CN113385148B

CN113385148B - Framework material with Ag nano-particle compound, preparation method and application

Info

Publication number: CN113385148B
Application number: CN202110854855.0A
Authority: CN
Inventors: 刘大欢; 王婷; 赵慧芳
Original assignee: Beijing University of Chemical Technology
Current assignee: Beijing University of Chemical Technology
Priority date: 2021-07-28
Filing date: 2021-07-28
Publication date: 2022-04-08
Anticipated expiration: 2041-07-28
Also published as: CN113385148A

Abstract

The invention relates to the technical field of nano porous materials, and discloses a framework material with an Ag nano particle compound, a preparation method and application. The material comprises organic frameworks UiO and Ag⁰Nanoparticles using a metal-organic framework material Zr-MOF (UiO-66- (OH)₂) Reacting with silver salt solution, and synthesizing by a one-step reduction method. The material has larger adsorption capacity and faster adsorption removal rate for radioactive iodide ions in water, and has good anti-ion interference capability. In the aspect of material preparation, the preparation method provided by the invention has the advantages of simple operation, economy, saving and the like.

Description

Framework material with Ag nano-particle compound, preparation method and application

Technical Field

The invention relates to the technical field of nano porous materials, in particular to a framework material with an Ag nano particle compound, a preparation method and application.

Background

Nuclear energy is a clean and efficient energy source and plays an important role in numerous energy sources. The radioactive iodine is widely applied to the aspects of nuclear accident detection, underground water search, underground water flow velocity and direction measurement, underground pipeline leakage and the like in nuclear energy, inevitably enters lakes or drinking water and directly causes harm to human beings, so that the radioactive iodine ions in the water body are effectively removed, and the long-term influence on the environment is reduced, thereby having very important significance.

Compared with methods such as ion exchange, membrane separation, electrochemistry and the like, the adsorption method (adsorption) has the advantages of simple operation, energy conservation and the like, thereby having good prospect in the aspect of application of removing radioactive iodine in water. The key to the adsorption process is the selection of a suitable adsorbent. At present, different types of adsorption materials such as porous carbon, zeolite, bismuth oxide and other compounds have been used for studying the adsorption removal of radioactive iodide ions in water, in particular, precipitation type adsorbents such as Hg⁺，Cu⁺，Ag⁺，Bi⁺Some of the adsorbents of (1). However, from the practical application point of view, the adsorption performance of these materials is not high, and the preparation process is relatively complicated, and it is still a concern to develop new materials with better performanceThe focus of the note. Metal-organic frameworks (MOFs) have good structure designability and chemical property controllability, and have shown wide application prospects in the field of adsorption materials. Therefore, it is very important to develop a metal-organic framework material loaded with a suitable metal adsorbent for adsorption removal of iodide ions.

Disclosure of Invention

The present invention is proposed for this purpose, and provides a framework material (Ag) having Ag nanoparticle composite⁰@ UiO). Ag contained in the material⁰The nano particles have strong affinity to radioactive iodide ions and strong chemical action between silver and iodine, so that the material has larger adsorption capacity and faster adsorption removal rate to the radioactive iodide ions in the water body, and is superior to other reported iodide ion adsorbents; in the aspect of material preparation, the preparation method provided by the invention has the advantages of simple operation, economy, saving and the like.

A skeleton material with Ag nano-particle composition is composed of organic skeleton UiO and Ag⁰And (3) nanoparticles. Wherein the organic framework UiO accounts for 97.6 to 98 percent of the mass portion, and the specific surface area is 400-800m²Ag, with a porosity of 0.6-0.7ml/g ⁰2 to 2.4 mass percent of nano particles with the size of 5 to 9.8 nm.

