A guanidinium-sulfide covalent organic polymer for efficient capture of iodine ions and a preparation method thereof

Abstract

The application discloses a guanidyl-sulfide covalent organic polymer for efficiently capturing iodine ions and a preparation method thereof, and relates to the technical field of iodine-containing wastewater treatment. The guanidyl-sulfide covalent organic polymer has a core structure of guanidyl and a sulfide group, and is formed by being connected through a strong covalent bond, and exhibits excellent chemical stability, thermal stability and radiation resistance, and is especially suitable for application requirements in extreme environments. Meanwhile, the unique N(+) cation in the guanidyl and the C-S-C bond in the sulfide cooperatively act, and the guanidyl-sulfide covalent organic polymer exhibits high removal efficiency and excellent selectivity for iodine ions in iodine-containing wastewater, and has a significant application prospect.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of iodine-containing wastewater treatment, and particularly relates to a guanidyl-sulfide covalent organic polymer for efficiently capturing iodine ions and a preparation method thereof. BACKGROUND

[0002] The isotopes of iodine in iodine-containing wastewater mainly include 129 I, 131 I. 129 I is a long-lived radioisotope (half-life of 1.57 x 10 7 years), which is produced in the nuclear fission process of uranium-235 and bears the burden of long-term disposal of nuclear waste. 131 I is a short half-life nuclide (about 8 days), which is widely used in the diagnosis and treatment of nuclear medicine, and a large amount of 131 I-containing wastewater is produced in the use of 131 I-containing drugs. In radioactive iodine wastewater, iodine mainly exists in the form of iodide (I - ) and iodate (IO3 - ). Due to its high radioactivity toxicity, extremely high solubility and migration rate, it becomes one of the most problematic radioisotopes in nuclear fuel cycle and nuclear medicine application, which brings many problems that must be considered for the safe disposal of radioactive iodine. Therefore, effective treatment of radioactive iodine produced in the nuclear industry environment and nuclear medicine application has important significance for the development of nuclear science and technology.

[0003] The treatment methods of iodine-containing wastewater mainly include chemical precipitation method, membrane separation method, adsorption method and biological method. A method for removing I - anion from water is to use compounds containing Ag(I), Cu(I), Bi(III) and Hg(II) cations to form low-solubility precipitates with I - . Traditional silver-based adsorbents are commercial products, which show effective I - removal, but the high cost limits its practical application. Adsorption method is widely used due to its simple operation and relatively low cost, and common adsorbents include carbon-based, bismuth-based and metal-organic framework materials, etc. Carbon-based materials such as activated carbon and graphene have many micropores, macropores and high specific surface area, which can provide I -A large amount of adsorption space is provided, and the removal rate of iodine ions in an aqueous solution reaches 90%, however, the microporous structure of carbon-based materials is easy to block, which can lead to a decrease in adsorption capacity. Bismuth-based compounds such as Bi2O3, BiVO4 and Bi5(NO3)O7 have been studied as one of the most promising candidates for iodine ion removal, with the advantages of low toxicity, high affinity and low cost, but bismuth-based materials are unstable in acidic conditions, which leads to difficulties in practical application. Emerging metal organic framework (MOF) materials exhibit high adsorption performance for radioactive iodine, however, due to the inherent limited stability and high cost of MOF, this material has not been commercialized. Therefore, it is necessary to develop a green and economical adsorbent that can effectively remove radioactive I - . SUMMARY

[0004] The purpose of the present application is to provide a guanidinium-sulfide covalent organic polymer for efficiently capturing iodine ions and a preparation method thereof, so as to solve the problems existing in the prior art, so that the compound has the characteristics of high stability, high selectivity, easy synthesis and low cost, thereby improving the energy utilization rate and the treatment efficiency of iodine-containing wastewater.

[0005] To achieve the above purpose, the present application provides the following solutions:

[0006] One of the technical solutions of the present application: a guanidinium-sulfide covalent organic polymer is provided, the structure is as shown below:

[0007]

[0008] The second technical solution of the present application: a preparation method of the above guanidinium-sulfide covalent organic polymer is provided, comprising the following steps:

[0009] N,N',N"-triaminoguanidine hydrochloride and 2,5-thiophenedicarboxaldehyde are used as raw materials, and an aldehyde-ammonia condensation reaction is performed to generate the guanidinium-sulfide bifunctional covalent organic polymer.

[0010] Further, the aldehyde-ammonia molar ratio of the aldehyde-ammonia condensation reaction is 3:2-2:1.

