Highly efficient and selective adsorption of uranium (VI) in acidic solution by TOPO impregnated PAN capsules

The adsorption capacity and adsorption rate of most adsorbents for U (VI) are maximum in the pH value range of 5 similar to 9. However, uranium-containing wastewater produced during uranium mining is usually highly acidic. Therefore, it is of great significance to prepare adsorbents suitable for the separation and enrichment of U(VI) ions from strongly acidic solutions. PAN capsules were synthesized by phase transformation method, and then impregnated TOPO in PAN capsules by impregnation method. TOPO/PAN has good morphology and higher adsorption capacity for U(VI) under acidic conditions. The effects of time, solid-liquid ratio, pH and ionic strength on TOPO/PAN adsorption of U(VI) were studied. The experimental results showed that the pseudo-second-order kinetic model and Langmuir model well described the kinetic and equilibrium data of adsorption process. The capsules have fast adsorption rate, good adsorption capacity and good ion selectivity in highly acidic solutions. After 5 cycles, the adsorption rate of TOPO/PAN is still above 96 % and the adsorption rate decreases by 1.2 %, which indicate that TOPO/PAN has good reusability. The research shows that TOPO/PAN has good practical application value.