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Giuliani L, Genova C, Stagno V, Paoletti L, Matulac AL, Ciccola A, Di Fazio M, Capuani S, Favero G. Multi-Technique Assessment of Chelators-Loaded PVA-Borax Gel-like Systems Performance in Cleaning of Stone Contaminated with Copper Corrosion Products. Gels 2024; 10:455. [PMID: 39057477 PMCID: PMC11276506 DOI: 10.3390/gels10070455] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2024] [Revised: 07/05/2024] [Accepted: 07/06/2024] [Indexed: 07/28/2024] Open
Abstract
Currently, one of the most important challenges for the conservation of stone artworks is the removal of metal corrosion products on their surfaces. Traditional cleaning methods, which typically involve the application of aqueous solutions containing chelating agents capable of complexing these metal ions, have shown some weaknesses. These weaknesses become apparent when such methods are applied to statues and other vertical surfaces or when aiming to limit the cleaning process to a specific area with controlled application times. Furthermore, the porosity of the stone surface plays a role concerning the cleaning efficiency. To address these issues, chelating agents can be incorporated into gel-like materials. This study is a proof of concept to evaluate the cleaning efficacy of various gel formulations composed of polyvinyl alcohol (PVA), borax (B), and agarose (AG), loaded with two chelators: ethylenediaminetetraacetic acid (EDTA) and potassium sodium tartrate (PST or Rochelle salt). Three types of carbonate stones (travertine, Lecce stone, and Carrara marble) characterized by different porosities were artificially stained with copper sulphates and treated with the different PVA-B-AG formulations. The effectiveness of the treatment was directly monitored on the stones using a multi-technique approach that included scanning electron microscopy with energy dispersive spectroscopy (SEM-EDS) and non-invasive portable nuclear magnetic resonance (NMR). Additionally, the rheological properties of the gels were investigated, and the Fourier transform infrared attenuated total reflection spectroscopy (FTIR ATR) was used to analyse the chemical structure of the gel before and after treatment, aiming to understand the changes induced by the cleaning process.
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Affiliation(s)
- Laura Giuliani
- Department of Earth Sciences, Sapienza University of Rome, P.le Aldo Moro 5, 00185 Rome, Italy; (L.G.); (M.D.F.)
| | - Chiara Genova
- Department of Environmental Biology, Sapienza University of Rome, P.le Aldo Moro 5, 00185 Rome, Italy; (C.G.); (A.C.); (G.F.)
| | - Valeria Stagno
- Department of Earth Sciences, Sapienza University of Rome, P.le Aldo Moro 5, 00185 Rome, Italy; (L.G.); (M.D.F.)
| | - Luca Paoletti
- Department of Chemistry and Technologies of Drug, Sapienza University of Rome, P.le Aldo Moro 5, 00185 Rome, Italy;
| | - Andrea Louise Matulac
- Erasmus Mundus Joint Master’s Degrees Archmat, Sapienza University of Rome, P.le Aldo Moro 5, 00185 Rome, Italy;
| | - Alessandro Ciccola
- Department of Environmental Biology, Sapienza University of Rome, P.le Aldo Moro 5, 00185 Rome, Italy; (C.G.); (A.C.); (G.F.)
| | - Melania Di Fazio
- Department of Earth Sciences, Sapienza University of Rome, P.le Aldo Moro 5, 00185 Rome, Italy; (L.G.); (M.D.F.)
| | - Silvia Capuani
- National Research Council Institute for Complex Systems (CNR-ISC) c/o Physics Department, Sapienza University of Rome, P.le Aldo Moro 5, 00185 Rome, Italy;
| | - Gabriele Favero
- Department of Environmental Biology, Sapienza University of Rome, P.le Aldo Moro 5, 00185 Rome, Italy; (C.G.); (A.C.); (G.F.)
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2
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Gabriele F, Casieri C, Spreti N. Efficacy of Chitosan-Carboxylic Acid Hydrogels in Reducing and Chelating Iron for the Removal of Rust from Stone Surface. Gels 2024; 10:359. [PMID: 38920906 PMCID: PMC11202951 DOI: 10.3390/gels10060359] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2024] [Revised: 05/17/2024] [Accepted: 05/20/2024] [Indexed: 06/27/2024] Open
Abstract
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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Affiliation(s)
- Francesco Gabriele
- Department of Physical and Chemical Sciences, University of L’Aquila, 67100 L’Aquila, Italy; (C.C.); (N.S.)
