{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,11,10]],"date-time":"2025-11-10T13:56:51Z","timestamp":1762783011300,"version":"build-2065373602"},"reference-count":27,"publisher":"MDPI AG","issue":"11","license":[{"start":{"date-parts":[[2023,10,25]],"date-time":"2023-10-25T00:00:00Z","timestamp":1698192000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"MCIN\/AEI\/10.13039\/501100011033","award":["PID2020-113391GB-I00"],"award-info":[{"award-number":["PID2020-113391GB-I00"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Gels"],"abstract":"<jats:p>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.<\/jats:p>","DOI":"10.3390\/gels9110843","type":"journal-article","created":{"date-parts":[[2023,10,25]],"date-time":"2023-10-25T06:19:58Z","timestamp":1698214798000},"page":"843","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":3,"title":["Looking for Novel Natural Gels to Improve Cleaning Methods for Bronze Leachates on Marble"],"prefix":"10.3390","volume":"9","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-7131-4168","authenticated-orcid":false,"given":"I\u00f1aki","family":"V\u00e1zquez-de la Fuente","sequence":"first","affiliation":[{"name":"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"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"In\u00e9s","family":"Barbier","sequence":"additional","affiliation":[{"name":"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"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Sara","family":"Puente-Mu\u00f1oz","sequence":"additional","affiliation":[{"name":"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"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-4649-2381","authenticated-orcid":false,"given":"Nagore","family":"Prieto-Taboada","sequence":"additional","affiliation":[{"name":"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"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Gorka","family":"Arana","sequence":"additional","affiliation":[{"name":"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"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-1685-6335","authenticated-orcid":false,"given":"Juan Manuel","family":"Madariaga","sequence":"additional","affiliation":[{"name":"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"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2023,10,25]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"155","DOI":"10.1179\/2159032X13Z.00000000011","article-title":"Values and Heritage Conservation","volume":"6","year":"2013","journal-title":"Herit. Soc."},{"key":"ref_2","doi-asserted-by":"crossref","unstructured":"Baglioni, M., Poggi, G., Chelazzi, D., and Baglioni, P. (2021). Advanced Materials in Cultural Heritage Conservation. Molecules, 26.","DOI":"10.3390\/molecules26133967"},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"249","DOI":"10.1016\/j.microc.2016.07.007","article-title":"A multi-analytical approach for the study of copper stain removal by agar gels","volume":"129","author":"Canevali","year":"2016","journal-title":"Microchem. J."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"29","DOI":"10.1186\/s40494-016-0102-5","article-title":"Effective cleaning of copper stained calcareous stone","volume":"4","author":"Spile","year":"2016","journal-title":"Herit. Sci."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"179","DOI":"10.1016\/j.ibiod.2008.01.007","article-title":"Deterioration of limestone structures associated with copper staining","volume":"62","author":"Gaylarde","year":"2008","journal-title":"Int. Biodeterior. Biodegrad."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"S10","DOI":"10.1186\/1752-153X-6-S2-S10","article-title":"XPS characterization of (copper-based) coloured stains formed on limestone surfaces of outdoor Roman monuments","volume":"6","author":"Salvi","year":"2012","journal-title":"Chem. Cent. J."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"1073","DOI":"10.1002\/sia.5220","article-title":"Analytical characterization of corrosion products of copper and its alloys on stained stone surfaces: Stone and metal","volume":"45","author":"Macchia","year":"2013","journal-title":"Surf. Interface Anal."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"1300","DOI":"10.1016\/j.jas.2011.01.005","article-title":"A new method to remove copper corrosion stains from stone surfaces","volume":"38","author":"Macchia","year":"2011","journal-title":"J. Archaeol. Sci."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"285","DOI":"10.1016\/j.culher.2020.01.008","article-title":"A review in using agar gels for cleaning art surfaces","volume":"44","author":"Sansonetti","year":"2020","journal-title":"J. Cult. Herit."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"12","DOI":"10.1016\/j.culher.2020.10.007","article-title":"An in-depth study on the agar gel effectiveness for built heritage cleaning","volume":"47","author":"Bertasa","year":"2021","journal-title":"J. Cult. Herit."