Desferrioxamine B: Investigating the Efficacy of Hydrogels and Ethanol Gels for Removing Akaganeite and Maghemite from Dry Wooden Substrates

Cultural heritage (CH) wooden artifacts are often stained by iron oxides/hydroxy-oxides, which may have detrimental effects on wood. Their removal is a common conservation practice, and it is usually achieved with non-eco-friendly chelators, such as ethylene diamine tetra acetic acid (EDTA) and diethylene triamine penta acetic acid (DTPA). Siderophores are green materials that have been recently explored as chelators, given the currently growing environmental concerns. This work investigated desferrioxamine B (DFO-B), a promising siderophore that has not been adequately studied for its potential in removing ferric oxides/hydroxy-oxides from dry CH wooden substrates. Mock-ups of maple (Acer platanoides L.) were artificially stained with akaganeite and maghemite, and DFO-B was employed via hydrogels (pH: 6.5 and 8.6) and ethanol gels. The chelator efficacy was assessed using Energy-Dispersive Spectroscopy (EDS), Attenuated Total Reflection-Fourier Transform Infrared Spectroscopy (ATR-FTIR), Scanning Electron Microscopy (SEM) and colorimetry. The hydrogels' impact on the wood was also assessed using ATR-FTIR and colorimetry. The obtained results demonstrate that the most effective DFO-B formulation was the alkaline hydrogel (pH 8.6), followed by the acidic (pH 6.5) hydrogel and the DFO-B ethanol gel. No differences in wood chemistry or color were recorded when using pH 6.5 or 8.6. The DFO-B ethanol gels were also proven to be potential alternatives to hydrogels for use with water-sensitive CH substrates.