UiO-66-NH2-BPDA material, preparation method and application

Abstract

The present invention belongs to the field of water treatment technology, and specifically relates to a BPDA-modified UiO‑66‑NH2‑BPDA material, a preparation method thereof, and an application thereof. The preparation method comprises: adding BPDA to thionyl chloride, heating and refluxing to fully dissolve it to obtain a first solution; refluxing the first solution under reduced pressure, and purifying it to obtain a first reaction product; adding triethylamine, UiO‑66‑NH2, and the first reaction product to dichloromethane, heating and refluxing to fully react it to obtain a second reaction product; washing the second reaction product with dichloromethane, and centrifuging to obtain a solid product; and drying the solid product to obtain a final product. The preparation method of the present invention is simple to operate, and the prepared UiO‑66‑NH2‑BPDA significantly improves the uranium adsorption efficiency and adsorption capacity, and has excellent potential in actual uranyl ion removal applications in complex water treatment processes.

Description

Technical Field

[0001] The present invention belongs to the technical field of water treatment, and in particular relates to a BPDA-modified UiO-66-NH2-BPDA material, a preparation method thereof, and an application thereof. Background Art

[0002] Nuclear energy has become one of the most important options in the global energy transition due to its high energy, cleanness and low carbon. Uranium is the main fuel of nuclear energy, but due to its high chemical toxicity and long radioactive half-life, it has a great safety risk when used. In addition, uranium can also be converted into uranyl ions (UO2 2+ ) is dissolved in water, so UO2 2+ It can migrate through the aquatic environment and accumulate in the human body through the food chain. Controlling uranium pollution is of great significance to human safety and sustainable development.

[0003] Currently, the reported methods for removing UO2 2+ Solutions include chemical precipitation, ion exchange, adsorption, biological treatment and photocatalysis, etc. Adsorption is simple to operate, low cost and has strong adsorption capacity. 2+ Treatment process. In recent years, the reported uranium adsorbent materials include carbon-based materials, silicon-based materials, covalent organic framework materials (COF), metal-organic framework materials (MOF), etc. Among them, metal-organic framework materials (MOFs) are a kind of crystalline metal-organic framework porous materials with adjustable periodic pore structure, metal-organic nodes, excellent hot water stability and can be modified in different application directions. Among various MOFs, UiO-66-NH2 is considered to be an excellent substrate MOF due to its chemical stability, beautiful crystal structure, radiation resistance and multiple active sites. However, its adsorption effect on uranyl ions in uranium-containing wastewater is not good enough, and the adsorption rate is slow. In particular, different metal ions in water still interfere with the enrichment of uranium, so it is very important to develop uranium removal materials with large adsorption capacity and good selectivity. Summary of the Invention

[0004] The purpose of the present invention is to provide a UiO-66-NH2-BPDA material, a preparation method and an application thereof, so as to solve the problem proposed in the background art that the adsorption effect of the current adsorption materials on uranyl ions in uranium-containing wastewater is not good enough, and different metal ions in water still interfere with the enrichment of uranium.

[0005] To achieve the above object, the present invention provides a method for preparing a BPDA-modified UiO-66-NH2-BPDA material, comprising the following steps:

[0006] Step 1: adding 2,2'-bipyridine-6,6'-dicarboxylic acid (BPDA) to thionyl chloride, heating and refluxing to fully dissolve the BPDA to obtain a first solution;

[0007] Step 2, distilling and refluxing the first solution obtained in step 1 under reduced pressure to purify it to obtain a first reaction product;

[0008] Step 3: adding triethylamine, UiO-66-NH2 and the first reaction product obtained in step 2 to dichloromethane, heating and refluxing to fully react to obtain a second reaction product;

[0009] Step 4: washing the second reaction product obtained in step 3 with dichloromethane and centrifuging to obtain a solid product;

[0010] Step 5: Dry the solid product obtained in step 4 to obtain the final product.

[0011] In a specific embodiment, in step 1, the concentration of BPDA in the first solution is 0.052-0.054 mol / L.

[0012] In a specific embodiment, in step 1, the heating temperature is 85-95° C., and the reflux time is 2-4 hours.

[0013] In a specific embodiment, in step 3, when the reaction starts, the mass concentration of UiO-66-NH2 in the reaction solution is 6.5-6.7 g / L.

[0014] In a specific embodiment, in step 3, when the reaction starts, the concentration of triethylamine in the reaction solution is 0.009 to 0.01 mol / L.

[0015] In a specific embodiment, in step 3, the heating temperature is 55-65° C., and the reflux time is 5-7 hours.

[0016] In a specific embodiment, in step 4, the second reaction product is washed with dichloromethane 2 to 5 times, the centrifugal speed is 6000 to 10000 r / min, and the centrifugal time is 5 to 30 min.

