阅读说明：本技术 一种改性蔗髓木素、制备方法及其应用 (Modified bagasse pith lignin, preparation method and application thereof ) 是由 刘新亮 王双飞 王加宝 刘静 覃程荣 梁辰 聂双喜 张健 于 2020-04-10 设计创作，主要内容包括：本发明公开了一种改性蔗髓木素、制备方法及其应用,所述制备方法为采用酸析法制取蔗髓木素,加入氧化剂制备氧化蔗髓木素,加入氢氧化钠、环氧氯丙烷、无水乙醇得到环氧化蔗髓木素,加入二乙烯三胺及高枝化多胺、碱溶液、甲醛得到胺化蔗髓木素。本发明的改性蔗髓木素对重金属的吸附容量有极大的提升。(The invention discloses a modified pith lignin, a preparation method and application thereof, wherein the preparation method comprises the steps of preparing pith lignin by an acid precipitation method, adding an oxidant to prepare oxidized pith lignin, adding sodium hydroxide, epoxy chloropropane and absolute ethyl alcohol to obtain epoxidized pith lignin, and adding diethylenetriamine, hyperbranched polyamine, an alkali solution and formaldehyde to obtain aminated pith lignin. The adsorption capacity of the modified bagasse pith lignin to heavy metals is greatly improved.)

1. The preparation method of the modified bagasse pith lignin is characterized by comprising the following steps:

(1) oxidizing the pith lignin by using the pith lignin as a raw material and sodium periodate, hydrogen peroxide or sodium persulfate as an oxidizing agent to prepare oxidized pith lignin;

(2) mixing oxidized bagasse pith lignin with sodium hydroxide and absolute ethyl alcohol, taking epoxy chloropropane as a halogenating agent, and reacting under stirring to prepare the epoxidized bagasse pith lignin;

(3) adding diethylenetriamine and high-branched polyamine derivatives, alkali solution and formaldehyde into the epoxidized pith lignin, and reacting under stirring to prepare the aminated pith lignin.

2. The method for preparing modified bagasse pith lignin according to claim 1, wherein the specific process of step (1) is: separating fiber by alkaline sulfite method, collecting separated black liquor, concentrating, adding sodium hydroxide into concentrated black liquor, adjusting pH to 11-13, filtering to remove insoluble substances, adjusting pH of supernatant to 2, standing for precipitation, washing precipitate to neutrality, oven drying, taking dried lignin, adjusting pH to 2-5 at room temperature, adding 10-50ml sodium periodate for oxidation treatment to obtain oxidized pith lignin, extracting, washing to neutrality, and drying at 40-80 deg.C for use.

3. The process for preparing modified bagasse pith lignin according to claim 2, wherein the pH of the supernatant is adjusted with sulfuric acid, the concentration of sulfuric acid being 20-21 wt%.

4. The method of claim 2, wherein the sodium periodate is present at a concentration of 1 mol/L.

5. The method for preparing modified bagasse pith lignin according to claim 1, wherein the specific process of step (2) is: and (2) putting the oxidized bagasse pith lignin obtained in the step (1) into a container with a stirrer and a thermometer, adding sodium hydroxide, epoxy chloropropane and absolute ethyl alcohol, heating for reaction, filtering, washing with water and acetone for three times, and drying to obtain the epoxidized bagasse pith lignin.

6. The process for preparing modified bagasse pith lignin according to claim 5, wherein the heating temperature in step (2) is 60-80 ℃ and the heating time is 3-5 hours.

7. The method for preparing modified bagasse pith lignin according to claim 1, wherein the specific process of step (3) is: placing the epoxidized bagasse pith lignin into a container with a stirrer and a thermometer, adding diethylenetriamine and hyperbranched polyamine derivatives, aqueous alkali and formaldehyde into the container, heating for reaction, filtering, washing with water and ethanol for three times, and drying to obtain the aminated bagasse pith lignin.

8. The process for preparing modified bagasse pith lignin according to claim 7, wherein the heating temperature in step (3) is 70-80 ℃ and the heating time is 4-5 hours.

9. A modified pith lignin prepared according to the method of any one of claims 1 to 8.

10. Use of the modified pith lignin of claim 9 in the preparation of a heavy metal ion adsorbent.

Technical Field

The invention relates to the technical field of heavy metal pollution treatment in environmental protection, in particular to modified bagasse pith lignin, a preparation method and application thereof.

