments. In contrast, the bio-based treatment resulted in the conversion of almost all copper hydroxychlorides into copper oxalates, providing a more efficient corrosion inhibition.

The Bad and the Good—Microorganisms in Cultural Heritage Environments—An Update on Biodeterioration and Biotreatment Approaches

“…The method is based on biopassivation resulting from the action of fungus Beauveria bassiana (eco-friendly non-toxic). This method proved to be more efficient than the traditional use of benzotriazole, while being safe for the environment and personnel, as opposed to benzotriazole [ 137 ]. The second example of fungi being used in the cultural heritage field is for the removal of starch paste adhesives from historical textiles using α-amylase enzyme produced by Aspergillus oryzae [ 138 ].…”

Recent Advances in Protective Coatings for Cultural Heritage–An Overview

“…The possibility of using fungal species on bronze lies on the fact that they can produce oxalic acids useful in converting the copper corrosion compounds into stable and less soluble products that do not participate in the corrosion reactions. Albini et al [56] obtained a bio-patina based on Beauveria bassiana, dispersing the fungal species in a water solution with nutrients and jellifying agents. After 2 weeks of application, the bio-patina was removed, and the samples cleaned from fungal residues.…”

Evaluation of Bio-Based Extraction Methods by Spectroscopic Methods

“…The copper is then transformed into copper oxalates. Applied on outdoor bronze sculptures, this biotechnology allows forming a protective and stable layer preventing the object from further degradation and leaching [19]. Microorganisms can also be employed to stabilize corroded layers of archaeological iron artefacts and akaganeite β-FeOOH, a chlorine-containing iron oxyhydroxide, can be converted into chemically stable vivianite Fe 3 (PO 4 ) 2 •8H 2 O, siderite FeCO 3 or magnetite Fe 3 O 4 .…”