Radiological characterization of peloids maturated with Águas de Lindóia, Poços de Caldas and Peruíbe waters

Abstract

One of the concerns about using mineral clay for therapy treatments is its radioactivity content due to natural radionuclides, normally, associated with the clays. This work proposes to characterize the natural radionuclides of the peloids obtained by the maturation process of mixing bentonite and montmorillonite with different mineral medicinal waters from Águas de Lindóia (SP), Peruíbe (SP) and Poços de Caldas (MG). For this procedure, gray end green bentonite samples were left in contact with running water for three, six and nine months, after this, they were collected, dried, transferred to a mortar, crushed and placed in approximately 40 cm3 polyethylene flasks, sealed and set apart for about four weeks, prior to the measurements. The concentration of 210Pb was determined by measuring the activity of its low energy peak (47 keV). Comparing the gray and green bentonite peloids, all the activity concentration of radionuclides are higher in gray ones, except 40K. The activity concentration varied from 84 to 156 Bq kg−1 (228Ra), 25 to 156 Bq kg−1 (228Th), 9 to 161 Bq kg−1 (226Ra), 39 to 256 Bq kg−1 (210Pb) and 162 to 1070 Bq kg−1 (40K).