Clay mineral: Radiological characterization

Author(s)

Cotomacio, J. G. ; Silva, P. S. C. ; Mazzilli, B. P. ; Paschoa, AS ; Steinhausler, F

• Document type: Journal article
• Source: MAGNETIC FIELDS IN THE UNIVERSE: FROM LABORATORY AND STARS TO PRIMORDIAL STRUCTURES; v. 1034, p. 2-pg., 2008-01-01.

Abstract

Since the early days, clays have been used for therapeutic purposes. Nowadays, most minerals applied as and-inflammatory, pharmaceutics and cosmetic are the clay minerals that are used as the active ingredient or, as the excipient, in formulations. Although their large use, few information is available in literature on the content of the radionuclide concentrations of uranium and thorium natural series and K-40 in these clay minerals. The objective of this work is to determine the concentrations of U-238, Th-232, Ra-226, Ra-228, Pb-210 and K-40 in commercial samples of clay minerals used for pharmaceutical or cosmetic purposes. Two kinds of clays samples were obtained in pharmacies, named green clay and white clay. Measurement for the determination of U-238 and Th-232 activity concentration was made by alpha spectrometry and gamma spectrometry was used for Ra-226, Ra-228, (210)Pn and K-40 determination. Some physical-chemical parameters were also determined as organic carbon and pH. The average activity concentration obtained was 906 +/- 340 Bq kg(-1) for K-40, 40 +/- 9 Bq kg(-1) for Ra-226, 75 +/- 9 Bq kg(-1) for Ra-228, 197 +/- 38 Bq kg(-1) for Pb-210, 51 +/- 26 Bq kg(-1) for U-238 and 55 +/- 24 Bq kg(-1) for Th-232, considering both kinds of clay. (AU)