A non-invasive monitoring method has been developed for electro-desalination (ED) of sandstone. Salts are one of the main culprits in deterioration of cultural heritage, and ED has been proven an effective treatment. However, until now there has not been an accurate non-invasive method to monitor treatment progress. This study investigates the use of impedance to estimate the salt content within a stone sample during desalination treatment. The salt used for the experimental setup have been N aCl due to its commonality in the environment. The stone samples have mainly been Clashach sandstone due to its pure mineralogy and uniform pore size that limits variations during experiments. The experiments trialled a four-point electrode setup and varying boundary conditions. The sensitivity of impedance measurements in relation to inherent variability within samples, porosity, moisture content and salt was investigated. The results showed that neither an individual sample's porosity or composition was directly correlated to impedance. Also, as long as there was more than 20% moisture content within the samples, impedance measurements were not affected. Salt however, clearly impacted impedance values, even at small concentrations. As salt was removed during ED treatment, impedance increased, showing a strong correlation with measured salt values from later destructive testing. The resulting curve of X against Y was robust for all tests. The experiments confirmed that ED is a much more effective method in removing salt compared to poulticing, as well as illuminating three phases of desalination: an initial, high removal rate phase, a constant removal phase and a final increasing phase. This concept needs further investigated and developed. Based on the findings in this study, impedance measurements can be used as a non-invasive monitoring and evaluation method for desalination though ED treatments. Future studies are required to develop a workflow for application in the field.
|Date of Award||9 Nov 2021|
- University Of Strathclyde
|Sponsors||University of Strathclyde|
|Supervisor||Zoe Shipton (Supervisor) & Marcus Perry (Supervisor)|