[0011] Further, the temperature of the aldehyde-ammonia condensation reaction is 90-120℃; and the time of the aldehyde-ammonia condensation reaction is 1-24h.

[0012] Further, the preparation method comprises the following steps:

[0013] (1) according to the aldehyde-ammonia molar ratio 3:2-2:1, N,N',N"-triaminoguanidine hydrochloride is dissolved in a first solvent to obtain a first solution, and 2,5-thiophenedicarboxaldehyde is dissolved in a second solvent to obtain a second solution; the first solution and the second solution are mixed to obtain a mixed solution;

[0014] (2) refluxing the mixed solution at 90-120℃ for 1-24h;

[0015] (3) centrifuging the reaction system obtained in step (2), collecting the precipitate and washing and drying to obtain the guanidyl-thioether covalent organic polymer.

[0016] Further, the first solvent is preferably deionized water, and the second solvent is preferably 1,4-dioxane.

[0017] Further, the mixing is performed by ultrasonic dispersion.

[0018] Further, the drying temperature is 55-65℃, and the drying time is 36-48h.

[0019] Further, the washing is preferably performed by sequentially washing with 1,4-dioxane, anhydrous ethanol and deionized water until the washing liquid is colorless.

[0020] The third technical solution of the present application provides the application of the guanidyl-thioether covalent organic polymer in the treatment of iodine-containing water bodies.

[0021] Further, the guanidyl-thioether covalent organic polymer is added into the iodine-containing water body for reaction to realize the treatment of the iodine-containing water body.

[0022] Further, during the treatment of the iodine-containing water body, the reaction is performed at room temperature, and the reaction time is preferably 1min-2h.

[0023] Further, the concentration of iodine in the iodine-containing water body is 0.1-800mg / L, and the pH of the iodine-containing water body is 2-10.

[0024] More specifically, the guanidyl-thioether covalent organic polymer is added into the iodine-containing water body to be treated, and reacted at room temperature for 1min-12h, and then solid-liquid separation is performed to obtain supernatant and iodine-containing solid, thereby realizing the capture and removal of iodine in the water body.

[0025] Further, 5-500mg of the guanidyl-thioether covalent organic polymer material is added into 1g / L iodine-containing wastewater.

[0026] The present application synthesizes a covalent organic polymer containing guanidyl and thioether bifunctional groups by using N,N',N"-triaminoguanidine hydrochloride and 2,5-thiophenedicarboxaldehyde as raw materials through aldehyde-ammonia condensation reaction. The polymer forms a stable structure through strong covalent bonds and exhibits excellent chemical stability, thermal stability and radiation resistance in extreme environments.

[0027] The present application has the following technical advantages:

[0028] (1) The guanidyl-sulfide covalent organic polymer prepared by the application can be synthesized rapidly under mild conditions, and the material has a porous structure and a high specific surface area, which helps to significantly improve the removal efficiency of iodine ions.

[0029] (2) The guanidyl-sulfide covalent organic polymer prepared by the application is formed through a Schiff base reaction, and has a strong covalent carbon-nitrogen double bond (C=N) as a core structure, and a π-π conjugated system in the thiophene group, which endows the material with excellent performance in extreme environments, including good chemical stability, thermal stability and radiation resistance.

[0030] (3) The material constructed by the guanidyl and thiophene groups has a dual functional property: on the one hand, the nitrogen cation in the guanidyl can be closely complexed with iodine ions through electrostatic interaction, thereby effectively removing iodine ions in iodine-containing wastewater; on the other hand, the sulfide bond in the thiophene group can form a coordination bond with iodine ions through the lone pair of electrons of the sulfur atom, showing good affinity for iodine ions. The synergistic effect of the two groups further improves the adsorption capacity of the material for iodine ions and the treatment efficiency of iodine-containing wastewater.

[0031] (4) Experimental results show that the guanidyl-sulfide covalent organic polymer synthesized by the application has a maximum capture capacity for iodine ions of up to 253 mg / g, showing excellent adsorption performance.

[0032] (5) The preparation method of the guanidyl-sulfide covalent organic polymer of the application is simple in material selection, simple in synthesis steps, mild in reaction conditions and low in cost, and is suitable for large-scale industrial production. At the same time, the method is green and environmentally friendly, and can be widely applied in the field of iodine-containing wastewater treatment.

[0033] The application discloses the following technical effects:

[0034] The application provides a guanidyl-sulfide covalent organic polymer, which has high chemical stability, thermal stability and radiation resistance in extreme environments.

