阅读说明：本技术 一种基于噻吩单元的多孔有机聚合物及其制备方法和应用 (Porous organic polymer based on thiophene unit and preparation method and application thereof ) 是由 布乃顺 许彦梅 夏立新 闫卓君 郑桂月 崔博 苏品杰 蔡慧颖 于 2021-02-02 设计创作，主要内容包括：本发明属于新材料技术领域,具体涉及一种基于噻吩单元的多孔有机聚合物,以具有π共轭结构的含硫噻吩单体和三(4-硼酸频呢醇酯苯基)胺为结构单元,通过Suzuki偶联反应一锅法有效的合成新型含硫多孔有机聚合物,具体制备方法如下：将具有π共轭结构的含硫噻吩单体与三(4-硼酸频呢醇酯苯基)胺放入准备好的反应容器中,加入N,N’-二甲基甲酰胺,使用液氮对混合物进行冷冻,用真空泵进行抽真空、通氮气至常压,反复循环三次；加入催化剂,继续使用液氮进行冷冻,用真空泵进行抽真空、通氮气至常压,反复循环三次；解冻后进行反应；洗涤,纯化,干燥得到目标产物。本发明制备的吸附剂分离富集效率高,可从混合离子溶液中选择性的吸附汞离子。操作简单、绿色无污染、适用广泛,具有实际应用性。(The invention belongs to the technical field of new materials, and particularly relates to a porous organic polymer based on a thiophene unit, which takes a sulfur-containing thiophene monomer with a pi conjugated structure and tris (4-chloronicotinyl alcohol borate phenyl) amine as structural units, and effectively synthesizes the novel sulfur-containing porous organic polymer by a Suzuki coupling reaction one-pot method, wherein the specific preparation method comprises the following steps: putting a sulfur-containing thiophene monomer with a pi conjugated structure and tris (4-chloronicotinyl borate phenyl) amine into a prepared reaction container, adding N, N' -dimethylformamide, freezing the mixture by using liquid nitrogen, vacuumizing by using a vacuum pump, introducing nitrogen to normal pressure, and repeatedly circulating for three times; adding a catalyst, continuously freezing by using liquid nitrogen, vacuumizing by using a vacuum pump, introducing nitrogen to normal pressure, and repeatedly circulating for three times; reacting after thawing; washing, purifying and drying to obtain the target product. The adsorbent prepared by the invention has high separation and enrichment efficiency, and can selectively adsorb mercury ions from the mixed ion solution. Simple operation, green and pollution-free, wide application and practical applicability.)

1. A porous organic polymer based on thiophene units is characterized in that a sulfur-containing thiophene monomer with a pi conjugated structure and tris (4-chloronicotinyl alcohol borate phenyl) amine (BBA) are used as structural units, and a novel sulfur-containing porous organic polymer is effectively synthesized by a Suzuki coupling reaction one-pot method, wherein the structures of the porous organic polymer are shown as formulas (I) and (II):

2. a preparation method of a porous organic polymer based on thiophene units is characterized by comprising the following steps:

1) putting a sulfur-containing thiophene monomer with a pi conjugated structure and tris (4-chloronicotinyl borate phenyl) amine into a prepared reaction container, and adding N, N' -dimethylformamide to dissolve the monomer; connecting an experimental device, freezing the mixture by using liquid nitrogen, vacuumizing by using a vacuum pump, introducing nitrogen to normal pressure, and repeatedly circulating for three times;

2) quickly adding a catalyst into the whole reaction system, continuously freezing by using liquid nitrogen, vacuumizing by using a vacuum pump, introducing nitrogen to normal pressure, and repeatedly circulating for three times; reacting after thawing;

3) after the reaction is finished, the obtained crude product is filtered, washed by excessive dichloromethane, deionized water and tetrahydrofuran, further purified and finally dried in vacuum at 90 ℃ for 12 hours to obtain the target product.