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3
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Canevali C, Sansonetti A, Rampazzi L, Monticelli D, D'Arienzo M, Di Credico B, Ghezzi E, Mostoni S, Nisticò R, Scotti R. The Chemistry of Chelation for Built Heritage Cleaning: The Removal of Copper and Iron Stains. Chempluschem 2024:e202300709. [PMID: 38683651 DOI: 10.1002/cplu.202300709] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2023] [Revised: 04/29/2024] [Accepted: 04/29/2024] [Indexed: 05/01/2024]
Abstract
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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Affiliation(s)
- Carmen Canevali
- Department of Materials Science, University of Milano-Bicocca, via Roberto Cozzi 55, 20125, Milan, Italy
| | - Antonio Sansonetti
- Istituto di Scienze del Patrimonio Culturale (ISPC-CNR), Via Roberto Cozzi 53, 20125, Milan, Italy
| | - Laura Rampazzi
- Dipartimento di Scienze Umane e dell'Innovazione per il Territorio (DiSUIT), Università degli Studi dell'Insubria, Via Sant'Abbondio 12, 22100, Como, Italy
| | - Damiano Monticelli
- Department of Science and High Technology, Università degli Studi dell'Insubria, Via Valleggio 11, Como, Italy
| | - Massimiliano D'Arienzo
- Department of Materials Science, University of Milano-Bicocca, INSTM, via Roberto Cozzi 55, 20125, Milan, Italy
| | - Barbara Di Credico
- Department of Materials Science, University of Milano-Bicocca, INSTM, via Roberto Cozzi 55, 20125, Milan, Italy
| | - Elena Ghezzi
- Brera Academy of Fine Arts, Via Brera 28, 20121, Milan, Italy
| | - Silvia Mostoni
- Department of Materials Science, University of Milano-Bicocca, INSTM, via Roberto Cozzi 55, 20125, Milan, Italy
| | - Roberto Nisticò
- Department of Materials Science, University of Milano-Bicocca, INSTM, via Roberto Cozzi 55, 20125, Milan, Italy
| | - Roberto Scotti
- Department of Materials Science, University of Milano-Bicocca, INSTM, via Roberto Cozzi 55, 20125, Milan, Italy
- Institute for Photonics and Nanotechnologies-CNR, Via alla Cascata 56/C, 38123, Povo (TN), Italy
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4
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Sonaglia E, Schifano E, Sharbaf M, Uccelletti D, Felici AC, Santarelli ML. Bacterial Nanocellulose Hydrogel for the Green Cleaning of Copper Stains from Marble. Gels 2024; 10:150. [PMID: 38391480 PMCID: PMC10887925 DOI: 10.3390/gels10020150] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2024] [Revised: 02/12/2024] [Accepted: 02/15/2024] [Indexed: 02/24/2024] Open
Abstract
Cultural heritage stone materials frequently experience significant discoloration induced by copper corrosion products, especially calcareous stones associated with bronze or copper statues and architectural elements. This alteration originates from the corrosion of unprotected copper, resulting in the formation of various Cu minerals and the migration of soluble ions to adjacent stone materials. Traditional cleaning methods involve mechanical, chemical, and laser techniques, which are generally time-consuming, costly, not ecological, or can possibly damage original materials. The loading of highly effective chelating agents, such as ethylenediaminetetraacetic acid (EDTA), into hydrogels has recently been exploited. However, the preference for synthetic hydrogels has been prominent until now, although they lack renewability and biodegradability and require high costs. This study explores for the first time the potential to clean copper corrosion with bacterial nanocellulose (BC) loaded with EDTA as a biologically based, sustainable, and biodegradable hydrogel. The BC hydrogel was characterised by field emission-scanning electron microscopy (FE-SEM), X-ray diffraction analysis (XRD), attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR), simultaneous thermal analysis (TG-DSC), and tensile testing. It revealed a nano-fibrous structure with high crystallinity and purity and mechanical properties suitable for cultural heritage applications. The EDTA-loaded hydrogel effectively removed copper stains from marble after 120 min of application. Micro-Raman and colorimetric analyses assessed the cleaning efficacy. The study introduces bacterial nanocellulose as a green and effective alternative for heritage conservation, aligning with sustainable methodologies in stone conservation.
