Use of Electrical Conductivity for Monitoring of Desalination Process of Historical Potteries

The deterioration of ancient porous materials due to the dehydration and crystallization of water-soluble salts is a well-known phenomenon. Salt crystallization is an important factor in the deterioration of ancient ceramics and will almost always cause some degree of damage, ranging from exfoliation of the glaze to complete disintegration of the body. To avoid any ultimate damage of aggressive salts, it is very important the essential desalination process be accomplished within a short period of time because of the direct contact of the historical porous material with water. Since EC is proportional to the concentration of ions, therefore desalination process can be monitored by EC readings. In this paper, it was documented that Electrical Conductivity (EC) is an accurate, reliable, fast and simple method for monitoring of salt extraction during desalination process. To validate this method, 52 experimental runs, designed by Response Surface Methodology (RSM) have been performed. RSM is carried out by Minitab software, version 16. Independent parameters in this research are firing temperature, immersing time, agitation rate, type, and concentration of surfactant. Calcium ion was selected as an indicator of soluble salts and measured through Atomic Absorption Spectroscopy (AAS). Electrical conductivity and calcium ion concentration are measured as desirable responses. The correlation between Ca2 concentration and EC readings was also investigated. Pearson correlation between EC and extracted Ca2 is .923 with p-value = 0.000 and linear function between these parameters are observed with approximately 96% goodness of the fit. Therefore, EC is introduced as a suitable indicator for monitoring of salt removal efficiency in the immersing system method. This monitoring method is recommended for determining the end point of desalination process especially in archaeological sites and restoration workshops where a reliable, and fast method is most desirable.