Changes in the pH of radioactive aqueous solutions in their decontamination by means of two carbon adsorbents

摘要

A wood charcoal, manufactured in Extremadura (Spain), and a oxidized carbon obtained by an air treatment at 250 °C from this charcoal have been used to eliminate radioactive cations by filtration beds from natural waters. Here, it is studied the changes in the pH of radioactive aqueous solutions in their decontamination. The results show that the carbon adsorbents exert a different influence on the initial pH of radiactive aqueous solutions. Independent of the carbon used, the final pH is approximately 7 if the initial solutions are acid. In contrast, the pH do not changes if basic solutions are filtered through the original charcoal, and tends to decrease slightly using the carbon resulting of air treatment. Theses changes are attributed to soluble mineral matter which carry the carbon adsorbents; to a different surface oxygen groups on their surfaces caused by the air treatment; and to a different p basicity of their exposed graphene layers.