Method for preparing nanofiber membrane for cobalt ion separation and having radiation stability

Abstract

The present application relates to the technical field of nanofiber membrane preparation, and particularly relates to a nanofiber membrane preparation method for cobalt ion separation and having radiation stability, preparation of amino-functionalized metal organic framework; mixing the amino-functionalized metal organic framework and preparation raw materials to prepare semi-finished nanofiber membrane; dispersing the semi-finished nanofiber membrane in ethanol, adding backflow raw materials to carry out reaction, and obtaining finished nanofiber membrane. Through electrospinning technology, MOFs are combined with polymers, the MOFs are uniformly dispersed on the fiber membrane, and then grafted with L-lysine, so that the hydrophilicity and separation capacity of the membrane material to cobalt ions are enhanced, the problem of difficult recycling of the adsorption material is solved, the anti-radiation stability is good, the practical application value is high, the problems of difficult separation and recycling of the existing adsorption and separation material, and low cobalt ion adsorption capacity of the material in the separation of low-concentration cobalt-containing wastewater are solved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of nanofiber membrane preparation, and particularly relates to a nanofiber membrane preparation method for cobalt ion separation and having radiation stability. BACKGROUND

[0002] With the rapid development of nuclear technology industry, radioactive isotopes have been widely used in many fields such as industry, agriculture and medicine. Co-60 (60Co) is a kind of artificial radioactive isotope of metallic cobalt, which is used in radiotherapy, medical preparations and instrument sterilization. During the production and use of 60Co, radioactive wastewater containing 60Co is generated. If the wastewater is directly discharged without treatment, it will not only pollute the environment, but also endanger human health.

[0003] Cobalt ions in wastewater can be removed by chemical precipitation, ion exchange, electrochemical treatment, biological remediation and adsorption. However, due to low treatment capacity, complex preparation process, unavoidable sludge treatment and difficult separation and recovery, the application of these methods is limited. Membrane separation method is considered as an economical wastewater treatment process because of its low energy consumption, environmental friendliness and high treatment efficiency.

[0004] Metal-organic framework material is a kind of three-dimensional network structure crystal material formed by the coordination bond between the nitrogen and oxygen multidentate organic ligand of aromatic acid or alkali and inorganic metal center. It has both organic and inorganic parts. The organic part enhances the permeability between the two phases and increases the strong interaction with the polymer matrix. MOFs have various types, strong functionality, high porosity, large specific surface area and adjustable pore size, and have wide application in metal ion separation. However, the particle size of MOFs material is small, which makes it difficult to separate after water treatment. In addition, the acid and alkali stability is not good, and the radiation resistance is poor.

[0005] Existing adsorption separation materials are not easy to separate and recover, and the adsorption capacity of the materials for cobalt ions is low when separating low-concentration cobalt-containing wastewater. Therefore, it is necessary to prepare functionalized nanofiber membrane materials. SUMMARY

[0006] The present application provides a nanofiber membrane preparation method for cobalt ion separation and having radiation stability, which aims to solve the problems of existing adsorption separation materials that are not easy to separate and recover, and the low adsorption capacity of the materials for cobalt ions when separating low-concentration cobalt-containing wastewater.

[0007] To achieve the above-mentioned purpose, the present application provides a nanofiber membrane preparation method for cobalt ion separation and having radiation stability, which comprises the following steps:

[0008] Preparation of amino-functionalized metal organic framework;

[0009] Mix the amino-functionalized metal organic framework and the preparation raw material to prepare a semi-finished nanofiber membrane;

[0010] Disperse the semi-finished nanofiber membrane in ethanol and add a refluxing raw material to react, to obtain a finished nanofiber membrane.

[0011] The specific method for preparing the amino-functionalized metal organic framework is as follows:

[0012] Put 2-amino terephthalic acid, concentrated hydrochloric acid and zirconium tetrachloride into dimethylformamide, and stir and mix to prepare a mixed solution;

[0013] Add the mixed solution into a reaction kettle with a polytetrafluoroethylene lining to perform a heating reaction, cool to room temperature after heating, take out and wash, to obtain the amino-functionalized metal organic framework.

