Separation Of Metal Ions Research Articles

Solvent effects on extractant conformational energetics in liquid-liquid extraction: a simulation study of molecular solvents and ionic liquids.

Extractant design in liquid-liquid extraction (LLE) is a research frontier of metal ion separations that typically focuses on the direct extractant-metal interactions. However, a more detailed understanding of energetic drivers of separations beyond primary metal coordination is often lacking, including the role of solvent in the extractant phase. In this work, we propose a new mechanism for enhancing metal-complexant energetics with nanostructured solvents. Using molecular dynamics simulations with umbrella sampling, we find that the organic solvent can reshape the energetics of the extractant's intramolecular conformational landscape. We calculate free energy profiles of different conformations of a representative bidentate extractant, n-octyl(phenyl)-N,N-diisobutyl carbamoyl methyl phosphinoxide (CMPO), in four different solvents: dodecane, tributyl phosphate (TBP), and dry and wet ionic liquid (IL) 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([EMIM][Tf2N]). By promoting reorganization of the extractant molecule into its binding conformation, our findings reveal how particular solvents can ameliorate this unfavorable step of the metal separation process. In particular, the charge alternating nanodomains formed in ILs substantially reduce the free energy penalty associated with extractant reorganization. Importantly, using alchemical free energy calculations, we find that this stabilization persists even when we explicitly include the extracted cation. These findings provide insight into the energetic drivers of metal ion separations and potentially suggest a new approach to designing effective separations using a molecular-level understanding of solvent effects.

Recovery of metal ion resources from waste lithium batteries by in situ electro-leaching coupled with electrochemically switched ion exchange

A new green pathway of in situ electro-leaching coupled with electrochemically switched ion exchange (EL-ESIX) technology was developed for the separation and recovery of valuable metal ions from waste lithium batteries. By using the in situ electro-leaching, the leaching rates of Li+ and Co2+ from the prepared LiCoO2 film electrodes reached 100 % and 93.30 %, respectively, under the combined effect of the acidic microenvironment formed by the anodic electrolytic water and electrostatic repulsion. Subsequently, the Li+ in the electrolyte was further extracted by an electrochemically switched ion exchange (ESIX) process using LiMn2O4 as the film electrode, and Li+ was further enriched in the eluate by a cyclic adsorption and desorption process. The results indicate that the in situ electro-leaching has significant advantages over powder leaching, and for the recycling of waste lithium batteries, the final lithium recovery rate reached 94.51 % by using this in situ EL-ESIX technology.

Green and Sustainable Imprinting Technology for Removal of Heavy Metal Ions from Water via Selective Adsorption

Revolutionary technological advances have posed new challenges to humans, and modern technology needs to seek new breakthroughs. Imprinting technology, also known as template technology, is a technology based on the interdisciplinary development of polymer chemistry, biochemistry, chemical engineering, and materials science. The polymer prepared with imprinting technology, termed as imprinted polymer, has a memory effect on specific ions and can realize the selective recognition and enrichment of target species. Therefore, imprinting technology has great potential for application in water environment remediation and industrial wastewater treatment, especially for the treatment of low-concentration, toxic, and difficult-to-degrade heavy metal-containing wastewater. Herein, an overview of recent advances in imprinting technology in the field of adsorption and separation is presented, focusing on methods for the synthesis of imprinted polymers and their application to the separation and enrichment of metal ions in water. Finally, we propose several key issues that remain to be solved in the near future.

Ionic liquid for selective extraction of lithium ions from Tibetan salt lake brine with high Na/Li ratio

β-Diketones are often used to separate brine with a high sodium-to‑lithium ratio but cannot be widely used because of their high toxicity and water solubility. In this work, a functionalized ionic liquid was synthesized from 4,4,4-trifluoro-1-phenyl-1,3-butanedione and 1-hexyl-3-methylimidazolium chloride, which was verified by FT-IR and 1H NMR spectroscopy. An organic phase system was formed with this ionic liquid as the extractant and 2-octanone as the diluent, which had the advantage of achieving good extraction and separation performances without co-extractant. In addition, the brine used in this work is the real Chaka salt lake brine in Tibet, which provides a reference value for industrial application of separation of metal ions. The experimental conditions were optimized and the single-stage extraction efficiency of Li+ reached up to 94 %. Using LiCl solution and HCl as the washing and stripping reagents, the washing efficiency of Na+ and stripping efficiency of Li+ were above 98 % and 99 %, respectively. The raffinate was used to regenerate the organic phase, which reduced the use of alkaline reagents. Over 10 cycles of the extraction process, the extraction efficiency of Li+ maintained at approximately 86 %. The extraction mechanism was identified as ionic association using slope analysis and ultraviolet and infrared measurements.

