Sustainable technology for cultural heritage preservation: The role of green corrosion inhibitors

Abstract

The preservation of metallic artefacts in cultural heritage necessitates effective corrosion control strategies to ensure structural stability and aesthetic integrity. Conventional synthetic corrosion inhibitors, while demonstrating high efficacy, present significant environmental and health concerns due to their inherent toxicity. Consequently, sustainable, plant-derived corrosion inhibitors have emerged as promising alternatives, offering comparable protective performance with reduced ecological impact. This review examines the potential of plant extracts as environmentally benign corrosion inhibitors, highlighting their diverse phytochemical constituents-including tannins, alkaloids, and amino acids-which exhibit functional similarity to synthetic organic inhibitors in electronic structure and adsorption mechanisms. These bioactive compounds mitigate corrosion through adsorption, leading to the formation of protective passive layers that hinder oxidation reactions and restrict electrochemical degradation. For instance, tannic acid reacts with iron to form ferric tannates, generating a stable barrier against aggressive electrolytes. Similarly, extracts from Ceratonia siliqua and Brassica campestris have demonstrated notable corrosion inhibition for copper alloys and Cor-Ten steel, respectively. The efficacy of these plant-derived inhibitors is commonly assessed using electrochemical techniques, particularly electrochemical impedance spectroscopy (EIS), where an increase in charge-transfer resistance (Rct) and a reduction in double-layer capacitance (Cdl) indicate enhanced corrosion protection. This study presents a comprehensive evaluation of the mechanisms, performance, and applicability of green corrosion inhibitors in metallic heritage conservation, with case studies demonstrating their successful implementation in preservation efforts. Furthermore, key challenges such as optimizing inhibitor concentrations, managing temperature sensitivity, and ensuring long-term stability are critically analyzed. Additionally, various inhibitor application methods are explored along with practical considerations for scaling up and integrating green inhibitors into conservation workflows. Additionally, a comparative analysis of conventional and sustainable inhibitors in real-world applications is presented. The review concludes by highlighting key research gaps and proposing future directions for advancing plant-based corrosion inhibitor technologies in heritage conservation. Through this analysis, it seeks to enhance the understanding and adoption of sustainable corrosion mitigation strategies for preserving metallic cultural artefacts.

Keywords: Corrosion; Corrosion inhibitors; Cultural heritage; Plant extract; Sustainability.