[0035] The polymer material utilizes the synergistic effect between the N(+) cation in the guanidyl and the C-S-C bond in the sulfide, and exhibits high removal efficiency and good selectivity for iodine ions in iodine-containing wastewater. Experimental results show that the capture capacity of the material for iodine can be up to 80 mg / g or more, which has significant application potential. BRIEF DESCRIPTION OF DRAWINGS

[0036] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments 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.

[0037] Figure 1 Scanning electron microscopy image of a guanidine-thioether covalent organic polymer;

[0038] Figure 2 The graph shows the effect of reaction time on the removal of iodide ions by guanidino-thioether covalent organic polymers.

[0039] Figure 3 This is a graph showing the adsorption capacity of guanidinyl-thioether covalent organic polymers for iodide ions.

[0040] Figure 4 The graph shows the effect of pH on the removal of iodide ions by guanidino-thioether covalent organic polymers.

[0041] Figure 5 Figure showing the effect of guanidinyl-thioether covalent organic polymers on the removal of iodide ions under different competing ion coexistence conditions;

[0042] Figure 6 Thermogravimetric diagram of guanidinyl-thioether covalent organic polymer;

[0043] Figure 7 Figure showing the effect of guanidinyl-thioether covalent organic polymers on the removal of iodide ions under strong acid, strong alkali and strong radiation environments;

[0044] Figure 8 The elemental energy spectrum of a guanidine-thioether covalent organic polymer;

[0045] Figure 9 This is a specific surface area diagram of guanidine-thioether covalent organic polymers. Detailed Implementation

[0046] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0047] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Any stated value or intermediate value within a stated range, as well as each smaller range between any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0048] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. Although methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present application, the preferred methods and materials are described. All publications mentioned in this specification are herein incorporated by reference to disclose and describe the methods and / or materials in connection with which the publications are cited. The citation of any reference is not an admission that it is prior art with respect to the present application.

[0049] Many modifications and variations of this application of the application can be made without departing from its spirit or scope, which will be apparent to those skilled in the art. Other embodiments of the application will be apparent to those skilled in the art from consideration of the specification and practice of the application disclosed herein. The specification and examples given are exemplary only.

[0050] It has to be noted that, as used herein, the terms "comprising", "including", "containing", "having" and the like are to be understood to be open-ended, i.e., to mean including but not limited to.

[0051] It has to be noted that, as used herein, the terms "comprising", "including", "containing", "having" and the like are to be understood to be open-ended, i.e., to mean including but not limited to.

[0052] The present application provides a guanidinium-sulfide covalent organic polymer with the following structure:

[0053]

[0054] The present application also provides a preparation method of the guanidinium-sulfide covalent organic polymer with the above structure, comprising the following steps:

[0055] The guanidinium-sulfide covalent organic polymer is prepared by an aldehyde-ammonia condensation reaction using N,N',N"-triaminoguanidine hydrochloride and 2,5-thiophenedicarboxaldehyde as raw materials.

[0056] As a more preferred technical solution, the molar ratio of aldehyde to ammonia in the aldehyde-ammonia condensation reaction is 3:2.

[0057] As a more preferred technical solution, the temperature of the aldehyde-ammonia condensation reaction is 90-120℃; and the time of the aldehyde-ammonia condensation reaction is 1-24h.

[0058] The more specific preparation method of the guanidinium-sulfide covalent organic polymer with the above structure comprises the following steps:

[0059] (1) 42.048 mg-4.2048 g of 2,6-thiophenedicarboxaldehyde (0.3-30 mmol) was dissolved in 15 mL of 1,4-dioxane to obtain a first solution; 28.115 mg-2.8115 g of N,N',N"-triaminoguanidine hydrochloride (0.2-20 mmol) was dissolved in 5 mL of deionized water to obtain a second solution; the first solution and the second solution were mixed and ultrasonically dispersed at room temperature for 10 minutes to obtain a mixed solution;

[0060] (2) The mixed solution was heated by an oil bath and refluxed at a temperature of 90-120℃ for 1-24 h to generate an orange substance.

[0061] (3) The orange substance was centrifuged to obtain a precipitate, and the precipitate was washed until the washing liquid was colorless to obtain an orange solid; the orange solid was dried in an oven at 55-65℃ for 36-48 h to obtain a guanidyl-sulfide covalent organic polymer in the form of an orange powder.

