Ionic liquids (ILs)-loaded hydrogels as a potential cleaning method of metallic stains for stone conservation

Irizar, P.; Gomez-Laserna, O.; Arana, G.; Madariaga, J.M.; Martínez-Arkarazo, I.

doi:10.1016/j.culher.2023.08.013

Cited by 7 publications

(3 citation statements)

References 46 publications

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“…Additionally, they have proven to be efficient carriers for inorganic compounds such as oxides, silicates, and aluminates commonly used as fillers in paper products [5,18,20]. Compared to water, surfactants, ethanol, or supercritical carbon dioxide, ILs can achieve better cleaning, deacidifying, and reconditioning results without causing brittleness or discoloration [22][23][24]. Studies conducted on cotton linters, alpha-cellulose, and wood have shown that ILs with 1-alkyl-3-methylimidazolium cation can enhance the resistance of cellulose and lignin to UV degradation, minimizing yellowing and preserving mechanical properties by preventing oxidation [25].…”

Section: Introductionmentioning

confidence: 99%

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Ionic Liquids as Potential Cleaning and Restoration Agents for Cellulosic Artefacts

Croitoru,

Roata

2024

Processes

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This study explores the efficacy of 1-hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide and 1-hexyl-3-methylimidazolium chloride as cleaning agents for aged cellulosic artifacts. A 10% v/v acetone solution of these ionic liquids (ILs) effectively removes the brownish-yellow color of aged paper in a 10 min immersion treatment. Colorimetric analysis shows a remarkable increase in lightness (L*) by up to 40% and a decrease in red/brownish tones (b*) after IL treatment. The cleaning process also deacidifies the paper, shifting the pH to neutral-slightly basic levels and enhancing its long-term stability. Optimal pH outcomes are achieved, with ionic liquid consumption values of 0.4–0.6 g/g of paper. The FTIR analysis revealed structural changes in cellulose induced by the washing step, which is mainly due to the reorganization effect imparted by the ionic liquids. Furthermore, ILs mobilized degraded compounds and acidic species, aiding in their extraction during the restoration process. Mechanical testing indicated an enhancement in the overall tensile strength and strain at break values for IL-treated papers by up to 33%. This study demonstrates the multiple benefits of alkylimidazolium ionic liquids for preserving and restoring cultural heritage artifacts made of cellulosic materials.

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Section: Introductionmentioning

confidence: 99%

“…However, it is worth mentioning that the application of ILs in paper-support treatment has been the subject of relatively few studies [20,[22][23][24][25].…”

Section: Introductionmentioning

confidence: 99%

Ionic Liquids as Potential Cleaning and Restoration Agents for Cellulosic Artefacts

Croitoru,

Roata

2024

Processes

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“…Inter alia, the review counts on the efficacy of agar-chelating agent gels in removing copper stains from marble surfaces [ 32 ]. Moreover, agar hydrogels, incorporating ionic liquids, have been applied to sequester iron and copper ions from stone materials, and the effectiveness of the formulations, selected by laboratory tests, have been validated in situ on naturally stained substrates [ 33 ]. Recently, an EDTA-loaded bacterial nanocellulose hydrogel has been able to completely remove copper stains from marble, proving to be an effective alternative to traditional hydrogels for the cleaning of cultural heritage materials [ 34 ].…”

Section: Introductionmentioning

confidence: 99%

Efficacy of Chitosan-Carboxylic Acid Hydrogels in Reducing and Chelating Iron for the Removal of Rust from Stone Surface

Gabriele,

Casieri,

Spreti

2024

Gels

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In the field of stone conservation, the removal of iron stains is one of the most challenging issues due to the stability and low solubility of the ferrous species. In the present paper, three different chitosan-based hydrogels added with acetic, oxalic or citric acids are applied on different lithotypes, i.e., granite, travertine and marble, widely diffused in monumental heritages, and artificially stained by deposition of a rust dispersion. The reducing power of carboxylic acids is combined with the good chelating properties of chitosan to effectively remove rust from stone surfaces. As evidenced by colorimetry on three samples of each lithotype and confirmed by 1H-NMR relaxometry and SEM/EDS analyses, the chitosan-oxalic acid hydrogel shows the best performance and a single application of 24 h is enough to get a good restoration of the stone original features. Lastly, the chitosan-oxalic acid hydrogel performs well when a rusted iron grid is placed directly on the lithic surfaces to simulate a more realistic pollution. Current work in progress is devoted to finding better formulations for marble, which is the most challenging to clean or, with a different approach, to developing protective agents to prevent rust deposition.

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The Chemistry of Chelation for Built Heritage Cleaning: The Removal of Copper and Iron Stains

Canevali,

Sansonetti,

Rampazzi

et al. 2024

ChemPlusChem

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Chelators are widely used in conservation treatments to remove metal stains from marble, travertine, and limestone surfaces. In the current review the chemical aspects underlying the use of chelators for the removal of copper and iron stains from built heritage are described and clear criteria for the selection of the most efficient stain removal treatment are given. The main chelator structural features are outlined and the operating conditions for effective metal stain removal (pH, time of application, etc.) discussed, with a particular emphasis on the ability to form stable metal complexes, the high selectivity towards the metal that should be removed, and the high sustainability for the environment. Dense matrices often host chelators for higher effectiveness, and further research is required to clarify their role in the cleaning process. Then, relevant case studies of copper and iron stain removal are discussed. On these bases, the most effective chelators for copper and stain removal are indicated, providing chemists and conservation scientists with scientific support for conservation operations on stone works of art and opening the way to the synthesis of new chelators.

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Ionic liquids (ILs)-loaded hydrogels as a potential cleaning method of metallic stains for stone conservation

Cited by 7 publications

References 46 publications

Ionic Liquids as Potential Cleaning and Restoration Agents for Cellulosic Artefacts

Ionic Liquids as Potential Cleaning and Restoration Agents for Cellulosic Artefacts

Efficacy of Chitosan-Carboxylic Acid Hydrogels in Reducing and Chelating Iron for the Removal of Rust from Stone Surface

The Chemistry of Chelation for Built Heritage Cleaning: The Removal of Copper and Iron Stains

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