阅读说明：本技术 一种MOFs衍生材料及其制备方法和应用 (MOFs derivative material and preparation method and application thereof ) 是由 魏健 张佳丽 刘雪瑜 宋永会 徐东耀 段亮 李丹 李明月 于 2020-04-28 设计创作，主要内容包括：本发明涉及功能材料技术领域,提供了一种MOFs衍生材料的制备方法,将钴盐、锌盐、2-甲基咪唑和有机溶剂混合进行溶剂热反应得到MOFs前驱体,再依次进行煅烧,酸洗得到MOFs衍生材料。本发明通过引入锌离子降低钴的负载,利用煅烧的方式将钴包裹在形成的碳纳米管中以及利用酸洗将材料中部分不牢固的钴颗粒脱除的方式,最终降低了材料在使用过程中钴的溶出,而且材料催化性能较高。实验结果表明,利用本发明提供的制备方法得到的MOFs衍生材料和过硫酸盐降解CBZ时,CBZ的降解率可达98％,同时Co离子溶出为78μg/L；降解双酚A时,CBZ的降解率可达100％,同时Co离子溶出为45μg/L。(The invention relates to the technical field of functional materials, and provides a preparation method of MOFs derivative materials. According to the invention, the load of cobalt is reduced by introducing zinc ions, cobalt is wrapped in the formed carbon nano tube by using a calcining mode, and partial loose cobalt particles in the material are removed by using acid washing, so that the dissolution of cobalt in the use process of the material is finally reduced, and the catalytic performance of the material is higher. Experimental results show that when the MOFs derivative material and persulfate prepared by the preparation method provided by the invention are used for degrading CBZ, the degradation rate of CBZ can reach 98%, and Co ions are dissolved out to 78 mug/L; when bisphenol A is degraded, the degradation rate of CBZ can reach 100%, and the dissolution rate of Co ions is 45 mug/L.)

1. A preparation method of MOFs derivative materials comprises the following steps:

(1) mixing cobalt salt, zinc salt, 2-methylimidazole and an organic solvent to obtain a mixed solution;

(2) carrying out solvothermal reaction on the mixed solution obtained in the step (1) to obtain an MOFs precursor;

(3) and (3) sequentially calcining and pickling the MOFs precursor obtained in the step (2) to obtain the MOFs derivative material.

2. The process for the preparation of MOFs derivative materials according to claim 1, wherein said cobalt salt in step (1) is Co (NO)₃)₂·6H₂O、CoCl₂·6H₂O、CoSO₄·7H₂O and Co (CH)₃COO)₂·4H₂At least one of O; the zinc salt is Zn (NO)₃)₂·6H₂O、ZnCl₂、ZnSO₄·7H₂O and Zn (CH)₃COO)₂·2H₂At least one of O; the organic solvent is methanol and/or ethanol.

3. The process for the preparation of MOFs derived materials according to claim 1 or 2, characterized in that the ratio of the amounts of cobalt salt, zinc salt and 2-methylimidazole substances in the mixed solution of step (1) is 1: (0.5-5): (4-18).

4. The method according to claim 1, wherein the temperature of the solvothermal reaction in the step (2) is 100-170 ℃, and the time of the solvothermal reaction is 2-6 hours.

5. The method for preparing MOFs derivative materials according to claim 1, wherein the calcination temperature in said step (3) is 900-1100 ℃ and the calcination time is 1.5-3 h.

6. The method according to claim 1, wherein the acid solution used in the acid washing in step (3) is at least one of sulfuric acid, nitric acid and hydrochloric acid, and the concentration of the acid solution is 0.3-1.0 mol/L.

7. The method for preparing MOFs derivative materials according to claim 1 or 6, wherein the acid washing temperature in said step (3) is 50-90 ℃ and the acid washing time is 5-12 hours.

