In situ desalination of a granitic column by the electrokinetic method

Desalination of rocks used in monuments is a common strategy to reduce the possibility of deterioration by soluble salt crystallization processes. In the last years, some laboratory studies have demonstrated that the application of electrokinetic techniques allow to achieve higher desalination effectiveness, overcoming most limitations of the traditional methods. However, to our knowledge no studies have been conducted on the effectiveness of this technique for in situ desalination of granite. The present study is aimed at filling this gap. The results of an in situ desalination intervention using electrokinetic methods, on a column highly contaminated with salts are presented. The desalination method was optimized to desalinate large in situ structures, trying to establish the necessary protocols (buffering system, irrigation system, setup, etc.) to obtain results as satisfactory as those obtained in laboratory. The results demonstrated the high effectiveness of this method in terms of total salt extraction and depth of salt extraction. The concentration of anions in the column was decreased by more than 80% after 55 days of treatment. No mineralogical and aesthetic damages on the stone were detected after the treatment, confirming the reliability of this method to be applied in situ on granitic rocks.     

Effectiveness of Phosphocitrate as Salt Crystallization Inhibitor in Porous Materials: Case Study of the Roman Mosaic of Orpheus and the Beasts (Perugia,Italy)

Salt crystallization in porous materials constitutes one of the major causes of decay of buildings/archaeological sites in a wide range of environments. Desalination is among the most common methodologies of conservative treatment for salt decay. However, classic desalination techniques might be not suitable for long-term conservation. During the past decade interest has been an increasing towards crystallization inhibitors as a new means of controlling crystallization damage. This study deals with the first in-field application of an environment-friendly inhibitor system— phosphocitrate (PC). In particular, the case study of the Roman mosaic of Orpheus and the Beasts in Perugia (Italy) is presented. The inhibitor is completely soluble in water or alcohol, non-toxic, and easy to apply, thus enabling its use in accordance with the volatile organic compounds emission control and safety during the conservation works. Relevant samples from control and treated mosaic areas were collected and analyzed comparatively by means of Fourier transform-infrared spectroscopy, scanning electron microscopy, and energy dispersive spectrometry to study the potential of the inhibitor system in preventing/controlling salt damage in such archaeological site.     

Critical review of desalination in Spain: a resource for the future?

There have been significant territorial changes in the Spanish Mediterranean in the last few decades because of the important growth of residential tourism functions. The Spanish National Hydrological Plan ( 2001 ) and, to a greater extent, the Action for Management and Use of Water Programme ( 2004 ) advocated large‐scale desalination of seawater to guarantee a supply for urban, tourism, and even future agricultural demands. The paralysis of urban development planning caused by the financial crisis (2007/08), together with the downward trend in the consumption of drinking water in the last decade, highlighted a capacity to produce desalinated water that was far superior to actual needs. This study reviews the current context in which desalinated water is produced in Spain, weighs up the advantages and disadvantages of this method of water management, and considers the potential role that this non‐conventional source of water could play as a strategic resource in the future. The main findings of the study are that desalination is not a panacea; rather, it should be considered in terms of technological parameters tailored to the circumstances of each geographical and socioeconomic environment.