Electrospinning Device for Nanofibers| Tailoring the coordinationmicroenvironment of electrospunnanofibers for the separation of thoriumions from ore wastewater

Zhao Rui from Northeast Normal University: Efficient and Selective Capture of Thorium Ions by Electrospun Nanofibers

With the intensification of global energy crisis and urgent need for low-carbon transition, developing new clean energy systems has become a strategic focus of scientific research worldwide. Nuclear energy technology, with its low-carbon attributes and high-efficiency thermal power generation characteristics under high-temperature conditions, is regarded as an ideal alternative to traditional fossil fuels. Among them, thorium-based molten salt reactors show significant advantages over conventional uranium-based nuclear reactors.To address the issue of thorium-containing radioactive wastewater generated during mining and smelting processes, developing efficient thorium (Th(IV)) ion separation and enrichment technologies has become a critical challenge for achieving clean utilization of thorium resources, with dual value for radioactive pollution control and strategic nuclear fuel recovery.

Recently, Associate Professor Zhao Rui's team from Northeast Normal University published their latest research "Tailoring the coordination microenvironment of electrospun nanofibers for the separation of thorium ions from ore wastewater" in Journal of Colloid and Interface Science. Through hyperbranched grafting strategy and salicylaldehyde group functionalization, the researchers successfully constructed precise coordination microenvironments on electrospun nanofibers, obtaining Sal-PEI-PAN nanofiber adsorbents that exhibit remarkable high affinity and selectivity for Th(IV) ions.The prepared electrospun nanofibers with macroscopic membrane structure maintain high-density coordination active sites while avoiding bottleneck problems of traditional powder adsorbents such as difficult solid-liquid separation and material loss causing secondary pollution. This study provides a potential technical pathway for thorium ion purification and recovery from wastewater.

Figure 1. Preparation schematic of Sal-PEI-PAN nanofibers

As shown in Figure 1, the hyperbranched grafting strategy was used to modify the fibers, converting one grafting unit into multiple functional groups, and further grafting salicylaldehyde molecules to obtain electrospun nanofibers with high-density hydroxyl and Schiff base groups, constructing numerous potential adsorption sites. Comparative adsorption experiments confirmed that hyperbranched grafting and introducing salicylaldehyde structure significantly improved the Th(IV) ion removal capacity.

Figure 2. Adsorption kinetics and isotherm data of Sal-PEI-PAN

Figure 3. Other adsorption performances of Sal-PEI-PAN nanofibers

Adsorption kinetics showed Sal-PEI-PAN nanofibers reached equilibrium in 60 min. Isotherm results fitted the Langmuir model with a theoretical adsorption capacity of 781.3 mg g-1, exceeding most formable adsorbents and many powder adsorbents in both kinetics and capacity (Figure 2). Moreover, Sal-PEI-PAN nanofibers showed good selectivity for Th(IV) ions in coexisting systems.The nanofibers achieved deep removal of Th(IV) ions (distribution coefficient (Kd) up to 3.1 × 105 mL g−1) and demonstrated high-flux dynamic filtration performance, capable of treating 996 times its own membrane volume of thorium wastewater (Figure 3), making it more practical for applications.

Figure 4. Theoretical calculations and removal mechanism schematic

Various characterizations confirmed successful thorium ion capture, identifying Schiff base, hydroxyl and amino groups as adsorption sites. Theoretical calculations verified that hydroxyl and Schiff base groups introduced by salicylaldehyde grafting were the main adsorption sites, with higher binding energy for thorium ions than other coexisting ions (rare earth and uranyl ions) (Figure 4).These experimental results and theoretical analyses validated that the high adsorption capacity and excellent selectivity of Sal-PEI-PAN nanofibers for thorium ions were based on the constructed hyperbranched structure and introduced Schiff base/hydroxyl groups. The related nanofiber materials show broad application prospects in thorium resource recovery and environmental remediation.

Paper link: https://doi.org/10.1016/j.jcis.2025.137957