Insight into effect of carbon doping on the enhanced capture capacity of lignin-derived carbon@CuBTC composite for gaseous iodine

While nuclear power advances as a sustainable low-carbon energy source, it may also contribute to higher emissions of radioactive iodine isotopes, which pose severe health risks and ecological disruptions. This study introduces a sustainable solution for radioactive iodine capture by developing lignin-derived carbon@CuBTC (C@CuBTC) composites. Scanning and Transmission electron microscopes show that lignin-derived carbon (LDC) doping reduces the particle sizes and lattice spacing of the composites. X-ray diffraction and thermogravimetric analyses confirm that LDC incorporation preserves the crystallinity and stability of CuBTC. The optimized 0.2C@CuBTC composite exhibits enhanced iodine adsorption capacity (920 mg/g at 75 °C), marking significant improvement over individual components. It also demonstrates adsorption equilibrium was obtained within four hours and the 0.2C@CuBTC composite has excellent recyclability (< 10% capacity loss after five cycles). Spectroscopic analysis with X-ray photoelectron reveals multiple iodine binding modes, including Cu I coordination, charge transfer, and π-complexation, forming the electrostatic attraction. The doping of LDC with CuBTC frameworks enables the material to achieve outstanding adsorption performance through synergistic physisorption-chemisorption mechanisms. This approach contributes to nuclear waste management by utilizing lignin byproducts, supporting a circular economy. The structure-activity relationship analysis provides a scientific basis for design, optimization, and preparation of high-performance carbon-based CuBTC composite adsorbents for pollution capture.