A Graphene Oxide-Doped Co Heteropolyacid Metal-Organic Composite and Its Preparation Method and Application

Abstract

The present invention belongs to the technical field of inorganic coordination chemistry, and discloses a cobalt-doped heteropolyacid metal-organic composite of graphene oxide, a preparation method thereof and an application thereof. It is obtained by dissolving 4,4'-bipyridine N-oxide, cobalt phosphotungstate and graphene oxide in a mixed solvent of acetonitrile / water, fully stirring, filtering and drying. This composite can activate PMS to remove rhodamine B, phenol, etc. in water, and has potential application value in removing organic small molecules.

Description

Technical Field

[0001] The present invention belongs to the technical field of inorganic coordination chemistry, and relates to a graphene oxide doped Co heteropolyacid metal-organic complex, a preparation method thereof and an application thereof. Background Art

[0002] The increasingly severe water pollution has posed a major threat to the survival safety of human beings and become a major obstacle to the sustainable development of human health, economy and society. On the other hand, sewage treatment also coincides with the "dual carbon" goal. Among various treatment technologies, the persulfate (PMS) activation technology, as one of the advanced oxidation technologies, is widely used in water purification and disinfection. However, its direct reaction rate with organic substances is very low, and it is necessary to utilize external activation to generate free radicals [References: Anipsitakis G.P., Dionysiou D.D. Environ. Sci. Technol., 2003, 37, 4790; Oh W.D., Dong Z., Lim T.T. Appl. Catal. B Environ., 2016, 194, 169.]. POM / MOF (heteropolyacid-based metal-organic framework), as a new type of solid material, can be used in the fields of adsorption separation, catalysis, drugs, etc. However, the particles of such materials are prone to aggregation, which affects the exposure of active sites and thus is not conducive to the exertion of catalytic performance. Further improvement is still needed at present to facilitate its application in the treatment of water purification by activating persulfate (PMS). Summary of the Invention

[0003] Based on the current technical status, the purpose of the present invention is to provide a graphene oxide doped Co heteropolyacid metal-organic complex, which is used for activating persulfate (PMS) to treat water purification, removing organic small molecules and improving the catalytic effect.

[0004] To achieve the purpose of the present invention, the present invention composes POM / MOF with graphene oxide (GO) and uses it as a heterogeneous catalyst for activating PMS.

[0005] The specific technical solution is as follows:

[0006] The graphene oxide doped Co heteropolyacid metal-organic complex is prepared by the following method: Dissolve 4,4'-bipyridine N-oxide, cobalt phosphotungstate and graphene oxide in a mixed solvent of acetonitrile / water, stir evenly, filter, and dry to obtain a black powdery material, which is the target product, abbreviated as GO@POM / MOF.

[0007] The molar ratio of 4,4'-bipyridine N-oxide to cobalt phosphotungstate is 2:1 - 1:5; the volume ratio of acetonitrile to water is 1:2 - 3:1.

[0008] Based on the molar ratio of 4,4'-bipyridine N-oxide to cobalt phosphotungstate of 1:1.8, the addition amount of graphene oxide is 1-30% of its total mass.

[0009] Advantages of the present invention: 1) Loading the catalyst with graphene oxide, it has good dispersibility, can effectively increase its effective contact area with pollutants, and is convenient for the catalytic efficiency to play. Moreover, GO has good chemical stability, so it can improve the stability of the material as a carrier of the composite; 2) By compounding POM / MOF with graphene oxide, the amount of catalyst used can be reduced. Moreover, the composite catalyst can be recycled, reducing costs; 3) The composite material has good activation performance for PMS and is applied to the removal of organic small molecules, with the advantages of rapidity and convenience. Description of the Drawings

[0010] Figure 1 It is the scanning electron microscope (SEM) image of the GO@POM / MOF material prepared in Example 1 of the present invention.

[0011] Figure 2 It is the XRD pattern of the GO@POM / MOF material prepared in Example 1 of the present invention.

[0012] Figure 3 It is the relationship curve of time and concentration when the GO@POM / MOF material prepared in Example 1 of the present invention is applied to activate persulfate to catalyze the removal of Rhodamine B. Test conditions: 50 mL of 20 mg / L Rhodamine B solution, 1 mL of 2 mM PMS, and 0.001 g of catalyst.

[0013] Figure 4 It is the relationship curve of the number of cycles and the removal efficiency when the GO@POM / MOF material prepared in Example 1 of the present invention is applied to activate persulfate to catalyze the removal of Rhodamine B, and the amount of catalyst used is 1 mg. Detailed Embodiments

[0014] To better illustrate the present invention, the following examples are given:

[0015] Example 1

[0016] Preparation of 10% GO + 90% POM / MOF composite by mass percentage:

[0017] Weigh 4,4'-bipyridine N-oxide (Dpdo) (69.7 mg, 0.05 mmol), cobalt phosphotungstate (270 mg, 0.09 mmol), and GO (37.74 mg), add them to 20 mL of a mixed solvent of acetonitrile / water (v / v = 1:1), stir well for 10 hours, filter, and dry to obtain a black powdery material.

