Steel rust has detrimental financial and environmental impacts. Could natural oils, nanocomposites, and even ostrich fat offer a green way to fight it?
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Corrosion is an irreversible process that degrades essential materials like steel, and environmental conditions heavily influence its progression. It's a global concern, causing trillions in economic losses and threatening infrastructure integrity.
Researchers are turning to greener, more sustainable solutions to traditional prevention methods to avoid their steep environmental cost.1,2
Corrosion Damage and Need for Corrosion Prevention
Corrosion affects more than just construction: its negative implications extend to the automotive, aerospace, oil and gas, and petrochemical industries. Studies have shown that the GDP of some countries has decreased by three to five per cent due to its destructive effects.2
It gets worse. The annual damages have been estimated to be up to 2.8 to 4.5 trillion U.S. dollars.2 But protecting steel is not only about reducing these costs; it’s about ensuring the durability and safety of critical infrastructure.
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Conventional Methods Have Environmental Implications
Traditional techniques to prevent corrosion include protective coatings, cathodic and anodic protective methods, and classical corrosion inhibitors. Although some of these methods are economically viable, they often rely on toxic chemical agents.
Chromates and phosphates, for instance, are highly efficient but environmentally hazardous, releasing volatile organic compounds (VOCs) and greenhouse gases. Their disposal poses risks to both ecosystems and human health.
Experts are devising novel eco-friendly techniques and inhibitors to solve these issues.3
Biopolymer Solutions: Chitosan Oligosaccharide Ammonium Salt
Some scientists have looked to biopolymers for a less toxic corrosion inhibitor. Naturally extracted chitosan oligosaccharide (COS) is known for its excellent durability and corrosion prevention, but there is limited academic research on its use as an inhibitor.
In a recent study by S. Liu et al., researchers chemically modified COS with vanillin and tri-methyl-glycine hydrochloride to create a COS quaternary ammonium salt (QCO). Compared with conventional agents, QCO showed superior adsorption, enhanced water solubility, and notable stability in metal chelation.
In lab tests, rectangular steel samples (50 mm × 10 mm × 3 mm) with 4 mm suspension holes were immersed in varying QCO concentrations. The baseline corrosion rate without QCO was 0.486 mm/year. A 60 % QCO solution reduced this to 0.083 mm/year with 86 % inhibition efficiency, and at full concentration, QCO achieved 92.8 % efficiency with a corrosion rate of just 0.034 mm/year.
Experts found that QCO follows the Langmuir adsorption isotherm model. Potentiodynamic polarization experiments revealed QCO as an anodic-inhibiting mixed-type corrosion inhibitor.4 The strong adsorption capability, high stability, and superior inhibition efficiency make QCO a viable green corrosion inhibitor ready to be scaled up for industrial applications.
Plant-Based Inhibitors To Protect Mild Steel
Mild steel, particularly in acidic environments, is notoriously corrosion-prone, and traditional inhibitors often fail under such conditions. Recent studies have shown that essential oils could mitigate this without a toxic chemical hangover. Highly concentrated plant extracts, these essential oils are biodegradable and naturally suited for hostile environments.
A 2023 study showed how Cuminum Cyminum extracts could protect steel. Extracted using a systematic multistep hydro-distillation process, the extract was tested on steel in 0.5 M HCl solutions at various concentrations (from 0.15 - 2 g/L).5
The results were compelling: corrosion inhibition climbed from 86.7 % at the lowest concentration to 99.71 % at the highest. The increased concentration allowed more complete surface coverage, enhancing protection.
Chemical analysis revealed that compounds p-cymene, γ-terpinene, and β-pinene were key contributors to the essential oil's ability to form a protective barrier on steel. This approach could be an effective and straightforward route to green steel protection.5
Nanocomposites as Corrosion Inhibitors
Nanocomposites are gaining a reputation across industry. These materials, engineered at the nanoscale, can be extremely versatile and are proving valuable in corrosion protection. One example is a silver nanoparticle and almond gum hybrid, investigated by O. Swathy et al. This almond gum-silver nanocomposite was tested in a 1M HCl solution, and structural analyses (X-ray, FTIR, and TEM) confirmed its successful synthesis.
