Constructing coconut shell biochar/MXenes composites through self-assembly strategy to enhance U(VI) and Cs(I) immobilization capability

Herein, a biochar-based composite (Ti3C2Tx@biochar-PDA/PEI) was constructed by decorating Ti3C2Tx and polydopamine on coconut shell biochar via electrostatic self-assembly method. Different characterization techniques were applied to explore the structure, morphology and composition of the sorbents. It was found that the higher porosity and diverse functional groups were conducive for Ti3C2Tx@biochar-PDA/PEI to capture radionuclides, and the water environmental conditions made a great contribution to the adsorption process. The process of removing U(VI)/Cs(I) well complied with the Langmuir isotherm and Pseudo-second-order equations, which indicated that the single layer chemical adsorption occurred on the solid liquid interface. Meanwhile, this produced composite exhibited superior removal performance under complex co-existing ion environment, and the maximum adsorption amounts of U(VI) and Cs(I) reached up to 239.7 and 40.3 mg g(-1). Impressively, this adsorbent still exhibited good adsorption performance after three cycles of regeneration. The spectral analysis and DFT calculation demonstrated that adsorption of U(VI) might be a chemical process, while the adsorption of Cs(I) should be ion exchange or electrostatic attraction. This study demonstrated the potential application of Ti3C2Tx@biochar-PDA/PEI as an effective remediation strategy for radioactive wastewater cleanup.

Automated summary

A biochar-based composite (Ti3C2Tx@biochar-PDA/PEI) was constructed by decorating Ti3C2Tx and polydopamine on coconut shell biochar via electrostatic self-assembly method. The study demonstrated that Ti3C2Tx@biochar-PDA/PEI exhibited excellent performance in capturing radionuclides, especially U(VI) and Cs(I), due to its high porosity and diverse functional groups. The composite also showed good adsorption performance in complex co-existing ion environment and could be successfully regenerated for multiple cycles.