Ultra-fast capture of U(vi) from aqueous solutions by chitosan-based foam with macropores

The construction and preparation of macroporous materials with strong uranium coordination groups are conducive to fast uranium capture from aqueous solutions. Herein, a novel eco-friendly glutamine-functionalized chitosan foam (CS-Gln) with a three dimensional macroporous structure was prepared for ultra-fast uranium capture. The uranium adsorption amount is 23 mg g^-1 within 2 min, which accounts for 92% of the equilibrium adsorption amount; equilibrium adsorption can be reached within 30 min, with an adsorption amount of 25 mg g^-1. Moreover, the uranium adsorption process is more consistent with pseudo-second-order kinetics and the Sips isothermal model, with a maximum uranium sorption amount of 294 mg g^-1. Uranium adsorption involves both electrostatic and coordination interactions. The coordination adsorption is dominant, with -COOH, -NH₂ and -C[double bond, length as m-dash]N as the main coordination groups. The experiments provide effective insights into the preparation of an ultrafast chitosan-based uranium adsorbent.