Some properties of thermal muds of some spas in Turkey

Abstract

In Turkey, over thirty spa centers use local, naturally occurring thermal muds for therapeutic, aesthetic, and pharmaceutical purposes. Mineralogical, chemical, and technological properties of thermal muds from nine different spas were investigated to identify the most suitable materials for pelotherapy. The muds consisted of smectite, illite, illite–smectite, quartz, feldspar, some calcite, amorphous silica, and rarely halite. The Na 2O/CaO ratio of the muds was lower than 0.09, representing non-swelling bentonites. Some mud samples contained higher levels of hazardous chemical elements, including As, Cd, Hg, Pb, Tl, Th and U, and some less dangerous elements, including Co, Cr, Cs, Ni, Sr, Zr, and REE, compared to argillaceous sediments and shales. In general, particle sizes of muds larger than 2 μm, and cation-exchange capacity and specific surface areas are lower than the standard value. Properties of a few thermo-mineral waters were also analyzed. The low swelling index, Na 2O/CaO ratio, plasticity, and specific surface area (due to the low content of the < 2 μm clay fraction), as well as the high content of non-clay minerals and exchange capacity of the muds, make them unsuitable for therapeutic and aesthetic applications. These results indicate that there is a need to develop suitable standards for thermal muds in relation to their use for therapeutic, pharmaceutical, and aesthetic medicine purposes. Appropriate materials can be obtained from the bentonite deposits at very low cost, and the material can be maturated using thermal–mineral water in different compositions for different types of applications.