Radiation-Assisted Synthesis of Crown Ether-Modified Covalent Organic Frameworks for Lithium Isotope Separation

Open AccessCCS ChemistryRESEARCH ARTICLES8 Mar 2024Radiation-Assisted Synthesis of Crown Ether-Modified Covalent Organic Frameworks for Lithium Isotope Separation Shouchao Zhong, Yue Wang, Jianhui Lan, Mingshu Xie, Yiqian Wu, Jiuqiang Li, Fujian Liu, Lilong Jiang, Jing Peng, Liyong Yuan, Maolin Zhai and Weiqun Shi Shouchao Zhong Radiochemistry and Radiation Chemistry Key Laboratory of Fundamental Science, Key Laboratory of Polymer Chemistry and Physics of the Ministry of Education, College of Chemistry and Molecular Engineering, Beijing National Laboratory for Molecular Sciences, Peking University, Beijing 100871 National Engineering Research Center of Chemical Fertilizer Catalyst, College of Chemical Engineering, Fuzhou University, Fuzhou, 350002 Fujian , Yue Wang Radiochemistry and Radiation Chemistry Key Laboratory of Fundamental Science, Key Laboratory of Polymer Chemistry and Physics of the Ministry of Education, College of Chemistry and Molecular Engineering, Beijing National Laboratory for Molecular Sciences, Peking University, Beijing 100871 , Jianhui Lan Laboratory of Nuclear Energy Chemistry, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049 , Mingshu Xie Radiochemistry and Radiation Chemistry Key Laboratory of Fundamental Science, Key Laboratory of Polymer Chemistry and Physics of the Ministry of Education, College of Chemistry and Molecular Engineering, Beijing National Laboratory for Molecular Sciences, Peking University, Beijing 100871 , Yiqian Wu Radiochemistry and Radiation Chemistry Key Laboratory of Fundamental Science, Key Laboratory of Polymer Chemistry and Physics of the Ministry of Education, College of Chemistry and Molecular Engineering, Beijing National Laboratory for Molecular Sciences, Peking University, Beijing 100871 , Jiuqiang Li Radiochemistry and Radiation Chemistry Key Laboratory of Fundamental Science, Key Laboratory of Polymer Chemistry and Physics of the Ministry of Education, College of Chemistry and Molecular Engineering, Beijing National Laboratory for Molecular Sciences, Peking University, Beijing 100871 , Fujian Liu National Engineering Research Center of Chemical Fertilizer Catalyst, College of Chemical Engineering, Fuzhou University, Fuzhou, 350002 Fujian , Lilong Jiang National Engineering Research Center of Chemical Fertilizer Catalyst, College of Chemical Engineering, Fuzhou University, Fuzhou, 350002 Fujian , Jing Peng *Corresponding authors: E-mail Address: [email protected] E-mail Address: [email protected] E-mail Address: [email protected] E-mail Address: [email protected] Radiochemistry and Radiation Chemistry Key Laboratory of Fundamental Science, Key Laboratory of Polymer Chemistry and Physics of the Ministry of Education, College of Chemistry and Molecular Engineering, Beijing National Laboratory for Molecular Sciences, Peking University, Beijing 100871 , Liyong Yuan *Corresponding authors: E-mail Address: [email protected] E-mail Address: [email protected] E-mail Address: [email protected] E-mail Address: [email protected] Laboratory of Nuclear Energy Chemistry, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049 , Maolin Zhai *Corresponding authors: E-mail Address: [email protected] E-mail Address: [email protected] E-mail Address: [email protected] E-mail Address: [email protected] Radiochemistry and Radiation Chemistry Key Laboratory of Fundamental Science, Key Laboratory of Polymer Chemistry and Physics of the Ministry of Education, College of Chemistry and Molecular Engineering, Beijing National Laboratory for Molecular Sciences, Peking University, Beijing 100871 and Weiqun Shi *Corresponding authors: E-mail Address: [email protected] E-mail Address: [email protected] E-mail Address: [email protected] E-mail Address: [email protected] Laboratory of Nuclear Energy Chemistry, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049 https://doi.org/10.31635/ccschem.024.202303787 SectionsSupplemental MaterialAboutAbstractPDF ToolsAdd to favoritesDownload CitationsTrack Citations ShareFacebookTwitterLinked InEmail γ-ray radiation-induced grafting strategy was first employed to immobilize 4-aminobenzo-15-crown-5 onto a covalent organic framework (COF). This endeavor culminated in the successful synthesis of a class of two-dimensional crown ether-modified COFs (named [15C5]n%-(TzDa-G-x%)), marking the maiden utilization of COFs in the