New Double Electrode System for the Electrochemical Desalination of Building Stones

The application of electrokinetic techniques for the mobilization and the removal of ions present in different porous materials, such as building construction materials, have shown high efficiency with respect to that reached with other techniques. However, some drawbacks related mainly with the mobilization efficiency of the ions of interest and with the integrity of the porous material due to the possible chemical and/or aesthetic damages have still to be overcome to
take advantage of the full potentiality of these techniques. To overcome these limitations the present study evaluates the effectiveness of a new electrokinetic configuration based on the use of two electrodes per compartment that allow modulating the net amount of OH⁻ and H⁺ groups produced at the electrodes’ surface. This effectiveness was evaluated desalinating sandstone samples contaminated with different salts. The results indicate that the new configuration allowed: maintaining a high moisture content, both in poultices and stones, which allowed the treatment to work properly for longer time; to reach high percentages of reduction of all the ions present in the treated stones; to effectively buffer the pH variations due to the possibility of modulate the net amount of OH⁻ and H⁺ groups produced.