阅读说明：本技术 一种阳离子型多孔材料的制备方法及其应用 (Preparation method and application of cationic porous material ) 是由 郑盛润 于 2020-04-29 设计创作，主要内容包括：本发明属于金属-有机框架领域,具体涉及一种阳离子型多孔材料的制备方法,包括以下步骤：S1.制备aMOC-1；S2.制备CL-aMOC-1：S21.将步骤S1得到的aMOC-1和BAPB按照质量比为(2～3):1混合,然后进行研磨25～40min；S22.将步骤S21研磨之后的混合物用有机溶剂进行洗涤,然后干燥即得。本发明通过固相反应来构建的基于Pd<Sub>12</Sub>L<Sub>24</Sub>的阳离子框架CL-aMOC-1,方法操作简易、产率高。本发明获得的CL-aMOC-1可以通过阴离子交换过程快速吸附含氧阴离子(CrO<Sub>4</Sub><Sup>2-</Sup>,Cr<Sub>2</Sub>O<Sub>7</Sub><Sup>2</Sup>),且呈现出吸附高容量、选择性良好和可回收重复使用等优点。(The invention belongs to the field of metal-organic frameworks, and particularly relates to a preparation method of a cationic porous material, which comprises the following steps: s1, preparing aMOC-1; s2, preparing CL-aMOC-1: s21, mixing aMOC-1 and BAPB obtained in the step S1 according to the mass ratio of (2-3) to 1, and then grinding for 25-40 min; and S22, washing the mixture ground in the step S21 by using an organic solvent, and drying to obtain the catalyst. Pd-based catalyst constructed by solid-phase reaction 12 L 24 The cation framework CL-aMOC-1 has simple and easy operation and high yield. The CL-aMOC-1 obtained by the present invention may beTo rapidly adsorb oxoanions (CrO) by anion exchange process 4 2‑ ，Cr 2 O 7 2 ) And has the advantages of high adsorption capacity, good selectivity, recyclability and the like.)

1. A preparation method of a cationic porous material is characterized by comprising the following steps:

s1, preparing aMOC-1

S11, dissolving 3, 5-bis (4-pyridyl) -benzaldehyde and palladium nitrate in a solvent according to a molar ratio of 2 (1-3), and reacting the solution at 60-80 ℃ for 5-10 hours after gas in the solution is removed;

s12, after the reaction in the step S11 is finished, adding dioxane with the volume 3-5 times of that of the solution into the solution, filtering and washing after complete precipitation, and keeping the precipitate;

s2, preparing CL-aMOC-1

S21, mixing aMOC-1 and BAPB obtained in the step S1 according to the mass ratio of (2-3) to 1, and then grinding for 25-40 min;

and S22, washing the mixture ground in the step S21 by using an organic solvent, and drying to obtain the catalyst.

2. The method of claim 1, wherein in step S11, the molar ratio of 3, 5-bis (4-pyridyl) -benzaldehyde to palladium nitrate is 2: 1.

3. The method for preparing a cationic porous material according to claim 1, wherein the reaction time in step S11 is 8 h.

4. The method for preparing a cationic porous material according to claim 1, wherein in step S12, the precipitate is washed with acetone and then dried at 60-80 ℃ for 5-7 h.

5. The method for preparing the cationic porous material according to claim 1, wherein in step S21, the mass ratio of aMOC-1 to BAPB is 2.5: 1.

6. the method for preparing a cationic porous material according to claim 1, wherein the grinding is performed at normal temperature in step S22.

7. The method for preparing the cationic porous material according to claim 1, wherein in step S22, the washing steps are: washing the mixture for 3-6 times by using dimethyl sulfoxide at the temperature of 60-75 ℃, and then washing the mixture for 2-5 times by using acetone.

8. A cationic porous material prepared by the method of any one of claims 1 to 7.

9. The method of claim 8 wherein the cationic porous material adsorbs CrO₄ ^2-And Cr₂O₇ ^2-The application of (1).

10. According to claim 9Cationic porous material for adsorbing CrO₄ ^2-And Cr₂O₇ ^2-The application is characterized in that the pH value of the solution is 2-8 for CrO₄ ^2-And Cr₂O₇ ^2-Adsorption of (3).

