Method for preparing flexible chain quaternary phosphonium salt ion single crystal under mild condition and application of flexible chain quaternary phosphonium salt ion single crystal in iodine capture

Abstract

The invention discloses a method for preparing a flexible chain quaternary phosphonium salt ion single crystal under a mild condition, which comprises the following steps: respectively dissolving a quaternary phosphonium salt cationic monomer and a sulfonic acid group anionic monomer in methanol or water, and then mixing the quaternary phosphonium salt cationic monomer and the sulfonic acid group anionic monomer to obtain a quaternary phosphonium salt ion single crystal material within 12 hours. And drying and grinding the obtained product to obtain the solid adsorbent for iodine capture. Considering that the single crystal contains abundant heteroatom groups (P, sulfonic acid) and abundant conjugated electrons (benzene rings), the material has the capability of capturing iodine. The work expands the application of a new material in the field of iodine adsorption, and fills the blank of the ion single crystal in the field of iodine adsorption. In addition, the preparation process is simple, the reaction condition is mild, the reaction time is short, the synthesis efficiency is high, and large-scale popularization and application are facilitated.

Description

Technical Field

[0001] The invention relates to a method for preparing a flexible chain quaternary phosphonium salt ion single crystal under mild conditions, and belongs to the field of single crystal materials. Background Art

[0002] Effective capture of radioactive iodine is of vital importance for managing radioactive nuclear waste and protecting human health. As the core of iodine capture, the structural characteristics of adsorbent materials directly determine the adsorption performance of iodine. At present, a variety of porous adsorbent materials such as metal organic frameworks (MOFs), covalent organic frameworks (COFs), hydrogen bonded organic frameworks (HOFs), porous organic polymers (POPs) and porous organic cages (POCs) have been used for efficient adsorption of iodine, but these materials also have some technical problems that cannot be ignored. First, due to the relatively weak van der Waals force between iodine and the porous framework, these materials face challenges in long-term storage of iodine, and the introduction of electrostatic force results in stronger electrostatic interactions between the material and the adsorbate; secondly, the rigid cross-linked macromolecular framework makes these materials less soluble, which in turn affects their processability in solution and limits the rapid release of iodine. These problems highlight the shortcomings of existing adsorbent materials in terms of structural flexibility and functionality, so there is an urgent need to develop new materials to overcome these defects. Organic ionic single crystal materials are based on the charge characteristics of ionic bonds in monomers and the designability of organic groups, allowing the design and preparation of materials with rich and diverse structures and properties by adjusting functional groups, active adsorption sites and physical and chemical properties. In addition, the successful acquisition of single crystal materials allows us to intuitively observe the microstructure of the material, and then accurately reveal the specific relationship between the action site and the interaction between the material and the iodine molecule. This in-depth understanding helps us further clarify the mechanism of action, which is of great theoretical and practical significance for research and application in key areas such as the nuclear industry and environmental governance. Summary of the invention

[0003] The purpose of the present invention is to disclose a method for preparing a flexible chain quaternary phosphonium salt ion single crystal, so as to realize the simple, mild and rapid synthesis of ion single crystal materials.

[0004] 1. Preparation of flexible chain quaternary phosphonium salt ion single crystals The flexible chain quaternary phosphonium salt ion single crystal of the present invention is prepared by dissolving the quaternary phosphonium salt monomer and the sulfonic acid monomer in their respective solvents, mixing the two, shaking them evenly, and standing them at room temperature for 10 to 15 hours to obtain a single crystal material.

[0005] The flexible chain quaternary phosphonium salt is one of ethylenebis(triphenylphosphonium bromide) (PEBTBr2) and tetramethylenebis(triphenylphosphonium bromide) (PBBTBr2), and the sulfonic acid monomer is one of 1,5-naphthalene disulfonic acid (NDSA), 1,3,6,8-pyrene tetrasulfonic acid tetrasodium salt (PTSS), and 4,4'-biphenyl disulfonic acid (BDSA).

