A gentle strategy to design amine-functionalized cellulose aerogel with tunable graft density for urea adsorption.

[Display omitted] • A mild method was developed to prepare the amine-functionalized cellulose aerogel. • The aerogel retains large specific surface area and low crystallinity. • Excessive graft density hinders urea adsorption. • Grafted amino or silicone hydroxy groups significantly promote urea adsorption. The development of efficient adsorbent materials to remove urea from dialysate is an effective way to solve the bottleneck limiting the development of a wearable artificial kidney. Three methods were used to fabricate amine-functionalized cellulose aerogels aiming to screen for excellent structures favorable for urea adsorption. The influence of APTES addition on the structure and adsorption performance of the adsorption materials was investigated. The kinetics and thermodynamics of urea adsorption were evaluated, and adsorption mechanisms were also discussed. Results indicate that the material prepared by the gentle method was still able to maintain a large specific surface area, large pore volume and low crystallinity. Amine-functionalized cellulose aerogels retain the original hydroxyl adsorption sites, and the amino or silanol hydroxyl as new adsorption active sites are also introduced. Furthermore, proper APTES graft density plays a critical role in the urea adsorption. The equilibrium adsorption capacity of urea on HA-N-NCA-10 is increased by 156%. [ABSTRACT FROM AUTHOR]