From the Problem of Corrosion to Green Solutions: The Role of Biosurfactants as Anti-Corrosion Agents

Corrosion remains one of the major contemporary technological challenges, causing significant economic, environmental, and operational impacts on industrial systems. Although it is a spontaneous process inherent to metals and their alloys, its progression can be significantly mitigated by appropriate protection strategies. Traditionally, synthetic inhibitors have been widely used; however, their toxicity, environmental persistence, and increasing regulatory restrictions have prompted a search for greener alternatives. Biosurfactants stand out as promising green anticorrosive agents, acting through the formation of adsorbed films, reduction in wettability, modification of the metal-medium interface, and, in some cases, antimicrobial effects that inhibit the formation of corrosive biofilms. This review presents an integrated analysis of the main corrosion mechanisms, including uniform, localized, galvanic, and microbiologically influenced corrosion, with an emphasis on critical industrial environments such as the maritime, petrochemical, energy, and infrastructure sectors. Additionally, the main classes of biosurfactants are discussed, along with their key physical and chemical characteristics, including critical micelle concentration, thermal and saline stability, adsorption capacity, and their mechanisms of action in mitigating corrosion. Finally, the article summarizes the advances of the last decade, highlighting experimental studies, emerging applications, and technological trends that consolidate biosurfactants as viable, efficient, and environmentally safe alternatives for industrial corrosion protection.