8. The MOFs derivative material prepared by the preparation method of any one of claims 1 to 7, comprising a zeolite imidazolate framework and a cobalt simple substance embedded in the zeolite imidazolate framework.

9. The MOFs derivative material according to claim 8, wherein the specific surface area of the zeolitic imidazolate framework in said MOFs derivative material is 240-280 m²Per g, pore diameter of 1About 10nm, pore volume of 0.2-1 cm³(ii)/g; the particle size of the MOFs derivative material is 180-220 nm.

10. Use of the MOFs derived materials of claim 8 or 9 for the treatment of refractory organics in wastewater.

Technical Field

The invention relates to the technical field of functional materials, in particular to an MOFs derivative material and a preparation method and application thereof.

Background

With the rapid development of the industry, a large number of artificially synthesized organic substances, such as skin care products, dyes, medicines and the like, are rapidly developed, and meanwhile, the organic substances are discharged into water environment through various ways, so that the water body is seriously polluted. At present, the organic wastewater treatment method mainly comprises biological, physical and chemical methods. The persulfate oxidation technology in the chemical method is an advanced oxidation technology with great development prospect for treating organic pollutants in water due to good stability, good solubility, multiple activation modes and wide pH application range.

Persulfate oxidation technology refers to the generation of sulfate radicals (SO) by the activation of persulfate₄ ^-.)，SO₄ ^-Degrading most of the organic matters in the wastewater into CO₂And H₂And O. In the method of activating a persulfate, however,the transition metal activation has the advantages of no need of external heat source and light source, realization of activation at normal temperature, and repeated use. Transition metal ion cobalt is proved to have a better activation effect on persulfate, but when the transition metal ion cobalt and the persulfate are used for jointly treating organic waste, a large amount of cobalt ions enter water, and secondary pollution is caused to a water body.

Metal organic framework compounds ((MOFs)) are crystalline porous materials with periodic network structures formed by connecting inorganic metal centers (metal ions or metal clusters) and bridged organic ligands with each other through self-assembly. In the prior art, a mode of embedding cobalt ions in the crystal through a MOFs mode is generally adopted to reduce the overflow of the cobalt ions. In practical applications, in order to ensure the catalytic performance of the MOFs materials, it is necessary to contain a large amount of cobalt ions in the metal-organic framework compound, but due to the existence of a large amount of cobalt ions, in practical applications, a large amount of cobalt ions are eluted (usually above 140 μ g/L), thereby causing serious secondary pollution to the water body.

Disclosure of Invention

In view of the above, the invention aims to provide an MOFs derivative material, a preparation method and an application thereof, wherein the MOFs derivative material prepared by the preparation method provided by the invention has good catalytic activity when degrading organic matters in water together with persulfate, and after the degradation is completed, the content of dissolved cobalt in a skeleton in water is lower than that of 140 [ mu ] g/L in the prior art, so that the pollution to the environment is reduced.

In order to achieve the above object, the present invention provides the following technical solutions:

the invention provides a preparation method of MOFs derivative materials, which comprises the following steps:

(1) mixing cobalt salt, zinc salt, 2-methylimidazole and an organic solvent to obtain a mixed solution;

(2) carrying out solvothermal reaction on the mixed solution obtained in the step (1) to obtain an MOFs precursor;

(3) and (3) sequentially calcining and pickling the MOFs precursor obtained in the step (2) to obtain the MOFs derivative material.

Preferably, the cobalt salt in step (1) is Co (NO)₃)₂·6H₂O、CoCl₂·6H₂O、CoSO₄·7H₂O and Co (CH)₃COO)₂·4H₂At least one of O; the zinc salt is Zn (NO)₃)₂·6H₂O、ZnCl₂、ZnSO₄·7H₂O and Zn (CH)₃COO)₂·2H₂At least one of O; the organic solvent is methanol and/or ethanol.

Preferably, the amount ratio of the cobalt salt, the zinc salt and the 2-methylimidazole in the mixed solution of the step (1) is 1: (0.5-5): (4-18).