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Affiliation(s)
- Erica Sonaglia
- Department of Chemical Engineering Materials and Environment, Sapienza University of Rome, Via Eudossiana 18, 00184 Rome, Italy
| | - Emily Schifano
- Department of Biology and Biotechnologies "C. Darwin", Sapienza University of Rome, Piazzale Aldo Moro 5, 00185 Roma, Italy
| | - Mohammad Sharbaf
- Department of Chemical Engineering Materials and Environment, Sapienza University of Rome, Via Eudossiana 18, 00184 Rome, Italy
| | - Daniela Uccelletti
- Department of Biology and Biotechnologies "C. Darwin", Sapienza University of Rome, Piazzale Aldo Moro 5, 00185 Roma, Italy
- Research Center for Nanotechnology Applied to Engineering, Sapienza University of Rome, Piazzale Aldo Moro 5, 00185 Rome, Italy
| | - Anna Candida Felici
- Department of Basic and Applied Sciences for Engineering, Sapienza University of Rome, Via Antonio Scarpa 16, 00161 Rome, Italy
| | - Maria Laura Santarelli
- Department of Chemical Engineering Materials and Environment, Sapienza University of Rome, Via Eudossiana 18, 00184 Rome, Italy
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5
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Cuvillier L, Passaretti A, Guilminot E, Joseph E. Agar and Chitosan Hydrogels' Design for Metal-Uptaking Treatments. Gels 2024; 10:55. [PMID: 38247779 PMCID: PMC10815442 DOI: 10.3390/gels10010055] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2023] [Revised: 12/16/2023] [Accepted: 12/20/2023] [Indexed: 01/23/2024] Open
Abstract
In the field of cultural heritage, the use of natural gels is rising for the application of active agents. Here, two natural polymers are assessed: agar, a pioneer hydrogel for conservation treatments, and chitosan, a rather novel and metal-binding gel. For chitosan, a state-of-the-art based formulation (CS-ItA-LCys) is evaluated as it was reported for silver-complexing properties. It is evaluated whether these polymers can withstand the addition of the chelating compound deferoxamine, which is a bacterial siderophore. This allows for the obtainment of completely bio-sourced gel systems. A Fourier-transformed (FT) infrared spectroscopy characterization is performed, completed with rheological measurements and Cryo-Scanning Electron Microscopy (cryo-SEM) to investigate the physico-chemical properties of the gels, as well as their interaction with deferoxamine. Both polymers are also tested for their inherent complexing ability on silver ions using FT-Raman spectroscopy. A multi-analytical comparison shows different microstructures, in particular, the presence of a thick membrane for chitosan and different mechanical behaviors, with agar being more brittle. Neither hydrogel seems affected by the addition of deferoxamine; this is shown by similar rheological behavior and molecular structures in the presence or absence of the chelator. The intrinsic abilities of the chitosan formulation to make silver complex are demonstrated with the observation of two peaks characteristic of Ag-S and Ag-O bonds. Agar and chitosan are both proven to be reliable gels to act as carriers for bio-based active agents. This paper confirms the potential asset of the chitosan formulation CS-ItA-LCys as a promising gel for the complexation of soluble silver.
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Affiliation(s)
- Luana Cuvillier
- Laboratory of Technologies for Heritage Materials, University of Neuchâtel, Bellevaux 51, 2000 Neuchâtel, Switzerland; (L.C.); (A.P.)
- Haute Ecole Arc Conservation Restauration, University of Applied Sciences and Arts Western Switzerland HES-SO, Espace de l’Europe 11, 2000 Neuchâtel, Switzerland
| | - Arianna Passaretti
- Laboratory of Technologies for Heritage Materials, University of Neuchâtel, Bellevaux 51, 2000 Neuchâtel, Switzerland; (L.C.); (A.P.)