[0006] The molar ratio of the quaternary phosphonium salt monomer to the sulfonic acid monomer is 1:1-2:1.

[0007] The solvent of the quaternary phosphonium salt monomer is methanol, the solvent of the sulfonic acid monomer is water, and the volume ratio of methanol to water is 1:3-3:1.

[0008] The synthesis mechanism of the present invention: Based on the principle of anion and cation self-assembly, by designing and selecting multiple anion and cation monomers with different charge characteristics, at room temperature, the anion and cation monomers undergo a spontaneous and ordered ionic self-assembly process to form ionic single crystal materials with a highly ordered structure.

[0009] 2. Characterization of Flexible Chain Quaternary Phosphonium Salt Ion Single Crystals 1. Crystal structure Figure 1 The following are schematic diagrams of the structures of four single crystals. As shown in Table 1, PEBT-NDS belongs to the triclinic system. Point group, Space group. Figure 1 As can be seen in a, NDS has 4 arrangements in the crystal, PEBT has 4 arrangements and is centrosymmetric between the two. PEBT-PTS belongs to the monoclinic system, 2 / m point group, P21 / n space group, and PTS and PEBT are centrosymmetric between the two. ( Figure 1 b). PBBT-PTS has the same unit cell structure and arrangement as PEBT-PTS ( Figure 1 c); Like PEBT-NDS, PBBT-BDS also belongs to the triclinic system, Point group, Space groups, BDS and PBBT each present two centrosymmetric structures ( Figure 1 d). In addition, the anions and cations of the four single crystals all present a lamellar structure.

[0010] Table 1 Lattice data of the four single crystals prepared in Examples 1-4 2. Optical microscope like Figure 2(ad) show the images of four single crystals under an optical microscope. As can be seen from the figures, the shapes of these four single crystals are relatively regular. Among them, PEBT-NDS is a rhombus with diagonals of 2495.6 μm and 966.8 μm; PEBT-PTS is a square with a side length of about 1282.4 μm; PBBT-PTS is a hexagonal crystal with a length of 2099.2 μm and a width of 1492.0 μm; PBBT-BDS presents a rod-like structure with a length of about 1718.0 μm.

[0011] 3. X-ray diffraction (PXRD) The crystallinity of the four materials was studied by PXRD analysis. Figure 3 As shown in (ad), the XRD results of the four single crystal powders are in good agreement with the simulated PXRD results given by the single crystal structure, indicating that all four single crystals have high crystallinity and phase purity.

[0012] 4. Specific surface area analysis (BET) like Figure 4 As shown in (ad), based on the CO2 adsorption-desorption test, the micropore surface areas of the four materials are calculated as follows: PEBT-NDS 16.041 m 2 / g, PEBT-PTS 10.179 m 2 / g, PBBT-PTS 15.682 m 2 / g, PBBT-BDS 26.951m 2 / g. The smaller specific surface area indicates that the four single crystals all have a relatively dense structure. From the isothermal adsorption curve, the adsorption curves of PEBT-NDS, PEBT-PTS, and PBBT-PTS are similar. At a lower relative pressure, the adsorption amount increases sharply, which belongs to monolayer adsorption, i.e. chemical adsorption. As the pressure rises, it gradually turns into multilayer adsorption, i.e. physical adsorption process. However, the adsorption amount of PBBT-BDS only increases slightly at low pressure, i.e. chemical adsorption process, and as the pressure gradually increases, the adsorption amount also gradually increases.

[0013] 5. Thermogravimetric analysis (TGA) The thermal stability of compounds is one of the important properties of compounds, especially for organic-inorganic hybrid complexes formed by supramolecular interactions. The strength of the interaction between its components has a great influence on the thermal stability. Figure 5 (ad) It can be seen that the heat resistance of the four single crystals is good, all above 299 °C, which lays the foundation for the iodine adsorption test in high temperature environment. In addition, the thermal weight loss starting temperature of the single crystal with PBBT as the monomer is about 100 °C higher than that of the single crystal with PEBT as the monomer, which shows that with the extension of the intermediate alkyl chain of the quaternary phosphonium salt monomer, the heat resistance of the material is improved.