Technical Field

The invention belongs to the field of metal-organic frameworks, and particularly relates to a preparation method and application of a cationic porous material.

Technical Field

Cr (VI) oxyanions (including CrO) which are generally generated during industrial production (metal plating industry, leather manufacturing and industry, and cement manufacturing industry)₄ ^2-，Cr₂O₇ ^2-And HCrO^4-) Has already been used forClassified as a class a human carcinogen by the united states environmental protection agency. Therefore, the removal of Cr (VI) oxyanions from wastewater is of great importance. At present, methods for removing Cr (VI) oxyanions include a redox method, a precipitation method, biological treatment, membrane filtration and the like, wherein an adsorption method is simple and convenient to operate, few in byproducts, high in feasibility and high in efficiency, and is one of the best choices for removing the oxyanions in water.

Cationic porous materials having cationic nanocavities and exchangeable anions in their structure are of interest because such materials can be used as anion adsorbents for the removal of anionic contaminants by anion exchange adsorption. However, the amount of cationic porous material is smaller compared to neutral and anionic porous materials. Currently, the main cationic porous materials are anion exchange resins, layered hydroxides (LDHs), cationic metal-organic frameworks (MOFs), Cationic Polymer Networks (CPNs), and the like. These cationic materials also have disadvantages such as low adsorption capacity, slow adsorption rate, low reuse rate, poor stability in water, etc. in the adsorption of oxoanions, and therefore, it is very necessary to develop a novel cationic porous material.

The coordination cage is a discrete coordination molecule with a special geometric shape and an inner cavity, and has potential application in the research fields of drug delivery, molecular recognition, homogeneous catalysis and the like at present. Some coordination cages have large cavities and high positive charges and can adsorb and contain anions, but are often used for molecular recognition, catalysis and the like in a solution due to the solubility of the coordination cages, and are rarely used as solid adsorbents in liquid phase adsorption. And at present, no cationic porous material based on coordination cage with efficient adsorption effect for heavy metal chromium exists.

Disclosure of Invention

The invention aims to solve the problems that the solubility of a coordination cage in the prior art is difficult to apply as a solid adsorbent to liquid phase adsorption, and a cation type porous material based on the coordination cage and having high-efficiency adsorption action for heavy metal chromium does not exist, and provides a preparation method and application of the cation type porous material.

The purpose of the invention is realized by the following technical scheme:

a preparation method of a cationic porous material comprises the following steps:

s1, preparing aMOC-1

S11, dissolving 3, 5-bis (4-pyridyl) -benzaldehyde and palladium nitrate in a solvent according to a molar ratio of 2 (1-3), and reacting the solution at 60-80 ℃ for 5-10 hours after gas in the solution is removed;

s12, after the reaction in the step S11 is finished, adding dioxane with the volume 3-5 times of that of the solution into the solution, filtering and washing after complete precipitation, and keeping the precipitate;

s2, preparing CL-aMOC-1

S21, mixing aMOC-1 and BAPB obtained in the step S1 according to the mass ratio of (2-3) to 1, and then grinding for 25-40 min;

and S22, washing the mixture ground in the step S21 by using an organic solvent, and drying to obtain the catalyst.

The method of the invention forms an expanded coordination cage-based framework material by linking coordination cages together further through covalent bonds, which can reduce the solubility of the material in water and improve the stability, making it suitable for liquid phase adsorption applications. As shown in figure 1, the method for constructing the cationic porous material comprises the steps of firstly selecting an organic ligand which simultaneously comprises coordination sites and covalent reaction sites and Pd (II) ions to assemble a coordination cage with the covalent reaction sites, namely forming a molecular cage Pd through the reaction of 3, 5-di (4-pyridyl) -benzaldehyde and palladium nitrate₁₂L₂₄(L is 3, 5-di (4-pyridyl) -benzaldehyde), and then reacting 1, 4-di (4-aminophenyl) benzene (BAPB) with aldehyde groups on the molecular cages to form covalent bonds, so that a plurality of molecular cages are connected to form the porous material with a three-dimensional framework.

Preferably, in the step S11, the molar ratio of the 3, 5-bis (4-pyridyl) -benzaldehyde to the palladium nitrate is 2: 1.

Preferably, in the step S11, the reaction time is 8 h.

