Highly efficient U(VI) capture from nuclear wastewater by an easily synthesized lignin-derived biochar: Adsorption performance and mechanism.

The efficient recycling of uranium (U) by adsorbents remains challenging due to the strong interference from coexisting impurities, insufficient desorption efficiency, and weak irradiation instability. In this work, a novel lignin-derived biochar (AL/BC) with high surface area and abundant functional groups was developed through a green and simple pyrolysis process, and an adsorbent for U(VI) capture was used. The optimist AL/BC-600 exhibited ultrahigh adsorption capacity for U(VI) of 4007 mg/g, possessing a wide pH range of 1-11, and powerful anti-interference ability when coexisting with various common cations and anions. In addition, AL/BC-600 showed high tolerance even under strong irradiation at a dose of 350 kGy. Most importantly, after the tenth round of the adsorption-desorption cyclic utilization, the adsorption efficiency and desorption rate of AL/BC-600 were actually over 95% and 80%, respectively. Hence, this study provides a green and simple process for synthesizing a novel adsorbent for highly efficient U(VI) capture, not only paving a path for alleviating the increasingly serious energy crisis, but also facilitating the low-carbon and circular development of lignin.