Starch, cellulose and plant extracts as green inhibitors of metal corrosion: a review

Traditional corrosion inhibitors have made great contributions to metal corrosion protection. However, environmental pollution caused by them is becoming more serious. To circumvent this tricky problem, green corrosion inhibitors have attracted increasing attention. Notably, plants are good raw materials of effective corrosion inhibitors and also meet the requirements of industrial production, where some active components really work. Therein, starch and cellulose are most abundant in plants which have great potential as industrial corrosion inhibitors. Besides, some other plant extracts are also available from rich sources, and show good corrosion inhibition efficiency. Starch, cellulose, and other plant extracts as representative green corrosion inhibitors have been reported without pollution to the environment. Although many advantages of starch, cellulose, and other plant extracts have been described, no such inhibitors are successfully applied to anticorrosion industry. These factors (source, solubility, dosage, composition, and others) seriously affect the applied industrialization of them. Currently, there are no analysis and discussions on these deficiencies and the related solutions: Herein, we review the factors that affect the industrial application of starch, cellulose, and other extracts from plants, and discuss specific solutions to make them potential industrial corrosion inhibitors. The major points are the following: 1) Why can't plant corrosion inhibitors be really applied to the industry? 2) The deficiencies of starch, cellulose, and other plant extracts as corrosion inhibitors are comprehensively analyzed from material source, solubility, dosage and composition. 3) Solutions that these green plant corrosion inhibitors cannot be used in industry are proposed. We aim to make appropriate recommendations for the early application of rich plant components into industry.