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This work synthesized polyethyleneimine and chitosan modified winter melon-derived biochar (PEI-CTS@WBC) using chemical crosslinking method for uranium(VI) removal. The factors influencing uranium(VI) adsorption by PEI-CTS@WBC, including pH, adsorbent dosage, time, temperature, and initial U(VI) concentration were explored. The material's performance was characterized, and the underlying mechanism of U(VI) removal was analyzed using various techniques. Compared with other reported adsorbents, the maximum adsorption capacity of PEI-CTS@WBC for U(VI) was 411.44 mg g−1, which was higher than most existing adsorbents. The dynamics studies showed that adsorption was more in line with the second-order kinetic model, indicating that chemical adsorption was the main process. The K d and S U value of U(VI) by PEI-CTS@WBC could reach 11194.44 mL g−1 and 76.47 % respectively, which exhibited a high selective adsorption characteristics for U(VI) in aqueous solutions. The XPS analysis demonstrated that the adsorption process was primarily due to the formation of stable complexes with N-H, N-C, C-O and O-H. This research showed that the introduction of polyethyleneimine and chitosan greatly improved the adsorption effect of WBC on U(VI). PEI-CTS@WBC had high selective adsorption characteristics and good reusability for U(VI) in aqueous solutions. PEI-CTS@WBC was an economical, efficient and stable composite material. These findings provided a theoretical basis for the treatment of wastewater contaminated with U(VI). [Display omitted] • PEI-CTS@WBC had advantages of low cost, easy preparation and good stability. • The maximum adsorption capacity of PEI-CTS@WBC for U(VI) was 411.44 mg g−1. • PEI-CTS@WBC exhibited a high selective adsorption for U(VI). [ABSTRACT FROM AUTHOR]

• N/P-co-doped hierarchical mesoporous biocarbon from sugar crystals was prepared. • Porous biocarbon was intercalated in 2D-MoS 2 nansheets. • Electrodeposition of polypyrrole was accomplished as a green method to enhance conductivity. • Composite electrode materials (SC/MoS 2 /PPy) exhibited fast kinetics and sorption capacity of 300.66 mg/g at −0.9 V. • Energy efficient recovery of U(VI) from aqueous solution. In this work, a templated N/P co-doped hierarchical porous biocarbon was prepared through the carbonization of sugar at high temperature (700 °C). Then, this porous biocarbon was in-situ functionalized with molybdenum disulfide nanosheets through a hydrothermal treatment reaction to get the composite, SC/MoS 2. Later, SC/MoS 2 on a nickel foam substrate was electrodeposited with different concentrations of polypyrrole, a conducting polymer, at −0.9 V. The prepared composite electrodes (SC/MoS 2 /PPy) were characterized thoroughly using FTIR, XRD, BET, and SEM. The orderly developed mesoporosity and N, P doping inside the porous carbon network was found to be highly conducive for the U(VI) electrosorption accomplished through capacitive deionization (CDI). The composites had remarkable specific capacitance (95.4 F/g), a large specific surface area (174.4–273.6 m2/g), improved mesopore volume (0.58 cm3/g) and excellent V m /V t ratio (0.80). SC/MoS 2 /PPy-2, among other composites, revealed fast electrosorption kinetics and excellent selectivity with a maximum sorption capacity of 300.66 ± 8.02 mg/g at −0.9 V. The SC/MoS 2 /PPy-2 retained relatively small charge transfer resistance R ct (1.22 Ω cm2), minute electrolytic resistance R s (0.77 cm2), and a large double layer constant phase element q dl (0.0369 S sn/cm2) which makes it suitable for U(VI) ion diffusion and fast electron transfer during CDI performance. The composite electrode materials offer novel and potent desalination applications, specifically in uranium extraction from aqueous media. [ABSTRACT FROM AUTHOR]