Electrokinetic desalination of glazed ceramic tiles
- 191 Downloads
Electrokinetic desalination is a method where an applied electric DC field is the driving force for removal of salts from porous building materials. In the present paper, the method is tested in laboratory scale for desalination of single ceramic tiles. In a model system, where a tile was contaminated with NaCl during submersion and subsequently desalinated by the method, the desalination was completed in that the high and problematic initial Cl− concentration was reduced to an unproblematic concentration. Further conductivity measurements showed a very low conductivity in the tile after treatment, indicating that supply of ions from the poultice at the electrodes into the tile was limited. Electroosmotic transport of water was seen when low ionic content was reached. Experiments were also conducted with XVIII-century tiles, which had been removed from Palacio Centeno (Lisbon) during renovation due to damage of the glazing from the presence of salts. These tiles were severely contaminated with both chlorides and nitrates, and one of the tiles also contained sulphates though at a low concentration. The charge transfer was too low in the experiments to obtain full desalination, but promising results were obtained as significant decreases (>81% Cl−, ~59% NO3 − and ~22% SO4 2−) were seen.
KeywordsDesalination Salt decay Azulejo tile Electrokinetics Electroosmosis
Joao-Manuel Mimoso, Laboratorio Nacional de Engenharia Civil (LNEC) Portugal is acknowledged for supplying the XIX tiles for the experimental work and for the idea of testing electrokinetic desalination for salt contaminated tiles.
- 1.Sawdy A, Heritage A, Pel L (2008) A review of salt transport in porous media, assessment methods and salt reduction treatments. In: Proceedings from the international conference on salt weathering on building and stone sculptures, Copenhagen, Denmark, 22–24 October 2008. pp 1–27Google Scholar
- 2.Gomes MMM, Monteiro JP (1996) Conservation and restoration of Azulejos—Portuguese tiles. Ricardo do Espírito Santo Foundation, LisbonGoogle Scholar
- 3.Mietz J (1998) Electrochemical rehabilitation methods for reinforced concrete structures. A state of the art report. European Federation of Corrosion Publications. Numer 24Google Scholar
- 4.Tritthart J (1998) Electrochemical chloride removal: an overwiev and scientific aspects. In: Skalny J, Mindess S (eds) Materials science of concrete V. American Ceramic Society, Westerville, OH, USA, pp 401–441Google Scholar
- 7.Ottosen LM, Rörig-Dalgaard I, Villumsen A (2008) Electrochemical removal of salts from masonry—experiences from pilot scale. In: Proceedings from the international conference on salt weathering on building and stone sculptures, Copenhagen, Denmark, 22–24 Oct 2008. pp 341–350Google Scholar
- 8.Rörig-Dalgaard I, Ottosen LM (2008) Method and device for removing an ionic impurity from building structures (Pub. No. WO/2009/124890)Google Scholar
- 9.Rörig-Dalgaard I (2008) Preservation of masonry with electrokinetics—with focus on desalination of murals. PhD Thesis, Department of Civil Engineering, Technical University of DenmarkGoogle Scholar
- 12.De Clercq H (2008) The effect of other salts on the crystallization damage tos tone caused by sodium sulphate. In: Proceedings from the international conference on salt weathering on building and stone sculptures, Copenhagen, Denmark, 22–24 Oct 2008. pp 307–315Google Scholar