Insights into electro-assisted and selective adsorption of U(VI) using hierarchical porous and activated biocarbon from lotus pods/2D-MoS2/ polypyrrole composites through capacitive deionization

The current research work involves the fabrication of orderly mesoporous composite materials based on layered molybdenum disulfide, a hierarchical porous biocarbon from Lotus pods electrodeposited with polypyrrole (2D-MoS2/BCL/PPy). The polypyrrole, as a conducting polymer, was electrodeposited in different mole ratios onto Ni foam supported by 2D-MoS2/BCL. The composite materials were analytically characterized by means of FTIR, SEM-EDX, BET, and XRD techniques. The Lotus pod-driven biocarbon exhibited a high surface area. Among different composites, BCL/PPy-3 (electrodeposited with 0.3 M PPy) was found highly efficient in electro-assisted hexavalent uranium recovery via capacitive deionization because of its impressive specific capacitance (Csp) (100.40 F/g) with improved active surface area and admirable total pore volume. These characteristics made BCL/PPy-3 competitive for enhanced hexavalent uranium ion electrosorption. These features were highly conducive to fast electron transfer and better diffusion of hexavalent uranium ions during the CDI process. The exposed S atoms in BCL/PPy-3 showed good coordination and complexing power for hexavalent uranium ions. The BCL/PPy-3 exhibited an inspiring sorption capacity of 417.90 mg/g at pH = 4.5 and applied voltage (-0.9 V), which is better than many other materials used in CDI applications having similar geometry and morphology. During the electrosorption, the composite electrode BCL/PPy-3 offered a small solution resistance (Rs) (0.69 cm2), a minute charge transfer resistance of Rct (1.19 omega cm2), and a substantial double layer constant phase element (qdl) of (0.0372 S sn/cm2). These features make this composite electrode highly effective for hexavalent uranium ions removal.