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http://hdl.handle.net/10174/28982
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Title: | Development of cleaning procedures of copper corrosion products by using “green” deep eutectic solvents |
Authors: | Khaire, Shraddha |
Advisors: | Navarra, Maria Assunta Tsurumaki, Akiko |
Keywords: | Conservation Copper Corrosion Archaeometry Materials |
Issue Date: | 21-Dec-2020 |
Publisher: | Universidade de Évora |
Abstract: | Abstract:
Selection and refinement of a method for copper corrosion removal were
undertaken in an environmentally friendly way by using deep eutectic solvents
(DES) integrated in a cellulose-based membrane.
DES is a potential “green” solvent based on natural compounds. In this thesis,
a DES composed of choline chloride and ascorbic acid in a 2:1 ratio, was prepared
and used for copper corrosion cleaning. The DES was diluted with water and the
DES to water ratio was optimized in terms of efficiency, time consumption, and
selectivity of cleaning.
It was found that DES solutions, having a concentration higher than 70 wt.%
were suitable for dissolving copper corrosion products. Meanwhile, they exhibited a
supressed dissolution ability of CaCO3 which is a common compound in many of
the supporting structures used for copper artefacts.
These solutions were then used for swelling cellulose membranes, and the
swelling capacity was monitored for a week. The swollen membrane was put on an
electrochemically corroded copper sheet for 24 hours. By removing the membrane,
the green malachite layer was successfully removed from the copper sheet while
preserving a reddish-brown cuprite layer. This was confirmed by performing X-ray
diffraction analysis before and after cleaning the copper sample.
For heritage objects, the defacing copper corrosion products of Cu (II) need to
be removed apart from protective layer of cuprite. We concluded that the cellulose
membranes containing DES solutions are promising materials for this purpose. |
URI: | http://hdl.handle.net/10174/28982 |
Type: | masterThesis |
Appears in Collections: | BIB - Formação Avançada - Teses de Mestrado
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