Electromigration of K+ and NO3-natural stone and brick under application of a constant voltage

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    Abstract

    Transport of ions in an applied electric field (electromigration) can be used in conservation actions both for removal (electro-desalination) and supply (electro-precipitation) of ions out from or into the substrate. For the further development of these methods, increased understanding of the influence from side effects on the transport of the target ions is necessary. Electromigration has most often been investigated under application of a constant current. In this work, a constant voltage is applied, and it reports a direct comparison of electromigration of K+ and NO3- through substrates with different porosities. Prisms, one brick and four natural stones, were prepared and contaminated with NaCl in exactly the same way. Electromigration experiments were made under the same applied constant voltage. During the first hours, the current was very different between the experiments (from 2.3 to 72 mA), showing major difference in the electrical conductivity of the substrates - the higher the porosity, the higher the conductivity (and current). The current developed differently between the experiments. By the end of the 3 days experiments, the current was between 3.4 and 9.2 mA, and independent of the substrate porosity. During the experiments, the electrode processes and the connected side effects influenced the electromigration of K+ and NO3- to different extents in the different substrates, and the most in the substrates with high porosity. The experiments underline that the electromigration of target ions depends strongly on the substrate when applying a constant voltage, because the substrate conductivity determines the current and thus the side effects. Applying a constant current instead, as in most of the previous works, enables better managing of the side effects. 
    Original languageEnglish
    Title of host publicationProceedings of SWBSS 2021 : Fifth International Conference on Salt Weathering of Buildings and Stone Sculptures
    EditorsBarbara Lubelli, Ameya Kamat, Wido Quist
    PublisherTU Delft
    Publication date2021
    Pages251-261
    ISBN (Electronic)978-94-6366-439-4
    Publication statusPublished - 2021
    EventFifth International Conference on Salt Weathering of Buildings and Stone Sculptures - Delft, Netherlands
    Duration: 22 Sept 202124 Sept 2021
    Conference number: 5

    Conference

    ConferenceFifth International Conference on Salt Weathering of Buildings and Stone Sculptures
    Number5
    Country/TerritoryNetherlands
    CityDelft
    Period22/09/202124/09/2021

    Keywords

    • Electromigration
    • Stone
    • Porosity
    • Salt
    • Side effects

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