[0018] Example 2

[0019] Preparation of 5 wt% GO + 95 wt% POM / MOF composite:

[0020] Weigh 4,4'-dipyridine N-oxide (Dpdo) (139.4 mg, 0.10 mmol), cobalt phosphotungstate (540 mg, 0.18 mmol), and GO (35.76 mg), add them to 20 mL of a mixed solvent of acetonitrile / water (v / v = 3:1), stir well for 10 hours, filter, and dry to obtain a black powdery material.

[0021] Example 3

[0022] Preparation of 20 wt% GO + 80 wt% POM / MOF composite

[0023] Weigh 4,4'-dipyridine N-oxide (Dpdo) (69.7 mg, 0.05 mmol), cobalt phosphotungstate (270 mg, 0.09 mmol), and GO (84.93 mg), add them to 20 mL of a mixed solvent of acetonitrile / water (v / v = 1:1), stir well for 10 hours, filter, and dry to obtain a black powdery material.

[0024] Application Example

[0025] Experiment on activating PMS to remove Rhodamine B:

[0026] Under dark and constant temperature conditions, accurately weigh 0.001 g of the catalyst prepared in Example 1 of the present invention, measure 1 mL of 2 mM PMS solution, and 50 mL of 20 mg / L Rhodamine B solution into a beaker, start stirring, take samples at certain time intervals, each time measure 1 mL of the sample, dilute it to 3 mL with deionized water, and take the supernatant after centrifugation. Measure the absorbance at 554 nm with a UV spectrophotometer to monitor the concentration of Rhodamine B, and then calculate the removal rate of Rhodamine B.

[0027] Result Analysis:

[0028] Within 1 minute, 80% of Rhodamine B can be rapidly removed, and then Rhodamine B is gradually removed completely.

[0029] After recycling the catalyst and continuing to add Rhodamine B solution, after 4 cycles, the removal rate of Rhodamine B still reaches 90%, indicating that this material has good recyclability.

[0030] Comparative Example 1

[0031] Experiment on removing Rhodamine B with PMS without adding the catalyst of the present invention:

[0032] Under light avoidance and constant temperature, measure 1 mL of 2 mM PMS solution and 50 mL of 20 mg / L rhodamine B solution into a beaker, start stirring, take samples at certain time intervals, measure 1 mL of the sample each time, dilute it to 3 mL with deionized water, and take the supernatant after centrifugation. Measure the absorbance at 554 nm with a UV spectrophotometer to monitor the concentration of rhodamine B, and then calculate the removal rate of rhodamine B.

[0033] Result analysis: Within 1 minute, 10% of rhodamine B can be quickly removed, and the final removal rate is about 10%.

[0034] Comparative Example 2

[0035] Compared with Example 1, the difference is that "cobalt phosphomolybdate" is used instead of "cobalt phosphotungstate", and the other raw materials, their amounts, and the preparation method are the same;

[0036] It is used in the experiment of activating PMS to degrade rhodamine B. Result analysis: Within 1 minute, 60% of rhodamine B can be quickly removed, and the final removal rate no longer increases.

[0037] Those skilled in the art should understand that the present invention is not limited by the above embodiments. What is described in the above embodiments and the specification only illustrates the principle of the present invention. Without departing from the spirit and scope of the present invention, the present invention will have various changes and improvements, and these changes and improvements all fall within the scope of the present invention claimed.

Claims

1. A graphene oxide doped with Co heteropolyacid metal-organic composite, characterized in that, It is prepared by the following method: Dissolve 4,4'-bipyridine N-oxide, cobalt phosphotungstate salt, and graphene oxide in a mixed solvent of acetonitrile / water, stir evenly, filter, and dry to obtain the target product, abbreviated as GO@POM / MOF; The molar ratio of 4,4'-bipyridine N-oxide to cobalt phosphotungstate salt is 2:1 - 1:5; the volume ratio of acetonitrile to water is 1:2 - 3:1; based on the molar ratio of 4,4'-bipyridine N-oxide to cobalt phosphotungstate salt of 1:1.8, the addition amount of graphene oxide is 1 - 30% of its total mass.

2. The application of the graphene oxide doped with Co heteropolyacid metal-organic complex according to claim 1, characterized in that, It is applied to the catalytic treatment of rhodamine B in water by peroxymonosulfate.

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