Meanwhile, the invention also provides a preparation method of the framework material with the Ag nano-particle compound, which comprises the following steps:

(1) dissolving zirconium salt and an organic ligand in a solvent and stirring to obtain a mixed solution;

(2) adding absolute ethyl alcohol and acetic acid into the mixed solution obtained in the step (1) to obtain a mixture, transferring the mixture into a reaction kettle, sealing and heating for reaction for a period of time;

(3) washing the product of the step (2) with N-N Dimethylformamide (DMF) solvent and absolute ethyl alcohol successively to obtain UiO-66- (OH)₂；

(4) Mixing UiO-66- (OH)₂Adding the solution into silver salt solution, stirring, reacting for a period of time, separating out solid, washing and drying to obtain the framework material with the Ag nano-particle compound.

Wherein, the zirconium salt in the step (1) is zirconium chloride, the organic ligand is 2, 5-dihydroxy terephthalic acid, and the solvent is DMF. The molar mass ratio of the zirconium salt to the organic ligand is 1:1 to 3:1, preferably 1.95: 1.

The molar mass ratio of the absolute ethyl alcohol to the acetic acid in the step (2) is 0.5:1-1:1, and preferably 0.98: 1. The reaction is carried out for 48 hours at 403K.

In the step (4), the silver salt solution is silver nitrate, and the silver salt and the UiO-66- (OH)₂The molar mass ratio of (a) to (b) is from 1:40 to 1:50, preferably 1: 43. The reaction is carried out for 12 hours at room temperature, and the drying is carried out for 24 hours at 100 ℃.

Step (4) Using a one-step reduction method, using UiO-66- (OH)₂The material has reductive-OH functional group to make silver nitrate solution Ag⁺Reduction to Ag⁰Adding Ag without adding extra reducing agent⁺Reduction to Ag⁰The Ag nano particles can be uniformly dispersed in the material, and the phenomena of agglomeration and the like are avoided, so that the adsorption performance of the material is not influenced.

Another object of the present invention is to provide a use of the framework material with Ag nanoparticle composite for adsorbing radioactive iodine in water, which comprises the following contents:

adding a sample into an iodine-containing solution, oscillating and adsorbing for a certain time at a certain temperature, sampling, measuring the absorbance of the sample by using an ultraviolet spectrophotometer (TU-1901), and calculating the mass concentration of the sample according to a standard curve of the iodine ion content so as to calculate the adsorption capacity and adsorption kinetics of the iodine ions.

And (2) adding the sample into a solution containing different impurity ions and iodide ions, wherein the adsorption time is 24 hours, the adsorption temperature is 30 ℃, and the influence of different competitive ions on the adsorption of the iodide ions by the sample is measured.

Ag⁰After @ UiO is added into water, Ag⁰Ag in @ UiO⁰The nano particles are oxidized into Ag by the dissolved oxygen in the water body⁺，Ag⁺To I^-Has strong affinity and Ag⁺And I^-The material Ag is caused by strong chemical action⁰@ UiO has a larger adsorption capacity for iodide ions, which is beneficial to the removal of radioactive iodide ions.

The invention has the beneficial effects that:

(1)Ag⁰ag contained in @ UiO⁰The nano particles have strong affinity to radioactive iodide ions and strong chemical action between silver and iodine, so that the material has large adsorption capacity (447.02mg g) to the radioactive iodide ions in water body^-1) Is superior to other reported iodide ion adsorbents, such as MIL-101(Cr) -SO₃Ag、Ag₂O@Mg(OH)₂15% -Bi @ MIL and LDH, etc. Meanwhile, the strong chemical acting force is beneficial to deep removal of radioactive iodide ions, and secondary pollution caused by leakage of the iodide ions is avoided.

(2)Ag⁰@ UiO has a relatively fast rate of adsorptive removal (about 3h to reach adsorption equilibrium).

(3)Ag⁰The @ UiO has stronger ion interference resistance and better chemical stability.

(4)Ag⁰The preparation method of @ UiO has the advantages of simple operation, economy and high efficiency, does not need to add extra reducing agent when loading Ag in the material, and simplifies Ag⁰And (3) a process of loading nanoparticles.

The Ag provided by the invention⁰The preparation method of @ UiO is simple and suitable for large-scale industrial production, and the @ UiO has a remarkable effect of adsorbing radioactive iodide ions in water bodies when being used for adsorbing the radioactive iodide ions. The material provides an efficient and remarkable method for further removing radioactive iodide ions.