In Situ Fabrication and Characterization of g-C3N4 onto Cellulose Nanofibers and Selective Separation of Heavy Metal Ions.

Graphitic carbon nitride nanosheets were synthesized onto cellulose nanofiber surfaces utilizing an eco-friendly salt melt approach. The fabricated material CNF@C3N4 selectively removes Ni(II) and Cu(II) from electroplating wastewater samples. The immobilization of g-C3N4 on solid substrates eases handling of nanomaterial in a flow-through approach and mitigates sorbent loss during column operations. Characterization techniques such as scanning electron microscopy, tunneling electron microscopy, and X-ray photoelectron microscopy were employed to analyze the surface morphology and chemical bonding within the synthesized material. Selective Cu(II) and Ni(II) sorption predominantly arises from the soft-soft interaction between metal ions and associated nitrogen groups. An inner-sphere surface complexation mechanism effectively elucidated the interaction dynamics between the metal and CNF@C3N4. Experimental findings demonstrated satisfactory separation of Ni(II) and Cu(II) ions, with the extraction of 340.0 and 385.0 mg g-1 of material, respectively. Additionally, the devised technique was executed for the preconcentration and quantification of trace metals ions in water samples with a detection limit and limit of quantification of 0.06 and 0.20 μg L-1, respectively.

Surface implantation of ionically conductive polyhydroxyethylaniline on cation exchange membrane for efficient heavy metal ions separation

Extraction of heavy metal ions from aqueous could enable recycling of wastewater and reusing of high-value ion resources. Recently, electrodialysis (ED) technology has been applied in the removal of heavy metal ions from wastewater, however, developing high-efficient and stable heavy metal ions selective cation exchange membrane (CEM) remains an elusive challenge. Herein, we demonstrate the fabrication of high-efficient cations selective CEM with the surface implantation of ionically conductive polyhydroxyethylaniline (PANI-OH) on a commercial CEM membrane (CTG) containing sulfonic acid groups via the electrostatic attraction. Implanted hydrophilic and positively charged PANI-OH facilitates fast and selective transfer of Cu2+ over Zn2+ cations through the membrane. Meanwhile, the synergistic effect of rigid conjugate structure and hydrogen-bond interaction of PANI-OH renders the resultant membrane CTG-PANI-OH with stable structure and separation performance. As such, the Cu2+/Zn2+ permselectivity of CTG-PANI-OH membrane is ~1.70, which is about 190 % of that of the pristine CTG membrane. This work provides a facile design and strategy for the construction of high-efficient cations selective CEMs with great application prospects in the purification and extraction of heavy metal ions from wastewater.

Deep Separation Between In(III) and Fe(III) Ions by Regulating the Lewis Basicity of Adsorption Sites on Electrospun Fibers

AbstractThe deep separation between In(III) and Fe(III) ions is considered as an important technological challenge in the engineering fields. The In(III) ions are closer to the soft acid in terms of Lewis acidity due to the smaller polarizability and greater deformability than the Fe(III) ions, which facilitates the possibility of separating them. Herein, the Lewis basicity of the N‐containing adsorption sites is regulated by the fluorine‐containing group to better match with the In(III) ions rather than Fe(III) ions, causing a significant discrepancy in the binding of the adsorption sites to them. Moreover, targeted programmed desorption techniques based on the potential energy differences of the adsorption sites can achieve the deep separation of In(III) and Fe(III) ions, and reach an exceptional concentration of 20.7 mmol L−1 for In(III) ions in the initial desorption solution with extremely high mass ratio (mIn/mFe = 151.7). This work provides a novel technique for in‐depth separation of In(III) and Fe(III) ions from mixed systems, and a new strategy for separating metal ions with similar or close properties.

