Scalable and Sustainable Zinc (II) Ions Glue Assisted Conversion of Biomass Waste Bits into Carbon Aerogels for Efficient Uranium Extraction

Carbon aerogels (CAs) are attracting great attention for their multifunctional applications. Additionally, a large amount of biomass bits waste generated from agriculture and industry is regarded as the main carbon resource. However, the development of a facile, sustainable, and efficient method to produce CAs from biomass waste remains challenging. Here, a one-step Zn2+ ions glue triggered carbonization technology was reported to construct large-scale and high-performance CAs. Multiple biomass bits (wood bits, peanut shells, bamboo bits, and straw waste) were treated in the molten salt system (ZnCl2/KCl) at 300 °C for 2h to obtain large-block biomass bits derived CAs. Zn2+ ions as the glue cleavage cellulose hydrogen bonds of natural biomass, then facilitate dehydration crosslinking reaction between cellulose, hemicellulose, and lignin for re-constructing the whole block structure. The obtained CAs show high porosity (95%) and low density (0.078 g/cm3). Meanwhile, numerous of hydroxyl and carbonyl groups were well maintained during low temperature treated process, which facilitate chemical modification for various applications. For instance, amidoxime functionalized CAs were utilized as a filter for selective and highly efficient extraction of U(VI) from wastewater. The adsorption capacity and extraction efficiency reached 801.2 mg/g and 95% with a flux rate of 6.1×103 L/m2·h, respectively.