Biomass-Based Cellulose Functionalized by Phosphonic Acid with High Selectivity and Capacity for Capturing U(VI) in Aqueous Solution

Uranium could be released into the aquatic ecological environment through various sorts of nuclear-related procedures, which has high toxicity and carcinogenicity even with a trace amount. A novel phosphonic acid functionalized cellulose adsorbent (PVKAP) with a simple synthesis strategy is developed based on pumpkin vine cellulose (PVK) as the substrate material for efficient and selective capturing U(VI). Because of the strong coordination between phosphonic acid groups and U(VI), the adsorption efficiency and adsorption selectivity of modified cellulose to U(VI) are greatly improved. The adsorption behavior follows the Langmuir adsorption model and pseudo-second-order kinetics model. The maximum adsorption capacities (pH = 5, T = 293 K) of PVK and PVKAP obtained from Langmuir isotherm are 57.2 and 714.3 mg∙g⁻¹, and the adsorption equilibrium are reached in 240 and 35 min, respectively. Additionally, PVKAP has a high adsorption selectivity which reached 70.36% for U(VI) in multi-ion condition, and recycling studies have shown that PVKAP has good recyclability. Furthermore, batch adsorption experiments and spectral analysis reveal that the efficient enrichment of U(VI) on PVKAP could mainly attribute to the inner layer complexation. Therefore, this environmentally friendly and simple route prepared PVKAP has good a potential application value for U(VI) enrichment in aqueous media related to nuclear waste.