Liquid membrane coupled electrodialysis system for highly-efficient lithium recovery from fly ash acid leaching solution

Recovering lithium (Li) from high Li-bearing coal fly ash (CFA) is a challenging task due to CFA's complexity and minor content of Li. Acid leaching is a common treatment, but it faces the difficulties of complex leaching solution and selective separation of Li+. This work evaluated a liquid membrane coupled with the electrodialysis (LME) system to separate Li+ from the CFA leach liquor. The liquid membrane (LM) performs as an ion carrier to selectively transport Li+, while the electric field can drive the ion migration. The results show that the LM TBP+[HOEmim][NTf2] (v/v, 5:5) exhibits the best recognition and releasing ability toward Li+. The selective migration of Li+ can be achieved in acidic environment in the presence of concentrated Al3+. The Al/Li ratio decreases from 30 of the feed to 0.55 in the receiving solution after 12 h at 3 V. The practical application in the CFA leach liquor indicates that the system has preferential selectivity for transmembrane transport of Li+, while other multivalent ions were mostly hindered. This work presents a new idea for Li recovery from the solid waste residues, and offers a deep insight into the separation of valuable metal ions from complex solutions.

Upscale Synthesis of Magnetic Mesoporous Silica Nanoparticles and Application to Metal Ion Separation: Nanosafety Evaluation.

The synthesis of core-shell magnetic mesoporous nanoparticles (MMSNs) through a phase transfer process is usually performed at the 100-250 mg scale. At the gram scale, nanoparticles without cores or with multicore systems are observed. Iron oxide core nanoparticles (IO) were synthesized through a thermal decomposition procedure of α-FeO(OH) in oleic acid. A phase transfer from chloroform to water was then performed in order to wrap the IO nanoparticles with a mesoporous silica shell through the sol-gel procedure. MMSNs were then functionalized with DTPA (diethylenetriaminepentacetic acid) and used for the separation of metal ions. Their toxicity was evaluated. The phase transfer procedure was crucial to obtaining MMSNs on a large scale. Three synthesis parameters were rigorously controlled: temperature, time and glassware. The homogeneous dispersion of MMSNs on the gram scale was successfully obtained. After functionalization with DTPA, the MMSN-DTPAs were shown to have a strong affinity for Ni ions. Furthermore, toxicity was evaluated in cells, zebrafish and seahorse cell metabolic assays, and the nanoparticles were found to be nontoxic. We developed a method of preparing MMSNs at the gram scale. After functionalization with DTPA, the nanoparticles were efficient in metal ion removal and separation; furthermore, no toxicity was noticed up to 125 µg mL-1 in zebrafish.

FEATURES OF EXTRACTION OF LUTETIUM AND SCANDIUM IONS BY THE INTERPOLYMER SYSTEMS LEWATIT CNP LF-AB-17-8

Interpolymer systems based on ion exchange resins Lewatit CNP LF and AB-17-8were used to separate metal ions from sample solutions containing lutetium and scandium.The researchaimsto achieve maximum absorption of lutetium and scandium ions by using the remote interaction effect of macromolecular polymers.Methodology.Jenway-6305 spectrophotometer (SK) was used to determine the residual concentration of metal ions in the solution.The obtained resultsshow that individual polymers Lewatit(6:0) and AB-17-8 (0:6) do not have a higher absorption of lutetium ions (24.96% and 21.13%, respectively) rather than interpolymer systems. The maximum degree of extraction of lutetium ions is observed at a ratio of 4:2.The maximum values of the degree of absorption of scandium ions are observed at ratios of 5:1 and 1:5.As a result of the conducted studies, it was found that with an increase in the amount of one polymer in the interpolymer pair, the degree of binding of the second polymer to the metal ion increases. The LewatitCNP LFcation exchanger has a binding degree of 2.99 mg/mol in a ratio of 6:0, and with an increase in the amount of anion exchanger AB-17-8 by 5times, the binding degree of the cation exchanger in a ratio of 1:5 has increased to13.84 mg/mol. The binding degree of AB-17-8 in the ratio of 0:6 increased from 2.03 mg/mol to 12.20 mg/mol witharatio of interpolymer systems of 5:1.The degree of binding of the cation exchanger with the lutetium ion increased by 4.5 times, and the degree of binding of the anion exchanger increased by 6times.Conclusion.The results obtained show the possibility of using interpolymer systems for the extraction of lutetium and scandium ions from industrial aqueous solutions.