Preferably, the temperature of the solvothermal reaction in the step (2) is 100-170 ℃, and the time of the solvothermal reaction is 2-6 hours.

Preferably, the calcining temperature in the step (3) is 900-1100 ℃, and the calcining time is 1.5-3 h.

Preferably, the acid solution used in the acid washing in the step (3) is at least one solution of sulfuric acid, nitric acid and hydrochloric acid, and the concentration of the acid solution is 0.3-1.0 mol/L.

Preferably, the pickling temperature in the step (3) is 50-90 ℃, and the pickling time is 5-12 hours.

The invention also provides the MOFs derivative material prepared by the preparation method in the technical scheme, which comprises a zeolite imidazolate framework and a cobalt simple substance embedded in the zeolite imidazolate framework.

Preferably, the specific surface area of the zeolite imidazole ester framework in the MOFs derivative material is 240-280 m²A pore diameter of 1 to 10nm and a pore volume of 0.2 to 1cm³(ii)/g; the particle size of the MOFs derivative material is 180-220 nm.

The invention also provides application of the MOFs derivative material in the scheme or the MOFs derivative material prepared by the preparation method in the scheme in the aspect of treating refractory organics in wastewater.

The invention provides a preparation method of MOFs derivative materials, which comprises the following steps: mixing cobalt salt, zinc salt, 2-methylimidazole and an organic solvent to obtain a mixed solution; carrying out solvothermal reaction on the mixed solution to obtain an MOFs precursor; and sequentially calcining and pickling the MOFs precursor to obtain the MOFs derivative material. The method comprises the steps of selecting transition metal ion cobalt and simultaneously introducing transition metal ion zinc, and carrying out solvothermal reaction on two transition metal ions and 2-methylimidazole to obtain an MOFs precursor of a zeolite imidazole ester framework structure; the content of cobalt ions in the material is reduced by introducing transition metal ion zinc, so that the dissolution of metal ion cobalt is reduced; the cobalt element generates a cobalt simple substance at high temperature by a calcining mode and is coated by the carbon nano tube, so that the dissolution of metal ion cobalt is further reduced; meanwhile, the cobalt element catalyzes a carbon structure to generate a graphitized carbon nano tube at high temperature, so that the graphitization degree of the carbon material is improved, and the catalytic performance of the material is improved; meanwhile, zinc ions are converted into a simple substance of zinc in the calcining process, and the simple substance of zinc volatilizes under the action of high temperature in the calcining process, so that the carbon material forms a more porous structure, and the catalytic performance of the material is further improved; partial loose cobalt particles in the material are removed by acid washing, the dissolution of cobalt in the use process of the material is further reduced, and the pore volume and the specific surface area of pores of the material are increased by acid washing, so that the catalytic performance of the material is further improved. Experimental results show that when the MOFs derivative material obtained by the preparation method provided by the invention and persulfate are used for degrading CBZ together, the degradation rate of CBZ can reach 98%, and Co ions are dissolved out to 78 mug/L; when bisphenol A is jointly degraded, the degradation rate of CBZ can reach 100%, and the Co ion dissolution rate is 45 mu g/L.

Drawings

FIG. 1 is an SEM image of MOFs derived material prepared in example 1 of the present invention;

fig. 2 is a XRD characterization pattern of the MOFs-derived materials prepared in example 1 and comparative example 1 of the present invention.

Detailed Description

The invention provides a preparation method of MOFs derivative materials, which comprises the following steps:

(1) mixing cobalt salt, zinc salt, 2-methylimidazole and an organic solvent to obtain a mixed solution;

(2) carrying out solvothermal reaction on the mixed solution obtained in the step (1) to obtain an MOFs precursor;

(3) and (3) sequentially calcining and pickling the MOFs precursor obtained in the step (2) to obtain the MOFs derivative material.

