An acid-resistant COFs material capable of quickly and efficiently adsorbing thorium ions and a preparation method thereof

Abstract

The application provides a kind of COFs material of acid resistance, fast and efficient adsorption thorium ion and preparation method thereof, the COFs material is prepared by the reaction of aldehyde monomer tri-aldehyde phloroglucinol and amine monomer, and the amine monomer is 2,5-diamino terephthalic acid or 4,4'-diamino-[1,1'-biphenyl]-3,3'-dicarboxylic acid.The functionalized COFs material prepared by regulating grafting carboxyl has excellent thorium ion adsorption performance, has high adsorption capacity under strong acid conditions (pH=1-3), wherein under the conditions of initial concentration C0=400ppm, pH=3, the maximum adsorption capacity reaches 696mg / g within 10 hours, under the conditions of initial concentration C0=400ppm, pH=1, the maximum adsorption capacity reaches 225mg / g within 10 hours, and simultaneously has high stability in strong acid environment, and exhibits excellent regeneration and recycling performance.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of material preparation, in particular to a COFs material capable of rapidly and efficiently adsorbing thorium ions in an acid-resistant manner and a preparation method thereof. BACKGROUND

[0002] With rapid industrial expansion and rising energy demand, nuclear energy, as a sustainable and stable low-carbon energy, plays an irreplaceable role in the global energy system. The recovery and purification of actinides is the central link of the nuclear fuel cycle and is currently one of the most complex and challenging chemical processes known. Due to the radioactivity and high toxicity of thorium and its indispensable role in the sustainable development of nuclear energy, its recovery and purification are of great importance.

[0003] Thorium in aqueous solution is tetravalent (Th(IV)), and the pH value has a great influence on its migration and dispersion process. When pH > 4, Th 4+ starts to hydrolyze strongly and can be completely precipitated at pH = 5-6. At pH < 4, Th(IV) is relatively easy to disperse and migrate, and has good solubility, so it is very difficult to remove. At present, the removal of thorium ions mainly includes solvent extraction, membrane separation, chemical precipitation method and adsorption method, etc. Among them, adsorption method is considered to be an effective means for the separation of actinides, which has the advantages of low energy consumption, convenient operation and less secondary waste. The adsorbents reported for Th(IV) ions include carbon-based materials, zeolites, natural minerals, biomass, etc. Although these adsorbents have low cost, they have the disadvantages of low adsorption capacity, slow adsorption rate and poor selectivity. In addition, when used under the high acidity conditions existing in the nuclear industry, most of the adsorbents are difficult to maintain good stability and functionality at the same time. Therefore, there is an urgent need to develop new functional materials for efficient adsorption and separation of thorium in a strong acidic environment.

[0004] Metal-organic frameworks (MOFs) and covalent organic frameworks (COFs) can exhibit high structural designability by customizing linker and node functions. Among them, MOF materials have been studied more in adsorbing Th(IV) ions, but the structural stability of MOF materials is poor in harsh environments. In contrast, COFs materials exhibit high chemical stability in harsh environments due to their covalent bond connection. However, the existing COFs materials are difficult to achieve efficient and high-selectivity adsorption of thorium in a strong acid environment (pH < 3), and even do not adsorb at all in the pH = 1-2 range. SUMMARY

[0005] In view of this, the application provides a COFs material capable of rapidly and efficiently adsorbing thorium ions in an acid-resistant manner and a preparation method thereof to solve the above problems. The COFs material prepared by the application has important scientific research significance and practical application value for the adsorption of thorium ions in nuclear wastewater.

[0006] The technical scheme of the present application is implemented as follows:

[0007] An acid-resistant COFs material capable of quickly and efficiently adsorbing thorium ions is prepared by reacting an aldehyde monomer, tri-aldehyde phloroglucinol, and an amine monomer.

[0008] The amine monomer is 2,5-diamino terephthalic acid or 4,4'-diamino-[1,1'-biphenyl]-3,3'-dicarboxylic acid.

[0009] Further, the molar ratio of the aldehyde monomer to the amine monomer is 1:1-2.5.

[0010] A preparation method of an acid-resistant COFs material capable of quickly and efficiently adsorbing thorium ions, comprising the following specific steps: adding an aldehyde monomer and an amine monomer into an organic solvent, uniformly mixing by ultrasonic, then adding a catalyst, freezing with liquid nitrogen, vacuumizing, flame-sealing a tube, heating for crystallization, Soxhlet extraction, washing and drying, to obtain the target COFs material.

[0011] Further, the organic solvent is 1,4-dioxane and mesitylene at a volume ratio of 1:1-9, or n-butanol and o-dichlorobenzene at a volume ratio of 1:1-4.5.

