CN108912338B - Preparation of supramolecular organic framework and application of supramolecular organic framework in adsorption removal of pollutants in water body - Google Patents

Abstract

The present invention designs and synthesizes a pillar[5]arene supramolecular organic framework material SOFs-P5G based on naphthalimide functionalization. The guest bis-4,4-bipyridyl salts self-assemble in equimolar ratios. The supramolecular organic framework SOFs-P5G showed a very good adsorption and removal effect on various organic pollutants in water. By monitoring with UV absorption spectrum, it was calculated that the removal rate of SOFs-P5G for various pollutants was greater than 50%, and the removal rate of potassium permanganate was up to 99%. The contaminant-adsorbed supramolecular organic framework material SOFs‑P5G powder was added to absolute ethanol, and after stirring in a water bath at 35-40 °C for 15 minutes, the adsorbed contaminants were released, and then filtered and dried to make the The supramolecular organic framework material SOFs‑P5G achieves the purpose of recycling.

Description

Preparation of a supramolecular organic framework and its application in adsorption and removal of pollutants in water application

technical field

The invention relates to a supramolecular organic framework SOFs-P5G self-assembled with naphthalimide-functionalized pillar[5]arene (P5N) as the main body and bis-4,4 bipyridine salt (G) as the guest. The invention is used for the separation and removal of pollutants in water bodies, and belongs to the technical field of water treatment.

Background technique

Over the past few decades, the large amount of dye wastewater discharges generated by the textile, leather, paper and printing industries have caused serious environmental problems, as most commercial dyes are highly toxic and even cause cancer by concentrating organisms. Many traditional physicochemical methods have been used to deal with dye contamination. At present, the adsorption process has become one of the most useful technologies in various treatment processes of dye-containing wastewater. Various adsorbents such as silica, clay, activated carbon and mesoporous silica have been used for this type of treatment. The use of adsorption materials (such as activated carbon) to adsorb organic pollutants in wastewater is a green and environmentally friendly method, but due to its long treatment time and high recovery cost, it is inefficient and costly for practical applications in industry. , and it is not conducive to convenient and fast practical application. Therefore, the rapid and efficient removal of pollutants has become a very challenging topic.

SUMMARY OF THE INVENTION

The purpose of this invention is to provide a kind of preparation method of supramolecular organic framework;

Another object of the present invention is to provide the application of the above supramolecular organic framework as an adsorbent in the adsorption and removal of organic pollutants.

1. Preparation of supramolecular organic framework materials

The preparation of the supramolecular organic framework material of the present invention is that in cyclohexanol, the pillar[5]arene (P5N) functionalized with the host naphthalimide and the guest bis-4,4-bipyridine salt (G) are assembled in an equimolar ratio , labeled as SOFs-P5G.

Among them, the structural formula of the main naphthalimide-functionalized pillar[5]arene (P5N) is:

n=1, 2, 3, 4;

The structure of the guest bis-4,4-bipyridyl salt (G) is as follows:

The assembly mode of host and object is as follows:

The mechanism of the formation of supramolecular polymer gel TDPG is analyzed below by NMR and NMR spectroscopy. Figure 1 is a partial concentration NMR image of P5N. In Figure 1, from (b) to (g) the concentration of P5N gradually increases, it can be found that H1-7 all move to the high field, indicating that there is a relationship between the pillar arene group and naphthalimide group of P5N and another molecule of P5N. π-π effect. Figure 2 shows the NMR titration spectra of P5N and G. Among them (a) P5N; (b)~(h) contain G with different equivalents. It can be seen from Fig. 2 that the hydrogen protons Ha, Hb, Hc, Hd and He on the guest G are all shifted to the low field, while the hydrogen protons H6 and H7 on the host P5N pillar aromatic group are shifted to the high field, indicating that the guest G The pyridinium salt moiety enters the cavity of the pillar arene. The above phenomena can indicate that the host P5N and the guest G are assembled through the host-guest recognition and π-π interactions, thereby obtaining the supramolecular organic framework material SOFs-P5G.

2. Adsorption of various pollutants by supramolecular organic framework SOFs-P5G

Take 12 clean 50mL volumetric flasks, respectively weigh the pollutant compounds to be adsorbed (such as: methylene blue, golden orange, Bismarck brown Y, Gibbs stain, methyl orange, rhodamine B, Sudan red 1, Sudan red 2. Picric acid, naphthol, potassium permanganate, potassium dichromate) in a beaker, then add 10 mL of distilled water to completely dissolve the solid, then pipette into the prepared colorimetric tubes, and then dilute with distilled water to 25mL scale, prepared with an aqueous solution with a concentration of 1×10 ^-3 mol·L ^-1 , ready for use.

