Efficient extraction of UO22+ from seawater by polyethylenimine functionalized activated carbon (PEI-AC): adsorption performance and mechanism

In this work, an inexpensive PEI-AC sorbent was synthesized by facile hydrothermal grafting method and used to uranium capture from seawater. Batch experimental demonstrated that the optimal operation pH of PEI-AC was 6.0. The adsorption process is conformed to pseudo-second-order kinetic model and Langmuir monolayer adsorption isotherm, and the maximum equilibrium adsorption capacity reached 50.27 mg/g. The PEI-AC samples exhibited better selective and efficiency in various competing ions and uranium-spiked seawater. Furthermore, the removal efficiency remained 88.52% after five sequence adsorption/desorption experiments. By the analysis of XPS, the interaction of UO 2 2+ with N/O-containing ligands were the primary immobilization mechanism.