PAN/NHVPO复合纳米纤维膜可控制备及其对模拟废水中Sr(Ⅱ)的高效选择性吸附机制OA

Efficient removal of radioactive strontium ions(Sr2+)from wastewater is critical for the sustainable development of nuclear energy and ecological security.Metal oxalatophosphate open frameworks(MOPOFs)are promising adsorbents for Sr2+capture,but their practical application is constrained by poor solid-liquid separation in powder form.To address this challenge,a novel polyacrylonitrile-based ammonium vanadium oxalatophosphate(PAN/70NHVPO)composite membrane was fabricated via airflow-assisted electrospinning,and its Sr2+adsorption performance was systematically evaluated.The PAN/70NHVPO membrane exhibits excellent structural stability:thermogravimetric analysis confirms minimal mass loss in the temperature range of 86.7-334.2 ℃,and a Zeta potential absolute value exceeding 40 mV indicates high colloidal stability.Batch adsorption experiments show that the membrane maintains high Sr2+removal rate over a wide pH range(2-11),reaching equilibrium within 280 min.The adsorption kinetics follow the pseudo-second-order model(R2=0.993 2),suggesting chemisorption as the rate-limiting step,with intraparticle diffusion also influencing the process.The equilibrium data fit the Langmuir isotherm model well(R2=0.991 8),giving a theoretical maximum monolayer adsorption capacity of 263.09 mg/g.Notably,the membrane displays remarkable selectivity for Sr2+:even in the presence of 200-fold excess Ca2+(a major competing ion),the Sr2+removal rate remains as high as 62.01%.Dynamic fixed-bed column experiments further validate its practical applicability,achieving>95%Sr2+removal rate from simulated seawater.Combined with multiple characterization techniques and density functional theory(DFT)calculations,the adsorption mechanism is elucidated:Sr2+first undergoes ion exchange with interlayer NH4+in NHVPO,followed by the formation of stable coordination bonds with oxygen atoms in the P-O and V-O groups of the vanadium oxalatophosphate anionic layers.This study presents PAN/70NHVPO as a highly effective and selective adsorbent for Sr2+,and provides a comprehensive understanding of its adsorption mechanism,laying a solid theoretical foundation for its potential application in radioactive wastewater treatment.