阅读说明：本技术 一种具有超快速吸附性能的新型环糊精聚合物 (Novel cyclodextrin polymer with ultra-fast adsorption performance ) 是由 谢显传 许贵洲 秦龙 于 2019-06-06 设计创作，主要内容包括：一种具有超快速吸附性能的新型环糊精聚合物：将环糊精与刚性交联剂和非刚性交联剂在一定温度下进行混合交联反应得到具有三维网络结构的环糊精聚合物。该聚合物能够超快速吸附水体中的多种有机污染物,且吸附后的聚合物很容易在常温下通过简单的洗涤进行再生,重复使用多次而不会造成吸附性能的下降。(A novel cyclodextrin polymer having ultra-fast adsorption properties: the cyclodextrin, a rigid cross-linking agent and a non-rigid cross-linking agent are subjected to mixed cross-linking reaction at a certain temperature to obtain the cyclodextrin polymer with a three-dimensional network structure. The polymer can adsorb various organic pollutants in water body at ultra-fast speed, and the adsorbed polymer is easy to regenerate through simple washing at normal temperature, and can be repeatedly used for many times without causing the reduction of adsorption performance.)

1. A process for preparing a cyclodextrin polymer, characterized in that,

mixing cyclodextrin with rigid crosslinking agent and non-rigid crosslinking agent, and performing crosslinking reaction.

2. The method of claim 1,

The cyclodextrin is alpha-cyclodextrin, beta-cyclodextrin, or gamma-cyclodextrin, and combinations thereof.

3. The method according to claim 1 or 2,

The rigid cross-linking agent is a cross-linking agent containing a benzene ring structure.

4. The method of claim 3, wherein the crosslinker comprising a benzene ring structure is selected from the group consisting of tetrafluoroterephthalonitrile, decafluorobiphenyl, decafluorobenzophenone, octafluoronaphthalene, or combinations thereof.

5. The method according to claim 1 or 2,

The molar ratio of the rigid cross-linking agent to the cyclodextrin is 0.375-1.5.

The addition amount of the rigid cross-linking agent is 0.375-1.5 times of that of the cyclodextrin on the basis of the amount of the substance.

6. The method according to claim 1 or 2,

The non-rigid cross-linking agent is epichlorohydrin.

7. The method of claim 6,

The molar ratio of the non-rigid cross-linking agent to the cyclodextrin is 20-50.

8. The method according to claim 1 or 2, characterized in that the crosslinking reaction is carried out in an aqueous alkaline solution, which is an aqueous sodium hydroxide or potassium hydroxide solution.

9. The cyclodextrin polymer of claim 8, wherein the concentration of the aqueous alkaline solution is 2-8 mol L^-1。

10. A cyclodextrin polymer obtained by mixing cyclodextrin with a rigid crosslinking agent and a non-rigid crosslinking agent to perform a crosslinking reaction,

The cyclodextrin polymer has a three-dimensional network structure.

11. Use of a cyclodextrin polymer of claim 10 for removing organics from a body of water.

Technical Field

the invention relates to a novel cyclodextrin polymer with ultra-fast adsorption performance.

Background

cyclodextrins are a generic term for cyclic oligosaccharides obtained by hydrolysis of starch, usually containing 6 to 12 glucose units. Of more research and practical interest are molecules containing 6, 7, 8 glucose units, called alpha, beta and gamma-cyclodextrins, respectively. The cyclodextrin has a circular cavity structure, is hydrophilic outside and hydrophobic inside, and can form a host-guest inclusion compound with various target molecules.

Because cyclodextrins have some water solubility, various cyclodextrin polymers are generally prepared as desired. So far, most cyclodextrin polymers are obtained by crosslinking cyclodextrin with a flexible crosslinking agent, such as citric acid and epichlorohydrin. The reaction is easy to be carried out in aqueous phase, and the obtained cyclodextrin polymer has certain swelling property, but because the used cross-linking agents are all non-rigid, the molecular chain segments of the generated cyclodextrin polymer are intertwined, so that the cyclodextrin polymer is non-porous and has very low specific surface area (less than 10 m)²/g), which limits their use, particularly as adsorbents, which have slow adsorption rates and generally take several hours or more to reach adsorption equilibrium.

recently, to solve such problems, Alsbaiee et al prepared a porous cyclodextrin polymer (P-CDP) having a high specific surface area by reacting cyclodextrin with a crosslinking agent having a rigid structure. Due to the introduction of the rigid structure, the molecular chain of the generated polymer is difficult to bend randomly, and the molecules are not tightly stacked to form a self-provided microporous structure. The cyclodextrin polymer shows a very rapid adsorption effect on various organic pollutants in a water body, and the adsorption rate can reach 15-200 times that of activated carbon and common non-porous cyclodextrin polymers.