- Haute Ecole Arc Conservation Restauration, University of Applied Sciences and Arts Western Switzerland HES-SO, Espace de l’Europe 11, 2000 Neuchâtel, Switzerland
| | - Elodie Guilminot
- Arc’Antique Conservation and Research Laboratory, 26 Rue de la Haute Forêt, 44300 Nantes, France;
| | - Edith Joseph
- Haute Ecole Arc Conservation Restauration, University of Applied Sciences and Arts Western Switzerland HES-SO, Espace de l’Europe 11, 2000 Neuchâtel, Switzerland
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6
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Vázquez-de la Fuente I, Barbier I, Puente-Muñoz S, Prieto-Taboada N, Arana G, Madariaga JM. Looking for Novel Natural Gels to Improve Cleaning Methods for Bronze Leachates on Marble. Gels 2023; 9:843. [PMID: 37998933 PMCID: PMC10670686 DOI: 10.3390/gels9110843] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2023] [Revised: 10/11/2023] [Accepted: 10/22/2023] [Indexed: 11/25/2023] Open
Abstract
Marble is one of the materials most susceptible to copper leaching, resulting in easily identifiable turquoise stains on the marble. This problem is particularly relevant when we are talking about marble structures of heritage value. For this reason, conservators look for cleaning materials that are specific to the structure to be treated without damaging the original surface. Materials such as agar have been studied for a long time. Agar creates a controlled water release system that adapts to the needs of conservators who seek the greatest possible cleanliness without damaging the material to be treated. To improve the cleaning, chelating agents such as EDTA are added to the agar composition. However, the microbiological growth and the damage it produces to the original material are disadvantages to take into account. In order to solve these problems, other natural materials with cleaning potential such as kudzu and konjac gels were studied in combination with other chelating agents such as citrate, oxalate, and gluconic acid. For the characterization and evaluation of copper cleaning, various analytical techniques were used, including Raman spectroscopy, colorimetry, X-ray fluorescence (XRF), and inductively coupled plasma mass spectrometry (ICP-MS). In this study, both konjac and kudzu emerged as promising alternatives to agar, revealing distinctive features such as simplified preparation methods and inherent antimicrobial properties. The EDTA chelator was found to be the most harmful for marble surfaces, as it extracted a greater amount of calcium from the marble during application of the gels doped with it. Citrate and gluconic acid have been identified as a promising substitute to prepare doped gels for the removal of copper stains. These compounds exhibit comparable or potentially superior cleaning capabilities than EDTA, with no negative side effects.
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Affiliation(s)
- Iñaki Vázquez-de la Fuente
- Department of Analytical Chemistry, Faculty of Science and Technology, University of the Basque Country UPV/EHU, P.O. Box 644, 48080 Bilbao, Basque Country, Spain; (I.B.); (S.P.-M.); (N.P.-T.); (G.A.); (J.M.M.)
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7
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Guilminot E. The Use of Hydrogels in the Treatment of Metal Cultural Heritage Objects. Gels 2023; 9:gels9030191. [PMID: 36975640 PMCID: PMC10048560 DOI: 10.3390/gels9030191] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2023] [Revised: 02/28/2023] [Accepted: 02/28/2023] [Indexed: 03/06/2023] Open
Abstract
Currently gels are widely used in the restoration of paintings, graphic arts, stuccowork and stonework, but their use in metal restoration is less widespread. In this study, several polysaccharide-based hydrogels (agar, gellan and xanthan gum) were selected for use in metal treatments. The use of hydrogels allows to localize a chemical or electrochemical treatment. This paper presents several examples of treatment of metal objects of cultural heritage, i.e., historical or archaeological objects. The advantages, disadvantages and limits of hydrogel treatments are discussed. The best results are obtained for the cleaning of copper alloys via associating an agar gel with a chelating agent (EDTA (ethylenediaminetetraacetic acid) or TAC (tri-ammonium citrate)). The hot application allows to obtain a peelable gel, particularly adapted for historical objects. Electrochemical treatments using hydrogels have been successful for the cleaning of silver and for the dechlorination of ferrous or copper alloys. The use of hydrogels for the cleaning of painted aluminum alloys is possible but it has to be coupled with mechanical cleaning. However, for the cleaning of archaeological lead, the cleaning using hydrogels was not very effective. This paper shows the new possibilities of using hydrogels for the treatment of metal cultural heritage objects: agar is the most promising hydrogel.
