Thermophysical behavior of clinically relevant peloid formulations: a study using residual smectitic soils and mineralized waters

Abstract

Abstract Thermotherapy is widely used in thermal centers and can be beneficial for certain pathologies. Peloids are mixtures of fine-grained clay materials and waters of different mineralization and are commonly applied in thermotherapy, where key performance parameters include specific heat capacity, thermal conductivity, and cooling behavior. Therefore, these properties were determined for mixtures of residual smectitic soils with thermo-mineral water and seawater to assess their potential therapeutic value. Mixtures prepared with 50% of thermo-mineral water (Beja-T, Bena-T and Monta-T) showed higher specific heat capacity (2640–2750 J kg-1 K -1 ), lower thermal conductivity (0.84–0.93 W m -1 K -1 ) and lower cooling rate (0.19–0.20 s −1 ). On the other hand, mixtures prepared with 46% (Beja-S), 33% (Bena-S) and 32% (Monta-S) of seawater showed lower specific heat capacity (1580–1680 J kg-1 K -1 ), higher thermal conductivity (0.89–0.99 W m -1 K -1 ) and higher cooling rate (0.20–0.24 s −1 ). Moreover, the cooling time of clay/water mixtures ranged from 21.5 min. (Monta-S) to 28.5 min. (Bena-T), suggesting a great heat retention capacity under the experimental conditions employed. Water content and mineralization strongly influence the thermal properties of the mixtures. Among all the mixtures, Bena-T – also the most smectitic-rich sample – appeared to be the most suitable candidate for thermotherapeutic use. However, further rheological characterization and handling characteristics are recommended to fully assess the application performance and therapeutic potential.