[0014] The specific method for mixing the amino-functionalized metal organic framework and the preparation raw material to prepare a semi-finished nanofiber membrane is as follows:

[0015] Dissolve the amino-functionalized metal organic framework and the preparation raw material in dimethylformamide, and remove bubbles to obtain a spinning raw material;

[0016] Use an electrostatic spinning machine to spin the spinning raw material to prepare the semi-finished nanofiber membrane.

[0017] The preparation raw material includes polyacrylonitrile and polyethylene glycol, and the polyacrylonitrile and the polyethylene glycol are both 1 g, the molecular weight of the polyacrylonitrile is 150,000, and the molecular weight of the polyethylene glycol is 2,000.

[0018] The refluxing raw material includes glutaraldehyde and L-lysine, the amount of the glutaraldehyde is 0.42 mL, the amount of the L-lysine is 0.15 g, and the ethanol is 120 mL.

[0019] This invention discloses a method for preparing a radiation-stable nanofiber membrane for cobalt ion separation. The method involves preparing an amino-functionalized metal-organic framework (UiO-66-NH2); mixing the amino-functionalized metal-organic framework (UiO-66-NH2) with raw materials to prepare a semi-finished nanofiber membrane (UiO-66-NH2 / PAN); dispersing the semi-finished nanofiber membrane (UiO-66-NH2 / PAN) in ethanol and adding refluxed raw materials to react, yielding a finished nanofiber membrane (UiO-66-Lys / PAN). This method combines MOFs with polymers through electrospinning, uniformly dispersing MOFs on the fiber membrane, and then grafting with L-lysine. This enhances the hydrophilicity of the membrane material and its ability to separate cobalt ions. It also solves the problem of difficult recycling of adsorbent materials, exhibits good radiation resistance, and has high practical application value. This method addresses the issues of existing adsorption separation materials being difficult to separate and recycle, and having a low adsorption capacity for cobalt ions when separating low-concentration cobalt-containing wastewater. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 The images show the XRD patterns of UiO-66-NH2, PAN, and UiO-66-Lys / PAN prepared according to this invention.

[0022] Figure 2 The images show the infrared analysis results of UiO-66-NH2, PAN, and UiO-66-Lys / PAN prepared according to this invention.

[0023] Figure 3 These are SEM images of the PAN and UiO-66-Lys / PAN prepared according to this invention.

[0024] Figure 4 This is a graph comparing the membrane flux of PAN and UiO-66-Lys / PAN prepared in this invention with that of pure PAN nanofibers.

[0025] Figure 5 This is a schematic diagram showing the cobalt ion rejection rate of PAN and UiO-66-Lys / PAN prepared in this invention.

[0026] Figure 6 This is a comparison of the contact angles of the PAN and UiO-66-Lys / PAN prepared in this invention with those of pure PAN nanofiber membranes.

[0027] Figure 7 is the XRD diagram of UiO-66-Lys / PAN prepared by the present application at different gamma doses.

[0028] Figure 8 is the infrared analysis diagram of UiO-66-Lys / PAN prepared by the present application at different gamma doses.

[0029] Figure 9 is the SEM diagram of UiO-66-Lys / PAN prepared by the present application at different gamma doses.

[0030] Figure 10 is a schematic diagram for measuring the adsorption amount of PAN and UiO-66-Lys / PAN by using a UV-visible spectrophotometer.

[0031] Figure 11 is a schematic diagram for measuring the adsorption amount of UiO-66-Lys / PAN by using a UV-visible spectrophotometer.

[0032] Figure 12 is a schematic diagram for measuring the adsorption amount of UiO-66-Lys / PAN by using a UV-visible spectrophotometer.

[0033] Figure 13 is a schematic diagram for measuring the adsorption amount of UiO-66-Lys / PAN by using a UV-visible spectrophotometer.

[0034] Figure 14 is a flow chart of the preparation method of the nanofiber membrane for cobalt ion separation and having radiation stability provided by the present application. DETAILED DESCRIPTION

[0035] The embodiments of the present application are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference signs represent the same or similar elements or elements having the same or similar functions throughout. The embodiments described below by referring to the accompanying drawings are exemplary and are intended to explain the present application, and cannot be understood as a limitation of the present application.

