Pel, Leo; Kamran, Kashif; Sawdy, Alison; Huinink, Henk:

Desalination by electrokinetics: Can it work?

The threats posed by salts to porous materials can be minimized either by controlling the environment or by removing the salts from the zone of deterioration. In the case of porous building materials typically salt extraction is accomplished by aqueous methods. In these methods the use of poultices to reduce salt content from building materials and structures is very common. The extraction efficiency of a poultice is largely limited by the permeability and pore size distribution of both the poultice and the substrate. It has been proposed that the limitations posed by poultices can be overcome by using electrokinetics as an alternative desalination method for building materials.
The electrokinetic method aims to remove ionic species from the zone of deterioration by externally applied electric fields. Although the electrokinetic technique has already been used to decontaminate soil and concrete, its application in the desalination and dehumidification of masonry bricks and walls is a recent phenomenon. During the electrokinetic desalination of masonry bricks, electromigration of salt ions is considered the dominant transport mechanism and the contribution of both diffusion and advection transport processes is usually neglected. In this study the effect of both diffusion and advection on the transport of salt ions through fired-clay bricks is also included in order to answer the effectivity of the electrokinetic method.

Leo Pel is a physicist (Ir applied physics, Eindhoven University of Technology, 1988). He undertook his PhD at the Department of Architecture (Eindhoven University of Technology, 1995), after which he joined the Transport in Permeable Media Group at the Department of Physics of Eindhoven University, where he has been an associate professor since 2000. A collaborator on both national and international projects, including several EU projects, he has been a partner in the EU Desalination project on poulticing. His main research interest is in the study of moisture and ion transport in porous building materials and the associated salt damage mechanism

Relevant publications:
- Leo Pel, Alison Sawdy, Victoria Voronina, Physical principles and efficiency of salt extraction by poulticing, Journal of Cultural Heritage 11 59–67 (2010)
- A. Heritage, L. Pel, A review of salt transport in porous media: assessment methods and salt reduction treat¬ments, Salt weathering on buildings and stone sculp¬tures, 22-24 Oct, Copenhagen, Denmark (2008)
- J. Petković, H.P. Huinink, L. Pel, K. Kopinga, R.P.J. van Hees, Moisture and salt transport in three-layer plaster/substrate systems, Construction and Building Materials 24, 118-127 (2010)
- T. Diaz Goncalves, L. Pel and J. Delgado Rodrigues, Drying of salt contaminated masonry: MRI laboratory monitoring, Environ Geol 52, 293 302 (2007)
- J. Petkovic, H.P. Huinink, L. Pel, K. Kopinga and R.P.J. van Hees, Salt transport in plas-ter/substrate layers, Materials and Structures 40, 475-490 (2007)
- H.P. Huinink, L. Pel and M.A.J. Michels, How ions distribute in a drying porous medium - A simple model, Phys. Fluids 14, 1389-1395 (2002).
- L. Pel, H. Huinink, K. Kopinga, Ion transport and crystallization in inorganic building materials as studied by nuclear magnetic resonance, Applied Physics Letters 81, 2893-2895 (2002)