Electrosorption of uranium (VI) from aqueous solution by phytic acid modified chitosan: An experimental and DFT study

The extraction of U(VI) from nuclear wastewater is of great importance for environmental protection. In this work, we try to remove uranium ions from uranium-containing wastewater by electrosorption. In order to improve the adsorption capacity and selectivity of the adsorption materials, the complex of chitosan and phytic acid (CSPA) was used as electrode material. The experimental results showed that the introduction of phytic acid can efficiently improve the adsorption capacity, adsorption selectivity and reusability of chitosan. The maximum adsorption capacity of CSPA was 429.1 mg/g and the theoretical maximum sorption capacity reached up to 572.1 mg/g. Moreover, the electrosorption capacity of CSPA for U(VI) was 68.6% of the total electrosorption capacity in the presence of competitive ions. After 5 cycles of reuse, CSPA still maintained 86.6% of its initial sorption capacity. Furthermore, we found that the selective adsorption mechanism of uranium ions was related to the inner-sphere complexation between UO22+ and the O atom of PO group according to the experimental analysis and the DFT calculation results. This work provided a novel strategy for effective removal of uranium (VI) from uranium-containing wastewater.