[0014] 3. Application of quaternary phosphonium salt ion single crystals in iodine adsorption The iodine capture performance of the quaternary phosphonium salt ion single crystal materials prepared in Examples 1-4 of the present invention in iodine-cyclohexane solution and iodine vapor was evaluated below.

[0015] 1. Evaluation of iodine adsorption performance in iodine-cyclohexane In order to evaluate the adsorption performance of the material to iodine solution, cyclohexane was used as the solvent of iodine to investigate its adsorption capacity. All iodine-cyclohexane solutions were tested for concentration using UV-Vis, and the absorbance of the solution at 525 nm was used as the quantitative standard. By testing the absorbance corresponding to samples of different concentrations (0, 0.39, 0.78, 1.56, 3.13, 6.25, 12.5, 25, 50 ppm), the corresponding relationship between absorbance and concentration was obtained, so that unknown samples could be quantified. The standard curve is shown in the figure below. Figure 6 As shown. Figure 7 The figure shows the change curve of the adsorption amount of iodine in iodine-cyclohexane solution of different concentrations by four single crystal materials over time. In order to study the effect of the concentration of iodine-cyclohexane solution on the adsorption amount of iodine, adsorption experiments were carried out on cyclohexane solutions with initial concentrations of 25 ppm and 50 ppm, respectively. The four materials showed similar properties and adsorbed iodine in cyclohexane solution quickly within 12 h. After more than 12 h, as the remaining active sites decreased, the adsorption rate slowed down, and the adsorption equilibrium was reached around 80 h, after which the adsorption amount remained basically unchanged. The equilibrium adsorption capacity of iodine in cyclohexane solution by PEBT-NDS, PEBT-PTS, PBBT-PTS and PBBT-BDS is 22.9 mg / g (25 ppm) and 31.5 mg / g (50 ppm), 27.5 mg / g (25 ppm) and 34.4 mg / g (50 ppm), 23.5 mg / g (25 ppm) and 32.1 mg / g (50 ppm), 23.5 mg / g (25 ppm) and 38.4 mg / g (50 ppm), respectively. The experimental data show that the adsorption of iodine in cyclohexane solution by the four single crystals increases with the increase of initial concentration, which is attributed to the increase of concentration to increase the driving force of mass transfer. Therefore, the adsorption capacity can be significantly increased in high concentration solution. In order to further evaluate the adsorption kinetics of iodine by the materials, the pseudo-first-order and pseudo-second-order kinetic models are used to fit the experimental data. The results show that the fitting degree of the four materials to the two kinetic models is very similar, indicating that the adsorption process is a mixed mechanism of physical and chemical. The fitting degree of the pseudo-second-order kinetic model is slightly higher than that of the pseudo-first-order kinetic model, so chemical adsorption dominates the adsorption process.

[0016] 2. Evaluation of iodine adsorption performance in iodine vapor In order to evaluate the adsorption capacity of the four invented materials for iodine vapor, the four materials were placed in a 4 mL vial and exposed to iodine vapor at 70°C. As time went by, the color of the sample gradually darkened from white or light yellow to black, indicating that iodine molecules diffused into the sample. Figure 8 The graph shows the change of adsorption amount of four single crystals over time. The four single crystals reach adsorption equilibrium within 145h (PEBT-NDS), 24h (PEBT-PTS), 60h (PBBT-PTS), and 36h (PBBT-BDS), and the maximum adsorption amount is 1620, 1410, 1190, and 590 mg / g, respectively. Combined with the BET data, although PBBT-BDS has the largest specific surface area, the adsorption effect is not as good as the other three single crystals. This may be because the adsorption effect of the material is not only related to the specific surface area of ​​the material, but also to the orientation of the active site of the functional group in the pore. In addition, the adsorption kinetics of the adsorption process of the four adsorbents were fitted. From the data, the pseudo-first-order and pseudo-second-order kinetics of the four materials are very similar, so it belongs to a physical and chemical mixed adsorption process.