Background

At present, there are many methods for treating heavy metal wastewater, and the common methods are chemical methods, membrane methods, ion exchange methods and adsorption methods. However, in comparison of several methods, the chemical method and the membrane method are effective methods in view of operation cost and operation stability, but the chemical method has high requirements for some treatment equipment, the treatment cost of the generated sludge containing heavy metals is high, and the maintenance cost of the equipment is also high. Membrane equipment is expensive, running and maintenance costs are high, and throughput is limited. The ion exchange method and the adsorption method have certain selectivity on heavy metals, but the ion exchange method has high activation cost on resin and is easy to inactivate; the biological method and the adsorption method can remove heavy metals to a certain extent, but the biological method needs domesticated organisms with a long period, and the biological activity can influence the treatment effect. The adsorbent available for the adsorption method has various types, different cost due to different materials, and larger difference of adsorption capacity, but the aim of high adsorption capacity can be achieved by further modifying the low-cost material, so the adsorption method is a convenient and effective treatment technology with a very promising prospect.

The main components of the bagasse pith are lignin, cellulose and hemicellulose. Lignin is a high molecular polymer with a three-dimensional network structure, widely exists in plants, and is a filling and bonding substance among cells. The chemical structure of lignin is mainly that phenylpropane unit or its derivative is used as basic skeleton, and is connected by carbon-carbon bond and ether bond. The lignin contains various functional groups such as methoxy, hydroxyl, carbonyl and the like in the molecule. These functional groups affect the physicochemical properties of lignin. Chinese patent CN102527348A discloses a method for preparing phenolic aldehyde modified lignin from reed raw material as adsorbent for adsorbing heavy metal ionsThe application and the preparation method thereof improve the adsorption capacity of lignin to heavy metals by modifying the lignin and increasing the content of hydroxyl groups of the lignin. However, the modified alkali lignin in the method only improves the Pb content²⁺、Cd²⁺、Cr³⁺The adsorption capacity of the three metal ions to other heavy metals is not improved. Therefore, it is desirable to provide an adsorbent having good removal ability for various heavy metal ions.

Disclosure of Invention

The invention aims to provide modified bagasse pith lignin, a preparation method and application thereof, so as to solve the problems in the prior art.

In order to achieve the purpose, the invention provides the following scheme:

the first technical scheme is as follows:

the invention provides a preparation method of modified bagasse pith lignin, which comprises the following steps:

(1) oxidizing the pith lignin by using the pith lignin as a raw material and sodium periodate, hydrogen peroxide or sodium persulfate as an oxidizing agent to prepare oxidized pith lignin;

(2) mixing oxidized bagasse pith lignin with sodium hydroxide and absolute ethyl alcohol, taking epoxy chloropropane as a halogenating agent, and reacting under stirring to prepare the epoxidized bagasse pith lignin; in the step, epichlorohydrin reacts with hydroxyl on the cellulose to generate elimination reaction, and chlorine and hydrogen on the hydroxyl are eliminated, so that epoxy groups are introduced into the cellulose;

(3) adding diethylenetriamine and high-branched polyamine derivatives, alkali solution and formaldehyde into the epoxidized pith lignin, and reacting under stirring to prepare the aminated pith lignin.

As a further improvement of the invention, the specific process of the step (1) is as follows: separating fiber by alkaline sulfite method, collecting separated black liquor, concentrating, adding sodium hydroxide into concentrated black liquor, adjusting pH to 11-13, filtering to remove insoluble substances, adjusting pH of supernatant to 2, standing for precipitation, washing precipitate to neutrality, oven drying, taking dried lignin, adjusting pH to 2-5 at room temperature, adding 10-50ml sodium periodate, oxidizing to obtain oxidized bagasse pith lignin, extracting, washing to neutrality, and drying at 40-80 deg.C for use.

As a further improvement of the invention, the pH of the supernatant is adjusted in step (1) with sulfuric acid, the concentration of which is 20 to 21% by weight, preferably 20.4% by weight.

As a further improvement of the invention, the concentration of the sodium periodate in the step (1) is 1 mol/L.

As a further improvement of the invention, the specific process of the step (2) is that the oxidized bagasse pith lignin obtained in the step (1) is put into a container with a stirrer and a thermometer, sodium hydroxide, epichlorohydrin and absolute ethyl alcohol are added, the mixture is heated and reacted, filtered, washed with water and acetone for three times, and dried to obtain the epoxidized bagasse pith lignin, wherein the mass ratio of the sodium hydroxide, the epichlorohydrin and the absolute ethyl alcohol in the step is 5-10: 3-5: 2(m L: g: m L).