3. The method for preparing a porous organic polymer material based on thiophene units according to claim 2, wherein: in the step 1), the sulfur-containing thiophene monomer is one of 5,5' -dibromo-2, 2' -bithiophene and 3,3',5,5' -tetrabromo-2, 2' -bithiophene.

4. The method for preparing a porous organic polymer based on thiophene units according to claim 2, wherein: in the step 2), the catalyst is tetrakis (triphenylphosphine) palladium and 2M potassium carbonate aqueous solution.

5. The method for preparing a porous organic polymer based on thiophene units according to claim 2, wherein: in the step 1), the sulfur-containing thiophene monomer is prepared by the following steps: the ratio of tris (4-chloronicotinyl alcohol phenyl) amine to tris (4-boronic acid pinacol ester phenyl) amine is 1-2: 1.

6. The method for preparing a porous organic polymer based on thiophene units according to claim 2, wherein: according to the mass ratio, the weight ratio of the tris (4-chloronicotinyl alcohol ester phenyl) amine: the ratio of the palladium tetrakis (triphenylphosphine) to the palladium tetrakis (triphenylphosphine) is 1: 0.05-0.06.

7. The method for preparing a porous organic polymer based on thiophene units according to claim 2, wherein: in step 2), the reaction temperature is 130 ℃ and the reaction time is 48 hours.

8. The method for preparing a porous organic polymer based on thiophene units according to claim 2, wherein: the purification is performed by Soxhlet extraction with tetrahydrofuran and dichloromethane for 48 hours.

9. Use of a thiophene unit-based porous organic polymer according to claim 1 for adsorbing mercury ions.

10. The use of a thiophene unit-based porous organic polymer according to claim 9 for adsorbing mercury ions, wherein the method comprises: a porous organic polymer based on thiophene units according to claim 1, added to a solution containing mercury for adsorption.

Technical Field

The invention belongs to the technical field of new materials, relates to preparation of a porous organic polymer based on a thiophene unit, and aims to selectively and efficiently adsorb and separate heavy metal mercury ions from sewage.

Background

Mercury is one of the most toxic and harmful heavy metals, and even at low concentrations, it can seriously threaten human health, destroy the central nervous system and endocrine system of human body, and further affect the normal operation of each organ of human body. The existing forms of mercury are various, and mercury is extremely toxic and difficult to biodegrade, thereby causing serious pollution to the ecological environment. In the natural environment, mercury, both inorganic and organic, is generally converted to the highly volatile elemental form, and it enters the atmosphere, soil and water, and is ultimately stored in our food chain as the highly potent neurotoxin methylmercury. Therefore, it is important to develop an eco-friendly strategy for the recovery of mercury ions from mine wastewater or industrial and municipal sewage, in view of the accumulation of mercury in the food chain and its toxicity to the human body.

At present, various methods such as a precipitation method, an ion exchange method, a membrane separation method, a coagulation method and the like are widely applied to separation and enrichment of mercury ions. However, most of them require expensive cost, are complicated to operate, and are inefficient particularly for treating mercury ions having low concentration. In contrast, adsorption allows mercury ions to be recovered from low concentration sources by a relatively simple process. The adsorption method is considered to be a green alternative method for separating and adsorbing mercury ions due to the advantages of simple operation, economic process, no toxicity, reusability, high efficiency, relatively less secondary waste generation, various adsorbents and the like.