[0017] In summary, the present invention has the following advantages over the prior art: 1. The present invention relies on ionic action to self-assemble two quaternary phosphonium salt cations and three sulfonic acid (salt) anions. Unlike covalent bonds and coordination bonds with fixed directions, the flexibility of electrostatic forces can bring multiple structural possibilities to the system, and the existence of single crystals makes the structural composition of the material visible. In addition, quaternary phosphonium salts, as an ionic liquid, have not been used in the field of ion self-assembly. Therefore, the quaternary phosphonium salt ion single crystal material proposed in the present invention fills the gap in this field.

[0018] 2. The quaternary phosphonium salt ion single crystal material prepared by the present invention has mild preparation process conditions, a simple process flow, a short time required, and is feasible for large-scale production. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 Crystal structure diagrams of four single crystals prepared in Examples 1-4 of the present invention: (a) PEBT-NDS, (b) PEBT-PTS, (c) PBBT-PTS, and (d) PBBT-BDS.

[0020] Figure 2 Optical microscope photos of four single crystals prepared in Examples 1-4 of the present invention: (a) PEBT-NDS, (b) PEBT-PTS, (c) PBBT-PTS, and (d) PBBT-BDS.

[0021] Figure 3PXRD characterization patterns of four single crystals prepared in Examples 1-4 of the present invention: (a) PEBT-NDS, (b) PEBT-PTS, (c) PBBT-PTS, and (d) PBBT-BDS.

[0022] Figure 4 BET characterization graphs of four single crystals prepared in Examples 1-4 of the present invention: (a) PEBT-NDS, (b) PEBT-PTS, (c) PBBT-PTS, and (d) PBBT-BDS.

[0023] Figure 5 TGA characterization images of four single crystals prepared in Examples 1-4 of the present invention: (a) PEBT-NDS, (b) PEBT-PTS, (c) PBBT-PTS, and (d) PBBT-BDS.

[0024] Figure 6 The standard curve for quantification is obtained by adsorbing the four single crystals prepared in Examples 1 to 4 of the present invention in iodine-cyclohexane at different concentrations.

[0025] Figure 7 Kinetic fitting curves of four single crystals prepared in Examples 1-4 of the present invention in iodine-cyclohexane with different concentrations: (a) PEBT-NDS, (b) PEBT-PTS, (c) PBBT-PTS, and (d) PBBT-BDS.

[0026] Figure 8 Kinetic fitting curves of four single crystals prepared in Examples 1-4 of the present invention in iodine vapor: (a) PEBT-NDS, (b) PEBT-PTS, (c) PBBT-PTS, and (d) PBBT-BDS. DETAILED DESCRIPTION

[0027] The following is a further description of the method for preparing a flexible chain quaternary phosphonium salt ion single crystal under mild conditions and its application in iodine adsorption by specific examples. The examples are only intended to illustrate the present invention, but not to limit the present invention.

[0028] Example 1 0.0356 g PEBTBr2 was weighed and dissolved in a mixed solution of 0.9 mL methanol and 0.1 mL water, and 0.0144 g NDSA was dissolved in 1 mL water, and placed in an oven at 25 °C for 12 h to obtain PEPT-NDS. PEPT-NDS was taken out, washed with ultrapure water three times and centrifuged, dried in an oven at 45 °C, and ground into powder with a mortar.

[0029] Weigh 10 mg of iodine and dissolve it in 10 mL of cyclohexane to obtain a 1000 ppm iodine-cyclohexane solution; take 1 mL of the 1000 ppm iodine-cyclohexane solution and add 19 mL of cyclohexane to dilute it to obtain a 50 ppm iodine-cyclohexane solution; take 4 mL of the 50 ppm iodine-cyclohexane solution and add 4 mL of cyclohexane to dilute it to obtain a 25 ppm iodine-cyclohexane solution.