[0012] Further, the solid-liquid ratio of the aldehyde monomer and the amine monomer to the organic solvent is 4.8-33.33 mg / mL.

[0013] Further, the catalyst is an acetic acid aqueous solution with a concentration of 6-12 mol / L; and the volume ratio of the catalyst to the organic solvent is 1:5-9.3.

[0014] Further, the ultrasonic time is 8-12 min.

[0015] Further, the heating crystallization temperature is 100-160℃, and the time is 3-9 days.

[0016] The COFs material obtained by the preparation method of any one of the above-mentioned embodiments has an application in quickly and efficiently adsorbing thorium ions.

[0017] Further, the solution pH of the thorium ions is 1-3.

[0018] Compared with the prior art, the present application has the following beneficial effects:

[0019] The functionalized COFs material prepared by regulating the grafted carboxyl has excellent thorium ion adsorption performance, has high adsorption capacity under the condition of strong acid (pH = 1-3), wherein the maximum adsorption capacity is 696 mg / g within 10 hours under the condition of initial concentration C0 = 400 ppm, pH = 3, the maximum adsorption capacity is 225 mg / g within 10 hours under the condition of initial concentration C0 = 400 ppm, pH = 1, has high stability in a strong acid environment, and exhibits excellent regeneration and recycling performance, and the adsorption capacity does not decrease after 5 cycles of adsorption experiments. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 is the adsorption principle diagram of the present application;

[0021] Figure 2 is the XPS spectrum of TP-DAT-COF of Example 1;

[0022] Figure 3 is the adsorption effect diagram of Example 1 (TP-DAT-COF) and Example 2 (TP-DBA-COF) under different cycle numbers;

[0023] Figure 4 is the adsorption effect diagram of Comparative Examples 1-3 under different cycle numbers. DETAILED DESCRIPTION

[0024] In order to better understand the technical content of the present application, specific examples are provided below to further illustrate the present application.

[0025] The experimental methods used in the embodiments of the present application are conventional methods unless otherwise specified.

[0026] The materials, reagents and the like used in the embodiments of the present application can be obtained from commercial channels unless otherwise specified.

[0027] The tri-aldehyde phloroglucinol, 2,5-diamino terephthalic acid, 4,4'-diamino-[1,1'-biphenyl]-3,3'-dicarboxylic acid, benzidine, 3,3'-dimethoxybenzidine and 3,3'-dihydroxybenzidine used in the present application are purchased from Huai Fang Xiaoyuan Chemical Trade Co., Ltd.

[0028] Abbreviation explanation

[0029]

[0030]

[0031] Example 1

[0032] In a 10 mL PIR tube, TP (7 mg, 0.033 mmol) and DAT (8 mg, 0.054 mmol) were added, followed by mixed organic solvents (0.9 mL mesitylene and 0.1 mL 1,4-dioxane), ultrasonic mixing for 10 min, adding acetic acid aqueous solution (6 mol / L, 0.2 mL), liquid nitrogen freezing, vacuum extraction, flame sealing tube, heating at 120°C for 3 days, tetrahydrofuran Soxhlet extraction for 24 h, washing, vacuum drying at 120°C for 12 h, to obtain a red powder of covalent organic framework material COFs material, named TP-DAT-COF.

[0033] The structural formula of TP-DAT-COF is:

[0034]

[0035] Example 2

[0036] In a 10 mL PIR tube, TP (9.5 mg, 0.045 mmol) and DBA (19 mg, 0.069 mmol) were added, followed by mixed organic solvents (0.55 mL mesitylene and 0.45 mL 1,4-dioxane), ultrasonic mixing for 10 min, adding acetic acid aqueous solution (6 mol / L, 0.2 mL), liquid nitrogen freezing, vacuum extraction, flame sealing tube, heating at 120°C for 3 days, acetone Soxhlet extraction for 24 h, washing, vacuum drying at 120°C for 12 h, to obtain a red powder of covalent organic framework material COFs material, named TP-DBA-COF.

[0037] The structural formula of TP-DBA-COF is:

[0038]

[0039] Example 3

[0040] In a 10 mL PIR tube, TP (10 mg, 0.047 mmol) and DAT (10 mg, 0.067 mmol) were added, followed by mixed organic solvents (0.5 mL n-butanol and 0.6 mL o-dichlorobenzene), ultrasonic mixing for 10 min, adding acetic acid aqueous solution (12 mol / L, 0.2 mL), liquid nitrogen freezing, vacuum extraction, flame sealing tube, heating at 120°C for 3 days, N,N-dimethylformamide Soxhlet extraction for 24 h, washing, vacuum drying at 120°C for 12 h, to obtain a red powder of covalent organic framework material COFs material, named TP-DAT-COF.