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Affiliation(s)
- Elodie Guilminot
- Arc'Antique Conservation and Research Laboratory, 26 Rue de la Haute Forêt, 44300 Nantes, France
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8
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Tamburini G, Canevali C, Ferrario S, Bianchi A, Sansonetti A, Simonutti R. Optimized Semi-Interpenetrated p(HEMA)/PVP Hydrogels for Artistic Surface Cleaning. MATERIALS (BASEL, SWITZERLAND) 2022; 15:6739. [PMID: 36234079 PMCID: PMC9571715 DOI: 10.3390/ma15196739] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/31/2022] [Revised: 09/18/2022] [Accepted: 09/21/2022] [Indexed: 06/16/2023]
Abstract
The synthesis of hydrogels that are based on poly-hydroxyethyl methacrylate, p(HEMA), network semi-interpenetrated with linear polyvinylpyrrolidone (PVP) was optimized in order to allow both a fast preparation and a high cleaning effectiveness of artistic surfaces. For this purpose, the synthesis parameters of the gel with PVP having a high molecular weight (1300 kDa) that were reported in the literature, were modified in terms of temperature, time, and crosslinker amount. In addition, the gel composition was modified by using PVP with different molecular weights, by changing the initiator and by adding maleic anhydride. The modified gels were characterized in terms of equilibrium water content (EWC), water uptake, conversion grade, and thermal properties by differential scanning calorimetry (DSC). The cleaning effectiveness of the gels was studied through the removal of copper salts from laboratory-stained specimens. Cleaning materials were characterized by electron paramagnetic resonance (EPR) spectroscopy, ultraviolet-visible (UV-Vis) spectroscopy, and inductively-coupled plasma-mass spectrometry (ICP-MS). Cleaning was assessed on marble specimens by color variation measurements. The gel synthesis is accelerated by using PVP 360 kDa. The addition of maleic anhydride in the p(HEMA)/PVP network allows the most effective removal of copper salt deposits from marble since it acts as a chelator towards copper ions.
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Affiliation(s)
- Giulia Tamburini
- Department of Materials Science, University of Milano-Bicocca, 20125 Milan, Italy
| | - Carmen Canevali
- Department of Materials Science, University of Milano-Bicocca, 20125 Milan, Italy
- Institute for Heritage Science (ISPC), National Research Council (CNR), 20122 Milan, Italy
| | | | | | - Antonio Sansonetti
- Institute for Heritage Science (ISPC), National Research Council (CNR), 20122 Milan, Italy
| | - Roberto Simonutti
- Department of Materials Science, University of Milano-Bicocca, 20125 Milan, Italy
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9
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Non-Invasive Assessment of PVA-Borax Hydrogel Effectiveness in Removing Metal Corrosion Products on Stones by Portable NMR. Gels 2021; 7:gels7040265. [PMID: 34940325 PMCID: PMC8701805 DOI: 10.3390/gels7040265] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2021] [Revised: 12/10/2021] [Accepted: 12/13/2021] [Indexed: 02/02/2023] Open
Abstract
The cleaning of buildings, statues, and artworks composed of stone materials from metal corrosion is an important topic in the cultural heritage field. In this work the cleaning effectiveness of a PVA-PEO-borax hydrogel in removing metal corrosion products from different porosity stones has been assessed by using a multidisciplinary and non-destructive approach based on relaxation times measurement by single-sided portable Nuclear Magnetic Resonance (NMR), Scanning Electron Microscopy—Energy Dispersive Spectroscopy (SEM-EDS), and Raman Spectroscopy. To this end, samples of two lithotypes, Travertine and Carrara marble, have been soiled by triggering acidic corrosion of some copper coins in contact with the stone surface. Then, a PVA-PEO-borax hydrogel was used to clean the stone surface. NMR data were collected in untreated, soiled with corrosion products, and hydrogel-cleaned samples. Raman spectroscopy was performed on PVA-PEO-borax hydrogel before and after cleaning of metal corrosion. Furthermore, the characterization of the dirty gel was obtained by SEM-EDS. The combination of NMR, SEM-EDS and Raman results suggests that the mechanism behind the hydrogel cleaning action is to trap heavy metal corrosion products, such as Cu2+ between adjacent boron ions cross-linked with PVA. Moreover, the PVA-PEO-borax hydrogel cleaning effectiveness depends on the stone porosity, being better in Carrara marble compared to Travertine.
