Environmentally friendly corrosion inhibitors: a modern alternative to traditional methods of protecting metal structures

Metal corrosion is a serious technical and environmental problem that leads to significant economic losses and threatens the safety of infrastructure. Traditional methods of protecting metal structures are based on the use of chemical inhibitors, which are often toxic, poorly biodegradable and hazardous to human health and the environment. In response to these challenges, there is a growing interest in the development of “green” corrosion inhibitors - non-toxic, biodegradable and environmentally friendly substances derived from natural sources. This study examines the effectiveness of aqueous, alcoholic and water-alcohol plant extracts as an alternative to traditional corrosion inhibitors for the protection of 17GS steel in the NS4 model environment. Experimental studies have shown that the water-alcohol extract of Echinacea provides up to 69% protection of steel, the water extract of tea - up to 50%, while the effectiveness of eucalyptus oil was only 12%. The results obtained indicate a significant dependence of the protection efficiency on the type of plant material, extract concentration, exposure temperature, and duration of contact with the environment. Gravimetric analysis confirmed the formation of a dense protective adsorption-oligomeric film on the metal surface, which significantly reduces the corrosion rate and increases the polarization resistance of steel to 15 kΩ at a concentration of 40 ml/l. Microstructural analysis shows that the most effective compounds are those with aromatic structures and nitrogen-containing heterocycles that are able to form stable chemical bonds with the metal surface. A multivariate regression analysis of the dependence of steel corrosion resistance on exposure time, inhibitor concentration, and temperature was performed, which confirmed the significant impact of these factors on metal protection. The studies indicate that it is possible to optimize the composition of inhibitors by using combined herbal preparations and nanostructured additives to increase the duration and effectiveness of the protective effect. The results of this work open up new prospects for the development of environmentally friendly metal protection technologies that meet the concept of sustainable development and the principles of green chemistry. Further research should be focused on finding new sources of bioactive compounds, improving extraction methods, and in-depth study of the mechanisms of protective coatings formation.