[0036] Referring to Figures 1 to 14 , the present application provides a preparation method of a nanofiber membrane for cobalt ion separation and having radiation stability, comprising the following steps:

[0037] S1, preparing an amino-functionalized metal organic framework;

[0038] Specifically,

[0039] S11, putting 2-amino terephthalic acid, concentrated hydrochloric acid and zirconium tetrachloride into dimethylformamide, stirring and mixing to prepare a mixed solution;

[0040] Specifically, 2-amino terephthalic acid, concentrated hydrochloric acid and zirconium tetrachloride are dissolved in N,N-dimethylformamide to obtain a uniform mixed solution after stirring for 0.5 h, the amount of 2-amino terephthalic acid is 2.7 g, the amount of zirconium tetrachloride is 3.5 g, the amount of N,N-dimethylformamide is 220 mL, and the amount of concentrated hydrochloric acid is 5 mL.

[0041] S12 adds the mixed solution to a reaction kettle with a polytetrafluoroethylene liner for heating reaction, cools to room temperature after heating, and then is taken out and washed to obtain the amino-functionalized metal organic framework.

[0042] Specifically, the mixed solution is transferred to a reaction kettle with a polytetrafluoroethylene liner, and is reacted at 120°C for 24 h, and then is cooled to room temperature, washed and dried to obtain a yellow solid powder, i.e. the amino-functionalized metal organic framework (UiO-66-NH2).

[0043] S2 mixes the amino-functionalized metal organic framework and the preparation raw material to prepare a semi-finished nanofiber membrane;

[0044] Specific ways:

[0045] S21 dissolves the amino-functionalized metal organic framework and the preparation raw material in dimethylformamide and removes bubbles to obtain a spinning raw material;

[0046] Specifically, the amino-functionalized metal organic framework (UiO-66-NH2) and the preparation raw material (polyacrylonitrile and polyethylene glycol) are dissolved in DMF (dimethylformamide), and after stirring for 12 h, the spinning raw material is obtained by standing for 0.5 h to remove bubbles, the polyacrylonitrile and the polyethylene glycol are both 1 g, the molecular weight of the polyacrylonitrile is 150000, the molecular weight of the polyethylene glycol is 2000, and the DMF is 10-15 mL.

[0047] S22 spins the spinning raw material by using an electrostatic spinning machine to prepare the semi-finished nanofiber membrane.

[0048] Specifically, the spinning raw material is spun by using an electrostatic spinning machine, and the prepared fiber membrane is immersed in deionized water at 60°C, washed, and dried to be used, to obtain the semi-finished nanofiber membrane, the spinning voltage of the electrostatic spinning is 12 kV, the needle hole diameter is 0.6 mm, and the spinning speed is 0.8 mL / h.

[0049] S3 disperses the semi-finished nanofiber membrane in ethanol and adds a reflux raw material for reaction to obtain a finished nanofiber membrane.

[0050] Specifically, the semi-finished nanofiber membrane (UiO-66-NH2 / PAN) is dispersed in ethanol at 70 DEG C and refluxed with glutaraldehyde for 6 hours, then L-lysine is added and refluxed for another 6 hours, and the solution turns into red brown. After the reaction is completed, the material is washed clean to obtain the finished nanofiber membrane (UiO-66-Lys / PAN), wherein the amount of UiO-66-NH2 / PAN is 0.3 g, the amount of glutaraldehyde is 0.42 mL, the amount of ethanol is 120 mL, and the amount of L-lysine is 0.15 g.

[0051] The UiO-66-Lys / PAN prepared by the above method is subjected to membrane performance testing, including the following operation process steps: first, the prepared fiber membrane is cut into a membrane with an effective area of 0.0022 m 2 , and the performance is tested at room temperature under a transmembrane pressure of 1 bar; before testing, the membrane is pre-pressurized with deionized water for 1 hour to ensure stable flux; the membrane flux is calculated by collecting the volume of deionized water after 15 minutes of filtration; under the same conditions, the rejection rate is determined by using 250 mL of cobalt ions with an initial concentration of 20 mg / L.