[0041] Example 4

[0042] In a 10 mL Pirex tube, TP (7 mg, 0.033 mmol) and DBA (15 mg, 0.054 mmol) were added, followed by mixed organic solvents (0.5 mL n-butanol and 1.0 mL o-dichlorobenzene), ultrasonic mixing for 10 min, adding acetic acid aqueous solution (12 mol / L, 0.2 mL), liquid nitrogen freezing, vacuum pumping, flame sealing tube, heating at 120°C for 3 days, ethanol Soxhlet extraction for 24 h, washing, vacuum drying at 120°C for 12 h, to obtain a red powder of covalent organic framework material COFs material, named TP-DBA-COF.

[0043] Comparative Example 1

[0044] The difference from Example 1 is that the DAT of the amine monomer is replaced by BD, and the others are consistent with Example 1.

[0045] In a 10 mL Pirex tube, TP (7 mg, 0.033 mmol) and DBA (15 mg, 0.054 mmol) were added, followed by mixed organic solvents (0.5 mL n-butanol and 1.0 mL o-dichlorobenzene), ultrasonic mixing for 10 min, adding acetic acid aqueous solution (12 mol / L, 0.2 mL), liquid nitrogen freezing, vacuum pumping, flame sealing tube, heating at 120°C for 3 days, ethanol Soxhlet extraction for 24 h, washing, vacuum drying at 120°C for 12 h, to obtain a red powder of covalent organic framework material COFs material, named TP-DBA-COF.

[0046] The structural formula of TP-BD-COF is:

[0047]

[0048] Comparative Example 2

[0049] The difference from Example 1 is that the DAT of the amine monomer is replaced by DMB, and the others are consistent with Example 1.

[0050] In a 10 mL Pirex tube, TP (7 mg, 0.033 mmol) and DBA (15 mg, 0.054 mmol) were added, followed by mixed organic solvents (0.5 mL n-butanol and 1.0 mL o-dichlorobenzene), ultrasonic mixing for 10 min, adding acetic acid aqueous solution (12 mol / L, 0.2 mL), liquid nitrogen freezing, vacuum pumping, flame sealing tube, heating at 120°C for 3 days, ethanol Soxhlet extraction for 24 h, washing, vacuum drying at 120°C for 12 h, to obtain a red powder of covalent organic framework material COFs material, named TP-DBA-COF.

[0051]

[0052] Comparative Example 3

[0053] Different from Example 1, DAT of the amine monomer is replaced by DHB, and the others are consistent with Example 1.

[0054] In a 10 mL pyrex tube, TP (7 mg, 0.033 mmol) and DHB (8 mg, 0.032 mmol) were added, then mixed with organic solvents (0.9 mL mesitylene and 0.1 mL 1,4-dioxane), ultrasonic mixed for 10 min, added with acetic acid aqueous solution (6 mol / L, 0.2 mL), liquid nitrogen refrigeration, vacuum extraction, flame tube sealing, heated at 120℃ for 3 days, extracted by tetrahydrofuran for 24 h, washed, and dried at 120℃ for 12 h to obtain a red powder of covalent organic framework COFs material, named TP-DHB-COF.

[0055] The structural formula of TP-DHB-COF is as follows:

[0056]

[0057] Test Example 1

[0058] The covalent organic framework COFs materials prepared in Examples 1-4 and Comparative Examples 1-3 were respectively weighed 2 mg, added into 6 mL thorium solution for adsorption experiment (initial concentration C0= 100 ppm, pH = 1-3), the rotation speed was 330 rpm, and the adsorption capacity was calculated after 10 h.

[0059] Q = [(C0- C t ) × V] / m

[0060] Wherein Q is the adsorption capacity, unit mg / g; C0is the initial concentration of thorium ions, unit ppm; C t is the concentration of thorium ions after 10 h, unit ppm; V is the volume of thorium solution, unit L; m is the mass of the prepared COFs material adsorbent, unit g.

[0061] The results are shown in Table 1.

[0062] Table 1

[0063]

[0064]

[0065] As shown in Table 1, under the conditions of an initial concentration of 100 ppm and pH of 1-3, the COFs material grafted with carboxyl groups (Examples 1-4) has an adsorption effect on Th(IV), and is obviously superior to the COFs material of Comparative Examples 1-3, indicating that the COFs material prepared in Examples 1-4 can effectively adsorb thorium under strong acid conditions.

[0066] Test Example 2

[0067] The covalent organic framework material COFs material prepared in Examples 1-4 and Comparative Examples 1-3 was weighed at 2 mg, respectively, and added into 6 mL of a thorium solution for adsorption experiments (initial concentration C0= 100 ppm, pH = 4-5), and the rotation speed was 330 rpm, and the adsorption capacity was calculated after 10 h.

[0068] The results are shown in Table 2.