[0030] Weigh 4 mg of PEPT-NDS, add 8 mL of 25 ppm and 50 ppm iodine-cyclohexane solution, respectively, and let stand at 25 °C. Use UV-Vis to test the absorbance of iodine-cyclohexane solution at 0, 3, 6, 12, 24, 36, 60, 84, and 108 h. Use the absorbance value at 525 nm as the quantitative standard, insert it into the standard curve, and calculate the amount of iodine adsorbed by the material. Figure 7 As shown in a, the adsorption reaches equilibrium at 84 h and no longer increases. The adsorption amount is 22.9 mg / g (25 ppm) and 31.5 mg / g (50 ppm). In addition, the data can be used to calculate the kinetic model of the adsorption process. The model shows that the pseudo-first-order and pseudo-second-order kinetic fits of the adsorption process are very similar, so it belongs to a physical and chemical mixed adsorption process. The pseudo-second-order kinetic model has a slightly higher fit than the pseudo-first-order kinetic model, so chemical adsorption dominates the adsorption process.

[0031] Weigh 10 mg PEPT-NDS powder and place it in a 4 mL sample bottle. Record the total weight of the adsorbent and the sample bottle as the initial weight. Place the 4 mL sample bottle in a 20 mL sample bottle containing 0.1 g iodine and place it in a 70 °C oven for adsorption. Weigh the total weight of the adsorbent and the sample bottle at 0, 0.167, 0.5, 1, 2, 4, 7, 13, 25, 37, 49, 61, 73, 85, 97, 109, 121, 133, 145, and 157 h, respectively. Calculate the amount of iodine adsorbed, and obtain the change curve of the amount of iodine adsorbed by PEPT-NDS over time, as shown in Figure 3. Figure 8 As shown in a. As can be seen from the figure, the material reaches adsorption equilibrium at 145 h, and the adsorption amount of iodine is 1620 mg / g. In addition, the fitting of the kinetic model shows that the pseudo-first-order and second-order kinetic fitting of the adsorption process are very similar, so the adsorption in gaseous iodine also belongs to a physical and chemical mixed adsorption process.

[0032] Example 2 0.0356 g PEBTBr2 was weighed and dissolved in 2 mL methanol, 0.0152 g PTSS was dissolved in 1.2 mL water, and then 0.8 mL methanol was added. The mixture was placed in an oven at 25 °C for 12 h to obtain PEPT-PTS.

[0033] Weigh 10 mg of iodine and dissolve it in 10 mL of cyclohexane to obtain a 1000 ppm iodine-cyclohexane solution; take 1 mL of the 1000 ppm iodine-cyclohexane solution and add 19 mL of cyclohexane to dilute it to obtain a 50 ppm iodine-cyclohexane solution; take 4 mL of the 50 ppm iodine-cyclohexane solution and add 4 mL of cyclohexane to dilute it to obtain a 25 ppm iodine-cyclohexane solution.

[0034] Weigh 4 mg of PEPT-PTS, add 8 mL of 25 ppm and 50 ppm iodine-cyclohexane solution, respectively, and let stand at 25 °C. Use UV-Vis to test the absorbance of iodine-cyclohexane solution at 0, 3, 6, 12, 24, 36, 60, 84, and 108 h. Use the absorbance value at 525 nm as the quantitative standard, insert it into the standard curve, and calculate the amount of iodine adsorbed by the material. Figure 7 As shown in Figure b, the adsorption reaches equilibrium at 24 h and no longer increases. The adsorption amount is 27.5 mg / g (25 ppm) and 34.4 mg / g (50 ppm). In addition, the data can be used to calculate the kinetic model of the adsorption process. The model shows that the first-order and second-order kinetic fits of the adsorption process are very similar, so it belongs to a physical and chemical mixed adsorption process. The pseudo-second-order kinetic model has a slightly higher fit than the pseudo-first-order kinetic model, so chemical adsorption dominates the adsorption process.

