Anchoring chitosan on phytic acid-doped polyaniline as capacitive deionization electrodes for uranium capture from wastewater

Capacitive deionization (CDI) has significant potential for the rapid and efficient separation of uranyl ions, although there remains substantial room to improve the development of an appropriate electrode material. Phytic acid-doped polyaniline (PA-PANI) was synthesized in a phytic acid (PA) environment in this work, followed by the immobilization of chitosan on the PA-PANI framework to produce a chitosan-modified spherical material (CS/PA-PANI). Experimental results showed that CS/PA-PANI exhibited much faster kinetics and much higher uranium uptake under applied voltage than systems dominated by either physical or chemical adsorption. UO22+ adsorption capacity reached a maximum of 942.4 mg g−1 at 1.2 V, which is higher than most polymer-based electrodes that have been reported to date. Electrochemical analysis and characterization of the structure suggested that the electroadsorption of UO22+ on CS/PA-PANI resulted from synergetic effect of capacitive processes and physical-chemical adsorption. The capacitive action was attributed to the formation of electric double layers by polyaniline, whereas the coordination of UO22+ with the amino or hydroxyl groups accounted for the physico-chemisorption part. This study is a novel and promising polymer electrode on CDI-based extraction of uranium in seawater and nuclear wastewater through integration of rational material design and excellent uranium-capture performance.