[0017] In a specific embodiment, in step 5, the drying is performed by vacuum drying at 50-70° C. for 12-24 hours.

[0018] The present invention also provides a BPDA-modified UiO-66-NH2-BPDA material prepared according to the aforementioned method for preparing the BPDA-modified UiO-66-NH2-BPDA material.

[0019] The present invention also provides the use of a BPDA-modified UiO-66-NH2-BPDA material prepared according to the aforementioned preparation method of the BPDA-modified UiO-66-NH2-BPDA material in removing uranyl ions from uranium-containing wastewater, wherein the dosage of the BPDA-modified UiO-66-NH2-BPDA material in the uranium-containing wastewater is 0.1 to 0.5 g / L.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] (1) The UiO-66-NH2-BPDA material described in the present invention is structurally stable below 200°C and has good thermal stability.

[0022] (2) Compared with UiO-66-NH2, the UiO-66-NH2-BPDA material of the present invention has a higher pH value than that of UiO-66-NH2 at pH 1 to 6. 2+ The adsorption capacity is larger. Among them, under the condition of pH=6, the uranium adsorption capacity of UiO-66-NH2 is 49.58 mg / g, compared with that of UiO-66-NH2. 2+ The adsorption capacity can reach 283.56 mg / g. In addition, in the UiO-66-NH2-BPDA, UO2 2+ The saturated adsorption capacity can reach 346.58 mg / g.

[0023] (3) The adsorption capacity of UiO-66-NH2-BPDA in the UiO-66-NH2-BPDA material of the present invention gradually increases with the increase of temperature within 20-35°C. The experimental results show that the increase of temperature is conducive to the adsorption of UO2 by UiO-66-NH2-BPDA. 2+ .

[0024] (4) The UiO-66-NH2-BPDA material described in the present invention has excellent chemical stability and anti-interference performance, and has broad application prospects in the treatment of uranium-containing wastewater.

[0025] In addition to the above-described objects, features and advantages, the present invention has other objects, features and advantages. The present invention is further described in detail below. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The accompanying drawings, which constitute part of this application, are intended to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are intended to explain the present invention and do not constitute an undue limitation of the present invention. In the accompanying drawings:

[0027] Figure 1 This is a SEM image of UiO-66-NH2 at high magnification.

[0028] Figure 2 This is a high magnification SEM image of UiO-66-NH2-BPDA obtained in Example 1.

[0029] Figure 3 This is the thermogravimetric curve of UiO-66-NH2-BPDA obtained in Example 1.

[0030] Figure 4 The UiO-66-NH2-BPDA obtained in Example 1 reacts with different UO2 2+ Removal performance of initial concentration.

[0031] Figure 5 The results of the UiO-66-NH2 and UiO-66-NH2-BPDA obtained in Example 1 on the effects of different pH values ​​on UO2 2+ adsorption performance.

[0032] Figure 6 The UiO-66-NH2-BPDA obtained in Example 1 reacts with UO2 at different temperatures. 2+ adsorption performance.

[0033] Figure 7 The UiO-66-NH2-BPDA obtained in Example 1 was used to analyze the UO2 under different concentrations of different interfering ions. 2+ adsorption performance. DETAILED DESCRIPTION

[0034] The embodiments of the present invention are described in detail below. The specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0035] Example 1

[0036] (1) Add 200 mg of 2,2'-bipyridine-6,6'-dicarboxylic acid (BPDA) to 15 mL of thionyl chloride and heat under reflux at 90°C for 3 hours to fully dissolve it;

[0037] (2) distilling the solution obtained in step (1) under reduced pressure and refluxing to purify the reaction product;

[0038] (3) Add the reaction product obtained in step (2), 100 mg of UiO-66-NH2 and 15 mL of triethylamine to 15 mL of dichloromethane, and reflux at 60°C for 6 hours to allow the reaction to proceed fully;

[0039] (4) The reaction product obtained in step (3) was washed three times with dichloromethane and centrifuged at 8000 rpm for 10 min to obtain a solid;

[0040] (5) The solid product obtained in step (4) was vacuum dried at 60° C. for 12 hours to obtain the final product UiO-66-NH2-BPDA.

[0041] Figure 1 This is the SEM image of UiO-66-NH2 at high magnification; Figure 2 This is a high magnification SEM image of UiO-66-NH2-BPDA obtained in Example 1. Figure 1 It can be observed that UiO-66-NH2 has a smooth appearance and a clearly visible octahedral structure. Figure 2 It can be seen that due to the post-modification grafting of BPDA, UiO-66-NH2-BPDA becomes a crystal structure with a rough surface.