As a further improvement of the invention, the heating temperature in the step (2) is 60-80 ℃, and the heating time is 3-5 h. In the step (2), the drying temperature is 40-80 ℃.

As a further improvement of the invention, the specific process of the step (3) is as follows: placing the epoxidized bagasse pith lignin into a container with a stirrer and a thermometer, adding diethylenetriamine and hyperbranched polyamine derivatives, aqueous alkali and formaldehyde into the container, heating for reaction, filtering, washing with water and ethanol for three times, and drying to obtain the aminated bagasse pith lignin.

As a further improvement of the invention, the heating temperature of the step (3) is 70-80 ℃, and the heating time is 4-5 h.

As a further improvement of the invention, the drying temperature in the step (3) is 40-80 ℃.

As a further improvement of the invention, in the step (3), the hyperbranched polyamine derivative comprises dopamine and polyethyleneimine, and the alkali liquor is sodium hydroxide solution.

As a further improvement of the invention, the mass ratio of the diethylenetriamine and the hyperbranched polyamine derivative added in the step (3) is 1: 3-5.

The second technical scheme is as follows:

the invention provides modified pith lignin prepared by the preparation method of the modified pith lignin.

The third technical scheme is as follows:

the invention provides application of the modified bagasse pith lignin in preparation of a heavy metal ion adsorbent.

The invention discloses the following technical effects:

(1) the pith lignin is taken as a renewable resource, the resource is rich, the modification and the utilization of the pith lignin can save a large amount of petroleum resources, the pith lignin is degradable after being adsorbed, used and abandoned, and the problem of environmental pollution caused by a large amount of non-degradable synthetic polymer adsorption resin material waste can be solved; the modified bagasse pith lignin modified adsorbent capable of adsorbing heavy metals has the characteristics of low cost and simple preparation process, can be completely biodegraded after being used by adsorption-desorption, and has no pollution to the environment.

(2) The modified pith lignin adsorbent for adsorbing heavy metal ions is obtained by taking pith lignin as a raw material through a grafting halogenation and amination modification method, is insoluble under acidic, neutral and alkalescent conditions, and can be used in a wide pH range; the adsorbent prepared by the invention has good mechanical strength and washing resistance, and can be suitable for industrial operation; the invention modifies lignin functional groups through chemical modification, and introduces new functional groups, such as aldehyde groups, carboxyl groups, amine groups or phenolic ester groups, and the like, thereby improving the heavy metal adsorption capacity of the pith lignin and having extremely high selective adsorption capacity on heavy metal ions. The removal rate of heavy metal ions can reach more than 90 percent, and the heavy metal ions can be repeatedly regenerated, so that the defects of poor adsorption selectivity and low repeated utilization rate of the activated carbon are overcome; the desorption regeneration can occur in ethanol or acetone, the desorption rate reaches more than 90 percent to 98 percent, and the adsorption capacity is basically unchanged after more than 20 times of regeneration. The cost of treating heavy metal ions in wastewater or soil will be substantially lower.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings needed to be used in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings without inventive exercise.

FIG. 1 shows the adsorption amounts of various heavy metal ions by modified pith lignin at different times;

FIG. 2 shows the adsorption amounts of various heavy metal ions by modified pith lignin at different pH values;

FIG. 3 shows the reuse times of modified bagasse pith lignin versus Cr⁶⁺Influence of ion removal rate.

Detailed Description

Reference will now be made in detail to various exemplary embodiments of the invention, the detailed description should not be construed as limiting the invention but as a more detailed description of certain aspects, features and embodiments of the invention.

It is to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. Further, for numerical ranges in this disclosure, it is understood that each intervening value, between the upper and lower limit of that range, is also specifically disclosed. Every smaller range between any stated value or intervening value in a stated range and any other stated or intervening value in a stated range is encompassed within the invention. The upper and lower limits of these smaller ranges may independently be included or excluded in the range.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Although only preferred methods and materials are described herein, any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present invention. All documents mentioned in this specification are incorporated by reference herein for the purpose of disclosing and describing the methods and/or materials associated with the documents. In case of conflict with any incorporated document, the present specification will control.

It will be apparent to those skilled in the art that various modifications and variations can be made in the specific embodiments of the present disclosure without departing from the scope or spirit of the disclosure. Other embodiments will be apparent to those skilled in the art from consideration of the specification. The specification and examples are exemplary only.

As used herein, the terms "comprising," "including," "having," "containing," and the like are open-ended terms that mean including, but not limited to.