[0069] Table 2

[0070]

[0071]

[0072] As shown in Table 2, under the conditions of an initial concentration of 100 ppm and pH of 4-5, the COFs material prepared in Examples 1-4 and Comparative Examples 1-3 has a saturated adsorption capacity (theoretical adsorption capacity), and the adsorption effect is not different. Therefore, the COFs material prepared in the present application can effectively adsorb thorium in the pH range of 1-5, and it is preferred to adsorb Th(IV) under strong acid conditions (pH = 1-3).

[0073] Test Example 3

[0074] The covalent organic framework material COFs material prepared in Examples 1-4 and Comparative Examples 1-3 was weighed at 2 mg, respectively, and added into 6 mL of a thorium solution for adsorption experiments (initial concentration C0= 400 ppm, pH = 1-3), and the rotation speed was 330 rpm, and the adsorption capacity was calculated after 10 h.

[0075] The results are shown in Table 3.

[0076] Table 3

[0077]

[0078] As shown in Table 3, under the conditions of an initial concentration of 400 ppm and pH of 1-3, the adsorption capacity of the carboxyl-functionalized COFs materials prepared in Examples 1-4 for Th(IV) is superior to that of the COFs materials prepared in Comparative Examples 1-3. Specifically, the carboxyl-functionalized COFs material prepared in Example 1 achieved a maximum adsorption capacity of 225 mg / g within 10 h at pH = 1, and a maximum adsorption capacity of 696 mg / g within 10 h at pH = 3, indicating that the carboxyl-grafted functionalized COFs material of Example 1 can achieve a high adsorption capacity for thorium under strongly acidic conditions.

[0079] from Figure 2 The XPS spectrum of TP-DAT-COF shows that after Th(IV) adsorption, TP-DAT-COF exhibits a significant Th 4f phase. 5 / 2 and Th 4f 7 / 2 The signal peak indicates that Th(IV) was successfully adsorbed. Furthermore, the electron binding energy of the signal peak corresponding to the O1s orbital on the carboxyl group in the sample shifted after adsorption, indicating that the carboxyl group in the functionalized COFs material of Example 1 has a coordination interaction with Th(IV).

[0080] from Figures 3-4 The adsorption effect graphs of different COFs materials under different cycles show that after 5 cycles of adsorption experiments (initial concentration of 100 ppm, pH=3), the adsorption capacity of the carboxyl-functionalized COFs materials prepared in Example 1 (TP-DAT-COF) and Example 2 (TP-DBA-COF) remained almost unchanged. This indicates that the carboxyl-functionalized COFs materials prepared in this invention have high stability under strong acid conditions and good regeneration cycle performance. The COFs materials prepared in Comparative Examples 1-3 showed a significant decrease in adsorption capacity after 5 cycles of adsorption experiments, indicating poor stability and poor regeneration cycle performance under strong acid conditions.

[0081] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. The use of an acid-resistant COFs material in the rapid and efficient adsorption of thorium ions, characterized by, The solution of the thorium ions has a pH of 1-3. The acid-resistant COFs material is prepared by reacting an aldehyde monomer, tri-aldehyde phloroglucinol, and an amine monomer; the amine monomer is 2,5-diamino terephthalic acid or 4,4'-diamino-【1,1'-biphenyl】-3,3'-dicarboxylic acid.

2. Use according to claim 1, wherein The molar ratio of the aldehyde monomer to the amine monomer is 1:1-2.

5.

3. The use according to claim 1, wherein The preparation method of the acid-resistant COFs material comprises the following steps: adding the aldehyde monomer and the amine monomer into an organic solvent, uniformly mixing by ultrasonic, adding a catalyst, freezing with liquid nitrogen, vacuumizing, flame-sealing a tube, heating and crystallizing, Soxhlet extraction and washing, and drying, so as to obtain the target COFs material.

4. The use according to claim 3, wherein the compound is ###0002### The organic solvent is 1,4-dioxane and mesitylene at a volume ratio of 1:1-9 or n-butanol and o-dichlorobenzene at a volume ratio of 1:1-4.

5.

5. The use according to claim 3, wherein the compound is ###0002### The solid-liquid ratio of the aldehyde monomer, the amine monomer and the organic solvent is 4.8-33.33 mg / mL.

6. The use according to claim 3, wherein the compound is ###0002### The catalyst is an acetic acid aqueous solution with a concentration of 6-12 mol / L; the volume ratio of the catalyst to the organic solvent is 1:5-9.

3.

7. The use according to claim 3, wherein the compound is ###0002### The ultrasonic time is 8-12 min.

8. The use according to claim 3, wherein the compound is ###0002### The heating and crystallizing temperature is 100-160 ℃, and the time is 3-9 days.

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