Shushan Yuan

Nuclear energy plays a crucial role as a clean energy source in modern society. The use of nuclear energy will result in the generation of a large amount of radioactive nuclear wastewater. Separation of nuclides from radioactive wastewater is crucial for the safe disposal of nuclear wastes and the sustainable development of resources. However, it remains a great challenge to achieve precise separation between different radionuclide ions due to their similar properties. Herein, we constructed a radiation-resistant graphene-based membrane via ethylenediaminetetraacetic acid (EDTA) functionalization with highly stable and aligned two-dimensional subnanochannels, which exhibits adjustable ion diffusion energy barrier and ultrahigh radionuclide ion selectivity. The functional groups within the GO-EDTA channel exhibit strong affinitive binding interactions with Sr ²⁺ and La ³⁺ . The mono/multivalent metal-ion selectivity up to 485 and 1300 for Cs ⁺ /Sr ²⁺ and Cs ⁺ /La ³⁺ , respectively, outperforms other reported membranes. Besides, the channel can still maintain stable separation performance under irradiation conditions. Furthermore, using quartz crystal microbalance, we break down the contributions of partitioning at the pore mouth and intrapore diffusion to the overall energy barrier for salt transport, indicating that the precise separation of ions is achieved by regulating the diffusion energy barrier. This work provides a mechanism for the design of membranes with high ionion selectivity and demonstrates the application potential of nuclear resource recycling.

The efficient separation of monovalent and divalent ions remains a core challenge in desalination and ion resource recovery. Here, we propose an electrochemical confinement strategy to spatially organize EDTA into aligned arrays within the one-dimensional transport channels of TFP-Tag membrane with a pore size of 1.1 nm. This structure establishes a biomimetic, gradient-functionalized conical nanochannel. The negatively charged upper channel regions capture and block divalent ions, while the lower regions with their larger pore size and an anion-affinitive local environment facilitate monovalent ion transport, thereby achieving highly selective monovalent/divalent ion separation. The membrane exhibits outstanding monovalent/divalent ion separation performance in multi-ion mixed solutions, with Na ⁺ flux reaching 10.6 mmol m ⁻² hour ⁻¹ and the selectivity of Na ⁺ /Mg ²⁺ exceeding 500. This breakthrough separation behavior is attributed to an induced transport lag effect arising from the synergy between the COF structure and the chelation-assisted retardation of divalent ions by EDTA. This study establishes a theoretical framework for the rational design of ion-separation membranes exhibiting simultaneous high-selectivity and high-flux performance.

Nuclear energy plays a crucial role as a low-carbon energy source. However, nuclear power generation produces large volumes of radioactive nuclear wastewater. The separation of nuclides from radioactive wastewater is essential for the safe disposal of nuclear wastes and the sustainable development of resources. Nevertheless, due to the similar properties of different radionuclide ions, achieving precise selective separation between them and recovering CsCl remains a significant challenge. Herein, a radiation-resistant graphene-based membrane with highly stable and well-ordered two-dimensional sub-nanoscale channels was constructed through ethylenediaminetetraacetic acid (EDTA) modification, which exhibits tunable ion diffusion energy barrier and ultra-high selectivity for radionuclide ions. The functional carboxylate groups within the GO-EDTA channel exhibit strong affinity for multivalent Sr ²⁺ and La ³⁺ . With selectivity ratios of up to 485 and 1,300 for mono/multivalent metal ions (Cs ⁺ /Sr ²⁺ and Cs ⁺ /La ³⁺ , respectively), this membrane outperforms other previously reported membranes. Additionally, the CsCl with a purity of 99.5% was recovered using an electrodialysis discharge method. Besides, the channel maintains stable separation performance even under irradiation conditions. Furthermore, by using a quartz crystal microbalance, the contributions of partitioning at the pore entry and intrapore diffusion to the total energy barrier for salt transport were decomposed, demonstrating that precise ion separation can be achieved by modulating the diffusion energy barrier. This study provides a useful mechanism for designing membranes with high ion selectivity and highlights their potential applications in the field of nuclear resource recovery.