UiO-66-NH2 modified thin film nanocomposite (TFN) membranes for selective separation of Li+/Co2+ in a flow electrode capacitive deionization system

As key metal elements in lithium-ion batteries (LIBs), the recovery of lithium (Li) and cobalt (Co) showed both economic and environmental benefits. In this study, a thin-film nanocomposite (TFN) membrane with high selectivity was fabricated based on nanoscale UiO-66-NH2 particles, and the modified membranes were applied in the flow-electrode capacitive deionization device (FCDI) for the separation of monovalent and divalent cations. UiO-66-NH2 provided hydrophilic water channels and increased the permeability of Li+. TFN exhibited a rejection rate of Co2+ over 95%, and the separation factor of Li+/Co2+ was 27.44 during the operation of 150 min in FCDI with the addition of 10 mg UiO-66-NH2, which was about 1.52 times greater than that of the commercial cation-selective membrane (CSO). The size repulsion effect caused by size difference between hydrated ions and membrane pores and Donnan electrostatic repulsion force generated by positively charged membranes were evaluated to be the main basis for the ion separation of prepared membranes. The novel system using TFN membrane in FCDI had a better ability to resist Co2+ fouling and a good Li+/Co2+ separation effect. We believe these modified membranes have promising potential for the selective separation of heavy metal ions and the recycling of metal resources.

Separation of rare earth elements using chelating agent-assisted electrodialysis: Phenomenological modeling and comparison with experimental data

The study presented here focuses on the development of a phenomenological model based on the Nernst-Planck equation for the separation of neodymium (Nd) and praseodymium (Pr) from a mixture containing cerium (Ce) and lanthanum (La) using chelated-assisted electrodialysis with hydroxyethylethylenediaminetriacetic acid (HEDTA) tri disodium salt as the chelating agent. This model considers solution selectivity, membrane selectivity, and ion migration within the membrane. The model is then used to study the optimal concentration of the chelating agent and pH conditions. It is demonstrated that the efficiency of the separation process could be enhanced through a multistage approach where the chelating agent concentration is maintained below the stoichiometric ratio of the elements to be masked. The model's predictive capabilities were evaluated by comparing its results with experimental data obtained at a HEDTA/Nd molar ratio of 1 and pH 3. The model showed an error of less than 26% for removal efficiency for all rare earth elements (REEs), and error values of 3% for purity and 9% for yield. These results indicate that the model can reasonably predict experimental outcomes with an acceptable level of accuracy. The developed model has the potential to be expanded for investigating chelation chemistry and electrodialysis operations involving various combinations of REEs and concentrations. It can be used to design experimental setups to study the effect of chelating agent to REE ratios and pH on key performance factors such as purity, yield, and separation factor. The versatility of the model makes it a valuable tool in the field of electrodialysis for the separation of rare earth metal ions using chelating agents.

Hydrothermal Ammonia Carbonization of Rice Straw for Hydrochar to Separate Cd(II) and Zn(II) Ions from Aqueous Solution.

Hydrochar is considered to be a good adsorbent for the separation of metal ions from aqueous solutions. However, the yield of hydrochar from raw straw is generally low, because the hydrothermal carbonization occurs via dehydration, polymerization, and carbonization. In this work, various hydrochar samples were prepared from rice straw with nitrogen and phosphorus salt; moreover, toilet sewage was used instead of nitrogen, and phosphorus salt and water were used to promote the polymerization and carbonization process. The modified carbon was characterized using XRD, XPS, SEM, and FTIR, and the adsorption capacity was investigated. A significant increase in hydrochar yield was observed when toilet sewage was used as the solvent in the hydrothermal carbonization process. The adsorption capacity of N/P-doped rice straw hydrochar for Cd2+ and Zn2+ metal ions was 1.1-1.4 times higher than that those using the rice straw hydrochar. The Langmuir models and pseudo-second-order models described the metal adsorption processes in both the single and binary-metal systems well. The characterization results showed the contribution of the surface complexation, the electrostatic interaction, the hydrogen bond, and the ion exchange to the extraction of Cd2+ and Zn2+ using N/P-doped rice straw hydrochar.

Titanium-embedded nanocomposite material stimulates ion-exchange characteristics to deal with toxic heavy metal pollutants in aquatic environment

ABSTRACT Nano-sized composite ion-exchanger can be applied as an electrochemically switchable ion-exchanger for waste water treatment, especially in the separation of heavy metal ions from the polluted aquatic system. Advanced polyaniline/Ti(IV) iodomolybdate nanocomposite ion-exchanger have been synthesized by in-situ chemical oxidation polymerization shows better ion-exchange capacity than individual inorganic counterpart. The physico-chemical characterization was done by FT-IR, XRD, simultaneous TGA-DTA, SEM, HR-TEM and electrochemical impedance studies. According to impedance/dielectrical study, it has high resistivity in the low-frequency region. The distribution studies and binary separation revealed that the ion-exchange material is highly selective for Pb2+, which is a most important environmental pollutant. Thus, PANI/TIM nanocomposite ion-exchanger can be used for Pb(II) ion-selective membrane for the treatment of aquatic pollutants in future.