[0052] The UiO-66-Lys / PAN adsorbent prepared by the above method is subjected to anti-irradiation testing, including the following process steps: first, a uniform membrane material is selected, and 0.2 g of the sample is loaded into a PE bag and transported to the cobalt source radiation center of the Sichuan Academy of Agricultural Sciences; static room temperature irradiation (0, 20, 50, 100, 200 kGy) is performed, and the radiation source is gamma rays; after the reaction is completed, the influence of irradiation on the structure of the material is observed by XRD, FT-IR, and SEM characterization methods.

[0053] The UiO-66-Lys / PAN adsorbent prepared by the above method is used for adsorbing and treating cobalt ions in wastewater, including the following operation process steps: first, 50 mL of cobalt-containing wastewater with a concentration of 30.0 mg / L is taken, and the pH value is adjusted to 5.0-9.0 by using 0.1 mol / L NaOH solution or 0.1 mol / L nitric acid solution; then, the prepared adsorbent is added, and the cobalt ions in the wastewater are adsorbed and treated at 5 DEG C-45 DEG C for 0-24 hours; finally, the UiO-66-Lys / PAN adsorbent is separated from the cobalt-containing wastewater, and the separated UiO-66-Lys / PAN adsorbent is eluted by 2.0 mol / L nitric acid for recycling.

[0054] The detection method of the cobalt ion content in the above-mentioned adsorbed wastewater is as follows: taking the above-mentioned adsorbed mixed solution, centrifuging for 5 min on a centrifuge, taking 1 mL of supernatant into a 25 mL volumetric flask, adding 1.0 mL of HAc-NaAc buffer solution with a pH of 4.7 and 1.0 mL of nitroso-R salt solution with a concentration of 4 g / L, and then constant volume with distilled water, and then using a UV-visible spectrophotometer to detect the content of cobalt ions.

[0055] In order to achieve better cobalt ion adsorption treatment effect, the application can further adopt the following measures:

[0056] In the above technical solution, the pH of the cobalt-containing wastewater is 5.0-9.0.

[0057] In the above technical solution, the pH of the cobalt-containing wastewater is adjusted to 8.3.

[0058] In the above technical solution, the adsorption temperature of the cobalt-containing wastewater is 5-45℃.

[0059] In order to better understand the technical solutions, the application provides the following examples, which are only used to illustrate the application and are not intended to limit the scope of protection of the application.

[0060] Example 1

[0061] Figure 1 The XRD analysis graph of UiO-66-NH2, PAN, UiO-66-Lys / PAN prepared by the application, combined with related literature and atlas, can prove that UiO-66-NH2 and UiO-66-Lys / PAN are successfully prepared.

[0062] Example 2

[0063] Figure 2 The infrared analysis graph of UiO-66-NH2, PAN, UiO-66-Lys / PAN prepared by the application, and the analysis atlas show that, by comparing the infrared spectrum of the prepared UiO-66-NH2, after electrospinning of PAN and modification of amino acids, the UiO-66-Lys / PAN has a stretching vibration peak at 2232 cm -1 a stretching vibration peak of C≡N appears, 1710 cm -1 a stretching vibration peak of C≡N appears, 1710 cm Figure 1 It is proved that UiO-66-Lys / PAN is successfully prepared.

[0064] Example 3

[0065] Figure 3The SEM images of PAN and UiO-66-Lys / PAN prepared in the application can be seen from the figure that the nanofiber morphology is formed on the surface of PAN and UiO-66-Lys / PAN, the two fibers appear similar multi-hole nanofiber network structure, the nanofiber membrane prepared by electrospinning is randomly arranged and the arrangement is uneven. However, compared with the smooth surface of single PAN nanofiber, the rough surface morphology appears on the surface of UiO-66-Lys / PAN fiber, which may be due to the modification of MOFs nanoparticles.

[0066] Example 4

[0067] Figure 4 The membrane flux of PAN and UiO-66-Lys / PAN prepared in the application is compared with that of pure PAN nanofiber, the membrane flux of UiO-66-Lys / PAN is reduced, which may be due to the addition of MOFs blocking the pores of nanofiber.

