From flexible hyperbranched PEI to ultralight and elastic ordered-porous all-organic aerogel for effectively removing uranium

Ultralight and elastic aerogels with high capture performance offer promising prospects in pollutant treatment and resource recovery. By using directional freezing and thermal crosslinking technologies, a unique all-organic PEI-based aerogel adsorbent with exceptional mechanical stability was successfully created in this instance, which was subsequently utilized to remove uranium from aqueous solutions. The results show that compared with the honeycomb structure prepared by the traditional ice crystal technology, the PEI aerogel had a structured lamellar structure. This structure dictated the stability of aerogel in water and was directly correlated with the molecular weight of PEI and the usage of glutaraldehyde. PEI aerogel showed significant uranium-adsorption capacity in an endothermic process. The maximum adsorption capacity can reach 1262.33 mg g-1 at 298 K according to the Langmuir adsorption model. In addition, over 90% of uranium was removed by the PEI aerogel in five cycles of adsorption and desorption process, indicating high structural stability of the PEI aerogel for practical applications. This implies that the solubility problem of hyperbranched PEI in water is effectively solved by the directional freezing method employed in this work, providing an innovative approach for the fabrication of PEI-based adsorbents.