A versatile MOF liquids-based Janus fibrous membrane towards complex oil/water separation and heavy metal ions removal

As an emerging material, porous liquids (PLs) have attracted wide attention and are applied in oily wastewater for the effective elimination of heavy metal ions due to their permanent pore structure, mobility, and superhydrophilicity. However, it remains a challenge to further enhance the separation performance of PLs. Here, a novel metal–organic framework (MOF) porous liquid was synthesized and mixed with a polyacrylonitrile (PAN) solution to produce an asymmetrical Janus fibrous membrane by electrostatic spinning technique. Benefiting from the synergistic effect of the electric field and self-migrating properties of MOF PLs, the Janus membranes exhibited ultrahigh flux of 25310.26 L m-2h−1 bar−1, outstanding separation efficiency (reaching up to 99.99 %) in various oil–water emulsions and high antimicrobial activity (>99.9 %). More impressively, the obtained Janus membranes maintained long-term stability, with separation efficiencies consistently as high as 99.5 %. Meanwhile, the porous structure of MOF PLs with abundant active sites and affinity of polyethylene glycol (PEG) flexible chain for metal ions facilitates the adsorption of metal ions with a maximum equilibrium adsorption capacity of 205 mg/g, which is superior to other literature reported. These results demonstrated that the versatile MOF PLs-based Janus fibrous membranes had a promising application prospect in addressing the challenges associated with such wastewater treatment.

Application of chitosan-based materials in wastewater treatment

Chitosan, as a natural polysaccharide material, plays a great role in the field of wastewater treatment due to its good biodegradability, antimicrobial activity, and other properties. However, it may have some differences in the processes of adsorption, flocculation, and membrane separation. We comprehensively describe the application effect and mechanism of action of chitosan-based materials on the above three major water treatment processes. In the adsorption process, chitosan-based adsorbents such as hydrogels and chitosan beads are prepared by cross-linking, impregnation, and the introduction of functional groups. These chitosan-based materials exerted efficient removal performance in the adsorption of heavy metals, organic dyes, anionic pollutants, etc., which was attributed to their large specific surface area and abundant functional groups. In the flocculation process, the chitosan-based materials were modified by grafting and modifying their shape, while heavy metal ions, organic dyes, and algae were removed using processes such as chelation and charge neutralization. In the membrane separation process, a number of nanofiltration and microfiltration membranes were created by coating chitosan ions, and physicochemical modification was done for the separation of heavy metal ions and emulsified oil droplets in water to improve the fouling resistance and retention rate of the membrane materials. This paper reviews the application of chitosan-based materials in wastewater treatment and proposes that in-depth studies on their toxicity and reusability should be conducted in the future, with a view to playing a role in areas such as the removal of malodorous water odors.

Aqueous Interfaces in Chemical Separations.

Chemical separations play a vital role in refinery and reprocessing of critical materials, such as platinum group metals, rare earths, and actinides. The choice of separation system─whether it is liquid-liquid extraction (LLE), sorbents, or membranes─depends on specific needs and applications. In almost all separation processes, the desired metal ions adsorb or transfer across an aqueous interface, such as the solid/liquid interface in sorbents or oil/water interfaces in LLE. Despite these separation technologies being extensively used for decades, our understanding of the molecular-scale mechanisms governing ion adsorption and transport at interfaces remains limited. This knowledge gap presents a significant challenge in meeting the increasing demands for these critical materials due to their growing use in advanced technologies. Fortunately, recent advancements in surface-specific experimental and computational techniques offer promising avenues to bridge this gap and facilitate the development of next-generation separation systems. Interestingly, unanswered questions regarding interfacial phenomena in chemical separations hold great relevance to various fields, including energy storage, geochemistry, and atmospheric chemistry. Therefore, the model interfacial systems developed for studying chemical separations, such as amphiphilic molecules assembled at a solid/water, air/water, or oil/water interface, may have far-reaching implications, extending beyond separations and opening doors to addressing a wide range of scientific inquiries. This perspective discusses recent interfacial studies elucidating amphiphile-ion interactions in chemical separations of metal ions. These studies provide direct, molecular-scale information about solute and solvent behavior at aqueous interfaces, including multivalent and complex ions in highly concentrated solutions, which play key roles in LLE of critical materials.