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Optimization of Copper Stain Removal from Marble through the Formation of Cu(II) Complexes in Agar Gels. Gels 2021; 7:gels7030111. [PMID: 34449612 PMCID: PMC8395995 DOI: 10.3390/gels7030111] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2021] [Revised: 08/02/2021] [Accepted: 08/03/2021] [Indexed: 01/22/2023] Open
Abstract
Copper complexes with different ligands (ethylenediaminetetraacetic acid, EDTA, ammonium citrate tribasic, TAC, and alanine, ALA) were studied in aqueous solutions and hydrogels with the aim of setting the optimal conditions for copper stain removal from marble by agar gels, with damage minimization. The stoichiometry and stability of copper complexes were monitored by ultraviolet-visible (UV-Vis) spectroscopy and the symmetry of Cu(II) centers in the different gel formulations was studied by electron paramagnetic resonance (EPR) spectroscopy. Cleaning effectiveness in optimized conditions was verified on marble laboratory specimens through color variations and by determining copper on gels by inductively coupled plasma-mass spectrometry (ICP-MS). Two copper complexes with TAC were identified, one having the known stoichiometry 1:1, and the other 1:2, Cu(TAC)2, never observed before. The stability of all the complexes at different pH was observed to increase with pH. At pH 10.0, the gel's effectiveness in removing copper salts from marble was the highest in the presence of ALA, followed by EDTA, TAC, and pure agar gel. Limited damage to the marble surface was observed when gels with added EDTA and TAC were employed, whereas agar gel with ALA was determined to be the most efficient and safe cleaning material.
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11
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Stagno V, Genova C, Zoratto N, Favero G, Capuani S. Single-Sided Portable NMR Investigation to Assess and Monitor Cleaning Action of PVA-Borax Hydrogel in Travertine and Lecce Stone. Molecules 2021; 26:3697. [PMID: 34204336 PMCID: PMC8235598 DOI: 10.3390/molecules26123697] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2021] [Revised: 06/11/2021] [Accepted: 06/14/2021] [Indexed: 11/16/2022] Open
Abstract
In this work, we investigated the potential of PVA-borax hydrogel for cleaning limestones and the dependence of the cleaning on the porosity of the rock and on the action time of the hydrogel treatment. Towards this goal, we used a nuclear magnetic resonance (NMR) spectrometer, developed for non-invasive and non-destructive applications on cultural heritage. T2-NMR parameters were quantified on different samples of Lecce stone and Travertine cut perpendicular (Pe) and parallel (Pa) to the bedding planes under different experimental conditions: untreated samples, treated with Paraloid B72 and cleaned with PVA-PEO-borax hydrogel applied for 4 min and 2 h. The T2 results suggest that the effectiveness of the cleaning strongly depended on the porosity of the stones. In Lecce stone, the hydrogel seemed to eliminate both the paramagnetic impurities (in equal measure with 4 min and 2 h treatment) and Paraloid B72. In Travertine Pe, characterized by a smaller pore size compared to Lecce stone, no significant effects were found regarding both the cleaning and the treatment with Paraloid B72. In Travertine Pa, characterized by a larger pore size than the other two samples, the hydrogel seemed to clean the paramagnetic agents (it worked better if applied for a longer time) but it did not appear to have any effect on Paraloid B72 removal.
