Electrochemical desalination of salt infected brick masonry applying a double electrode system

Abstract

Salt weathering is recognized as one of the main deterioration mechanisms that affect cultural heritage. The damage caused by this decay mechanism can range from a simple aesthetic damage, when salts crystallize on the surface as efflorescence, to cause the loss of material, when salts crystalize beneath the material surface as sub- and crypto-efflorescence. To reduce the risk associated to salt induced deterioration, the use of electrokinetic treatments, as desalination method applied on site, is undoubtedly the one that has allowed obtaining higher extraction percentages in a short period of time. Recently a new double electrode system per compartment allowed, at laboratory scale, to overcome the results achieved with the traditional electrokinetic configuration (using one electrode per compartment). In the present study, a comparison between the results achieved by this new system, in terms of percentage of anion reduction and water content, with respect to the traditional one is shown. Both methods were applied to desalinate two brick walls affected by salts located in the ancient stables of the 18th century Bernstorff Palace (Gentofte-Denmark). The obtained results shows that the new system, as occurs at laboratory scale, allows maintaining a high moisture content in poultices, which improve the contact between poultices and brick wall, allowing a proper current flow for longer time. In consequence, this new system achieves higher percentages of reduction of all the anions present than those achieved using the traditional configuration.