realm of 6Li/7Li isotope separation. These COFs exhibited swifter adsorption kinetics than alternative adsorbents. Among them, [15C5]57%-(TzDa-G-50%) with its excellent crystallinity, porosity, and stability exhibited the best performance in Li+ adsorption and 6Li/7Li isotope separation. The Li+ adsorption in acetonitrile achieved a capacity of 3.6 mg · g−1 within 30 min and a saturation capacity of 7.3 mg · g−1. The single-stage separation factor of 6Li/7Li isotopes was 1.014 ± 0.001. The results of dynamic adsorption column experiments showed that the packed column made of [15C5]57%-(TzDa-G-50%) maintained stable performance during four cycles of Li+ adsorption-elution, with over 99% Li+ removal rate in acetonitrile. This crown ether-modified COF has potential application in 6Li/7Li isotope separation, and this radiation-assisted synthesis strategy is expected to become universal in the modification of COFs for diverse applications. Download figure Download PowerPoint Introduction In order to cope with the depletion of fossil fuels and related environmental problems, the access to greener, more efficient, and sustainable energy is necessary. Controlled nuclear fission with 235U is an important alternative to traditional energy, but there are still problems such as radioactive pollution and limited uranium storage. In contrast, controlled nuclear fusion is cleaner and more efficient. To obtain inexhaustible energy, nuclear fusion will become a priority for the future development of nuclear energy.1 The fusion reaction generally refers to the fusion of deuterium (D) and tritium (T) into helium (4He), from which huge amounts of nuclear energy are released through the mass deficit.2 Although seawater contains a large amount of D, T is one of the rarest isotopes on Earth with an abundance of only 0.004% in nature. In a D–T fusion reactor, 6Li can be bombarded by neutrons to produce T, which provides enough reactant for the fusion reactor. It is estimated that the energy produced by 1 kg of 6Li through a fusion reaction is higher than the energy provided by burning 20,000 tons of high-quality coal and far greater than the energy released by the same amount of 235U fission. 7Li plays an important role in fission reaction regulation and equipment maintenance due to its small neutron cross section. For example, ultrapure 7LiF can be used as an important component of the new-generation molten salt reactor coolant, while 7LiOH can be used to regulate the pH value of pressurized water reactors and reduce the corrosion of equipment. According to statistics, in 2012 pressurized water reactors in the US nuclear power plant industry required 400 kg 7Li, and 109 W thorium molten salt reactors (TMSR) required 21–56 tons of high-purity 7Li.3 There are only two stable isotopes of lithium, 6Li and 7Li, with natural abundances of about 7.42% and 92.58%, respectively.4 In order to be used as a T precursor, the abundance of 6Li must be above 30%,5,6 while 7LiOH used to stabilize the pH value of pressurized water reactors requires an abundance of 7Li greater than 99.92%, and the coolant for the TMSR requires an abundance of 7Li greater than 99.995%.7 Therefore, high-purity lithium isotopes are required for both nuclear fusion and TMSR. The study of lithium adsorption and its isotope separation is of great significance. Through physical and chemical methods, lithium isotope separation can be achieved. Physical methods include laser, electromagnetic, molten salt electrolysis, electron migration, and molecular distillation,8 while chemical methods include lithium-mercury amalgamation, ion exchange chromatography, extraction, and fractional precipitation.9 Crown ether extraction is a new method that has attracted a significant amount of research.10,11 According to the Bigeleisen theory,12 in the process of two-phase exchange, the heavier isotope tends to aggregate in the phase with stronger bonding energy. The crown ether can be efficiently extracted and separate into lithium isotopes by chelation. Common crown ethers used for lithium isotope separation include 12-crown-4,13,14 15-crown-5,15 and 14-crown-4.16 Crown ether extraction has some drawbacks, however, such as high usage of organic solvents, serious environmental pollution, and easy loss of crown ethers. Immobilizing crown ethers onto a solid substrate to prepare adsorbents can reduce the loss of crown ethers, simplify the process, and make recycling easier. The separation