However, in the prior art, the synthesis of the porous cyclodextrin polymer P-CDP needs to be carried out in an organic phase for a long time (48h) under a closed condition, which limits the industrial production. Although Alsbaiee et al also prepared cyclodextrin polymers (NP-CDP) in the aqueous phase using cyclodextrin and a rigid crosslinker, the resulting polymers were non-porous and had a slow rate of adsorption of organic contaminants. Therefore, how to prepare cyclodextrin polymer materials in an aqueous phase by a simple method while maintaining its rapid adsorption performance is a new subject.

Disclosure of Invention

Technical problem to be solved by the invention

the invention provides a method for preparing cyclodextrin polymer by using non-rigid cross-linking agent and rigid cross-linking agent simultaneously on the basis of previous research, the introduction of the non-rigid cross-linking agent can enable cyclodextrin monomer to be cross-linked and enable the polymer material to have certain swelling performance, and the rigid cross-linking agent can be used as a structure regulating and controlling reagent, can enable the polymer material to have certain microporosity and can be used as a framework to keep the stability of polymer pore channels after swelling. The cyclodextrin polymer material prepared by the method shows very quick adsorption performance to organic pollutants in water, and the preparation of the polymer is only carried out in a water phase, so that the synthetic process is very simple, and the industrial production is very easy to carry out.

the technical scheme of the invention is as follows,

A cyclodextrin polymer with ultrafast adsorption performance is prepared through cross-linking reaction between cyclodextrin, non-rigid cross-linking agent and rigid cross-linking agent in alkaline aqueous solution at a certain temp, filtering, washing with water and tetrahydrofuran, and drying.

Accordingly, the present invention provides

1. A method for preparing cyclodextrin polymer, characterized in that, cyclodextrin is mixed with rigid cross-linking agent and non-rigid cross-linking agent to carry out cross-linking reaction.

2. Preferably, the cyclodextrin is alpha-cyclodextrin, beta-cyclodextrin, or gamma-cyclodextrin, and combinations thereof.

3. Preferably, the rigid crosslinker is a crosslinker containing a benzene ring structure.

4. Preferably, the crosslinker containing a benzene ring structure is selected from the group consisting of tetrafluoroterephthalonitrile, decafluorobiphenyl, decafluorobenzophenone, octafluoronaphthalene, or a combination thereof.

5. Preferably, the molar ratio of the rigid cross-linking agent to the cyclodextrin is 0.375-1.5.

6. preferably, the non-rigid crosslinker is epichlorohydrin.

7. Preferably, the molar ratio of the non-rigid cross-linking agent to the cyclodextrin is 20-50.

8. Preferably, the crosslinking reaction is carried out in an aqueous alkaline solution, which is an aqueous solution of sodium hydroxide or potassium hydroxide.

9. Preferably, the concentration of the alkaline aqueous solution is 2-8 mol L^-1。

10. A cyclodextrin polymer obtained by mixing cyclodextrin with a rigid crosslinking agent and a non-rigid crosslinking agent to perform a crosslinking reaction, wherein the cyclodextrin polymer has a three-dimensional network structure.

11. Use of the cyclodextrin polymer of (10) for removing organic matter from a body of water.

The cyclodextrin, the non-rigid cross-linking agent and the rigid cross-linking agent are mixed and cross-linked, so that the prepared cyclodextrin polymer has certain swelling property, porosity and rigidity, and the novel cyclodextrin polymer can very quickly remove organic matters in a water body.

Drawings

FIG. 1 is a schematic diagram of a synthetic route for preparing a novel cyclodextrin polymer by mixing and crosslinking epichlorohydrin and tetrafluoroterephthalonitrile with cyclodextrin, and a structure of the obtained polymer.

FIG. 2 is a table showing elemental analysis, water absorption analysis and specific surface area analysis of example 2 and comparative examples 1 and 2.

FIG. 3 is an infrared spectrum of example 2 and comparative examples 1 and 2.

Fig. 4 is a macroscopic view (upper) and a scanning electron micrograph (middle and lower) of example 2 and comparative example 1, comparative example 2, in which the electron micrograph at the middle is magnified 5000 times and the electron micrograph at the bottom is magnified 20000 times.

FIG. 5 is a powder X-ray diffraction pattern of example 2 and comparative examples 1 and 2.

Fig. 6 is a thermogravimetric plot of example 2 and comparative examples 1 and 2.

FIG. 7 shows N in example 2 and comparative examples 1 and 2₂(a) and CO₂(b) Adsorption and desorption isotherm diagram.

FIG. 8 is a graph showing the removal rate of bisphenol A (BPA) as a function of time for example 2 and comparative examples 1 and 2.

FIG. 9 is a chart of the adsorption kinetics fit parameters for BPA for example 2 and comparative examples 1 and 2.

FIG. 10 is a table of parameters fitted to the quasi-second order kinetic equation and the Elovich equation for the adsorption kinetics of BPA for example 2 and comparative example 1, comparative example 2.

FIG. 11 is a graph showing the effect of the number of reuses of the cyclodextrin polymer CDP-2 prepared in example 2 on the BPA adsorption performance of the material.

