Anti-bacterial and super-hydrophilic bamboo charcoal with amidoxime modified for efficient and selective uranium extraction from seawater

Abstract With the growing demand for nuclear energy, uranium extraction from seawater (UES) is becoming increasingly important due to the ocean reserves 4.5 billion tons for uranium(VI) [U(VI)]. Herein, two kinds of amidoxime modified bamboo charcoal (AOOBCS and AOOBCH) with porous structure, anti-bacterial, and super-hydrophilic properties were successfully synthetized by two etching methods (soaking and hydrothermal). The super-hydrophilic property of AOOBCH accelerated the contact between the amidoxime group and uranyl ions (UO22+), and promoted the action of anti-bacterial substances (bamboo-quinone) on bacteria to restrain the form of bacterial membrane. In addition, the amidoxime groups not only didn’t destroy the super-hydrophilic surface, but also adjusted the adsorbents’ pKa by changing the amidoxime grafting rate. Under PH=7, the adsorption capacity of AOOBCH was about 1.97 times that of AOOBCS and 2.95 times that of BC. Importantly, the AOOBCH exhibited ultra-high uptake capacity (6.37 mg g-1) and exceptional selectivity for U(VI) in 100-fold interfering ions simulated seawater system due to the chelation between –C(NH2)= N - O H and UO22+ to form a more stable coordination structure (Eads=-36.56 eV). Benefiting from the superior performance and selectivity, the AOOBCH is a potential candidate for UES.