Abstract
Uranium (U) and thorium (Th) separation by batch adsorption onto rice straw-based activated carbon (RS carbon) was studied. The effect of pH, contact time adsorption, and desorption media on the selectivity and sensitivity of the removal process was investigated. Results show that the metal ion species rapidly move from liquid phase to carbon surface with 40-100min equilibrium time for uranium and thorium, respectively. Uranium and thorium sorption reaches its maximum at pH 5.5 and 4, respectively. Thus, these radio nuclides can be separated by the careful adjustment of pH and contact time. Thorium can be highly selective separated from uranium at lower time and at pH 4. Lower concentration of acetic acid enhance uranium and thorium uptake when compared with other mineral and organic acids. Uranium can be selectively desorbed from RSK carbon using HCl leaving thorium onto the adsorbents. Thorium can be selectively eluted from RSK carbon by using HNO3 or H2SO4 and from RSN carbon by NaHCO3. These procedures may be successfully applied, in most cases, where a careful separation of two elements is required.