In the present invention, the raw materials used are all commercial products which are conventional in the art, unless otherwise specified.

In the present invention, the operation is carried out at room temperature unless otherwise specified.

According to the invention, cobalt salt, zinc salt, 2-methylimidazole and an organic solvent are mixed to obtain a mixed solution. The invention has no special regulation on the mixing mode of the cobalt salt, the zinc salt, the 2-methylimidazole and the organic solvent, and the cobalt salt, the zinc salt, the 2-methylimidazole and the organic solvent are mixed uniformly. According to the invention, cobalt salt, zinc salt and part of organic solvent are preferably mixed to obtain a solution of cobalt salt and zinc salt; mixing the 2-methylimidazole with the rest of the organic solvent to obtain a 2-methylimidazole solution; and slowly pouring the solution of the cobalt salt and the zinc salt into the solution of 2-methylimidazole to obtain a mixed solution.

In the present invention, the ratio of the amounts of the cobalt salt, the zinc salt, and the 2-methylimidazole in the mixed solution is preferably 1: (0.5-5): (4-18), more preferably 1: (0.8-4): (5-10), most preferably 1: 8.3. in the present invention, the ratio of the amount of the cobalt salt to the volume of the solvent is preferably 0.01 to 0.05 mol/L. In the present invention, the cobalt salt can reduce the dissolution of cobalt ions while ensuring the catalytic performance thereof within the above range. The zinc salt can reduce the dosage of the cobalt salt in the range, and the obtained material has a better pore structure due to the volatilization of the zinc, so that the finally obtained MOFs derivative material has better catalytic performance. The adoption of the 2-methylimidazole with the dosage is beneficial to obtaining the pure-phase zeolite imidazolate framework material, and the catalytic performance of the material is better.

In the present invention, the cobalt salt provides the main active ingredient for the finally prepared MOFs-derived material. In the present invention, the cobalt salt is Co (NO)₃)₂·6H₂O、CoCl₂·6H₂O、CoSO₄·7H₂O and Co (CH)₃COO)₂·4H₂At least one of O. The cobalt salt is selected to be better dissolved in the organic solvent. In the examples of the present invention, the cobalt salt is specifically Co (NO)₃)₂·6H₂And O, the solubility of the material in an organic solvent is optimal, and the obtained material has smaller crystal form and better catalytic effect.

In the invention, the zinc salt is used as a common additive with cobalt salt, on one hand, the dosage of the cobalt salt is reduced when the MOFs derivative material is prepared, and on the other hand, the zinc salt is used as a pore-forming agent. In the present invention, the zinc salt is preferably Zn (NO)₃)₂·6H₂O、ZnCl₂、ZnSO₄·7H₂O and Zn (CH)₃COO)₂·2H₂At least one of O. The zinc salt can be better dissolved in an organic solvent by the selection of the zinc salt. The zinc salt is preferably Zn (NO) in the present embodiment₃)₂·6H₂O, which is most soluble in organic solvents. Due to Co (NO)₃)₂·6H₂O and Zn (NO)₃)₂·6H₂The ZIF materials prepared by O independently have the same frame structure and are all regular dodecahedral structures, and Zn (NO) is selected in the invention₃)₂·6H₂O to reduce Co (NO) in the preparation of ZIF materials₃)₂·6H₂O is used in an amount to ensure that ZIF crystals can be formed.

In the present invention, the 2-methylimidazole is an important component forming a ZIF (zeolitic imidazolate framework) material.

In the present invention, the organic solvent is preferably methanol and/or ethanol, and more preferably methanol. The invention selects methanol with moderate protonation capability as a reaction solvent to obtain particles with uniform particle size and regular appearance.

After the mixed solution is obtained, the mixed solution is subjected to solvothermal reaction to obtain the MOFs precursor. In the present invention, Co ions and Zn ions are linked to N atoms in methylimidazole by solvothermal reaction to form CoN₄And ZnN₄Zeolite imidazole ester framework materials MOFs consisting of tetrahedral structural units.