of lithium isotopes by immobilizing crown ethers onto polysulfone,17 porous silicon,18 chitosan,19 carbon nanotubes,20 and cellulose microspheres21 has been studied. Compared to these substrates, covalent organic frameworks (COFs) have regular channels, extremely high specific surface area, excellent heat stability, and great radiation resistance.22,23 For immobilizing the same adsorption groups, using COFs as substrates can make the product reach adsorption equilibrium faster.24,25 Since the single-stage separation factor of lithium isotopes by adsorption is low, multistage separation is required to better enrich lithium isotopes. Lithium adsorbents based on COFs have fast adsorption kinetics and good cycling stability, which makes them promising for the separation of lithium isotopes. There has been some work on the synthesis of crown ether COFs using precursors containing crown ethers,26–29 but no research regarding the postmodification of crown ethers onto COFs or the utilization of crown ether-modified COFs in lithium isotope separation has been reported yet. Postmodification exerts a lesser influence on the crystallinity of COF than premodification.30 Compared with the chemical method, the γ-ray radiation method has many advantages such as low energy consumption, environmental friendliness, simplicity of operation, controllable conditions at room temperature, and atmospheric pressure operation. The γ-ray radiation method has proven to be a controllable postmodification method for COFs.31,32 Herein, a COF with rich hydroxyl groups (TzDa) was prepared as substrate. Through γ-ray radiation-induced grafting and chemical modification, benzene 15-crown-5 (or 14-crown-4) modified COFs were synthesized successfully (Figure 1, the product was named [15C5]n%-(TzDa-G-x%), where x% represented glycidyl methacrylate (GMA) grafting yield, and n% represented the immobilization yield of crown ether). The effects of COF crystallinity, GMA grafting yield, crown ether immobilization yield, and crown ether type on the Li+ adsorption and 6Li/7Li isotope separation were investigated in detail. This work further expands the application scope of radiation grafting and COFs. Figure 1 | Synthetic route of [15C5]n%-(TzDa-G-x%). Download figure Download PowerPoint Experimental Methods Synthesis of TzDa The synthesis method for TzDa is as follows: 31.9 mg (0.09 mmol) of 1,3,5-tris(4-aminophenyl) triazine (Tz) and 21.6 mg (0.13 mmol) of 2,5-dihydroxyl-terephthalaldehyde (Da) were placed in a heat-resistant necked quartz tube. Then, 1.8 mL of o-dichlorobenzene, 0.2 mL of N,N-dimethylacetamide, and 0.2 mL of 6 mol · L−1 acetic acid aqueous solution were added into a quartz tube. After sonication for 10 min, the system was cooled with liquid nitrogen until it was completely transformed into a solid, then vacuumed and slowly melted at room temperature to release frozen gas. This freeze-pump cycle was repeated three times to achieve a near-vacuum state. Afterward, the glass tube was sealed with a hydrogen flame torch and placed in an oven at 120 °C for 3 days. The resulting solid was washed with tetrahydrofuran (THF), then put into a Soxhlet extractor and extracted with THF for 1 day, and finally dried under vacuum at 80 °C for 24 h, yielding a red powder product with a stable yield of over 85% (>205 mg). Synthesis of TzDa-G-x% The radiation-induced grafted products of TzDa were named TzDa-G-x% (where x% represented the GMA grafting yield). The synthetic route of TzDa-G-x% was as follows: 30 mg TzDa was placed in a vial, and 10 mL of a 2 wt % GMA methanol solution was added into the vial. After being deoxygenated for 10 min with nitrogen, the vial was sealed and exposed to a 60Co γ-ray radiation source (Institute of Applied Chemistry, Peking University, Beijing, China). The dose rate was controlled at approximately 10 Gy · min−1, and the absorbed dose was controlled at 3, 10, 15, 25, and 40 kGy. The dose rate was traced by a Fricke dosimeter. After irradiation, the product was placed in a Soxhlet extractor for 1 day of methanol extraction. It was then vacuum-dried at 80 °C for 24 h to obtain a red powder product. The grafting yield x (%) of GMA was calculated by the change in nitrogen content before and after grafting as follows: x ( % ) = N 1 − N 2 N 2 × 100 (1)where N1(%) and N2(%) are the nitrogen contents of TzDa and TzDa-G-x%, respectively. The method for calculating the grafting yield x(%) of GMA by thermogravimetry was as