Taihong Yan

Steric and electronic effects were systematically tuned in benzodioxodiamide ligands to regulate Pu( iv ) coordination and extraction. Experimental and DFT studies identify L2 as the optimal ligand with superior Pu( iv ) extraction performance.

The traditional aqueous‐organic biphasic extraction for separating radioactive metal ions faces major challenges due to heavy reliance on volatile organic solvents and the resulting refractory radioactive waste. Herein, we propose a customizable, sustainable, and efficient separation strategy for radioactive ions by using liquid–liquid phase separation (LLPS) phenomenon in two coexisting aqueous phases. Unlike conventional organic extraction systems, the LLPS platform operates without forming a bulk organic extraction phase. The LLPS is formed by sodium dodecyl sulfate (SDS), cetyltrimethyl ammonium bromide (CTAB), and hexafluoroisopropyl alcohol (HFIP) (termed as SCH‐extraction system) and enables customized encapsulation of commercial extractants. The selectivity of SCH‐extraction system can be precisely tuned by adjusting parameters like the type of extractant and solution acidity, making it highly versatile for various separation scenarios. In simulated high‐level liquid waste (HLLW), the strategy achieved the separation factors of /Nd ³⁺ reaching 2.33 × 10 ⁴ , outperforming existing methods. This superior efficiency is driven by a dual mechanism: hydrophobic entrapment of metal‐extractant complexes and electrostatic attraction to the negatively charged condensate interface. Based on this, a thermodynamic model is proposed, providing rational design principles for optimizing the system for diverse separation applications. This strategy holds significant promise for separating valuable radioactive metal ions.

Actinide separation is pivotal to resolving spent nuclear fuel reprocessing bottlenecks for nuclear power development, and the development of efficient and environmentally friendly extraction technology is crucial to meet the growing demands. This work investigates how different central atoms between oxygen and nitrogen in amide-acid ligands affect their extraction performance for actinides, aiming to facilitate the design and development of advanced ligands for the selective separation of actinides. For this purpose, N,N-di(2-ethylhexyl) diglycolamic acid (HDEHDGA, HA) and N,N-di(2-ethylhexyl)-N-methyliminodiacetic acid monoamide (HDEHNDGA, HB) were synthesized. Their extraction behaviors toward key actinides, U(VI), Pu(IV) and Am(III), were evaluated via slope analysis, FT-IR and DFT calculations. At HNO₃ concentrations in the range of 0.01–1 M, the distribution ratio of HA in 1-octanol extracting Pu(IV) can reach 113, with separation factors of 500 for Pu(IV)/U(VI) and 120 for Pu(IV)/Am(III). For HB, the Pu(IV)/Am(III) and U(VI)/Am(III) separation factors are as high as 4000 and 750. Spectroscopic and thermodynamic studies revealed distinct coordination modes and thermal behaviors of HA and HB: HA binds via CO and C–O–C in an exothermic process, whereas HB coordinates through CO without the central nitrogen atom in an endothermic manner. These findings clarify the coordination properties of amide-acid ligands and provide a foundation for advancing actinide separation technologies.

Microreactors offer remarkable advantages in intensifying mixing/mass transfer and hold promising prospects for industrial applications. In this study, T-shaped microreactors (TMRs) integrated with baffle, orifice-plate, and venturi structures (featuring different contraction angles) were designed. Based on the Villermaux–Dushman reaction system, three-dimensional computational fluid dynamics (CFD) models were established to simulate the fluid flow and mixing-reaction processes in these microreactors. The results demonstrate that peaks in velocity, turbulent kinetic energy, and turbulent dissipation rate consistently emerge in the confluence region of the two fluid streams. In the operating range of this study, the baffle configuration exhibits the highest micromixing performance but also induces the largest pressure drop, followed by the orifice-plate structure. Notably, the venturi structure not only enhances micromixing efficiency but also results in a minimal increase in pressure drop and eliminates flow dead zones. Specifically, the venturi structure with a 45° contraction angle achieves a balance between energy consumption and micromixing efficiency. Using the agglomeration model, the micromixing times of the microreactors with various structures were determined to range from 0.025 to 0.234 ms.