[0062] In step (3), the precipitate was sequentially centrifuged and washed with 1,4-dioxane, anhydrous ethanol and a deionized water solution until the supernatant was clear and colorless.

[0063] In the embodiments of the present application, the synthesis route of the guanidyl-sulfide covalent organic polymer material is as follows:

[0064]

[0065] Example 1

[0066] Preparation of the guanidyl-sulfide covalent organic polymer material:

[0067] (1) 42.048 mg of 2,5-thiophenedicarboxaldehyde (0.3 mmol) was dispersed in 6 mL of 1,4-dioxane, and 28.115 mg of N,N',N"-triaminoguanidine hydrochloride (0.2 mmol) was dissolved in 2 mL of ultrapure water solution, and then the two solutions were placed in a 25 mL round-bottom flask and ultrasonically dispersed for 10 minutes.

[0068] (2) The round-bottom flask was placed in an oil bath and equipped with a spherical condenser, then the temperature was raised and a magnetic stirrer was added for magnetic stirring, the target temperature was set to 90℃, and finally the temperature was kept constant at this temperature for 1 h to generate an orange substance.

[0069] (3) The orange substance was centrifuged to obtain a precipitate, and the precipitate was washed with 1,4-dioxane, anhydrous ethanol and ultrapure water until the washing liquid was colorless, and then solid-liquid separation was performed to obtain an orange solid, and finally the guanidyl-sulfide covalent organic polymer was obtained by drying in an oven at about 60℃ for 42 h, with a yield of 94%.

[0070] The guanidyl-sulfide covalent organic polymer prepared in this embodiment 1 is a porous structure, which is an orange powdery solid.

[0071] Figure 8 Elemental spectrum of the guanidyl-sulfide covalent organic polymer; Figure 9 Specific surface area graph of the guanidyl-sulfide covalent organic polymer. It can be seen that the guanidyl-sulfide covalent organic polymer of the present application is composed of four light elements of carbon, nitrogen, sulfur and hydrogen. The specific surface area is 20-35 m 2 / g, the pore size is 1.7-6.5 nm, and the pore volume is 0.03-0.11 cm 3 / g. The polymer surface contains nitrogen cations with high charge density and reactivity, which is composed of strong covalent bond carbon-nitrogen double bond (C=N) and has good stability in strong acid, strong base and strong radiation environment.

[0072] Embodiment 2

[0073] Preparation of guanidyl-sulfide covalent organic polymer material:

[0074] (1) 1.6819 g of 2,5-thiophenedicarboxaldehyde (12 mmol) was dispersed in 15 mL of 1,4-dioxane, and 0.8435 g of N,N',N"-triaminoguanidine hydrochloride (6 mmol) was dissolved in 5 mL of ultrapure water solution, then the two solutions were placed in a 50 mL round-bottom flask and ultrasonically dispersed for 10 minutes.

[0075] (2) The round-bottom flask was placed in an oil bath and a spherical condenser was installed, then the temperature was raised and a magnetic stirrer was added for magnetic stirring, the target temperature was set to 100°C, and finally the temperature was kept constant at this temperature for 24 h to generate an orange substance.

[0076] (3) The orange substance was centrifuged to obtain a precipitate, which was washed with 1,4-dioxane, anhydrous ethanol and ultrapure water until the washing liquid was colorless, and the solid-liquid separation was carried out to obtain an orange solid, and finally, the guanidyl-sulfide covalent organic polymer was obtained by drying in an oven at about 60°C for 42 h, with a yield of 91%.

[0077] The guanidyl-sulfide covalent organic polymer prepared in this embodiment 2 is a porous structure, which is an orange powdery solid, composed of four light elements of carbon, nitrogen, sulfur and hydrogen, with a specific surface area of 20-35 m 2 / g, a pore size of 1.7-6.5 nm, and a pore volume of 0.03-0.11 cm 3 / g; the polymer surface contains nitrogen cations with high charge density and reactivity, which is composed of strong covalent bond carbon-nitrogen double bond (C=N) and has high stability in strong acid, strong base and strong radiation environment.

[0078] The guanidinium-sulfide covalent organic polymer material prepared in Example 1 was subjected to performance characterization:

[0079] Figure 1 It can be seen that the prepared guanidinium-sulfide covalent organic polymer presents a porous structure, which is conducive to the removal of iodine ions.