follows: x ( % ) = R 1 − R 2 R 2 × 100 (2)where R1(%) and R2(%) are the residual carbon contents of TzDa and TzDa-G-x% after thermal degradation, respectively. Synthesis of [15C5]n%-(TzDa-G-x%) The synthetic route of [15C5]n%-(TzDa-G-x%) (where n% represents the immobilization yield of 4-aminobenzo-15-crown-5) was as follows: 60 mg 4-aminobenzo-15-crown-5 was dissolved in 5 mL n-propanol, and then 30 mg TzDa-G-x% was added into the system. The mixture was shaken at 200 rpm, 80 °C for 3 days. The resulting product was washed with acetone and water and then put in a Soxhlet extractor to extract with acetonitrile for 3 days. Finally, the product was vacuum-dried at 80 °C for 24 h to obtain a dark red powder. The immobilization yield n% of 4-aminobenzo-15-crown-5 was calculated by the change in nitrogen content before and after immobilization as follows: n ( % ) = N 1 − N 3 N 3 − N 2 × 100 (3)where N1(%), N2(%), and N3(%) represent the nitrogen content of TzDa-G-x%, 4-aminobenzo-15-crown-5, and [15C5]n%-(TzDa-G-x%), respectively. The immobilization yield n% of 4-aminobenzo-15-crown-5 was calculated by the thermogravimetry as follows: n ( % ) = R 2 − R 3 R 3 × 100 (4)where R2(%) and R3(%) represent the residual carbon content of TzDa-G-x% and [15C5]n%-(TzDa-G-x%) after thermal degradation, respectively. The further details of the experimental methods can be found in the Supporting Information. Results and Discussion Controls of GMA grafting yield, crown ether immobilization yield, and crystallinity of COFs As shown in Supporting Information Figure S1, the attenuated total reflection-Fourier transform infrared (ATR-FTIR) spectrum of TzDa exhibited a stretching vibration peak of C=N at around 1579 cm−1. Compared with the typical C=N vibration peak, the C=N vibration peak of TzDa redshifted. This is due to the fact that the N atom of imine in the TzDa was in a large conjugated structure and formed intramolecular hydrogen bonds with adjacent –OH, thereby reducing the vibrational energy of C=N. In addition, the N–H characteristic peaks (3324 and 3354 cm−1) of the precursor Tz and the –CHO characteristic peak (2889 cm−1) of Da disappeared, which confirmed the formation of the imine bond. These results proved the successful synthesis of TzDa. With GMA concentration of 2 wt % and dose rate of 10 Gy · min−1, the relationship between GMA grafting yield and absorbed dose was investigated under different absorbed doses of 3, 10, 15, 25, and 40 kGy. The grafting yield of GMA-grafted TzDa (TzDa-G-x%) at each absorbed dose was obtained by elemental analysis and thermogravimetric analysis (Figure 2a and Supporting Information Figure S2). Within the range of 3–25 kGy absorbed dose, the grafting yield of TzDa-G-x% increased gradually with the increase of absorbed dose; within the range of 25–40 kGy absorbed dose, the grafting yield of TzDa-G-x% decreased slightly with the increase of absorbed dose, possibly due to the saturation of grafting and partial degradation of the graft chain caused by excessive absorbed dose. Compared with thermogravimetric analysis, the results obtained by elemental analysis had better repeatability. Thus, the grafting yield obtained by elemental analysis was used for subsequent discussions. It should be noted that after GMA grafting, the crystallinity of TzDa was still maintained (Figure 2b), indicating that the radiation-induced grafting did not destroy the crystalline structure of TzDa, and TzDa had good radiation resistance. In order to investigate the effect of GMA grafting yield on crown ether immobilization, GMA grafted TzDa with grafting yields of 50%, and 158% (TzDa-G-50% and TzDa-G-158%) were selected for subsequent chemical modification experiments. Figure 2 | GMA grafting yield, crown-ether immobilization yield and crystallinity of COFs (a) Grafting yield versus absorbed dose. (b) PXRD patterns of TzDa-G-22%, TzDa-G-50%, TzDa-G-119%, TzDa-G-158%, and TzDa-G-155%. (c) Immobilization yield versus reaction time. (d) PXRD patterns of TzDa, TzDa-G-50%, and [15C5]57%-(TzDa-G-50%). (e) PXRD patterns of [15C5]57%-(TzDa-G-50%); experimental data in black, Pawley refinement in red, computational simulation in blue, and refinement-experiment difference in olive green. (f) Unit cell mode of [15C5]57%-(TzDa-G-50%) with C atoms in gray, N in blue, O in red, and H in white. Download figure Download PowerPoint In the experiment of immobilizing 4-aminobenzo-15-crown-5 onto TzDa-G-x%, dimethylformamide, n-propanol, and