阅读说明：本技术 一种超支化的纤维素冠醚及其制备方法 (Hyperbranched cellulose crown ether and preparation method thereof ) 是由 张志明 姚慧萍 洪钟强 华超君 杨龙 于 2019-11-19 设计创作，主要内容包括：本发明提供一种超支化的纤维素冠醚及其制备方法。首先将纤维素氧化为二醛纤维素；随后二醛纤维素上的醛基与聚乙烯亚胺反应,制备出富含氨基的超支化纤维素；最后4-甲酰苯并-15-冠醚-5与超支化纤维素的氨基反应,制备得到超支化的纤维素冠醚。本发明的有益效果是：超支化纤维素富含氨基基团可以提高冠醚活性基团的负载量,同时超支化的冠醚基团也有利于重金属离子的吸附。(The invention provides hyperbranched cellulose crown ether and a preparation method thereof. Firstly, oxidizing cellulose into dialdehyde cellulose; then aldehyde groups on dialdehyde cellulose react with polyethyleneimine to prepare hyperbranched cellulose rich in amino; finally, 4-formyl benzo-15-crown ether-5 reacts with the amino group of the hyperbranched cellulose to prepare the hyperbranched cellulose crown ether. The invention has the beneficial effects that: the hyperbranched cellulose is rich in amino groups, so that the loading capacity of the crown ether active groups can be improved, and the hyperbranched crown ether groups are also beneficial to the adsorption of heavy metal ions.)

1. A hyperbranched cellulose crown ether and a preparation method thereof are characterized by comprising the following steps:

step 1: oxidizing cellulose with potassium periodate to prepare dialdehyde cellulose;

step 2: dialdehyde cellulose reacts with polyethyleneimine to prepare hyperbranched cellulose rich in amino;

and step 3: the hyperbranched cellulose rich in amino group reacts with 4-formyl benzo-15-crown ether-5 to prepare hyperbranched cellulose crown ether.

2. The hyperbranched cellulose crown ether and the method for preparing the same according to claim 1, wherein: the preparation method of the dialdehyde cellulose in the step 1 comprises the following steps: adjusting the PH value of the purified water by using dilute hydrochloric acid, then weighing a proper amount of cellulose, uniformly dispersing the cellulose in the purified water, adding potassium periodate under the condition of keeping out of the sun, and magnetically stirring and reacting for a period of time at a certain temperature; after the reaction is finished, collecting precipitate, washing the precipitate for several times by using purified water to remove unreacted sodium periodate; and finally, freeze-drying the product to obtain dialdehyde cellulose.

3. Hyperbranched cellulose crown ether and a process for its preparation according to claim 1 or 2, characterized in that: the preparation method of the hyperbranched cellulose in the step 2 comprises the following steps: uniformly dispersing a proper amount of dialdehyde cellulose prepared in the step 1 into purified water, adding a certain amount of polyethyleneimine into the purified water, stirring the mixture to uniformly disperse the solution, and carrying out water bath heating reaction at a certain temperature for a period of time; after the reaction is finished, separating out the precipitate, washing the precipitate for a plurality of times by using purified water, and finally drying to obtain the hyperbranched cellulose.

4. A hyperbranched cellulose crown ether and a process for its preparation according to claim 1 or 3, characterized in that: the preparation method of the hyperbranched cellulose crown ether in the step 3 comprises the following steps: uniformly dispersing a proper amount of hyperbranched cellulose in water, dropwise adding an ethanol solution of 4-formylbenzo-15-crown ether-5 under the protection of nitrogen, reacting under the conditions of vigorous stirring and heating reflux, separating out precipitate after the reaction is finished, performing reflux extraction by using absolute ethanol through a Soxhlet extractor, and drying to obtain the hyperbranched cellulose crown ether.

5. A hyperbranched cellulose crown ether and a process for its preparation according to claim 1 or 2, characterized in that: in the step 1, the pH value of the purified water is adjusted to 3-5; the mass ratio of the cellulose to the purified water to the sodium periodate is 1: 50-60: 1-2; stirring and reacting at the temperature of 40-60 ℃; the reaction time is 3-5 h.

6. The hyperbranched cellulose crown ether and the preparation method thereof according to claim 1 or 3 are characterized in that the mass ratio of dialdehyde cellulose, purified water and polyethyleneimine in the step 2 is 1: 50-100: 0.5-1.5, the water bath temperature is 40-60 ℃, and the reaction time is 2-4 h.

7. The method according to claim 1 or 4, wherein the mass ratio of the hyperbranched cellulose to the water to the 4-formylbenzo-15-crown-5 to the absolute ethyl alcohol in the step 3 is 1:50 to 100:2 to 5:50 to 100, the reflux reaction temperature is 90 ℃, and the reflux time is 24 hours.

Technical Field

The invention relates to hyperbranched cellulose crown ether and a preparation method thereof, belongs to the field of adsorption materials, and particularly relates to an adsorption material for heavy metal ions.