Drawings

FIG. 1 is Ag⁰The structure and preparation schematic diagram of the @ UiO material;

FIG. 2(a) shows UiO-66- (OH)₂And Ag⁰PXRD of @ UiO; (b) ag⁰@ UiO is soaked for 24 hours under different pH conditions to obtain a PXRD pattern;

FIG. 3 is UiO-66- (OH)₂And Ag⁰The BET specific surface area spectrum of @ UiO;

FIG. 4(a) is Ag⁰Material scanning electron microscope picture of @ UiO; (b) the (c) and (d) are high-resolution transmission electron micrographs;

FIG. 5 is UiO-66- (OH)₂And Ag⁰The adsorption isotherm of @ UiO for iodide ions;

FIG. 6 is Ag⁰Kinetics model of adsorption of @ UiO to iodide ion (initial concentration 500mg L)^-1At 30 ℃);

FIG. 7 is coexisting salt vs. Ag⁰Adsorption Effect of @ UiO on iodide ion (initial concentration 500mg L)^-1The temperature is 30 ℃ and the time is 12 h);

FIG. 8 is Ag⁰The adsorption mechanism diagram of @ UiO to iodide ions.

Detailed Description

The technical solutions of the present invention will be described clearly and completely with reference to the following embodiments of the present invention, and it should be understood that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments of the present invention without making any creative effort, shall fall within the protection scope of the present invention.

Example 1

A skeleton material with Ag nano-particle composition is composed of organic skeleton UiO and Ag⁰And (3) nanoparticles. Wherein the organic skeleton UiO accounts for 97.8 percent of the mass part, and the specific surface area is 501.03m²(iii) a porosity of 0.6397ml/g, the Ag⁰2.2 percent of nano particles in mass portion, and the size of the nano particles is 5-9.8 nm. The preparation method is shown in figure 1,

(1) 5.15mmol of ZrCl₄And 2.63mmol of 2, 5-dihydroxyterephthalic acid were dissolved in 774.93mmol of DMF solvent, and the mixture was stirred at room temperature for 15min to obtain a mixed solution.

(2) 171.26mmol of absolute ethanol and 174.68mmol of acetic acid were added to the mixed solution obtained in step (1), and the mixture was transferred to a polytetrafluoroethylene-lined autoclave. The vessel was sealed and the reaction was heated in an oven at 403K for two days and the sample was allowed to cool to room temperature.

(3) Washing the solid sample obtained in the step (2) with a DMF solvent for 3 times, then washing with absolute ethyl alcohol for 3 times to remove unreacted organic ligand and residual DMF solvent, and collecting yellow solid which is UiO-66- (O)H)₂。

(4) 15mL of the solution with a concentration of 0.25mol L^-1Is placed in a 20mL glass vial, and 100mg of UiO-66- (OH) prepared in step (2) is added₂Adding the solid powder into silver nitrate solution, stirring to mix thoroughly, reacting at room temperature for 12h, and wrapping tin foil paper outside the glass vial to prevent oxidation of silver nitrate. After the reaction, the solid was collected by centrifugation, washed with deionized water and ethanol several times, and in order to verify that no excess Ag remained in the reaction mixture⁺The washed solvent was collected and added to sodium chloride (1.0mol L)^-1) In the solution, it was examined whether or not a silver chloride precipitate was generated. And washing for many times by using ethanol and deionized water to remove incompletely reacted substances. Finally, centrifugally collecting the solid, and drying the solid for 24 hours at 100 ℃ by using a vacuum oven to obtain Ag⁰@ UiO solid.

The amount of adsorbed iodide ions was measured as shown in FIG. 7, and 5mg of Ag was added⁰Addition of @ UiO to the initial I^-The mass concentration is 100mg L^-1And contains 100mg L of^-1CO₃ ^2-Na of (2)₂CO₃In the solution, the adsorption time is 24 hours, the adsorption temperature is 30 ℃, I^-The removal rates were 82.5%, respectively.