Porous Organic Polymers (POPs) are porous materials with different topologies formed by strong covalent bonds interconnecting. POPs are considered as candidate materials for many potential application areas, such as gas adsorption and separation, chemical and biological sensors, heterogeneous catalysis, drug delivery and energy storage, etc., due to their tunable pore structure, high specific surface area, low skeletal density and excellent physicochemical stability. In recent years, the application of porous organic polymers in sewage treatment is receiving more and more attention. Compared with the traditional adsorbent, the POPs have the advantages of high specific surface area, adjustable aperture, capability of introducing various functional groups into the framework through post-modification and the like, so that the POPs are very suitable for being used as a novel solid adsorbent to be applied to the field of adsorption and separation of heavy metal ions in sewage. According to the literature, the sulfur-containing group can form a complex with mercury ions, and further adsorb the mercury ions. In order to improve the application potential of POPs in heavy metal mercury ion adsorption separation, the invention designs a preparation method of a porous organic polymer based on a thiophene unit, directly selects a sulfur-containing organic monomer with pi conjugation, prepares a functional porous organic polymer by a Suzuki coupling reaction one-pot method, and avoids the steps of complicated post-modification and the like. The prepared material has an extended pi conjugated framework and high-density sulfur active sites, can quickly chelate mercury ions, and has good adsorption selectivity and high separation efficiency. The mercury ion adsorbent also has higher adsorption capacity under strong acid, can be recycled, and has practical application to treatment of acid industrial waste liquid.

Disclosure of Invention

The invention aims to overcome the defects in the prior art, and provides a preparation method of a porous organic polymer based on a thiophene unit, which is applied to the field of adsorption and separation of heavy metal mercury ions in sewage.

The invention is realized by the following technical scheme: a porous organic polymer based on thiophene units takes a sulfur-containing thiophene monomer with a pi conjugated structure and tris (4-chloronicotinyl borate phenyl) amine (BBA) as structural units, and a novel sulfur-containing porous organic polymer is effectively synthesized by a Suzuki coupling reaction one-pot method, and has the structures shown in formulas (I) and (II):

a preparation method of a porous organic polymer based on thiophene units comprises the following steps:

1) putting a sulfur-containing thiophene monomer with a pi conjugated structure and tris (4-chloronicotinyl borate phenyl) amine into a prepared reaction container, and adding N, N' -dimethylformamide to dissolve the monomer; connecting an experimental device, freezing the mixture by using liquid nitrogen, vacuumizing by using a vacuum pump, introducing nitrogen to normal pressure, and repeatedly circulating for three times;

2) quickly adding a catalyst into the whole reaction system, continuously freezing by using liquid nitrogen, vacuumizing by using a vacuum pump, introducing nitrogen to normal pressure, and repeatedly circulating for three times; reacting after thawing;

3) after the reaction is finished, the obtained crude product is filtered, washed by excessive dichloromethane, deionized water and tetrahydrofuran, further purified and finally dried in vacuum at 90 ℃ for 12 hours to obtain the target product.

Preferably, in the above method for preparing a porous organic polymer material based on thiophene units, in step 1), the sulfur-containing thiophene monomer is one of 5,5' -dibromo-2, 2' -bithiophene and 3,3',5,5' -tetrabromo-2, 2' -bithiophene.

Preferably, in the above preparation method of a porous organic polymer based on thiophene units, in step 2), the catalyst is tetrakis (triphenylphosphine) palladium and 2M potassium carbonate aqueous solution.

Preferably, in the above method for preparing a porous organic polymer based on thiophene units, in step 1), the ratio of the sulfur-containing thiophene monomer: the ratio of tris (4-chloronicotinyl alcohol phenyl) amine to tris (4-boronic acid pinacol ester phenyl) amine is 1-2: 1.

Preferably, in the preparation method of the porous organic polymer based on thiophene units, the ratio of the substances is, the weight ratio of tris (4-chloronicotinyl alcohol phenyl) amine: the ratio of the palladium tetrakis (triphenylphosphine) to the palladium tetrakis (triphenylphosphine) is 1: 0.05-0.06.

Preferably, in the above method for preparing a porous organic polymer based on thiophene units, in step 2), the reaction temperature is 130 ℃ and the reaction time is 48 hours.

Preferably, in the above method for preparing a porous organic polymer based on thiophene units, the purification is performed by soxhlet extraction with tetrahydrofuran and dichloromethane for 48 hours.

The porous organic polymer based on the thiophene unit is applied to adsorbing mercury ions.

