Preparation of polydopamine-functionalized polyamidoxime membrane for uranium recovery from seawater

A stable supply of uranium resources is essential to the sustainable development of nuclear energy. Extraction of uranium from seawater or uranium-containing wastewater with abundant uranium reserves has attracted much attention. Here, a polydopamine-functionalized polyamidoxime membranes (PDA@PAO membranes) were fabricated via nonsolvent induce phase separation method coupling with polymerization deposition process of dopamine and further applied to capture U(VI) from solution. The PDA@PAO membranes exhibited impressive adsorption capacity and convenient separation from solution. The adsorption kinetics and equilibrium adsorption of PDA@PAO membranes satisfactorily fitted with the pseudo-second-order model and the Langmuir model, respectively. The maximum adsorption capacity for uranium calculated according to the Langmuir model at pH 5.00 and 298 K reached 730 mg·g−1. Moreover, the adsorption capacity of the PDA@PAO membranes was maintained at 212 mg·g−1 under the interference of 9 different kinds of competing ions and the removal of U(VI) all reached more than 90 % in three different concentrations of uranium-spiked natural seawater, which revealed that the adsorbent possessed the promising selectivity for uranium. In addition, the PDA@PAO membranes exhibited satisfactory reusability, and the uranium adsorption capacity and desorption rate were maintained above 96.5 % after five adsorption–desorption cycles. The high capacity, excellent selectivity and good reusability endow PDA@PAO membranes as a suitable candidate for the extraction of U(VI) from actual industrial wastewater or seawater.