[0035] Weigh 10 mg of PEPT-PTS powder and place it in a 4 mL sample bottle. Record the total weight of the adsorbent and the sample bottle as the initial weight. Place the 4 mL sample bottle in a 20 mL sample bottle containing 0.1 g of iodine and place it in a 70 °C oven for adsorption. Weigh the total weight of the adsorbent and the sample bottle at 0, 0.5, 1.5, 3, 6, 12, 24, 36, 48, and 60 h, respectively, and calculate the adsorption amount of iodine. The change curve of the adsorption amount of iodine by PEPT-PTS over time is obtained, as shown in Figure 2. Figure 8 As shown in Figure b. As can be seen from the figure, the material reaches adsorption equilibrium at 24 h, and the adsorption amount of iodine is 1430 mg / g. In addition, the fitting of the kinetic model shows that the first-order and second-order kinetic fitting of the adsorption process are very similar, so the adsorption in gaseous iodine also belongs to a physical and chemical mixed adsorption process.

[0036] Example 3 0.0370 g PBBTBr2 was weighed and dissolved in 2 mL methanol, and 0.0152 g PTSS was dissolved in 1 mL of a mixed solution of 1 mL and 1 mL of methanol, and the mixture was placed in an oven at 25 °C for 12 h to obtain PEPT-PTS.

[0037] Weigh 10 mg of iodine and dissolve it in 10 mL of cyclohexane to obtain a 1000 ppm iodine-cyclohexane solution; take 1 mL of the 1000 ppm iodine-cyclohexane solution and add 19 mL of cyclohexane to dilute it to obtain a 50 ppm iodine-cyclohexane solution; take 4 mL of the 50 ppm iodine-cyclohexane solution and add 4 mL of cyclohexane to dilute it to obtain a 25 ppm iodine-cyclohexane solution.

[0038] Weigh 4 mg of PBBT-PTS, add 8 mL of 25 ppm and 50 ppm iodine-cyclohexane solution, respectively, and let stand at 20 °C. Use UV-Vis to test the absorbance of iodine-cyclohexane solution at 0, 3, 6, 12, 24, 36, 60, 84, and 108 h. Use the absorbance value at 525 nm as the quantitative standard, insert it into the standard curve, and calculate the amount of iodine adsorbed by the material. Figure 7 As shown in Figure c, the adsorption reaches equilibrium at 84 h and no longer increases. The adsorption amount is 23.5 mg / g (25 ppm) and 32.1 mg / g (50 ppm). In addition, the data can be used to calculate the kinetic model of the adsorption process. The model shows that the first-order and second-order kinetic fits of the adsorption process are very similar, so it belongs to a physical and chemical mixed adsorption process. The pseudo-second-order kinetic model has a slightly higher fit than the pseudo-first-order kinetic model, so chemical adsorption dominates the adsorption process.

[0039] Weigh 10 mg of PBBT-PTS powder and place it in a 4 mL sample bottle. Record the total weight of the adsorbent and the sample bottle as the initial weight. Place the 4 mL sample bottle in a 20 mL sample bottle containing 0.1 g of iodine and place it in a 70 °C oven for adsorption. Weigh the total weight of the adsorbent and the sample bottle at 0, 0.5, 1.5, 3.5, 12, 36, 60, 84, and 108 h, respectively, and calculate the amount of iodine adsorbed. The change curve of the amount of iodine adsorbed by PBBT-PTS over time is obtained, as shown in Figure 2. Figure 8 c. As shown in the figure, the material reaches adsorption equilibrium at 60 h, and the adsorption amount of iodine is 1190 mg / g. In addition, the fitting of the kinetic model shows that the first-order and second-order kinetic fitting of the adsorption process are very similar, so the adsorption in gaseous iodine also belongs to a physical and chemical mixed adsorption process.

[0040] Example 4 0.0370 g PBBTBr2 was weighed and dissolved in a mixture of 1 mL methanol and 1 mL water. 0.0158 g BDSS was dissolved in 1.2 mL water and then 0.8 mL methanol was added. The mixture was placed in an oven at 25 °C for 12 h to obtain PEPT-PTS.