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Affiliation(s)
- Valeria Stagno
- Earth Sciences Department, Sapienza University of Rome, Piazzale Aldo Moro 5, 00185 Rome, Italy;
- National Research Council Institute for Complex Systems (CNR-ISC) c/o Physics Department, Sapienza University of Rome, Piazzale Aldo Moro 5, 00185 Rome, Italy;
| | - Chiara Genova
- Department of Chemistry and Drug Technologies, Sapienza University of Rome, Piazzale Aldo Moro 5, 00185 Rome, Italy;
| | - Nicole Zoratto
- Department of Chemistry and Drug Technologies, Sapienza University of Rome, Piazzale Aldo Moro 5, 00185 Rome, Italy;
| | - Gabriele Favero
- Department of Chemistry and Drug Technologies, Sapienza University of Rome, Piazzale Aldo Moro 5, 00185 Rome, Italy;
| | - Silvia Capuani
- National Research Council Institute for Complex Systems (CNR-ISC) c/o Physics Department, Sapienza University of Rome, Piazzale Aldo Moro 5, 00185 Rome, Italy;
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12
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New Insights to Characterize Paint Varnishes and to Study Water in Paintings by Nuclear Magnetic Resonance Spectroscopy (NMR). MAGNETOCHEMISTRY 2020. [DOI: 10.3390/magnetochemistry6020021] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Paintings are complex multi-layered systems made of organic and inorganic materials. Several factors can affect the degradation of paintings, such as environmental conditions, past restoration works and, finally, the type of painting technique and the art materials used over the centuries. The chemical–physical characterization of paintings is a constant challenge that requires research into and the development of novel analytical methodologies and processes. In recent years, solvents and water-related issues in paintings are attracting more attention, and several studies have been focused on analyzing the interaction between water molecules and the constitutive materials. In this study, recent applications applying different NMR methodologies were shown, highlighting the weakness and the strength of the techniques in analyzing paintings. In particular, the study of water and its diffusive interactions within wall and oil paintings was performed to prove how the portable NMR can be used directly in museums for planning restoration work and to monitor the degradation processes. Furthermore, some preliminary results on the analysis of varnishes and binders, such us linseed oil, shellac, sandarac and colophony resins, were obtained by 1H HR-MAS NMR spectroscopy, highlighting the weakness and strengths of this technique in the field of conservation science.
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Bertasa M, Dodero A, Alloisio M, Vicini S, Riedo C, Sansonetti A, Scalarone D, Castellano M. Agar gel strength: A correlation study between chemical composition and rheological properties. Eur Polym J 2020. [DOI: 10.1016/j.eurpolymj.2019.109442] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Di Tullio V, Sciutto G, Proietti N, Prati S, Mazzeo R, Colombo C, Cantisani E, Romè V, Rigaglia D, Capitani D. 1H NMR depth profiles combined with portable and micro-analytical techniques for evaluating cleaning methods and identifying original, non-original, and degraded materials of a 16th century Italian wall painting. Microchem J 2018. [DOI: 10.1016/j.microc.2018.04.034] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Bertasa M, Poli T, Riedo C, Di Tullio V, Capitani D, Proietti N, Canevali C, Sansonetti A, Scalarone D. A study of non-bounded/bounded water and water mobility in different agar gels. Microchem J 2018. [DOI: 10.1016/j.microc.2018.03.016] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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Chew KW, Juan JC, Phang SM, Ling TC, Show PL. An overview on the development of conventional and alternative extractive methods for the purification of agarose from seaweed. SEP SCI TECHNOL 2017. [DOI: 10.1080/01496395.2017.1394881] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Affiliation(s)
- Kit Wayne Chew
- Nanotechnology & Catalysis Research Centre (NANOCAT), University of Malaya, Kuala Lumpur, Malaysia
- Department of Chemical and Environmental Engineering, Faculty of Engineering, University of Nottingham Malaysia Campus, Jalan Broga, Semenyih, Selangor Darul Ehsan, Malaysia
| | - Joon Ching Juan
- Nanotechnology & Catalysis Research Centre (NANOCAT), University of Malaya, Kuala Lumpur, Malaysia
- Laboratory of Advanced Catalysis and Environmental Technology, Monash University Sunway Campus, Bandar Sunway, Malaysia
| | - Siew Moi Phang
- Institute of Biological Sciences, University of Malaya, Kuala Lumpur, Malaysia
- Institute of Ocean and Earth Sciences, University of Malaya, Kuala Lumpur, Malaysia
| | - Tau Chuan Ling
- Institute of Biological Sciences, University of Malaya, Kuala Lumpur, Malaysia
| | - Pau Loke Show
- Department of Chemical and Environmental Engineering, Faculty of Engineering, University of Nottingham Malaysia Campus, Jalan Broga, Semenyih, Selangor Darul Ehsan, Malaysia
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