Background

With the rapid development of economy and the rapid promotion of industrialization in China, such as electroplating, metallurgy, mining, tanning, dye, chemical engineering and the like, the potential of rapid development is kept. The sewage containing heavy metals formed in these industries is increasingly discharged into water bodies, causing serious heavy metal pollution. Heavy metal ions are highly toxic at low concentrations and can accumulate in biological organisms causing a range of disorders and diseases that pose serious threats to the ecological environment and human health. The data show that the cellulose has better heavy metal adsorption capacity by introducing polar functional groups capable of being combined with heavy metal on a cellulose macromolecular chain through chemical reaction.

Crown ether compounds have a unique molecular structure and can form complexes with many metal ions due to the variable size of the crown ether cavity. The crown ether is grafted to prepare high molecular crown ether, which can strengthen the complexing performance of the crown ether. For example, patent CN105080497A takes glycidyl methacrylate as a medium to prepare a crown ether modified cellulose, and static and dynamic adsorption and renewable adsorption performance studies are performed on heavy metal ion Cu (ii), and the result proves that the synthesized novel crown ether modified cellulose adsorbent has good adsorption capacity and good renewable performance on heavy metal ion Cu (ii) in an aqueous solution.

In 1952, Flory first proposed a synthetic form of a highly branched polymer and predicted the structure of the highly branched polymer. At the end of the 20 th century, Kim and Webste synthesized a branched polyphenyl called "Hyperbranched Polymer", translated as a "Hyperbranched Polymer". Since then, hyperbranched polymers have become a focus of much research and development.

Hyperbranched polymers have many advantageous properties as a highly branched polymer. Owing to the high degree of branching, they contain a large number of terminal functional groups, which can be modified to impart particular properties to the hyperbranched polymer.

Disclosure of Invention

The invention aims to overcome the defects of the prior art and provide hyperbranched cellulose crown ether and a preparation method thereof. The purpose is as follows: cellulose is used as a base material to prepare a macromolecular adsorption material with a hyperbranched structure and a crown ether group-rich terminal group.

In order to achieve the above purpose, the hyperbranched cellulose crown ether and the preparation method thereof of the invention comprise the following steps:

the method comprises the following steps: preparation of dialdehyde cellulose:

adjusting the PH value of the purified water by using dilute hydrochloric acid, then weighing a proper amount of cellulose, uniformly dispersing the cellulose in the purified water, adding potassium periodate under the condition of keeping out of the sun, and magnetically stirring and reacting for a period of time at a certain temperature; after the reaction is finished, collecting precipitate, washing the precipitate for several times by using purified water to remove unreacted sodium periodate; and finally, freeze-drying the product to obtain dialdehyde cellulose.

Step two: preparing hyperbranched cellulose;

taking a proper amount of dried dialdehyde cellulose, uniformly dispersing the dried dialdehyde cellulose in purified water, adding a certain amount of polyethyleneimine into the purified water, stirring the mixture to uniformly disperse the solution, and carrying out water bath heating reaction for a period of time at a certain temperature; after the reaction is finished, separating out precipitate, washing the precipitate for a plurality of times by using purified water, and finally drying to obtain the hyperbranched cellulose

Step three: preparation of hyperbranched cellulose crown ether.

Uniformly dispersing proper amount of hyperbranched cellulose in water, dropwise adding an ethanol solution of 4-formylbenzo-15-crown ether-5 under the protection of nitrogen, violently stirring, reacting under heating reflux conditions, separating out precipitate after the reaction is finished, performing reflux extraction by using absolute ethanol through a Soxhlet extractor, and drying to obtain hyperbranched cellulose crown ether

Further, adjusting the pH value of the purified water to 3-5 in the first step; the mass ratio of the cellulose to the purified water to the sodium periodate is 1: 50-60: 1-2; stirring and reacting at the temperature of 40-60 ℃; the reaction time is 3-5 h.

Further, in the step 2, the mass ratio of the dialdehyde cellulose to the purified water to the polyethyleneimine is 1: 50-100: 0.5-1.5, the water bath temperature is 40-60 ℃, and the reaction time is 2-4 hours.

Further, in the third step, the mass ratio of the hyperbranched cellulose to the water to the 4-formylbenzo-15-crown-5 to the absolute ethyl alcohol is 1: 50-100: 2-5: 50-100, the reflux reaction temperature is 90 ℃, and the reflux time is 24 hours.

Based on the above, the invention provides a hyperbranched cellulose crown ether and a preparation method thereof. Firstly, oxidizing cellulose into dialdehyde cellulose; then aldehyde on dialdehyde cellulose reacts on the basis of polyethyleneimine to prepare hyperbranched cellulose rich in amino; finally, 4-formyl benzo-15-crown ether-5 reacts with the amino group of the hyperbranched cellulose to prepare the Deda hyperbranched cellulose crown ether. The invention has the beneficial effects that: the hyperbranched cellulose is rich in amino groups, so that the loading capacity of the crown ether active groups can be improved, and the hyperbranched crown ether groups are also beneficial to the adsorption of heavy metal ions.

Detailed Description

The present invention will be described in detail with reference to the following embodiments