In the invention, the temperature of the solvothermal reaction is preferably 100-170 ℃, more preferably 110-140 ℃, and most preferably 120 ℃. In the present invention, the solvothermal reaction time is preferably 2 to 6 hours, more preferably 3 to 5 hours, and most preferably 4 hours. The material obtained by adopting the hydrothermal temperature and time has regular shape and better catalytic performance.

After the solvothermal reaction is finished, products of the solvothermal reaction are preferably subjected to centrifugation, washing and drying in sequence to obtain the MOFs precursor.

The operation of the centrifugation is not particularly specified in the present invention, and the solid-liquid separation may be performed by a centrifugation operation known to those skilled in the art. The washing operation is not specially specified in the invention, and the solid material obtained after centrifugation is washed clean by adopting a washing mode well known to a person skilled in the art. The drying mode is not specially specified in the invention, and the drying mode known by the technicians in the field can be adopted; vacuum drying is preferred in embodiments of the present invention. The invention adopts a vacuum drying mode, the drying temperature is low, the drying time is short, and the obtained MOFs derivative material powder can not be blown by flowing air.

After the MOFs precursor is obtained, the MOFs precursor is sequentially calcined and pickled to obtain the MOFs derivative material.

In the present invention, the condition of the calcination is preferably an inert gas condition. In the present invention, the inert gas is preferably at least one of argon, nitrogen and helium. The invention adopts inert atmosphere to prevent the oxidation of the cobalt simple substance in the finally formed MOFs derivative material.

In the invention, the calcination temperature is preferably 900-1100 ℃, more preferably 950-1050 ℃, and most preferably 1000 ℃. In the invention, the calcination time is preferably 1.5-3 h, and more preferably 2 h. According to the invention, by adopting the calcination temperature and time, cobalt ions form a cobalt simple substance under the action of high temperature, the obtained cobalt simple substance catalyzes a carbon structure to generate a graphitized carbon nanotube, the catalytic performance of the MOFs derivative material is enhanced, and the obtained carbon nanotube wraps the obtained cobalt simple substance, so that the dissolution of cobalt in the application process of the MOFs derivative material is reduced; under the action of high temperature, zinc ions are converted into a simple substance of zinc, and the simple substance of zinc is volatilized under the action of high temperature, so that a pore structure is left in the prepared MOFs derivative material, and due to the fact that the pore structure in the MOFs derivative material is increased in specific surface area, the catalytic performance of the MOFs derivative material is improved, and meanwhile, the adsorption performance of the MOFs derivative material is improved.

In the present invention, the acid solution used for the acid washing is preferably a solution of at least one of sulfuric acid, nitric acid and hydrochloric acid, and more preferably sulfuric acid. In the present invention, the hydrochloric acid introduces Cl^-Will have certain influence on activating persulfate; nitric acid is slightly more oxidizing; the sulfuric acid is selected, so that ions which influence the activation of the persulfuric acid are not introduced, and the oxidizing property is moderate. In the invention, the concentration of the acid solution is preferably 0.3-1.0 mol/L, more preferably 0.4-0.6 mol/L, and most preferably 0.5 mol/L. The invention adopts the acid with the concentration, the oxidability is moderate, and the obtained MOFs derivative material has better catalytic performance.

In the invention, the pickling temperature is preferably 50-90 ℃, more preferably 65-85 ℃, and most preferably 80 ℃. In the present invention, the time for the acid washing is 5 to 12 hours, more preferably 6 to 10 hours, and most preferably 8 hours. The method adopts the temperature and the time for washing, and is beneficial to removing part of loose Co particles in the MOFs derivative material.

