Abstract
Iron oxidation, known as rust formation, causes enormous loss in term of property damages and associated economic risks. Depending on the degree of formation, rust consists of several layers of iron in different oxidation states. The brownish top layer is mostly iron (III) oxide-hydroxide [FeO(OH), Fe(OH)3] while the deepest black layers possess iron oxide (Fe2O3.nH2O). The flaky nature of surface rust meditates diffusion of oxygen and water to inner material sections which can lead to total disintegration of iron mass. As a result, it is desirable to remove rust and protect fresh surface from oxidizers. The common rust removal reagents are mainly based on complex formation of ferric ion with organic and inorganic acids such as citric acid, oxalic acid, and phosphoric acid. Rust removal ability is typically a qualitative observation which makes direct comparison between treatment options cumbersome if not impractical. In our recent work (Ahmadi et al., 2015), we have developed a colorimetric assay to measure ferric concentration in rust removal treatment media using a bacterially-produced siderophore (yersiniabactin) in comparison to a commercial rust removal reagent. In this approach, ferric concentration is correlated to the mass of rust being dissolved in the presence of different removal agents. This assay is based on a modification of the 1, 10-phenanthroline assay (Skoog and West, 1979) to enable detection using a 96-well plate format for higher throughput screening and assessment.
Materials and Reagents
Equipment
Procedure
Representative data
The following are typical data for a commercial rust remover (Rust-Oleum): Table 1. Protocol results for a commercial rust remover (Rust-Oleum) Dilution factor (D1 and D2): 1,250 times; Treatment volume for rust removal experiment (V1): 10 ml; Treatment volume for remaining rust removal experiment (V2): 15 ml. Figure 2. Visual examples of metal samples treated with rust removal agents. Metal samples before treatment (A), after 2 h of treatment with a commercial rust removal agent (B; Rust-Oleum) and after thirty minutes treatment with 10% oxalic acid (C).
Notes
Recipes
Acknowledgments
The authors recognize support from the New York State Pollution Prevention Institute, the NSFI-Corps program, and a SUNY-4F grant. The protocol provided here was adapted from work previously published (Ahmadi et al., 2015).
References
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