The adsorption mechanism shown in fig. 8:

Example 2

The material and the preparation method were the same as example 1, except that the amount of adsorbed iodide ions was measured as shown in FIG. 7, and 5mg of Ag was added⁰Addition of @ UiO to the initial I^-The mass concentration is 100mg L^-1And contains 100mg L of^-1Cl^-In the NaCl solution, the adsorption time is 24 hours, the adsorption temperature is 30 ℃, I^-The removal rates were 89.5%, respectively.

Example 3

The material and the preparation method were the same as example 1, except that the amount of adsorbed iodide ions was measured as shown in FIG. 7, and 5mg of Ag was added⁰Addition of @ UiO to the initial I^-The mass concentration is 100mg L^-1And contains 100mg L of^-1SO₄ ^2-Na of (2)₂SO₄In the solution, the adsorption time is 24 hours, the adsorption temperature is 30 ℃, I^-The removal rates were 99.3%, respectively.

Example 4

The material and the preparation method were the same as example 1, except that the amount of adsorbed iodide ions was measured as shown in FIG. 7, and 5mg of Ag was added⁰Addition of @ UiO to the initial I^-The mass concentration is 100mg L^-1And contains 100mg L of^-1NO₃ ^-NaNO of (2)₃In the solution, the adsorption time is 24 hours, the adsorption temperature is 30 ℃, I^-The removal rates were 99.1%, respectively.

Example 5

The material and the preparation method were the same as example 1, except that the amount of adsorbed iodide ions was measured as shown in FIG. 7, and 5mg of Ag was added⁰Addition of @ UiO to the initial I^-The mass concentration is 100mg L^-1And contains 100mg L of^-1HCO₃ ^2-NaHCO of₃In the solution, the adsorption time is 24 hours, the adsorption temperature is 30 ℃, I^-The removal rates were 82.6%, respectively.

It can be seen that these coexisting ion pairs Ag⁰The adsorption influence sequence of @ UiO on iodide ions is CO₃ ²>HCO₃ ^2->Cl^->NO₃ ^->SO₄ ^2-In which CO is₃ ^2-And HCO₃ ^-Is a weak acid anion, which hydrolyzes to a basic environment, producing OH^-With iodine ion to Ag⁰The active site of @ UiO produces a competitive effect. And NO₃ ^-And SO₄ ^2-Belonging to strong acid anions, to Ag⁰The effect of adsorption of iodide ions is smaller at @ UiO, from which it appears that the alkaline environment follows OH^-Increase of Ag is unfavorable⁰The adsorption of the @ UiO to the iodide ions is facilitated by the acidic environment. Further, Cl^-Can compete with the active site for iodine ion adsorption, but Ag and I are used^-Gibbs free energy of reaction less than Ag and Cl^-Reaction, thereby having less influence on the adsorption removal of iodide ions, and in general, Ag⁰The @ UiO has better anti-ion interference capability on the adsorption of iodide ions.

Comparative example 1

For UiO-66- (OH) as shown in FIG. 2(a)₂And Ag⁰@ UiO for PXRD, it can be seen that UiO-66- (OH)₂With AgNO₃After the aqueous solution reaction, the XRD pattern remains substantially unchanged, but two new peaks appear at 38.1 ℃ and 44.3 ℃, which correspond to zero-valent silver (Ag)⁰) The (1,1,1) and (2,0,0) crystal planes of (1,1,1) and (2,0, 0). Mixing Ag with water⁰@ UiO was soaked in water solutions of different pH for 24h and then dried to test its XRD, as shown in FIG. 2(b), its XRD peak could still be compared with Ag without soaking in solutions of different pH⁰@ UiO remains consistent, indicating that Ag⁰@ UiO has excellent chemical stability.

As shown in FIG. 3, for UiO-66- (OH)₂And Ag⁰@ UiO BET specific surface area measurement was performed. UiO-66- (OH) was calculated by Barrett Joyner Halenda (BJH) method₂And Ag⁰Specific surface areas of @ UiO's are 960.51m, respectively²G and 501.03m²(ii) in terms of/g. The result shows that the introduction of the nano silver reduces Ag⁰The specific surface area of @ UiO also proves that the nano silver is successfully loaded in the material.