Preferably, in the step S12, the precipitate is washed with acetone and then dried at 60-80 ℃ for 5-7 h.

Preferably, in step S21, the mass ratio of aMOC-1 to BAPB is 2.5: 1.

preferably, in step S22, the washing specifically includes: washing the mixture for 3-6 times by using dimethyl sulfoxide at the temperature of 60-75 ℃, and then washing the mixture for 2-5 times by using acetone.

The cationic porous material prepared by the preparation method of the cationic porous material.

The cationic porous material is used for adsorbing CrO₄ ^2-And Cr₂O₇ ^2-The application of (1).

Preferably, CrO is treated in an environment with pH of 2-8₄ ^2-And Cr₂O₇ ^2-Adsorption of (3).

Compared with the prior art, the invention has the following technical effects:

the preparation method of the cationic porous material provided by the invention has mild reaction conditions, and under the reaction condition of normal-temperature grinding, the aldehyde group-containing cationic coordination cage (aMOC-1) and 1, 4-bis (4-aminophenyl) benzene (BAPB) are connected into the amorphous cationic porous framework material CL-aMOC-1 through an aldehyde-amine condensation reaction. CL-aMOC-1 can quickly and efficiently adsorb CrO in water₄ ^2-And Cr₂O₇ ^2-The saturated adsorption capacities were 245.1mg/g and 311.5mg/g, respectively. The adsorbed Cr (VI) oxyanion can be quickly eluted, and the recycling performance of the material is good. In addition, the CL-aMOC-1 can be used for removing Cr (VI) in the electroplating waste liquid.

Drawings

FIG. 1 is a schematic flow diagram of the synthetic principle of the present invention;

FIG. 2 PXRD pattern of CL-aMOC-1 obtained in the example (a), IR spectra of aMOC-1, CL-aMOC-1 and BAPB (b), and Raman spectra of aMOC-1 and CL-aMOC-1 (c);

FIG. 3 thermogravimetric curve (a) of CL-aMOC-1 obtained in example, CL-aMOC-1N at 77K₂Adsorption isotherms (inset corresponding pore size distribution) (b);

FIG. 4 is a scanning electron micrograph of CL-aMOC-1 obtained in the example;

FIG. 5 CL-aMOC-1 and Cr₂O₇ ^2-(a) And CrO₄ ^2-(b) Time-varying ultraviolet spectra of ionic interactions;

FIG. 6 CL-aMOC-1 adsorption data for three oxoanions were fitted to a pseudo-first order kinetic model (a) and a pseudo-second order kinetic model (b);

fig. 7 CL-aMOC-1 adsorption isotherms for two oxoanions (T48 h, T30 ℃) (a); fitting oxoanion adsorption data to Langmuir (b), Freundlich (c), and Temkin (d) adsorption equations, respectively;

FIG. 8 Cr₂O₇@ CL-aMOC-1 in NaNO₃Ultraviolet spectrum (a) desorbed in solution for 20 min; CL-aMOC-1 to Cr₂O₇ ^2-The cyclable adsorption performance of (b);

FIG. 9 influence of pH on the adsorption of Cr (VI) by CL-aMOC-1 (a); the influence of competing anions on the removal rate of the adsorbed oxoanions of CL-aMOC-1 (b);

FIG. 10 shows the UV spectrum (a) of the CL-aMOC-1 adsorption of Cr (VI) -containing electroplating wastewater at different times; a change (b) in the concentration of Cr in the electroplating wastewater when the CL-aMOC-1 adsorbs Cr (VI) at different time points; and (c) desorption experiments (the color change of the corresponding solution or solid is shown in an inset) after the electroplating waste liquid Cr (VI) is adsorbed.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the technical solutions of the present invention will be described in detail below with reference to specific examples and comparative examples. It is to be understood that the described embodiments are merely exemplary of the invention, and not restrictive of the full scope of the invention. All other embodiments, which can be derived by a person skilled in the art from the examples given herein without any inventive step, are within the scope of the present invention.

Unless otherwise specified, the devices used in the present examples, comparative examples and experimental examples were all conventional experimental devices, the materials and reagents used were commercially available without specific reference, and the experimental methods without specific reference were also conventional experimental methods.