acetone were used as solvents. The results showed that when n-propanol was used as the solvent, the product maintained good crystallinity while having a higher crown ether immobilization yield. The fixed ratio used was TzDa-G-x%: 4-aminobenzo-15-crown-5: n-propanol = 6 mg: 12 mg: 1 mL. The effect of GMA grafting yield and reaction time on crown ether immobilization yield was studied under the reaction temperature of 80 °C. The results of elemental analysis showed that with the increase of reaction time, the crown ether immobilization yield was improved, as shown in Figure 2c. A higher GMA grafting yield would lead to a higher crown ether immobilization yield. Specifically, the crown ether immobilization yields of [15C5]n%-(TzDa-G-50%) and [15C5]n%-(TzDa-G-158%) obtained by immobilizing 4-aminobenzo-15-crown-5 onto TzDa-G-50% and TzDa-G-158% for 3 days were 57 ± 6% and 108 ± 19%, corresponding to 3.02 ± 0.35 and 9.8 ± 1.7 mmol · g−1, respectively. COFs with more GMA groups have more reaction sites (epoxide groups), thus exhibiting higher crown ether immobilization yields. In the thermogravimetric experiment, [15C5]57%-(TzDa-G-50%) showed more weight loss than TzDa-G-50% ( Supporting Information Figure S3), and the crown ether immobilization yield calculated from the thermogravimetric results was 46%. However, the material containing abundant hydroxyl groups will result in a higher residual carbon content in the thermogravimetric analysis, which will lead to a lower crown ether immobilization yield.33 Therefore, the crown ether immobilization yield obtained from the elemental analysis was used for further discussion. The crystallographic properties of TbDa, which has a similar structure to TzDa, was prepared. As shown in Supporting Information Figure S4, the ATR-FTIR spectrum of TbDa revealed a stretching vibration peak of C=N at approximately 1587 cm−1, while the N–H characteristic peaks of the Tb precursor at 3463 and 3434 cm−1 and the CHO characteristic peak of Da at 2889 cm−1 disappeared, proving the formation of imine bonds. The powder X-ray diffraction (PXRD) results showed that TbDa and TzDa had a similar crystalline structure. As shown in Supporting Information Figure S5, TbDa exhibited a strong diffraction peak at 2.78° and weak peaks at 4.80°, 5.52°, and 7.28°, corresponding to the (100), (110), (200), and (210) crystal planes, respectively. In comparison, TzDa had strong diffraction peaks at 2.76°, 4.80°, 5.56°, and 7.38° and weak peaks at 9.76° and 25.78°, corresponding to the (100), (110), (200), (210), (220), and (001) crystal planes. The PXRD results indicated that both COFs were stacked in AA form, but TzDa exhibited superior crystallization to TbDa. Infrared characterization was performed on the products of GMA-grafted TbDa (TbDa-G) and crown ether-immobilized TbDa (15C5-TbDa-G), as shown in Supporting Information Figure S6. The ATR-FTIR spectrum of TbDa-G revealed a characteristic stretching vibration peak of C=O at 1729 cm−1, indicating that GMA was successfully grafted onto TbDa. The presence of the antisymmetric and symmetric stretching vibration peaks of cyclic ethers at 1050 and 933 cm−1, respectively, and the broad peaks of N–H and O–H at 3000–2700 cm−1 demonstrated that the 4-aminobenzo-15-crown-5 was successfully immobilized on the skeleton of TbDa. The difference in crystallinity of using TzDa and TbDa as substrates was compared. After grafting GMA at the absorbed dose of 10 kGy and immobilizing crown ether for 3 days, TzDa-G-50% and [15C5]57%-(TzDa-G-50%) retained the original crystal diffraction peaks (Figure 2d). In comparison, although TbDa-G retained the original crystal diffraction peaks after radiation-induced grafting with GMA, the crystal structure of the original COF disappeared after immobilizing crown ether ( Supporting Information Figure S7). The reason is that TzDa containing triazine groups has better planarity and more robust crystal structure than TbDa, resulting in the ability to maintain the crystallinity of the original COF under harsh conditions. Since 15C5-TbDa-G cannot maintain the original crystallinity of TbDa, further characterization and adsorption experiments were performed using [15C5]n%-(TzDa-G-x%). The influence of the GMA grafting yield and crown ether immobilization yield on the crystallinity was studied. Although TzDa-G-158%, which was grafted with more GMA, could immobilize more crown ether, it lost the crystal structure of the original COF