[0068] Example 5

[0069] Figure 5 The rejection rate of cobalt ions of PAN and UiO-66-Lys / PAN prepared in the application can be seen from the figure that the rejection rate of cobalt ions of PAN nanofiber membrane is low, which indicates that the rejection rate of pure polymer to metal ions is low, and the rejection rate of cobalt ions is increased after adding MOFs material, which may be due to the coordination effect of the pore structure of MOFs and the amino group introduced after the modification of amino acid.

[0070] Example 6

[0071] Figure 6 The contact angle of PAN and UiO-66-Lys / PAN prepared in the application is compared with that of pure PAN nanofiber membrane, the hydrophilicity of UiO-66-Lys / PAN is increased, and the reduction of membrane contact angle may be due to the hydrogen bond between water molecules and the surface of the membrane, which is due to the carboxyl and amino groups in L-lysine are polar groups and have strong hydrophilicity.

[0072] Example 7

[0073] Figure 7 The XRD pattern of UiO-66-Lys / PAN prepared in the application under different gamma doses can be seen that the diffraction peak intensity of UiO-66-Lys / PAN is weakened to a certain extent with the increase of gamma dose, but the material still has a relatively stable crystal structure, which indicates that 3% UiO-66-Lys / PAN has a certain radiation resistance.

[0074] Example 8

[0075] Figure 8The infrared analysis diagram of the UiO-66-Lys / PAN prepared in the application under different gamma doses, from the diagram, the peaks of the materials under different gamma doses at 500-3000 cm -1 are basically consistent with those of the unirradiated 3% UiO-66-Lys / PAN, and the intensity change and slight shift at 1568 cm -1 compared with the unirradiated material, which may be the influence of irradiation on the stretching vibration of O-C-O and C=O in terephthalic acid, and the spectrum does not change significantly, indicating that the material has certain anti-irradiation performance.

[0076] Example 9

[0077] Figure 9 The SEM diagram of the UiO-66-Lys / PAN prepared in the application under different gamma doses, compared with the unirradiated UiO-66-Lys / PAN, the morphology of the nanofibers after irradiation does not change significantly, indicating that irradiation cannot change the morphology of the fiber membrane.

[0078] Example 10

[0079] Take 50 mL of cobalt-containing solution with a concentration of 30.0 mg / L, adjust the pH to 5.0-9.0 with 0.1 mol / L HNO3 solution, then add 30.0 mg of adsorbent PAN and UiO-66-Lys / PAN respectively, and then place in a 25℃ constant temperature oscillator for adsorption treatment of cobalt ions in wastewater, oscillate at 150 rpm for 24.0 h, then take 3.0 mL of mixed solution after adsorption, centrifuge at 12000 rpm for 5 min on a centrifuge; then take 1 mL of supernatant in a 25 mL volumetric flask, add 1.0 mL of HAc-NaAc buffer solution with pH of 4.7 and 1.0 mL of nitroso-R salt solution with a concentration of 4 g / L, and then dilute to volume with distilled water, then use a UV-visible spectrophotometer to measure the adsorption amount of PAN and UiO-66-Lys / PAN, from the diagram, the adsorption amount is the largest at pH=8.3, which is 25.12 mg / g

[0080] Example 11

[0081] Take 50 mL of cobalt-containing solution with concentration of 10, 20, 30, 40, 50, 60 mg / L, adjust the pH to 8.3 with 0.1 mol / L NaOH solution, then add 30.0 mg of adsorbent UiO-66-Lys / PAN, and place it in a constant temperature oscillator at 25°C for adsorption treatment of cobalt ions in wastewater. After oscillation at 150 rpm for 24.0 h, take 3.0 mL of the mixed solution after adsorption, centrifuge at 12000 rpm for 5 min on a centrifuge; then take 1 mL of supernatant in a 25 mL volumetric flask, add 1.0 mL of HAc-NaAc buffer solution with pH of 4.7 and 1.0 mL of nitroso-R salt solution with concentration of 4 g / L, and then make up the volume with distilled water. The adsorption amount of UiO-66-Lys / PAN is determined by ultraviolet-visible spectrophotometer as shown in Figure 11 .