[0080] 10 mg of guanidinium-sulfide covalent organic polymer was reacted with 10 mL of an aqueous solution containing iodine ions (concentration of 50 mg / L), the pH of the system was 6.0, the reaction temperature was 25°C, and a magnet was added for magnetic stirring. After the reaction was completed, the solid-liquid was separated, and the supernatant was subjected to ultraviolet spectrophotometer measurement. The test data obtained were analyzed and arranged, and the results showed that the guanidinium-sulfide covalent organic polymer could capture more than 90% of iodine ions, and the adsorption equilibrium could be reached in 20 minutes. Figure 2 It is a graph showing the effect of reaction time on the removal of iodine ions by the guanidinium-sulfide covalent organic polymer.

[0081] At room temperature, 5 mg of guanidinium-sulfide covalent organic polymer was added to 10 mL of iodine-containing wastewater with a concentration of 10, 20, 40, 60, 80, 100, 150, 200, 300, 500, and 800 mg / L at pH 7.0, and the reaction was carried out for 2 h. The experimental results showed that the guanidinium-sulfide covalent organic polymer had a very good effect on the removal of iodine from iodine-containing wastewater, and the maximum adsorption capacity reached 253 mg / g. The results showed that the guanidinium-sulfide covalent organic polymer exhibited an ultra-high adsorption capacity for iodine. Figure 3 It is a graph showing the adsorption capacity of guanidinium-sulfide covalent organic polymer for iodine ions.

[0082] At room temperature, 10 mg of guanidinium-sulfide covalent organic polymer material was added to 7 groups of 10 mL of iodine-containing wastewater with a concentration of 50 mg / L, and 0.01 mol / L hydrochloric acid (HNO3) and sodium hydroxide (NaOH) solution were used to adjust the pH of the mixed system to 3 to 9. The results showed that within the pH range of 3 to 9, the guanidinium-sulfide covalent organic polymer maintained an iodine removal capacity of more than 80 mg / g. Figure 4 It is a graph showing the effect of pH on the removal of iodine ions by the guanidinium-sulfide covalent organic polymer.

[0083] At room temperature, 5 mg of guanidinium-sulfide covalent organic polymer material was added to 10 mL of iodine-containing wastewater with a concentration of 50 mg / L NaCl + 50 mg / L I - , 50 mg / L NaNO3 + 50 mg / L I - , 50 mg / L Na2SO4 + 50 mg / L I -and 50 mg / L Na2CO3+50 mg / L I - The removal capacity of iodine varied with the anion species as shown in Figure 5 The results showed that the removal capacity of iodine was only slightly decreased in the presence of competitive ions, indicating that the material had good selectivity for iodine ions.

[0084] A certain amount of guanidyl-sulfide covalent organic polymer material sample was taken for thermogravimetric analysis. The results showed that the decomposition stage of guanidyl-sulfide covalent organic polymer was divided into four stages, and when the temperature reached 413.5K, the mass loss of the polymer was 8.22%, indicating that the material had good thermal stability. Figure 6 The thermogravimetric diagram of guanidyl-sulfide covalent organic polymer.

[0085] A certain amount of guanidyl-sulfide covalent organic polymer material sample was taken and placed in a gamma irradiation and strong acid environment, respectively, with no treatment as a blank group. The treated samples were verified for iodine ion removal effect, specifically 5mg of guanidyl-sulfide covalent organic polymer sample before and after treatment was added to 10mL of 50mg / L iodine ion solution and reacted for 6h. The iodine ion removal capacity under different irradiation conditions and strong acid environment is shown in Figure 7 The removal capacity of iodine by the polymer material after gamma irradiation treatment did not decrease significantly, indicating that the polymer material had good anti-irradiation performance. The removal capacity of iodine by the polymer material after strong acid treatment decreased slightly, still showing good chemical stability.

[0086] The above-described embodiments are only to describe the preferred modes of the present application, and do not limit the scope of the present application. Without departing from the design spirit of the present application, various modifications and improvements to the technical solutions of the present application made by those of ordinary skill in the art shall fall within the protection scope determined by the claims of the present application.

Claims

1. Use of a guanidinium-sulfide covalent organic polymer in the treatment of water bodies containing iodine, characterized in that, The guanidyl-sulfide covalent organic polymer is used for removing iodine ions in iodine-containing wastewater, and the structure of the guanidyl-sulfide covalent organic polymer is shown as follows: 。 2. Use according to claim 1, characterized in that, The guanidyl-sulfide covalent organic polymer is added into the iodine-containing water body to react, so that the iodine-containing water body is treated.

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