after immobilizing crown ether ( Supporting Information Figure S8). This is attributed to the fact that the introduction of excess crown ether produced significant steric hindrance, making it impossible for the COF to maintain its original crystal structure. Characterizations of COFs The structural modeling of [15C5]57%-(TzDa-G-50%) was conducted using Material Studio software (Accelrys, Inc., San Diego, California, United State). According to previous work,34 the initial lattice of TzDa was generated. The space of TzDa is = = = Experimental data showed that the GMA and crown-ether groups in [15C5]57%-(TzDa-G-50%) were grafted onto the TzDa in an approximately ratio ( Supporting Information Therefore, a [15C5]57%-(TzDa-G-50%) was in which each on the TzDa was to one GMA and crown-ether was performed using the with a universal and the lattice were using the Pawley refinement until The resulting with the Therefore, [15C5]57%-(TzDa-G-50%) to the space and the lattice are a = = = and = = = Figure the PXRD of the experimental and indicating that this COF is in the AA Figure the cell of [15C5]57%-(TzDa-G-50%). For the TzDa the space is to the GMA and crown ether PXRD and results that [15C5]57%-(TzDa-G-50%) has a high of The electron indicated that TzDa exhibited a before grafting (Figure However, after radiation-induced grafting and immobilization, the of TzDa-G-50% and [15C5]57%-(TzDa-G-50%) gradually and exhibited a (Figure TzDa-G-158% and with higher grafting and immobilization yields showed ( Supporting Information and These results further demonstrated the of the radiation-induced grafting of GMA and immobilization of High electron results showed that the structure and lattice of [15C5]57%-(TzDa-G-50%) were to of TzDa, further proving that [15C5]57%-(TzDa-G-50%) retained its original crystal structure after radiation-induced grafting with GMA and immobilization with crown ether (Figure Figure 3 | of COFs. of (a) TzDa, (b) TzDa-G-50%, and (c) [15C5]57%-(TzDa-G-50%). of (d) TzDa and (e) [15C5]57%-(TzDa-G-50%). Download figure Download PowerPoint As shown in Figure after the GMA grafting, the ATR-FTIR spectrum of the TzDa-G-50% exhibited a characteristic stretching vibration peak of C=O at cm−1, indicating that GMA successfully grafted onto the TzDa. After the crown ether immobilization, [15C5]57%-(TzDa-G-50%) exhibited the antisymmetric and symmetric stretching vibration peaks of cyclic ether at and 933 cm−1, respectively, and a broad peak in the cm−1, corresponding to the of N–H and which proved that 4-aminobenzo-15-crown-5 was successfully immobilized onto the TzDa through the reaction with the GMA Figure | Characterizations of COFs. (a) ATR-FTIR of TzDa, TzDa-G-50%, and [15C5]57%-(TzDa-G-50%). (b) of TzDa, TzDa-G-50%, and [15C5]57%-(TzDa-G-50%). (c) of TzDa, TzDa-G-50%, and [15C5]57%-(TzDa-G-50%). (d) of TzDa, TzDa-G-50%, and [15C5]57%-(TzDa-G-50%). Download figure Download PowerPoint X-ray analysis results of TzDa before and after radiation-induced grafting and crown ether immobilization are shown in Figure After radiation-induced grafting with GMA, in the C peak of TzDa-G-50%, new characteristic peaks of and at and respectively, the successful grafting of [15C5]57%-(TzDa-G-50%) obtained by immobilizing 4-aminobenzo-15-crown-5 onto TzDa-G-50% showed a significant increase in the content of crown ether at further the successful immobilization of 4-aminobenzo-15-crown-5 on The nuclear carbon are shown in Figure After grafting with GMA, new peaks and peaks in immobilization with crown ether in a significant of the peak in further proving the successful grafting of GMA and the successful immobilization of 4-aminobenzo-15-crown-5 onto TzDa. Figure and Supporting Information Figure showed the in specific surface of TzDa-G-x% with different GMA grafting yields and [15C5]n%-(TzDa-G-x%) with different crown ether immobilization yields. It can be that the introduction of GMA and crown ether has a great on the of The specific surface of [15C5]57%-(TzDa-G-50%) was · g−1, but for excessive groups the of resulting in a in specific surface to · g−1. This result had an effect on the adsorption It is thus to a between the specific surface and crown ether immobilization yield when TzDa. and isotope separation performance for lithium The advantages of lithium isotope separation in acetonitrile with water include higher capacity and lower of Figure the adsorption kinetics of Li+ by [15C5]57%-(TzDa-G-50%) and in acetonitrile