Preferably, the application of the porous organic polymer based on thiophene units in mercury ion adsorption is as follows: adding the porous organic polymer based on the thiophene unit into a solution containing mercury for adsorption.

The invention has the beneficial effects that:

1) the porous organic polymer containing thiophene units prepared by the invention has a prolonged pi conjugated skeleton and simultaneously contains rich sulfur active sites, and can form a complex with mercury ions to quickly chelate the mercury ions.

2) The solid adsorbent prepared by the invention has high separation and enrichment efficiency, and can selectively adsorb mercury ions from the mixed ion solution. The method disclosed by the invention is simple to operate, green, pollution-free, wide in application range and practical in application.

3) The prepared solid adsorbent can be used for recovering heavy metal mercury ions in sewage by utilizing the advantages of good specific surface area and high thermochemical stability of the porous organic polymer, the existence of sulfur active sites which can be subjected to coordination functionalization with a metal center and the like.

4) The porous organic polymer containing thiophene units overcomes the low interaction between the ligand and the target metal caused by the irregular porous structure, and improves the adsorption performance of the adsorbent on mercury ions.

5) The porous organic polymer containing thiophene units prepared by the invention has higher adsorption capacity for mercury ions in a solution under strong acid, has high-density coordination sites, can pre-enrich the mercury ions in the adsorption process, further reduces the balance time, and has practical applicability to treatment of acidic industrial waste liquid.

6) The porous organic polymer material containing thiophene units prepared by the invention can be recycled in the process of enriching mercury ions.

In conclusion, the solid adsorbent prepared by the invention can effectively adsorb and separate mercury ions, is convenient to prepare, high in adsorption efficiency, green and pollution-free, and has practical applicability.

Drawings

FIG. 1-1 is an infrared spectrum of a porous organic polymer LNU-48 containing thiophene units and a reactive monomer according to the present invention;

FIGS. 1-2 are infrared spectra of porous organic polymers LNU-49 containing thiophene units and reactive monomers of the present invention;

FIG. 2-1 is a scanning electron micrograph of a porous organic polymer LNU-48 containing thiophene units according to the present invention;

FIG. 2-2 is a scanning electron micrograph of a porous organic polymer LNU-49 containing thiophene units according to the present invention;

FIG. 3-1 is a transmission electron micrograph of a porous organic polymer LNU-48 containing thiophene units according to the present invention;

FIG. 3-2 is a transmission electron micrograph of a porous organic polymer LNU-49 containing thiophene units according to the present invention;

FIG. 4 is a thermogravimetric plot of porous organic polymers LNU-48 and LNU-49 containing thiophene units of the present invention;

FIG. 5-1 is a nitrogen adsorption-desorption isotherm of the porous organic polymer LNU-48 containing thiophene units of the present invention;

FIG. 5-2 is a nitrogen adsorption-desorption isotherm of the porous organic polymer LNU-49 containing thiophene units of the present invention;

FIG. 6-1 is a pore size distribution plot of porous organic polymers LNU-48 containing thiophene units according to the present invention;

FIG. 6-2 is a pore size distribution plot of porous organic polymers LNU-49 containing thiophene units according to the present invention;

FIG. 7-1 is a mercury ion adsorption performance test of the porous organic polymers LNU-48 containing thiophene units of the present invention at different pH's;

FIG. 7-2 is a mercury ion adsorption performance test of the porous organic polymers LNU-49 containing thiophene units of the present invention at different pH;

FIG. 8-1 is an equilibrium adsorption test of porous organic polymers LNU-48 containing thiophene units according to the present invention;

FIG. 8-2 is an equilibrium adsorption test of porous organic polymers LNU-49 containing thiophene units according to the present invention;

FIG. 9-1 is a cycle performance test of the porous organic polymers LNU-48 containing thiophene units of the present invention;

FIG. 9-2 is a cycle performance test of the porous organic polymers LNU-49 containing thiophene units of the present invention.

