U(VI) adsorption by biochar fiber-MnO2 composites

The removal of U(VI) by biochar fibers from aqueous solutions has been investigated prior and after MnO2 surface-deposition. The removal efficiency has been studied as a function of pH, U(VI) concentration, ionic strength, temperature and contact time. The fibers morphology and surface complexes were analyzed by SEM-EDX and FTIR, respectively. Evaluation of the experimental data indicates that the composite presents extraordinary adsorption capacity (q(max )= 3.8 mmol g(-1), 904 mg g(-1)), which is attributed to the formation of inner-sphere surface complexes, and that the adsorption reaction is a relatively fast, endothermic and entropy-driven process.