Corrosion Inhibition of Aluminum Alloys With Sodium Benzoate in Acidic Environments: A Current Literature Review for Research Gaps

This paper presents a current literature review of the general uses, production, availability level, and cost of sodium benzoate, showcasing it as an effective and eco-friendly corrosion inhibitor of aluminum alloys in acidic environments. The study aims to reveal any research gaps or limitations in its usage as a corrosion inhibitor. The study shows that aluminum alloys are some of the most important and best structural metals used in modern engineering and construction, and acidic environments are among the most common corrosion-aggressive types of environments to which they are frequently exposed. Aluminum alloys are often used as lightweight alternatives to steel for certain components or systems that need to be strong, light, and resistant to corrosion. However, acidic environments are capable of degrading the thin protective oxide coating that is often instantly formed on the surface of the alloys on exposure to oxygen, accelerating pitting corrosion, general surface attack, and other corrosion forms of the alloys as the environmental acidity level increases. Sodium benzoate is an organic salt with significant industrial applications in acidic environments. It is manufactured globally on a large scale and is available at cost-effective rates and sustainably in most countries, including Nigeria. According to reports, it works best to lower the corrosion rates of aluminum alloys in near-neutral to alkaline environments with pH values between 6 and 12. Its corrosion inhibition efficiency increases with the concentration and immersion time of the alloys in the environment. However, its inhibition performance data on aluminum alloys in highly acidic solutions of less than 5.5 pH has not been reconciled from the literature, and there is an indication that the corrosion inhibition decreases as the pH decreases downwards from 4. Some claims of sodium benzoate converting to benzoic acid and to benzene, a carcinogen, require further research, including field studies, to confirm some initial findings about its safety and optimal corrosion inhibition using individual aluminum alloys and pH in highly acidic conditions for its better usage.