[0042] Figure 3 This is the thermogravimetric curve of UiO-66-NH2-BPDA obtained in Example 1. The mass of the UiO-66-NH2-BPDA material decreased by only 9.68% at a temperature of 200°C, indicating that the BPDA-modified UiO-66-NH2-BPDA material has good thermal stability.

[0043] Example 2

[0044] This example provides an application of a BPDA-modified UiO-66-NH2-BPDA material for removing uranyl ions from uranium-containing wastewater.

[0045] Different UO2 2+ Effect of initial concentration on the adsorption performance of UiO-66-NH2-BPDA by:

[0046] Weigh 4 mg of UiO-66-NH2-BPDA obtained in Example 1 and add 30 mL of UO2 2+ In a conical flask containing the solution, the pH of the solution was adjusted to 4 with negligible volumes of 1 mol / L HNO3 and 1 mol / L NaOH. The adsorption reaction was carried out on an air shaker at a constant temperature of 25°C and a rotational shaking speed of 250 rpm. After 10 hours of adsorption reaction, 1 mL of the supernatant was filtered through a 0.22 μm syringe filter and the concentration of uranyl ions before and after adsorption was determined using azoarsenic III spectrophotometry. 2+ Adsorption capacity q e (mg / g) and UO2 2+ The removal rate R (%) is calculated by the following formula (1) and formula (2) respectively.

[0047]

[0048] In formula (1) and formula (2), C0 (mg / L) and Ce (mg / L) represents the initial uranium concentration and adsorption equilibrium uranium concentration, respectively; V (mL) represents the volume of the adsorption solution, m (mg) is the mass of the adsorbent, and q e (mg·g -1 ) is UO2 2+ Equilibrium adsorption capacity, R is the UO2 at adsorption equilibrium 2+ removal rate.

[0049] Specifically, the initial UO2 2+ The concentrations are 5, 10, 15, 20, 30, 40, 50, 60, 70, and 80 mg / L.

[0050] Figure 4 The UiO-66-NH2-BPDA obtained in Example 1 reacts with different UO2 2+ The removal performance of the initial concentration. Figure 4 As shown, when the initial concentration is 80 mg / L, the UO2 2+ Adsorption equilibrium capacity q e =346.58 mg / g, indicating that UiO-66-NH2-BPDA has excellent UO2 2+ Adsorption capacity.

[0051] Table 1 Uranium adsorption capacity of different adsorption materials

[0052] adsorbent Optimal pH Adsorption capacity (mg / g) <![CDATA[UiO-66-NH2-BPDA]]> pH = 6 346.58 <![CDATA[UiO-66-NH2]]> pH=5.5 114.9 UiO-66 pH=5.5 109.9 UiO-66-NH-(AO) pH=5.5 134.1 UiO-66-2COOH pH=3 120 UiO-66-AO pH=5.5 106 UiO-66-2AO pH = 5 299.6

[0053] According to Table 1, UiO-66-NH2-BPDA has a larger uranium adsorption capacity than UiO-66 and its composite materials.

[0054] Example 3

[0055] This example provides an application of a BPDA-modified UiO-66-NH2-BPDA material for removing uranyl ions from uranium-containing wastewater.

[0056] Different UO2 2+ Effect of solution pH on the adsorption performance of UiO-66-NH2-BPDA:

[0057] The method is the same as that of Example 2, except that 4 mg of UiO-66-NH2 and UiO-66-NH2-BPDA were weighed and added to the initial UO2 2+ UO2 at different pH with a concentration of 40 mg / L 2+ Adsorption experiments were carried out in solution.

[0058] Specifically, the pH values ​​of the solution were adjusted to 1, 2, 3, 4, 5, and 6 respectively using negligible volumes of 1 mol / L HNO3 and 1 mol / L NaOH.

[0059] Figure 5 The results of the UiO-66-NH2 and UiO-66-NH2-BPDA obtained in Example 1 on the effects of different pH values ​​on UO2 2+ Adsorption performance. Figure 5 As shown, the pH value ranges from 1 to 6, UiO-66-NH2 to UO2 2+ The adsorption amount showed an upward trend with the increase of pH value, reaching a maximum value of 49.58 mg / g at pH = 6. After modification with BPDA, the adsorption amount increased significantly to 283.56 mg / g.

[0060] Example 4

[0061] This example provides an application of a BPDA-modified UiO-66-NH2-BPDA material for removing uranyl ions from uranium-containing wastewater.

[0062] Effect of different temperatures on the adsorption performance of UiO-66-NH2-BPDA:

[0063] The method is the same as that of Example 2, except that 4 mg of UiO-66-NH2-BPDA were weighed and the initial UO2 2+ UO2 at a concentration of 40 mg / L 2+ Adsorption experiments were carried out in solution.

[0064] Specifically, the temperatures were maintained at 20, 25, 30, and 35° C. using an air shaker.