Pipette 50uL of the above-prepared aqueous solutions of various pollutants (1.0×10 ^-3 mol/L) into a 5mL reagent bottle, then add distilled water to dilute to the 5mL mark, and shake well to form a concentration of 1.0×10 ^{- 5} mol/L dilute solutions of various pollutants, let stand, and wait for use.

Weigh 12 parts of the supramolecular organic framework SOFs-P5G powder prepared above, each 2 mg, and add them to the above prepared dilute solutions of various pollutants with a concentration of 1.0 × 10 ^-5 mol/L, respectively. After stirring at room temperature for 40 minutes, it was left to stand. It was found that the color of the dilute solution of various pollutants faded. Figure 3 is a bar graph of the adsorption and removal efficiency of SOFs-P5G for 12 pollutants (from left to right: methylene blue, golden orange, Bismarck brown Y, Gibbs stain, methyl orange, rhodamine B, Sudan red 1, Sudan Red 2, picric acid, cresol, potassium permanganate, potassium dichromate). It can be seen from Fig. 3 that the supramolecular organic framework SOFs-P5G powder prepared by the present invention is not effective for the pollutants methylene blue, golden orange, Bismarck brown Y, Gibbs stain, methyl orange, rhodamine B, Sudan red 1, Sudan red 2. Picric acid, cresol, potassium permanganate and potassium dichromate all have good adsorption and removal effects. By monitoring with ultraviolet absorption spectrum, the removal rate of various pollutants was calculated. As a result, the removal rate of all pollutants is greater than 50%, and the removal rate of potassium permanganate is up to 99%.

3. Desorption of supramolecular organic framework SOFs-P5G

The above-mentioned supramolecular organic framework material SOFs-P5G powder adsorbed with pollutants was added to absolute ethanol, and after stirring for 15 minutes in a water bath of 35~40 °C, the adsorbed pollutants were released; filter, dry, So that the supramolecular organic framework material SOFs-P5G can achieve the purpose of recycling. Figure 4 is a bar graph of the removal efficiency of supramolecular organic framework SOFs-P5G for methyl orange (a), rhodamine B (b), picric acid (c), and potassium permanganate (d) after multiple cycles. It can be seen from Figure 4 that the supramolecular organic framework material SOFs-P5G is used to adsorb pollutants in water after desorption, and still has a high removal rate.

4. The adsorption and removal of various pollutants by SOFs-P5G

By taking methyl orange adsorption as an example, we discussed the adsorption mechanism. First, we carried out the NMR titration experiment of SOFs-P5G with methyl orange (see Figure 5). From Fig. 5, we can see that the peaks of hydrogen protons Ha, Hb, Hc and Hd on the pyridinium salt are all shifted to the high field, and the hydrogen protons H1, H2, H3 and H4 on the methyl orange are shifted to the low field, indicating that There are electrostatic interactions between methyl orange and the pyridinium salt in SOFs-P5G through anion and cation (see Figure 3). At the same time, it is also demonstrated by 2D NMR. As shown in Figure 6, the four relevant points A, B, C and D are the hydrogen protons H6, H7 and H11 on the pillar arene and the hydrogen proton H1 on the methyl orange, respectively. The correlation points of H2, H3 and H4 indicate that there are C-H-π and π-π interactions between methyl orange and pillar aromatics. From these phenomena, it can be speculated that in the process of removing various pollutants, there are various interaction forces (such as: C-H-π interaction, π-π interaction, electrostatic interaction of anions and cations, etc.). Therefore, SOFs-P5G can be used for Various pollutants in the aqueous solution can be efficiently separated and removed. Moreover, this adsorption is formed by weak interactions with various compounds, but these weak interactions are easily destroyed, so desorption can be carried out to separate various pollutants, and the recovery and recycling of adsorbent materials can be achieved. This adsorption and separation performance has important application value in the field of molecular removal.

Description of drawings

Figure 1 is the concentration of P5N hydrogen NMR spectrum.

Figure 2 shows the NMR titration spectra of P5N and G.

Figure 3 is a bar graph of the adsorption and removal efficiency of SOFs-P5G for 12 pollutants.

Figure 4 is a bar graph of the removal efficiency of supramolecular organic framework SOFs-P5G for (a) methyl orange, (b) rhodamine B, (c) picric acid, and (d) potassium permanganate for multiple cycles.

Figure 5 is the hydrogen NMR titration spectrum of methyl orange on SOFs-P5G.

Figure 6 shows the two-dimensional hydrogen NMR spectra of methyl orange and SOFs-P5G.

Detailed ways

The preparation of the supramolecular organic framework material SOFs-P5G of the present invention and the performance of adsorbing organic pollutants in wastewater will be further described below through specific examples.