The researchers tested the nanocomposite against unmodified silver to understand its impact. Gravimetric analysis revealed that the nanocomposite was two times more efficient in preventing corrosion than unmodified Ag. Polarization studies classified it as a mixed-type inhibitor, while SEM imaging revealed smoother, more protected steel surfaces. The material also followed the Langmuir isotherm model, indicating strong, consistent adsorption.
Other nanocomposites based on chitosan, such as CS-g-PAM/TiO2 and CS-g-PAM/Fe3O4, created via free radical copolymerization, also showed excellent performance. The titanium dioxide variant achieved 97.19 % inhibition efficiency, and the magnetite version followed closely at 95.4 %. Both form strong, adsorptive protective layers, offering scalable protection for steel (particularly ASTM A36) in highly acidic environments. 6
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Ostrich Oil for Corrosion Inhibition
Ostrich oil, which is slightly unusual, has also been investigated as a corrosion-protection solution. Rich in fatty acids and other bioactive molecules, this animal waste by-product has recently emerged as a viable inhibitor.
A 2024 study investigated the corrosion resistance of C38 steel when protected by ostrich fat waste extracts. The oils achieved an astounding corrosion inhibition of 94 %, which scientists attributed to the adsorption capability of fatty acid compounds.
This adsorption went further, developing a double electrochemical layer formulation with twice the resistive capability against corrosion.7
The findings suggest animal-derived waste, particularly from industries already processing such materials, could be part of a circular, sustainable corrosion strategy.
Challenges and Opportunities
Despite their potential, natural corrosion inhibitors are not ready to roll out just yet. Their biggest issue is cost: most are significantly more expensive than conventional chemicals. Some also pose fire and explosion hazards, so higher flashpoint formulations and safer storage practices are needed.
It is also difficult to regulate these alternatives. For widespread industrial use, these green solutions must meet or exceed the performance and safety benchmarks of traditional inhibitors. The lack of global regulatory consistency makes this even more difficult, though international agencies are working to create shared frameworks.
Looking ahead, research into smart coatings, self-healing materials, and life cycle assessment will be key. Having a holistic understanding of environmental impact and performance over time will help guide sustainable choices in materials development.8
Further Reading
- Rasaq, M. et. al. (2023). Sustainable approach for corrosion control in mild steel using plant-based inhibitors: a review. Materials Today Sustainability. 22. 100373. Available at: https://doi.org/10.1016/j.mtsust.2023.100373
- Okon, K. et. al. (2025). Corrosion inhibition of mild steel and Aluminium using extracts of Vernonia Amygdalina: a Review. Nexus of Future Materials. 2. 154-166. Available at: http://dx.doi.org/10.70128/590516
- Montemor, M. (2016). Fostering Green Inhibitors for Corrosion Prevention. In: Hughes, A. et. al. (eds) Active Protective Coatings. Springer Series in Materials Science. 233. Springer, Dordrecht. Available at: https://doi.org/10.1007/978-94-017-7540-3_6
- Liu, S. et. al. (2025). Chitosan oligosaccharide derivatives as green corrosion inhibitors for 20# steel in 25° C carbon dioxide environments. Gas Science and Engineering. 205738. Available at: https://doi.org/10.1016/j.jgsce.2025.205738
- Rizi, A. et. al. (2023). Sustainable and green corrosion inhibition of mild steel: insights from electrochemical and computational approaches. ACS Omega. 8(49). 47224-47238. Available at: https://doi.org/10.1021/acsomega.3c06548
- Swathy, O. et. al. (2025). Advances in corrosion inhibition: nanomaterials as sustainable solutions for protecting metals. Journal of Chemical Technology & Biotechnology. Available at: https://doi.org/10.1002/jctb.7917
- Errami, M. et. al. (2024). Green Ostrich fat waste extracts as a novel potential inhibitor to sustainable corrosion of steel in acidic environments: Electrochemical and DFT evaluation. Colloids and Surfaces A: Physicochemical and Engineering Aspects. 689. 133684. Available at: https://doi.org/10.1016/j.colsurfa.2024.133684
- Al-Amiery, A. et. al. (2024). Sustainable corrosion Inhibitors: A key step towards environmentally responsible corrosion control,‖ Ain Shams Eng. J. 15(5). 102672. Available at: https://doi.org/10.1016/j.asej.2024.102672
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