Detailed Description

EXAMPLE 1 preparation of porous organic polymers LNU-48 containing thiophene units

400mg (0.641mmoL) of tris (4-chloronicotinyl borate phenyl) amine and 312mg (0.962mmoL) of 5,5' -dibromo-2, 2' -bithiophene were added to a round-bottomed flask containing 60mL of a solution of N, N ' -dimethylformamide under a nitrogen atmosphere, then the whole was frozen with liquid nitrogen and degassed with a vacuum pump and then repeatedly circulated three times with aeration, 5mL of a 2M-concentrated aqueous solution of potassium carbonate and 40mg of tetrakis (triphenylphosphine) palladium were rapidly added to the reaction system, the freezing-degassing-aeration process was repeated three times, and after the system was thawed, the reaction was stirred at 130 ℃ for 48 hours. After the reaction is finished, carrying out suction filtration on the reactant to leave solid insoluble substances, and washing the solid insoluble substances for multiple times by respectively using excessive dichloromethane, water and tetrahydrofuran solvents for removing unreacted monomers or catalyst residues which may exist. The crude product was further purified by soxhlet extraction with dichloromethane and tetrahydrofuran, respectively. And finally drying in a vacuum drying oven at 90 ℃ for 12 hours to obtain yellow powder, namely the target porous organic polymer LNU-48 containing thiophene units.

The reaction equation for the porous organic polymers LNU-48 is as follows:

EXAMPLE 2 preparation of porous organic polymers LNU-49 containing thiophene units

400mg (0.641mmoL) of tris (4-chloronicotinyl) amine and 412mg (0.855mmoL) of 3,3',5,5' -tetrabromo-2, 2 '-bithiophene were added to a round-bottomed flask containing 60mL of a solution of N, N' -dimethylformamide under a nitrogen atmosphere, and then the whole was frozen with liquid nitrogen and degassed with a vacuum pump and then repeatedly circulated with aeration three times, 5mL of a 2M-concentrated aqueous potassium carbonate solution and 40mg of tetrakis (triphenylphosphine) palladium were rapidly added to the reaction system, and the freezing-degassing-aeration process was repeated three times, and after the system was thawed, the reaction was stirred for 48 hours while heating to 130 ℃. After the reaction is finished, carrying out suction filtration on the reactant to leave solid insoluble substances, and washing the solid insoluble substances for multiple times by respectively using excessive dichloromethane, water and tetrahydrofuran solvents for removing unreacted monomers or catalyst residues which may exist. The crude product was further purified by soxhlet extraction with dichloromethane and tetrahydrofuran, respectively. And finally drying in a vacuum drying oven at 90 ℃ for 12 hours to obtain green powder, namely the porous organic polymer LNU-49 containing thiophene units.

The reaction equation for the porous organic polymers LNU-49 is as follows:

example 3 characterization

1. Infrared spectrum analysis: referring to FIGS. 1-1 to 1-2, the IR spectra of the porous organic polymers LNU-48 and LNU-49 containing thiophene units prepared in examples 1 and 2 of the present invention and their corresponding monomers are shown, wherein curve a in each figure is the IR spectrum of the polymer, and curves b and c belong to the monomer. From the figure, a characteristic absorption peak of C-B (1417 cm) in the boric acid monomer can be clearly observed^-1) And B-O characteristic absorption Peak (1351 cm)^-1) And C-Br characteristic absorption peak (500 cm) in thiophene-containing monomer^-1) In porous organic polymersThe above results show that the polymerization reaction occurs, and the target porous organic polymer containing thiophene units is successfully obtained.

2. Scanning electron microscope analysis: when the porous organic polymers LNU-48 and LNU-49 containing thiophene units prepared in examples 1 and 2 were observed by scanning electron microscopy, it was observed that LNU-48 and LNU-49 were each formed by irregular deposition of granular solids, as shown in fig. 2-1 and 2-2. It was found that the particle size of the polymer LNU-48 was around 40nm and the particle size of the polymer LNU-49 was around 25 nm.

