Fully biobased and robust antibacterial cellulose aerogel for uranium extraction

Developing efficient adsorbent is imperative for the utilization of uranium resources in seawater. Marine microorganisms and bacteria play an important role in the process of adsorption of uranium. In this work, a completely bio-based antimicrobial aerogel (quaternary cellulose/chitosan aerogel-QCNF/CS) was prepared by cross-linking quaternary cellulose nanofibers (QCNF) and chitosan (CS) via citric acid (CA). The QCNF/CS aerogel has a high adsorption capacity of 565.97 mg g¹, high selectivity (K_d = 1.6 × 10⁴ mL g^-1). Moreover, the incorporation of CS improved the mechanical properties and enhanced the shape recovery property. The adsorption system reached equilibrium within 300 min and had good recovery of 93 % for UO₂²⁺. After seven cycles of adsorption-desorption, QCNF/CS aerogel still maintained its original structure and retained 80.7 % of its initial adsorption capacity. The introduction of quaternary ammonium salt groups gives the QCNF/CS aerogel strong antimicrobial activity, and the inhibition rate can be up to 96 %. The aerogel also showed good adsorption performance in spiked natural seawater. DFT results and XPS analysis further indicated that -COOH of CA and -OH of CNF functional groups could enhance the adsorption capacity of QCNF/CS aerogel. Therefore, QCNF/CS aerogel was a potential adsorbent for the extraction of uranium from seawater.