Corrosion poses significant threats to the preservation of artifacts made from brass, particularly those exposed to harsh environmental conditions. A new study reveals the effectiveness of palm kernel oil (PKO) extract as a promising solution for inhibiting corrosion on brass artifacts, such as the crescent atop the Al-Maradani Mosque pulpit. Researchers employed advanced metallographic techniques and electrochemical testing to evaluate the protective effects of PKO on brass, leading to remarkable findings.
The study, published on March 7, 2025, by researchers from the Conservation Department at the Faculty of Archaeology, Fayoum University, highlights the challenges of preserving valuable metallic artifacts exposed to pollutants and moisture. The crescent, which is approximately 5780 grams and made from brass—a copper-zinc alloy—was subjected to corrosion resulting from environmental factors.
Utilizing methods such as scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), and X-ray diffraction (XRD), the researchers analyzed the microstructure and composition of the crescent. They discovered corrosion products such as malachite and atacamite, which are indicative of brass degradation due to environmental exposure. Determining the need for effective corrosion prevention strategies, the team turned their focus to green inhibitors like PKO.
Prior studies have shown the promise of plant extracts as effective corrosion inhibitors, but this research extends those findings by showcasing the potential of PKO extracted from the seeds of the palm fruit. PKO's chemical composition is rich in fatty acids and has demonstrated biodegradability and safety advantages over synthetic alternatives.
The main experimental phase involved subjecting brass coupons, crafted from the same alloy as the crescent, to electrochemical tests with varying concentrations of PKO (1%, 3%, 5%, and 7%). Results indicated an impressive increase in corrosion inhibition efficiency, culminating at 99.7% with the highest concentration of PKO.
Through electrochemical impedance spectroscopy (EIS) and Tafel extrapolation measurements, it became clear how PKO functions as a protective barrier. The oil adsorbs onto the brass surface, slowing electrochemical reactions and decreasing the overall corrosion rates. The blank sample showed severe corrosion with rates reaching up to 7559.5 µm/year, whereas the sample with 7% PKO saw this drop to just 20.696 µm/year.
One statement from the authors of the article emphasized the significance of their findings: "The incorporation of palm kernel oil has been demonstrated to be effective as it reduced corrosion rates significantly, particularly at higher concentrations." This successful application of PKO supports the notion of using natural extracts for heritage preservation.
Following the tests, researchers conducted analyses via gas chromatography to confirm the presence of specific fatty acid methyl esters, confirming the high quality of the commercially sourced PKO. Its rich composition aligns well with corrosion-inhibiting properties, making it suitable for prolonged application on cultural artifacts.
Perhaps more compelling is the broader implication of this research for conservation practices. Cultural heritage preservation faces increasing challenges from environmental factors, and green alternatives like PKO could become standard practice, facilitating the protection of delicate artifacts without introducing harmful chemicals. The authors concluded, "This research highlights the need for targeted conservation strategies to mitigate corrosion risks and preserve historical artifacts."
With the study yielding significant results, it presents not only a remarkable step forward for the conservation of brass artifacts but also for sustainable practices within the field. Researchers hope these findings invigorate international interest toward employing natural substances for protecting our cultural heritage.