Biocarbon/polyaniline nanofiber electrodes with high hybrid capacitance and hierarchical porous structure for U(VI) electrosorption

The removal of U(VI) from nuclear effluents is significant for uranium resource recovery and environmental safety. Herein, polyaniline (PANI) was electrodeposited on porous biocarbon (cotton derived carbon, CC) to fabricate a high-performance composite electrode (CC/PANI) for U(VI) electrosorption. The CC/PANI electrode showed high specific capacitance and excellent cyclic stability, it also exhibited capacitive control characteristics for which the capacitance contribution has been quantified. The electrosorption results indicate that CC/PANI-2 has the highest specific capacitance among various CC/PANI electrodes, and also exhibits the highest electrosorption capacity for U(VI), reaching a maximum value of 282.2 mg/g at pH 4.0 and 0.9 V. The modeling results of electrosorption isotherms and kinetics for U(VI) indicated the good simulation by Langmuir and PFO models, respectively. The excellent electrosorption performance of CC/PANI-2 for U (VI) is attributed to its high hybrid capacitance, good conductivity, and improved hydrophilicity. The electrosorption mechanism for U(VI) removal is mainly ascribed to EDL and pseudocapacitive electrosorption, with possible contribution from U(VI) coordination by N atoms of CC/PANI. This work provides the strategy of incorporating PANI with biocarbon to fabricate a novel electrode for the efficient CDI treatment of radioactive nuclear wastewater.