The rapid advancement of electric vehicles is expected to significantly increase the production volume of spent lithium-ion batteries. Separation of lithium from complex spent battery leaching solution is crucial for critical metal recovery and the sustainability of the circular economy. However, achieving precise separation between Li+ and competing multivalent ions remains a challenge due to their similar hydrated radii. In this study, an EDTA-functionalized graphene oxide membrane that exhibits pH-responsive properties and ultrahigh selectivity for monovalent and divalent ions was constructed. The EDTA ligands anchored within the nanochannels demonstrate pH-dependent coordination chemistry: under neutral or alkaline conditions, deprotonated EDTA binds strongly to multivalent cations, effectively gating the channels and facilitating preferential Li+ permeation. Conversely, under acidic conditions, the protonation of the carboxyl groups in EDTA weakens its binding to divalent ions. This results in a Li ⁺ /M ²⁺ selectivity of 300 under neutral or alkaline conditions, surpassing previously reported membranes. Additionally, through electrodialysis, a Li ₂ CO ₃ product with a purity of 98.5% was obtained. Furthermore, using quartz crystal microbalance, we decoupled the contributions of partitioning and diffusion energy barriers to the overall transport energy barrier, revealing that precise ion separation is achieved by modulating the diffusion barrier through pH-responsive coordination. This work provides mechanistic insights for the design of membranes with high ion selectivity and demonstrates the potential for sustainable lithium recovery from spent batteries.

Pervaporation provides a selective route to high purity solvents that are indispensable for high precision industry. Here, we introduce structurally engineered nanoporous graphene oxide membranes (N-GOm), obtained by heterogeneous co-assembly of nanoporous graphene oxide (NPGO) and GO nanosheets. The NPGO nanosheet characterized by nanoporous sp ³ carbon domains and oxygen functionalized groups, synergistically increases water affinity, effectively elevating the water adsorption energies (E _ads ). The N-GOm integrates defective sp ³ /sp ² heterogeneous stacked cavity to facilitate water transport, effectively improve the solution self-diffusion coefficient ( D ), thereby improve diffusion activation energy (E _D ) indirectly, while graphitic sp ² -stacked regions ensure stable structure and enable precise molecular sieving. Here, the thermal crosslinking rN-GOm achieves a remarkable flux of 18.4 kg·m ^-2 ·h ^-1 , highlighting the potential for industrial solvent dehydration. These complementary structural properties enable rapid and highly selective transport via densely packed sieving channels and interconnected internal pathways, providing atomistic insight into how carbon microenvironment and stacking structure regulate adsorption and diffusion in ultrathin two-dimensional membranes.

Bamboo-derived biochar (BC) is promising for high-salinity wastewater treatment through photothermal evaporation. This study systematically evaluated BCs synthesized at 400–800 °C with residence times of 40 or 70 min. Pyrolysis temperature proved dominant, with 600 °C representing a critical threshold. Below this temperature, BCs maintained high carbon content and polar functional groups but exhibited limited porosity. Above it, structural reorganization enhanced pore development and aromaticity while reducing polar surface groups. Residence time primarily influenced volatile retention, and prolonged pyrolysis led to pore collapse. The optimal BC—produced at 800 °C for 40 min—combined hierarchical porosity with balanced surface chemistry, achieving an evaporation rate of 1.21 kg/m²·h and a photothermal efficiency of 70.45% under high-salinity conditions. Mechanistic analysis indicates that short, high-temperature pyrolysis preserves structural integrity and interfacial activity with minimal energy input. These results establish a thermal processing approach that reconciles carbon stability with surface functionality, offering practical guidance for scaling efficient and sustainable biochar-based wastewater treatment systems.

This novel strategy of fabricating a GO-PEI membrane from spent graphite offers a green process for recovering lithium from the leachate of spent lithium-ion battery cathode materials.

Polyamide membranes with ultrahigh permeance and exceptional solute selectivity present a significant opportunity to reduce energy consumption in desalination, pharmaceutical purification, and solvent recovery. We report a nanomolding phase inversion strategy for constructing high-resolution pillar-array patterns on a nanofibrous Kevlar hydrogel support, enabling controlled interfacial polymerization (IP) of polyamide active layers with pillar-arrayed structures. The rigid polyamide layers preserve pillar textures under pressurized filtration, increasing permeable area, while the nanofibrous Kevlar regulates amine diffusion to enhance polyamide layer homogeneity. The resulting nanoimprinted composite membranes with thin, structurally homogeneous, highly negatively charged polyamide layers demonstrate a water permeance of 53.9 L m^-2 h^-1 bar^-1 with 98.1% Na₂SO₄ rejection, high Cl^-/SO₄^2- selectivity (45), and improved antifouling properties. In active pharmaceutical ingredients enrichment, they achieve one order of magnitude faster methanol transport, e.g., 31.3 L m^-2 h^-1 bar^-1, than commercial membranes. Our nanoimprinted strategy may inspire advanced membrane designs for diverse high-value separations.