3. Transmission electron microscopy analysis: when the porous organic polymers LNU-48 and LNU-49 containing thiophene units prepared in examples 1 and 2 were observed by a transmission electron microscope, it can be seen that the channels of both materials have disordered worm-like structures as shown in fig. 3-1 and 3-2.

4. Thermogravimetric analysis: porous organic polymers LNU-48 and LNU-49 containing thiophene units prepared in examples 1 and 2 were subjected to an air atmosphere at 5 ℃ for min^-1Thermogravimetric analysis was performed under the test conditions, and the thermogravimetric curve is shown in fig. 4. As can be seen from the figure, the polymer skeletons are very stable in air, and the decomposition is not started until 300 ℃, and is probably finished at about 500 ℃, which indicates that the polymer has very good thermal stability. Meanwhile, the samples are not dissolved or decomposed in common organic solvents (methanol, ethanol, dichloromethane, chloroform, tetrahydrofuran, acetone, N' -dimethylformamide and the like), and the polymers are proved to have very good chemical stability.

5. Nitrogen adsorption analysis: the porous organic polymers LNU-48 and LNU-49 containing thiophene units prepared in examples 1 and 2 were subjected to nitrogen adsorption-desorption isotherm curve test, and as a result, as shown in FIGS. 5-1 and 5-2, polymers LNU-48 and LNU-49 were obtained having BET specific surface areas of 21m² g^-1And 200m² g^-1。

6. Pore size distribution: pore size distribution diagrams calculated according to the non-local density functional theory method for the porous organic polymers LNU-48 and LNU-49 containing thiophene units prepared in examples 1 and 2 show that the LNU-48 pore size distribution is mainly large pores, and the LNU-49 pore size distribution is mainly micro pores and meso pores, as can be seen from fig. 6-1 and 6-2.

Example 4 application of porous organic Polymer containing thiophene units to Mercury ion adsorption

10mg of porous organic polymers LNU-48 and LNU-49 containing thiophene units were added to 10mL of 100ppm mercury solutions with different pH values (pH 2-10) at room temperature, and the effect of the different pH values on the adsorbent was tested. As shown in fig. 7-1 and 7-2, the results showed that the adsorption effect was the best with both adsorbents at pH 3. The results prove that the porous organic polymer containing thiophene units is very suitable for the adsorption separation treatment of heavy metal mercury ions in acidic sewage.

1. And (3) equilibrium adsorption test: when the pH was chosen at 3, equilibrium isotherms for mercury ion adsorption were tested at room temperature for both polymers and as can be seen from figures 8-1 and 8-2, the adsorption followed the Langmuir model with LNU-48 having a maximum adsorption capacity of 295mg/g and LNU-49 having a maximum adsorption capacity of 374 mg/g. Due to the fact that LNUs have extended pi conjugated frameworks and high-density sulfur active sites, the mercury ions can be chelated quickly, adsorption selectivity is good, and high adsorption capacity is shown for the mercury ions.

2. And (3) testing the cycle performance: the porous organic polymers LNU-48 and LNU-49 containing thiophene units prepared in examples 1 and 2 were subjected to a cycle performance test as follows: LNU-48 and LNU-49 which adsorb mercury ions are respectively dispersed in 6M HCl aqueous solution to be stirred, and demetallization reaction is carried out to remove the mercury ions adsorbed in the porous organic polymer skeleton. And stirring and washing the sample, drying, and carrying out mercury ion adsorption on the regenerated porous organic polymer in the next round. As can be seen from FIGS. 9-1 and 9-2, the adsorption efficiencies of the adsorbents LNU-48 and LNU-49 after 5 cycles are 89.07% and 92.48%, respectively, and the adsorbents can be recycled and have good application prospects for treatment of acidic industrial waste liquid.