Performance and mechanism of phytic acid-doped porous carbon sphere flow electrode in treating uranium-containing wastewater

To address the challenge of uranium-contaminated wastewater, flow-electrode capacitive deionization (FCDI) has emerged as a promising technology owing to its advantages of electric field enrichment and electrode recyclability. In this study, porous carbon spheres were synthesized from aniline via a hard-template carbonization method and subsequently functionalized with phytic acid to obtain phytic acid-doped porous carbon spheres (PAPCS) as a novel flow-electrode material. Under optimized conditions, PAPCS displayed a specific activity of 13.95 μL·cm −2 ·s −1 , which is much higher than reported in previous studies. Further, only 4 h was required to reduce uranium concentration in wastewater from 0.1 mg L −1 to 25.2 μg L −1 . Thus, the uranium concentration in the treated wastewater reached the national drinking water standard (<30 μg L −1 ). At higher initial concentrations (1.0, 5.0, and 30.0 mg L −1 ), the removal efficiencies reached 88.29 %, 92.7 %, and 95.57 %, respectively. After nine adsorption cycles, the material retained over 80 % of its initial capacity, showing that its stability and reusability remain reasonably high. Density functional theory (DFT) calculations further revealed that the adsorption energies of porous carbon spheres toward uranyl ions decreased significantly decreased from −2.9556 eV to −3.5095 eV after phytic acid functionalization, confirming that phytic acid substantially enhance the adsorption capacity. These results highlight that the integration of phytic acid-functionalized porous carbon with FCDI technology provides an efficient, stable, recyclable, and environmentally friendly approach for uranium wastewater treatment, offering enormous potential for practical applications.