Example 1. Preparation of supramolecular organic framework material SOFs-P5G

(1) Synthesis of host P5N: In 50ml of acetonitrile, add 0.58g (5×10 ^-3 mol) brominated column[5]arene P5, 0.43g (1.5×10 ^-3 mol) naphthalimide Derivatives were reacted at 80°C for 48h; after the reaction was completed, cooled to room temperature, the solvent was removed by rotary evaporation, the sample was mixed and loaded onto the column, and eluted with petroleum ether:ethyl acetate=10:1~10:5 (v/v) , the yellow solid product was gel factor P5N; the yield was 75.6%.

(2) Synthesis of guest G: 1.9801 g (1.89 g, 6.3 mmol) of 1,10-dibromodecane and 4,4'-bipyridine (5.56 g, 35.7 mmol) were added to 100 ml of acetonitrile. The mixture was stirred and refluxed for 18 hours at ℃; cooled to room temperature, filtered with a Buchner funnel, washed with acetonitrile and ethanol for 3 to 5 times, and obtained 3.3 g of a light yellow-green powdery product, which was the guest compound G. The yield was 86%.

(3) Synthesis of supramolecular organic framework material SOFs-P5G: In 0.2ml cyclohexanol, host P5N (0.0050g, 4.5× ^10-6 mol), guest G (0.0047g, 4.5× ^10-6 mol) were added , heated to dissolve it completely, then cooled to room temperature and dried to obtain a stable supramolecular organic framework material SOFs-P5G.

Example 2. Efficient separation and removal of pollutants by supramolecular organic framework SOFs-P5G

Various pollutants (methylene blue, golden orange, Bismarck brown Y, Gibbs stain, methyl orange, rhodamine B, Sudan red 1, Sudan red 2, picric acid, methyl alcohol) were prepared at a concentration of 5 mL of 1×10 ^-5 M. Naphthol, potassium permanganate, potassium dichromate) aqueous solution; Weigh supramolecular organic framework material SOFs-P5G powder, weigh 12 parts, each part is 2 mg, add them to the dilute solutions of the above various pollutants, shake After 40 minutes, let stand, take the residual supernatant for UV spectrophotometric test, and record its absorbance. Then, the concentration of the residual solution was calculated according to Lambert Beer's law to calculate the adsorption removal rate. The removal rates of supramolecular organic framework SOFs-P5G for various pollutants are shown in Table 1:

Example 3. Supramolecular organic framework SOFs-P5G recycling and recycling

The aqueous solution of organic framework material SOFs-P5G powder adsorbed with various pollutants was filtered and dried. Then move the dry powder to 12 5 ml reagent bottles, add 4 ml of absolute ethanol, shake for 15 minutes in a water bath with a temperature of 35 degrees Celsius, and find that the color of the aqueous solution changes to the color of various pollutants before adsorption, indicating that the organic The frame material SOFs-P5G releases all kinds of adsorbed pollutants. Then, it is filtered once, washed with ethanol for 3-5 times, and dried to obtain the original organic framework material SOFs-P5G powder. At the same time, the recovered organic framework material SOFs-P5G powder can also be recycled for multiple times.

Claims (7)

1. A preparation method of supermolecular organic framework SOFs-P5G is characterized in that in cyclohexanol, a main body of naphthalimide functionalized column [5] arene and a guest of bis 4,4 bipyridyl salt are self-assembled according to an equimolar ratio;

the structural formula of the main body naphthalimide functionalized column [5] arene is as follows:

n=1、2、3、4；

the structural formula of the guest bis 4,4 bipyridine salt is as follows:

。

2. use of the supramolecular organic frameworks SOFs-P5G prepared by the method of claim 1 for adsorptive removal of contaminants in water.

3. Use of the supramolecular organic frameworks SOFs-P5G as claimed in claim 2 for the adsorptive removal of pollutants in water bodies, characterized in that: the contaminant is an organic dye.

4. Use of the supramolecular organic frameworks SOFs-P5G as claimed in claim 3 for the adsorptive removal of pollutants in water bodies, characterized in that: the organic dye is methylene blue, golden orange, bismarck brown Y, Gilford staining agent, methyl orange, rhodamine B, Sudan Red 1, Sudan Red 2.

5. Use of the supramolecular organic frameworks SOFs-P5G as claimed in claim 2 for the adsorptive removal of pollutants in water bodies, characterized in that: the pollutants are potassium permanganate and potassium dichromate.

6. Use of the supramolecular organic frameworks SOFs-P5G as claimed in claim 2 for the adsorptive removal of pollutants in water bodies, characterized in that: the pollutants are picric acid and methyl naphthol.

7. Use of the supramolecular organic frameworks SOFs-P5G as claimed in claim 2 for the adsorptive removal of pollutants in water bodies, characterized in that: adding the supermolecule organic framework material SOFs-P5G adsorbed with the pollutants into absolute ethyl alcohol, stirring in a water bath at 35-40 ℃, and releasing the pollutants, so that the supermolecule organic framework material SOFs-P5G is recycled.

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