Polyamidoxime‐Coated Coconut Haustorium Derived Magnetic Biochar Adsorbent with Photothermal Conversion for Highly Efficient Uranium Recovery from Nuclear Wastewater

Abstract Efficient removal of uranium from uranium‐containing nuclear wastewater is of great significance for utilizing uranium resources and protecting the environment from uranium hazards. In this paper, a polyamidoxime‐coated coconut haustorium derived magnetic biochar (CHMBC‐PAO) composite adsorbent with excellent adsorption performance, magnetism, recyclability, and photothermal conversion properties in complex environments is prepared through a simple soak‐gelation coating method for efficient removal of uranium from nuclear wastewater. The coconut haustorium biochar, carbonized by a sponge‐like organ inside the sprouted coconut, can provide rich functional groups and electronegative surface, which are conducive to the loading of functional materials and the adsorption of uranyl, respectively. The CHMBC‐PAO presents 2.4 emu g −1 saturation magnetization, making it can be efficiently recovered through magnetic recovery. It can convert absorbed light into thermal energy through molecular thermal vibration and non‐radiative relaxation process of excitons. Enhanced by the photothermal effect, CHMBC‐PAO shows an extra high uranium adsorption capacity of 310.30 mg g −1 in acidic nuclear wastewater within a short period of time, surpassing the adsorption capacity of most reported uranium removal materials. Meanwhile, the CHMBC‐PAO also presented excellent ion selectivity and reusability. Therefore, CHMBC‐PAO composite adsorbent can be considered as a potential candidate for treating radioactive nuclear wastewater.