Highly efficient and antibacterial uranium adsorbents derived from disubstituted amidoxime functionalized chitosan

In this work, C 2 and C 6 disubstituted amidoxime functionalized chitosan foam adsorbent (CMNSC-AO foam) were successfully synthesized with the disubstituted carboxylation reaction and diaminomaleonitrile following with an amidoximation reaction, using cheap and readily available chitosan materials in nature. Newly synthesized CMNSC-AO foam demonstrates efficient uranium (U(VI)) adsorption performance, with a maximum capacity of 470.36 mg/g at pH = 6, and the adsorption effect is significantly better than the traditional mono-substituted amidoxime-functionalized foam chitosan adsorbent (CMC-AO foam) (Q e = 354.75 mg/g). The static and dynamic adsorption of U(VI) under different conditions was evaluated, and the influencing factors in the adsorption process were investigated. Among them, the CMNSC-AO foam exhibits excellent selectivity for U(VI) and the removal rate of U(VI) reaches 92.56% ( K d = 62,200) in a 10 mg/L solution of co-existing various metal ions. In addition, CMNSC-AO foam shows antibacterial properties against Gram-negative Escherichia coli ( E. coli ) and Gram-positive Staphylococcus aureus ( S. aureus ) without adding antibacterial agents and antibacterial ions, reducing the adhesion and contamination of bacteria on the foam adsorbent. CMNSC-AO foam is an effective adsorbent for the removal of U(VI) from the environment due to its excellent adsorption and antibacterial properties owing to the presence of a large number of –NH 2 and –NOH groups. Graphical abstract