As shown in FIG. 4, for Ag⁰@ UiO scanning electron microscope and high resolution transmission electron microscope measurements were performed.

Carrying out iodine ion adsorption experiment on the sample:

5mg of UiO-66- (OH) were weighed₂And Ag⁰And @ UiO, which is respectively added into 10mL of sodium iodide solution with certain initial mass concentration and certain pH value, is subjected to oscillation adsorption for certain time under the condition of certain temperature, is sampled, the absorbance of the sample is measured by adopting an ultraviolet spectrophotometer (TU-1901), and the mass concentration of the sample is calculated by using a standard curve of the content of the iodide ions, so that the adsorption quantity of the iodide ions is calculated.

Drawing an adsorption isotherm: ag⁰@ UiO and UiO-66- (OH)₂To iodineThe adsorption isotherm of the ions is shown in FIG. 5, Ag⁰@ UiO at an iodide ion concentration of 0-500mgL^-1The maximum adsorption amount of the iodine ions in the range is 447.01mg g^-1And UiO-66- (OH)₂Has an adsorption amount of 162.32mg g^-1It can be seen that Ag⁰The adsorption performance of @ UiO on iodide ions is greatly improved.

Ag⁰The kinetics curve of absorbing iodide ions for @ UiO is shown in FIG. 6, Ag⁰The balance of the adsorption of the @ UiO on the iodide ions is achieved at about 1h, and the adsorption and removal rate is higher.

Furthermore, those skilled in the art will appreciate that while some embodiments herein include some features included in other embodiments, rather than other features, combinations of features of different embodiments are meant to be within the scope of the invention and form different embodiments. For example, in the claims above, any of the claimed embodiments may be used in any combination. The information disclosed in this background section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.

Claims

1. The framework material with Ag nano-particle composite is characterized by comprising organic frameworks UiO and Ag⁰Nanoparticles by UiO-66- (OH)₂Reduction of Ag from silver salt solutions⁺Direct loading of Ag⁰The skeleton structure of the nano-particles and the organic skeleton is unchanged.

2. The framework material with Ag nano-particle composite of claim 1, wherein the organic framework UiO is 97.6-98% by mass, and the Ag is in the range of⁰2 to 2.4 mass percent of nano particles.

3. The framework material with Ag nanoparticle composite of claim 1, wherein the organic framework is Ag⁰Ratio of @ UiOThe surface area is 400-800m²Ag, with a porosity of 0.6-0.7ml/g⁰The size of the nano particles is 5-9.8 nm.

4. The method for preparing a framework material with Ag nanoparticle composites as claimed in any one of claims 1-3, comprising the following steps:

(3) washing the product obtained in the step (2) with N, N-Dimethylformamide (DMF) solvent and absolute ethyl alcohol successively to obtain UiO-66- (OH)₂ ；

5. The method according to claim 4, wherein the zirconium salt in step (1) is zirconium chloride, the organic ligand is 2, 5-dihydroxyterephthalic acid, and the solvent is DMF.

6. A method according to claim 4 or 5, wherein the molar ratio of the zirconium salt to the organic ligand is from 1:1 to 3: 1.

7. The method according to claim 4, wherein the molar ratio of the absolute ethanol to the acetic acid in the step (2) is 0.5:1 to 1: 1.

8. The production method according to claim 4, wherein the silver salt solution in the step (4) is silver nitrate, and the silver salt is reacted with the UiO-66- (OH)₂In a molar ratio of 1:40 to 1: 50.

9. The method according to claim 4, wherein the reaction in step (2) is carried out at 403K for 48h, the reaction in step (4) is carried out at room temperature for 12h, and the drying is carried out at 100 ℃ for 24 h.

10. Use of a framework material with Ag nanoparticle complexes as claimed in any one of claims 1-3 for the adsorption of radioiodine in water.