In the present invention, the pickling is preferably performed by immersion. In the invention, the weak Co particles in the MOFs derivative material are removed by acid washing, the dissolution of Co in the use process of the MOFs derivative material is reduced, the pore volume and the specific surface area of pores of the MOFs derivative material are increased, and the catalytic performance of the MOFs derivative material is improved.

After the acid washing is finished, the acid-washed product is preferably separated, washed and dried in sequence to obtain the MOFs derivative material.

In the present invention, the separation is preferably magnetic separation. The MOFs derivative material prepared by the invention has magnetism, and the magnetic separation mode is simple and rapid. The washing operation is not specially specified, and the solid after magnetic separation is washed clean by adopting a washing mode well known to a person skilled in the art. The drying method is not particularly limited in the present invention, and a drying method known to those skilled in the art may be used. Vacuum drying is preferred in embodiments of the present invention. The invention adopts a vacuum drying mode, the drying temperature is low, the drying time is short, and the obtained MOFs derivative material powder can not be blown by flowing air.

According to the invention, the content of cobalt ions in the MOFs derivative material is reduced by introducing the transition metal ion zinc, cobalt is wrapped in the formed carbon nano tube by using a calcining mode, and partial loose cobalt particles in the MOFs derivative material are removed by using acid washing, so that the dissolution of cobalt in the use process of the MOFs derivative material is finally reduced, and the MOFs derivative material has high catalytic performance.

The invention also provides the MOFs derivative material prepared by the preparation method in the technical scheme, which comprises a zeolite imidazole ester framework and a cobalt simple substance embedded in the zeolite imidazole ester framework.

In the invention, the specific surface area of a zeolite imidazole ester framework in the MOFs derivative material is 240-280 m²A pore diameter of 1 to 10nm and a pore volume of 0.2 to 1cm³(ii)/g; the particle size of the MOFs derivative material is 180-220 nm.

The invention also provides application of the MOFs derivative material in the technical scheme in the aspect of treating refractory organics in wastewater. In the invention, the organic matter concentration of the wastewater is preferably 3-8 mg/L, more preferably 4-6 mg/L, and most preferably 5 mg/L. In the invention, the pH value of the wastewater is preferably 2-14, more preferably 4-7, and most preferably 5.8. The invention adopts a slightly acidic environment, and the MOFs derivative material has the best activation effect on persulfate, so that the degradation rate of pollutants is highest.

The invention preferably adds persulfate and MOFs derivative materials into the waste water containing organic matters to carry out waste water treatment. The method for treating wastewater by adding persulfate and MOFs derivative materials is not specially specified, and the method known by the technical personnel in the field can be adopted. In the invention, the ratio of the mass mg of the MOFs derivative material to the mass mg of the persulfate in mmol and the mass mg of the organic matters in the wastewater is preferably (6-16): (0.04-0.12): 1, more preferably (8 to 12): (0.06-0.1): 1, most preferably 10: 0.08: 1.

in the present invention, the persulfate includes at least one of a peroxymonosulfate and a peroxydisulfate. In the present invention, the peroxymonosulfate is preferably KHSO₅·0.5KHSO₄·0.5K₂SO₄. In the present invention, the peroxodisulfate is preferably K₂S₂O₈And/or Na₂S₂O₈。

The MOFs derivative material prepared by the invention is used for activating persulfate to generate sulfate radical (SO)₄ ^-.) use SO₄ ^-The strong oxidizing property of the catalyst degrades most of organic matters in the wastewater into CO₂And H₂And O. Experimental results show that when the MOFs derivative material obtained by the preparation method provided by the invention and persulfate are used for degrading CBZ together, the degradation rate of CBZ can reach 98%, and Co ions are dissolved out to 78 mug/L; when bisphenol A is jointly degraded, the degradation rate of CBZ can reach 100%, and the Co ion dissolution rate is 45 mu g/L.

The MOFs derived materials provided by the present invention, the preparation method and the application thereof are described in detail below with reference to the examples, but they should not be construed as limiting the scope of the present invention.