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"012076","DOI":"10.1088\/1757-899X\/364\/1\/012076","article-title":"Soluble Salts Extraction with Different Thickeners: Monitoring of the Effects on Plaster","volume":"364","author":"Bertasa","year":"2018","journal-title":"IOP Conf. Ser. Mater. Sci. Eng."},{"key":"ref_12","doi-asserted-by":"crossref","unstructured":"Sansonetti, A., Bertasa, M., Corti, C., Rampazzi, L., Monticelli, D., Scalarone, D., Sassella, A., and Canevali, C. (2021). Optimization of Copper Stain Removal from Marble through the Formation of Cu(II) Complexes in Agar Gels. Gels, 7.","DOI":"10.3390\/gels7030111"},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"5939","DOI":"10.1007\/s11356-013-1576-2","article-title":"Application of a new generation of complexing agents in removal of heavy metal ions from different wastes","volume":"20","year":"2013","journal-title":"Environ. Sci. Pollut. Res."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"2027","DOI":"10.1007\/s10570-013-9975-6","article-title":"Evaluation of the effect of cleaning on the morphological properties of ancient paper surface","volume":"20","author":"Casoli","year":"2013","journal-title":"Cellulose"},{"key":"ref_15","first-page":"71","article-title":"The use of agar as a solvent gel in objects conservation","volume":"19","author":"Scott","year":"2012","journal-title":"Objects Spec. Group Postprints"},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"164","DOI":"10.1179\/sic.2010.55.3.164","article-title":"Cleaning Marble with Ammonium Citrate","volume":"55","author":"Gervais","year":"2010","journal-title":"Stud. Conserv."},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"79","DOI":"10.1186\/s40494-022-00715-4","article-title":"A green approach to clean iron stains from marble surfaces","volume":"10","author":"Campanella","year":"2022","journal-title":"Herit. Sci."},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"15598","DOI":"10.1038\/s41598-020-72643-x","article-title":"A first evaluation of the usefulness of Kudzu starch in cultural heritage restoration","volume":"10","author":"Lama","year":"2020","journal-title":"Sci. Rep."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"106817","DOI":"10.1016\/j.foodhyd.2021.106817","article-title":"Structure, properties and applications of kudzu starch","volume":"119","author":"Zhao","year":"2021","journal-title":"Food Hydrocoll."},{"key":"ref_20","doi-asserted-by":"crossref","unstructured":"Yang, D., Yuan, Y., Wang, L., Wang, X., Mu, R., Pang, J., Xiao, J., and Zheng, Y. (2017). A Review on Konjac Glucomannan Gels: Microstructure and Application. Int. J. Mol. Sci., 18.","DOI":"10.3390\/ijms18112250"},{"key":"ref_21","doi-asserted-by":"crossref","unstructured":"Lee, C., Di Turo, F., Vigani, B., Weththimuni, M.L., Rossi, S., Beltram, F., Pingue, P., Licchelli, M., Malagodi, M., and Fiocco, G. (2022). Biopolymer Gels as a Cleaning System for Differently Featured Wooden Surfaces. Polymers, 15.","DOI":"10.3390\/polym15010036"},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"550","DOI":"10.1039\/b419080g","article-title":"Micro Raman spectroscopy used for the study of corrosion products on copper alloys: Study of the chemical composition of artificial patinas used for restoration purposes","volume":"130","author":"Hayez","year":"2005","journal-title":"Analyst"},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"105","DOI":"10.1023\/A:1011857303823","article-title":"EDTA enhanced heavy metal phytoextraction: Metal accumulation, leaching and toxicity","volume":"235","author":"Vodnik","year":"2001","journal-title":"Plant Soil"},{"key":"ref_24","unstructured":"European Chemicals Bureau (2004). European Union Risk Assessment Report Edetic Acid (EDTA), European Commission."},{"key":"ref_25","unstructured":"Patnaik, P. (2004). Dean\u2019s Analytical Chemistry Handbook, McGraw-Hill Education. [2nd ed.]."},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"2053","DOI":"10.1139\/v92-259","article-title":"Complexes of Cu(II) with D-aldonicand D-alduronicacids in aqueous solution","volume":"70","author":"Escandar","year":"1992","journal-title":"Can. J. Chem."},{"key":"ref_27","first-page":"187","article-title":"Colorimetry applied to the field of cultural heritage: Examples of study cases","volume":"7","author":"Lorusso","year":"2007","journal-title":"Conserv. Sci. Cult. Herit."}],"container-title":["Gels"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2310-2861\/9\/11\/843\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,10]],"date-time":"2025-10-10T21:11:15Z","timestamp":1760130675000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2310-2861\/9\/11\/843"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2023,10,25]]},"references-count":27,"journal-issue":{"issue":"11","published-online":{"date-parts":[[2023,11]]}},"alternative-id":["gels9110843"],"URL":"https:\/\/doi.org\/10.3390\/gels9110843","relation":{},"ISSN":["2310-2861"],"issn-type":[{"type":"electronic","value":"2310-2861"}],"subject":[],"published":{"date-parts":[[2023,10,25]]}}}