[0065] Figure 6 The UiO-66-NH2-BPDA obtained in Example 1 reacts with UO2 at different temperatures. 2+ Adsorption performance. Figure 6 As shown in the figure, with the increase of temperature, the adsorption amount gradually increases, indicating that the increase of temperature promotes the adsorption of UiO-66-NH2-BPDA on UO2 2+ absorption.

[0066] Example 5

[0067] This example provides an application of a BPDA-modified UiO-66-NH2-BPDA material for removing uranyl ions from uranium-containing wastewater.

[0068] Effects of different interfering ions at different concentrations on the adsorption performance of UiO-66-NH2-BPDA:

[0069] The method is the same as that of Example 2, except that 4 mg of UiO-66-NH2-BPDA was weighed and the initial UO2 2+ UO2 at a concentration of 40 mg / L 2+ Adsorption experiments were carried out in solution.

[0070] Specifically, the different concentrations are 0.001, 0.005, and 0.01 mol / L.

[0071] Specifically, the interfering ion is Mn 2+ 、Zn 2+ , K + Mg 2+ 、Ni 2+ 、Na + .

[0072] Figure 7 The UiO-66-NH2-BPDA obtained in Example 1 was used to analyze the UO2 under different concentrations of different interfering ions. 2+ Adsorption performance. Figure 7 As shown, the UO2 of BPDA-modified UiO-66-NH2-BPDA material 2+ The adsorption capacity was not significantly affected by metal ions. Even in 0.01 mol / L metal ion solution, the UO2 2+ The adsorption capacity can still be absorbed more than 250 mg / g. Therefore, in complex water, UiO-66-NH2-BPDA has a good adsorption capacity for UO2 2+ Has excellent selectivity.

[0073] The above content is a further detailed description of the present invention in conjunction with specific preferred embodiments, and the specific implementation of the present invention should not be considered to be limited to these descriptions. For those skilled in the art of the present invention, several simple deductions and substitutions can be made without departing from the concept of the present invention, and all of these should be considered to fall within the scope of protection of the present invention.

Claims

1. A method for preparing BPDA-modified UiO-66-NH2-BPDA material, characterized in that: The following steps are involved: Step 1: adding 2,2'-bipyridine-6,6'-dicarboxylic acid (BPDA) to thionyl chloride, heating and refluxing to fully dissolve it to obtain a first solution; in step 1, the concentration of BPDA in the first solution is 0.052 to 0.054 mol / L; Step 2, distilling and refluxing the first solution obtained in step 1 under reduced pressure to purify it to obtain a first reaction product; Step 3: adding triethylamine, UiO-66-NH2 and the first reaction product obtained in step 2 to dichloromethane, heating and refluxing to fully react to obtain a second reaction product; in step 3, at the start of the reaction, the mass concentration of UiO-66-NH2 in the reaction solution is 6.5-6.7 g / L; Step 4: washing the second reaction product obtained in step 3 with dichloromethane and centrifuging to obtain a solid product; Step 5: Dry the solid product obtained in step 4 to obtain the final product.

2. The method for preparing the BPDA-modified UiO-66-NH2-BPDA material according to claim 1, characterized in that: In the step 1, the heating temperature is 85 to 95° C., and the reflux time is 2 to 4 hours.

3. The method for preparing the BPDA-modified UiO-66-NH2-BPDA material according to claim 1, characterized in that: In step 3, when the reaction starts, the concentration of triethylamine in the reaction solution is 0.009 to 0.01 mol / L.

4. The method for preparing the BPDA-modified UiO-66-NH2-BPDA material according to claim 1, characterized in that: In step 3, the heating temperature is 55-65° C., and the reflux time is 5-7 hours.

5. The method for preparing the BPDA-modified UiO-66-NH2-BPDA material according to claim 1, characterized in that: In the step 4, the second reaction product is washed with dichloromethane 2 to 5 times, the centrifugal speed is 6000 to 10000 r / min, and the centrifugal time is 5 to 30 minutes.

6. The method for preparing the BPDA-modified UiO-66-NH2-BPDA material according to claim 1, characterized in that: In step 5, the drying is performed by vacuum drying at 50-70° C. for 12-24 hours.

7. The BPDA-modified UiO-66-NH2-BPDA material prepared according to the method for preparing the BPDA-modified UiO-66-NH2-BPDA material according to any one of claims 1 to 6.

8. Use of the BPDA-modified UiO-66-NH2-BPDA material prepared by the method for preparing the BPDA-modified UiO-66-NH2-BPDA material according to any one of claims 1 to 6 in removing uranyl ions from uranium-containing wastewater, characterized in that: The dosage of the BPDA-modified UiO-66-NH2-BPDA material in uranium-containing wastewater is 0.1-0.5 g / L.

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