Sustainable and effective gold(I) separation from aurocyanides wastewater and its mechanism using guanidinium ionic liquids

Efficient recovery of gold(I) from aurocyanide wastewater offers a dual opportunity for secondary resource utilization and environmental harm reduction. Herein, four environmentally friendly hexaalkylguanidium ionic liquids (HGILs) were synthesized and for the first time used to extract gold(I) from aurocyanide wastewater. Critical parameters, including HGILs and modifier species, dosage, pH, initial gold(I) concentration, and temperature, were optimized. The HGIL systems exhibited excellent gold(I) extraction performance with over 99.0% of gold(I) being extracted under optimal conditions. The composition ratio of the extracted complex was determined by Job's method and slope analysis. Spectral characterization included X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy and nuclear magnetic resonance spectroscopy and density functional theory calculations confirmed that gold(I) extraction followed an anion exchange mechanism. A dicyanoaurate Au(CN)2− anion and two n-octanol molecules produced the supermolecule anion [Au(CN)2−·2 n-octanol] via hydrogen bonding, which combined with a guanidium cation to generate the stable extraction complex [HGIL+·Au(CN)2−·2 n-octanol] through electrostatic attraction. The gold(I) loaded in the ionic liquid phase was effectively stripped with potassium thiocyanate solution. The regenerated HGIL system maintained a high gold(I) extraction efficiency of over 90.0% after five extraction–stripping cycles. In addition, a two-step stripping strategy was developed for the selective separation of gold(I) and other impurity metal ions from real aurocyanide wastewater. This study proposes an efficient green process for recovering gold(I) from mine wastewater, which has potential practical application prospects.

Novel poly (N-methacryloyl-L-alanine acid) grafted chitosan microspheres based solid-phase extraction coupled with ICP-MS for simultaneous detection of trace metal elements in food

Poly (N-methacryloyl-L-alanine acid) grafted tartaric acid-crosslinked chitosan microspheres (PNMA-TACS) were successfully synthesized and employed as a novel adsorbent for the separation and enrichment of metal ions in the food system. PNMA-TACS microspheres-based solid phase extraction (SPE) was coupled with ICP-MS for accurate quantification of trace V(V), Cr(III), As(III), Pb(II), Cd(II) and Cu(II). The obtained PNMA-TACS microspheres were characterized, and parameters influencing the method were optimized. Under optimal conditions, the calibration curves for Cu(II) and V(V) were linear within 0.01–30 μg L−1, the linear ranges of Cr(III), As(III), Pb(II) and Cd(II) were 0.01–15 μg L−1, and the detection limit of the developed approach was 1.1–3.7 ng L−1. The results were consistent with the consensus values of method validation implemented by two standards. Moreover, standard addition recovery experiments were performed in rice and milk powder, which achieved satisfactory recovery of 86.1–103.5%.

Decorating Channel Walls in Metal-Organic Frameworks with Crown Ethers for Efficient and Selective Separation of Radioactive Strontium(II).

Nuclear accidents and the improper disposal of nuclear wastes have led to serious environmental radioactive pollutions. The rational design of adsorbents for the highly efficient separation of strontium(II) is essential in treating nuclear waste and recovering radioactive strontium resources. Metal-organic frameworks (MOFs) are potential materials for the separation of aqueous metal ions owing to their designable structure and tunable functionality. Herein, a novel 3D MOF material MOF-18Cr6, in which 1D channels are formed using 18-crown-6-ether-containing ligands as channel walls, is fabricated for strontium(II) separation. In contrast to traditional MOFs designed by grafting functional groups in the framework pores, MOF-18Cr6 possesses regular 18-crown-6-ether cavities on the channel walls, which not only can transport and intake strontium(II) via the channels, but also prevent blockage of the channels after the binding of strontium(II). Consequently, the functional sites are fully utilized to achieve a high strontium(II) removal rate of 99.73 % in simulated nuclear wastewater. This study fabricates a highly promising adsorbent for the separation of aqueous radioactive strontium(II), and more importantly, can provide a new strategy for the rational design of high-performance MOF adsorbents for separating target substances from complex aqueous environments.