[0041] Weigh 10 mg of iodine and dissolve it in 10 mL of cyclohexane to obtain a 1000 ppm iodine-cyclohexane solution; take 1 mL of the 1000 ppm iodine-cyclohexane solution and add 19 mL of cyclohexane to dilute it to obtain a 50 ppm iodine-cyclohexane solution; take 4 mL of the 50 ppm iodine-cyclohexane solution and add 4 mL of cyclohexane to dilute it to obtain a 25 ppm iodine-cyclohexane solution.

[0042] Weigh 4 mg of PBBT-BDS, add 8 mL of 25 ppm and 50 ppm iodine-cyclohexane solution, respectively, and let stand at 20 °C. Use UV-Vis to test the absorbance of iodine-cyclohexane solution at 0, 3, 6, 12, 24, 36, 60, 84, and 108 h. Use the absorbance value at 525 nm as the quantitative standard, insert it into the standard curve, and calculate the amount of iodine adsorbed by the material. Figure 7 As shown in Figure d, the adsorption reaches equilibrium at 84 h and no longer increases. The adsorption amount is 23.5 mg / g (25 ppm) and 38.4 mg / g (50 ppm). In addition, the data can be used to calculate the kinetic model of the adsorption process. The model shows that the first-order and second-order kinetic fits of the adsorption process are very similar, so it belongs to a physical and chemical mixed adsorption process. The pseudo-second-order kinetic model has a slightly higher fit than the pseudo-first-order kinetic model, so chemical adsorption dominates the adsorption process.

[0043] Weigh 10 mg of PBBT-BDS powder and place it in a 4 mL sample bottle. Record the total weight of the adsorbent and the sample bottle as the initial weight. Place the 4 mL sample bottle in a 20 mL sample bottle containing 0.1 g of iodine and place it in a 70 °C oven for adsorption. Weigh the total weight of the adsorbent and the sample bottle at 0, 0.5, 1.5, 3.5, 6.5, 12, 24, 36, 48, 72, and 96 h, respectively, and calculate the adsorption amount of iodine. The change curve of the adsorption amount of iodine by PBBT-BDS over time is obtained, as shown in Figure 2. Figure 8 d. As shown in the figure, the material reaches adsorption equilibrium at 36 h, and the adsorption amount of iodine is 590 mg / g. In addition, the fitting of the kinetic model shows that the first-order and second-order kinetic fitting of the adsorption process are very similar, so the adsorption in gaseous iodine also belongs to a physical and chemical mixed adsorption process.

Claims

1. A method for preparing a flexible chain quaternary phosphonium salt ion single crystal under mild conditions, characterized in that: Weigh the quaternary phosphonium salt monomer and the sulfonic acid monomer and dissolve them in their respective solvents, mix and shake them well, and let them stand at room temperature for 10 to 15 hours to obtain a flexible chain quaternary phosphonium salt ion single crystal material.

2. A method for preparing a flexible chain quaternary phosphonium salt ion single crystal under mild conditions as claimed in claim 1, characterized in that: The structure of the quaternary phosphonium salt monomer is: , where: n is either 2 or 4.

3. A method for preparing a flexible chain quaternary phosphonium salt ion single crystal under mild conditions as claimed in claim 1, characterized in that: The structure of the sulfonic acid monomer is one of the following three: , or .

4. A method for preparing a flexible chain quaternary phosphonium salt ion single crystal under mild conditions as claimed in claim 1, characterized in that: The molar ratio of the quaternary phosphonium salt monomer to the sulfonic acid monomer is 1:1-2:

1.

5. A method for preparing a flexible chain quaternary phosphonium salt ion single crystal under mild conditions as claimed in claim 1, characterized in that: The solvent of the quaternary phosphonium salt monomer is methanol, the solvent of the sulfonic acid monomer is water, and the volume ratio of methanol to water is 1:3-3:

1.

6. A flexible chain quaternary phosphonium salt ion single crystal prepared by the method as claimed in claim 1 is used for the adsorption of iodine in iodine-cyclohexane and iodine vapor.

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