FIG. 12 is a graph of BPA removal rate versus time for polymers prepared from different types of cyclodextrins.

FIG. 13 is a graph of the removal rate of beta cyclodextrin polymers prepared with different rigid crosslinkers for BPA as a function of time.

FIG. 14 is a graph of the removal rate of beta cyclodextrin polymers prepared with different amounts of rigid crosslinker versus time for BPA.

Fig. 15 is a graph of the removal rate of beta cyclodextrin polymers prepared with different amounts of epichlorohydrin for BPA as a function of time.

FIG. 16 is a graph of the removal rate of beta cyclodextrin polymers prepared in different alkaline environments versus time for BPA.

FIG. 17 is a graph of the removal rate of beta cyclodextrin polymers versus BPA prepared at different base concentrations as a function of time.

FIG. 18 is a graph of the removal rate of the cyclodextrin polymer CDP-2 prepared in example 2 for various organic micropollutants in a water body as a function of time.

Detailed Description

Synthesis of cyclodextrin polymers

Weighing a certain amount of cyclodextrin into a round-bottom flask, adding an alkaline aqueous solution to completely dissolve the cyclodextrin, then adding a proper amount of rigid cross-linking agent and a proper amount of flexible cross-linking agent, placing the round-bottom flask into an oil bath kettle equipped with a magnetic stirrer, placing the round-bottom flask into the magnetic stirrer, adjusting the temperature and the rotating speed of the oil bath, continuing to react for 3 hours after the set temperature is reached, filtering the mixed solution after the reaction is finished, sequentially washing the precipitate with distilled water and organic washing solvents (such as tetrahydrofuran, ethanol and the like, so as to dissolve unreacted complete cross-linking agent), and continuing to vacuum-dry the obtained solid for 12 hours to obtain the novel cyclodextrin polymer.

FIG. 1 is a schematic diagram of a synthetic route of a novel cyclodextrin polymer, and it can be seen that the preparation process of the polymer is very simple, the raw materials are easily available, and the obtained polymer has a three-dimensional network structure.

The cyclodextrin used is a cyclodextrin of a cyclic oligosaccharide having 6 to 8 glucose units, namely alpha, beta and gamma cyclodextrins.

the cyclodextrins used may be purchased directly from companies, e.g. from Aladdin, Sigma-Aldrich.

The cyclodextrin used may be a polymer of 2-mer or 3-mer of each of the above cyclodextrins.

As the rigid crosslinking agent, a crosslinking agent having a structure such as a benzene ring, a naphthalene ring or other rigid cyclic structure can be selected. Furthermore, the crosslinking agent used needs to have at least two groups capable of reacting with the hydroxyl groups on the cyclodextrin. The rigid crosslinking agent may be selected from tetrafluoroterephthalonitrile, tetrachloroterephthalonitrile, decafluorobiphenyl, octafluoronaphthalene, etc., or a mixture thereof. The most preferable rigid crosslinking agent is tetrafluoroterephthalonitrile from the viewpoint of cost and reactivity.

the flexible crosslinking agent may be epichlorohydrin, from the viewpoint of reactivity and economy. One skilled in the art will recognize that in principle any chain crosslinker can be selected that is capable of reacting with a hydroxyl group on the cyclodextrin or a group on the rigid crosslinker. The length of the chain is not particularly limited and is determined according to the actual requirement, but it is preferable that the rigid crosslinking agent is dissolved.

The cyclodextrin polymer disclosed by the invention combines the advantages of rigid materials and flexible materials, has certain porosity and swelling property, and the swollen materials can keep a certain pore structure. Therefore, the polymer shows ultra-fast adsorption performance to various organic micropollutants.

The organic micropollutants to be adsorbed are organic pollutants which are harmful to the environment and generally paid attention to. Mainly comprises endocrine disruptors, plastic components, organic phenolic substances and the like. For example, the endocrine disrupters include, but are not limited to, ethinylestradiol, estriol, estradiol. For example, the plastic component includes bisphenol A, bisphenol S, but is not limited thereto. Examples of the organic phenolic substances include, but are not limited to, 2-naphthol, 3-phenylphenol and 2,4, 6-trichlorophenol.

The concentration of the organic micropollutants is not particularly limited as long as it can be dissolved. The addition amount of the cyclodextrin polymer is based on actual needs. In the examples, the concentration of organic micropollutants was 0.1mmol/L, but the concentration of ethinylestradiol and estradiol was 0.05mmol/L, since their solubility in water was too low and the cyclodextrin polymer was added in an amount of 1 mg/ml.

The cyclodextrin polymer is isolated by filtration after contacting the cyclodextrin polymer with an aqueous solution of an organic micropollutant for a period of time. And analyzing the content of the organic micro-pollutants in the filtrate by using high performance liquid chromatography to determine the removal rate of the organic micro-pollutants.

The cyclodextrin polymer after filtration separation is washed with methanol, thereby regenerating the cyclodextrin polymer. The regenerated cyclodextrin polymer can be reused in the process of the invention.