[0082] Example 12

[0083] Take 50 mL of cobalt-containing solution with concentration of 30 mg / L, adjust the pH to 8.3 with 0.1 mol / L NaOH solution, then add 30.0 mg of adsorbent UiO-66-Lys / PAN, and then place it in constant temperature oscillators at 5, 15, 25, 35, 45°C for adsorption treatment of cobalt ions in wastewater. After oscillation at 150 rpm for 24.0 h, take 3.0 mL of the mixed solution after adsorption, centrifuge at 12000 rpm for 5 min on a centrifuge; then take 1 mL of supernatant in a 25 mL volumetric flask, add 1.0 mL of HAc-NaAc buffer solution with pH of 4.7 and 1.0 mL of nitroso-R salt solution with concentration of 4 g / L, and then make up the volume with distilled water. The adsorption amount of UiO-66-Lys / PAN is determined by ultraviolet-visible spectrophotometer as shown in Figure 12 .

[0084] Example 13

[0085] Take 50 mL of cobalt-containing solution with concentration of 30 mg / L, adjust the pH to 8.3 with 0.1 mol / L NaOH solution, then add 30.0 mg of adsorbent UiO-66-Lys / PAN, and then place it in a constant temperature oscillator at 25°C for adsorption treatment of cobalt ions in wastewater. After oscillation at 150 rpm for 0.5, 1, 1.5, 3, 6, 12, 15, 18 h respectively, take 3.0 mL of the mixed solution after adsorption, centrifuge at 12000 rpm for 5 min on a centrifuge; then take 1 mL of supernatant in a 25 mL volumetric flask, add 1.0 mL of HAc-NaAc buffer solution with pH of 4.7 and 1.0 mL of nitroso-R salt solution with concentration of 4 g / L, and then make up the volume with distilled water. The adsorption amount of UiO-66-Lys / PAN is determined by ultraviolet-visible spectrophotometer as shown in Figure 13 .

[0086] The above disclosed is only the preferred embodiment of the application for the preparation method of the nanofiber membrane for cobalt ion separation and having radiation stability, of course, cannot limit the scope of the application, those skilled in the art can understand that all or part of the processes of the above-mentioned embodiments are implemented, and the equivalent changes made according to the claims of the application still belong to the scope covered by the application.

Claims

1. A method for preparing a nanofiber membrane for cobalt ion separation and having radiation stability, characterized by, The method comprises the following steps: preparing an amino-functionalized metal organic framework; mixing the amino-functionalized metal organic framework and preparation raw materials to prepare a semi-finished nanofiber membrane; dispersing the semi-finished nanofiber membrane in ethanol and adding a refluxing raw material to react, to obtain a finished nanofiber membrane, wherein the refluxing raw material comprises glutaraldehyde and L-lysine, the amount of the glutaraldehyde is 0.42 mL, the amount of the L-lysine is 0.15 g, and the ethanol is 120 mL.

2. The method for preparing a nanofiber membrane for separating cobalt ions and having radiation stability according to claim 1, wherein the amino-functionalized metal organic framework is prepared in the following manner: 2-amino terephthalic acid, concentrated hydrochloric acid and zirconium tetrachloride are put into dimethylformamide, stirred and mixed to prepare a mixed solution; the mixed solution is added into a reaction kettle with a polytetrafluoroethylene lining to perform a heating reaction, and after being cooled to room temperature, the amino-functionalized metal organic framework is obtained after being taken out and washed.

3. The method for preparing a nanofiber membrane for separating cobalt ions and having radiation stability according to claim 1, wherein the semi-finished nanofiber membrane is prepared in the following manner: the amino-functionalized metal organic framework and preparation raw materials are dissolved in dimethylformamide, and air bubbles are removed to obtain a spinning raw material; the spinning raw material is spun by using an electrostatic spinning machine to prepare the semi-finished nanofiber membrane.

4. The method for preparing a nanofiber membrane for separating cobalt ions and having radiation stability according to claim 1, wherein the preparation raw materials comprise polyacrylonitrile and polyethylene glycol, and the polyacrylonitrile and the polyethylene glycol are both 1 g, the molecular weight of the polyacrylonitrile is 150000, and the molecular weight of the polyethylene glycol is 2000. ​ ​ ​

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