Owing to their superior mass and heat transfer performance, microreactors have emerged as a research hotspot in novel intensified equipment in recent years. This study experimentally investigates the gas–liquid flow behavior and mass transfer characteristics in microchannel reactors for viscous systems, focusing on the effects of superficial gas and liquid velocities, viscosity, and spiral turbulence elements on T-type microchannel reactors (T-MCRs). Four flow regimes are identified in the T-MCR, where viscosity significantly influences regime distribution and Taylor bubble morphology. In contrast, the spiral-wired T-MCR (T-MCR-SW) is dominated by “serpentine Taylor flow”. Increased viscosity leads to elevated pressure drop and reduced CO₂ saturation in both reactors, with the T-MCR-SW exhibiting a notably higher pressure drop. The impact of gas–liquid flow rates on CO₂ saturation varies with reactor type and viscosity. The total volumetric mass transfer coefficient (K_La) of the T-MCR-SW is substantially higher than that of the T-MCR, but its pressure drop is nearly doubled. Thus, a balance between mass transfer efficiency and energy consumption must be considered for practical applications. This work provides valuable insights for the design and optimization of microreactors in viscous systems.

The separation of palladium from radioactive waste streams represents a critical aspect of the secure handling and disposal of such hazardous materials. Palladium, in addition to its radioactive nature, holds intrinsic value as a resource. Despite the urgency, prevailing adsorbents fall short in their ability to effectively separate palladium under highly acidic environments. To surmount this challenge, our research has pioneered the development of 1,3,5-tris(4-aminophenyl)benzene-2,5-Bis(methylthio)terephthalaldehyde COF (TAPB-BMTTPA-COF), a novel material distinguished by its remarkable stability and an abundance of sulfur-containing functional groups. Leveraging the pronounced affinity of the soft ligands’ nitrogen and sulfur within its molecular architecture, TAPB-BMTTPA-COF demonstrates an exceptional capability for the selective adsorption of palladium. Empirical evidence underscores the material’s swift adsorption kinetics, with equilibrium achieved in as little as ten minutes, and its broad tolerance to varying acidity levels ranging from 0.1 to 3 M HNO₃. Furthermore, TAPB-BMTTPA-COF boasts an impressive adsorption capacity, peaking at 343.6 mg/g, coupled with high selectivity in 13 interfering ions’ environment and the ability to be regenerated, making it a sustainable solution. Comprehensive analyses, including Fourier Transform Infrared Spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS), alongside Density Functional Theory (DFT) calculations, have corroborated the pivotal role played by densely packed nitrogen and sulfur active sites within the framework. These sites exhibit a robust affinity for Pd(II), which is the cornerstone of the material’s outstanding adsorption efficacy. The outcomes of this research underscore the immense potential of COFs endowed with resilient linkers and precisely engineered functional groups. Such COFs can adeptly capture metal ions with high selectivity, even in the face of severe environmental conditions, thereby paving the way for the more effective and environmentally responsible management of radioactive waste.

A commercial polymeric nanofiltration membrane (NF270, DuPont) was employed for uranium removal from ammonium diuranate filtrate (ADUF). Carbonate supplementation through ammonium carbonate addition enhanced uranium rejection via formation of uranyl–carbonate coordination complexes. Systematic speciation analysis of uranium species in ADUF was conducted, coupled with calculation of the concentration polarization modulus to optimize ammonium carbonate dosage. The experimental results demonstrated that with 680 mg/L ammonium carbonate addition, the permeate uranium concentration decreased from 1.2 mg/L to 0.64 mg/L. This study confirms the technical feasibility of ADUF carbonation pretreatment for improving uranium retention efficiency in nanofiltration processes, achieving 46.7% reduction in uranium permeation flux.

Developing a new efficient separation ligand based on the “CHON” principle to address the limitations of phosphorus containing extractants in nuclear fuel reprocessing can help further simplify the process flow and reduce the amount of secondary waste. Building upon this critical need, a novel ligand was developed through a strategic application of the Hard and Soft Acids and Bases (HSAB) theory, integrating a soft donor nitrogen atom into the linear architecture of bis-diglycolamide. This groundbreaking ligand, named N,N′-bis[2-(2-(N,N-dioctylcarbamoyl)ethoxy)ethylacetamido]-N″-diethylenetriamine (TOMDEA-BisDGA), has demonstrated remarkable potential in the extraction of Pu(IV). The study unveils that the ligand demonstrates remarkable selectivity and separation efficiency towards Pu(IV) ions while maintaining an exceptionally low extraction capacity for U(VI) across a wide acidity spectrum of 0.1~6 mol/L. To explain the structure properties of complex formed by the ligand and Pu(IV), a systematic analysis was performed, including slope analysis, proton nuclear magnetic resonance (NMR) titration, and Fourier-transform infrared (FT-IR) spectroscopy. This study explores the coordination and separation behavior of diglycolamide ligands with actinide. This work is expected to provide important information and theoretical bases upon which advanced design and optimization of ligands for high-performance processes for the separation of plutonium might be carried out. Such findings will contribute to the understanding of actinide chemistry and further the design of improved separation methods for nuclear applications.