A method for preparing modified carboxymethyl cellulose adsorption material

Abstract

The invention relates to the technical field of water treatment, and discloses a method for preparing a modified carboxymethyl cellulose adsorbent material, wherein N,N'-bis(2-ethyl acrylate)ethylenedi(hydroxybenzyl)amine and diethylenetriamine are subjected to Michael addition reaction to obtain an amino-terminated hyperbranched polymer containing phenolic hydroxyl groups. Glutaraldehyde is then used as a cross-linking agent to carry out a cross-linking reaction with carboxymethyl cellulose, and the obtained modified carboxymethyl cellulose adsorbent material has a three-dimensional cross-linked network, a larger specific surface area, can increase more adsorption sites, and contains a large number of phenolic hydroxyl groups, carboxyl groups, amino groups, imino groups, phenolic hydroxyl groups and other functional groups, which significantly improves the adsorbent material's ability to absorb phenolic pollutants and Cu. 2+ Adsorption properties of metal ions.

Description

Technical Field

[0001] The invention relates to the technical field of water treatment, in particular to a method for preparing a modified carboxymethyl cellulose adsorption material. Background Art

[0002] Cellulose is green, environmentally friendly, pollution-free, abundant in reserves, cheap and easy to obtain. Currently, countries around the world are vigorously developing and exploiting cellulose resources. Cellulose contains a large number of hydroxyl groups, which can be grafted and polymerized with chloroacetic acid, epichlorohydrin, acrylic acid, acrylamide, etc. to obtain functional cellulose materials, which are widely used in adsorbents, dressings, packaging materials, phase change materials, etc.

[0003] Hyperbranched polymers are a class of highly branched three-dimensional macromolecular polymers with abundant terminal functional groups, diverse polymerization monomers and preparation methods. They are widely used in wastewater treatment, environmental remediation and other fields. Patent CN114471481B discloses a method for preparing a cellulose-based spherical nanoparticle microcluster heavy metal adsorbent, wherein regenerated cellulose is oxidized with sodium periodate, and then reacted and grafted with glutaraldehyde and amino-terminated hyperbranched polymers. The resulting cellulose-based adsorbent has a good adsorption capacity for heavy metal ions. However, the cellulose-based adsorbent does not have a good adsorption effect on phenol pollutants. Summary of the invention

[0004] The invention solves the problem that carboxymethyl cellulose has poor adsorption performance on phenol pollutants.

[0005] The technical solution of the present invention is: a method for preparing a modified carboxymethyl cellulose adsorption material, comprising the following steps:

[0006] S1. Add chloroform solvent, N,N'-bis(2-ethyl acrylate)ethylenedi(hydroxybenzyl)amine and diethylenetriamine into a flask, introduce nitrogen, stir for reaction, and then distill under reduced pressure, wash with petroleum ether, and dry to obtain a phenolic hydroxyl-terminated amino group hyperbranched polymer.

[0007] S2. Add distilled water and carboxymethyl cellulose into a flask, stir to dissolve, add phenolic hydroxyl-terminated amino-group hyperbranched polymer, stir to mix, then add glutaraldehyde aqueous solution, stir to react, filter, wash with distilled water and ethanol in turn, and dry to obtain a modified carboxymethyl cellulose adsorption material.

[0008] Wherein, the structural formula of N,N'-bis(2-ethyl acrylate)ethylenedi(hydroxybenzyl)amine is as shown in formula (I):

[0009]

[0010] In S1, the molar amount of diethylenetriamine is 100-110% of the molar amount of N,N'-bis(2-ethyl acrylate)ethylenedi(hydroxybenzyl)amine.

[0011] In S2, the mass of the phenolic hydroxyl-terminated amino-group hyperbranched polymer is 80-300% of the mass of the carboxymethyl cellulose.

[0012] Wherein, in S1, the reaction is carried out at 45-60°C for 12-24h.

[0013] Wherein, in S2, the mass fraction of the aqueous solution of glutaraldehyde is 1-3%.

[0014] Wherein, in S2, the reaction is carried out at 20-30°C for 3-8h.

[0015] Wherein, the preparation method of N,N'-bis(2-ethyl acrylate)ethylenedi(hydroxybenzyl)amine is:

[0016] (1) Ethyl acetate and N,N'-bis(2-ethyl acrylate)ethylenediamine are added to a flask, stirred to dissolve, and then a 2-3.5 mol / L hydrogen chloride ethyl acetate solution is added dropwise under an ice-water bath, followed by reaction at 20-30°C for 2-4 hours, and a saturated sodium bicarbonate solution is added. After mixing, the mixture is allowed to stand for separation to obtain an ethyl acetate organic phase, which is distilled under reduced pressure to obtain an intermediate.

[0017] The structural formula of the N,N'-bis(2-ethyl acrylate)ethylenediBoc amine is

[0018]

[0019] (2) Add dichloromethane, the intermediate, and triethylamine to a flask, stir to dissolve, then add 4-hydroxybenzyl chloride, wherein the molar amounts of triethylamine and 4-hydroxybenzyl chloride are 200-250% and 200-230% of the molar amount of the intermediate, respectively; react at 20-35° C. for 18-24 hours, distill under reduced pressure after the reaction, wash with water, and recrystallize the product in ethanol to obtain N,N'-bis(2-ethyl acrylate)ethylenedi(hydroxybenzyl)amine.

[0020] The technical effect is as follows: the present invention utilizes N,N'-bis(2-ethyl acrylate)ethylenediBocamine to remove Boc protection in an ethyl acetate solution of hydrogen chloride, and then undergoes a substitution reaction with 4-hydroxybenzyl chloride in a triethylamine catalyst system to obtain N,N'-bis(2-ethyl acrylate)ethylenedi(hydroxybenzyl)amine, and undergoes a Michael addition reaction with diethylenetriamine to obtain an amino-terminated hyperbranched polymer containing phenolic hydroxyl groups.

[0021] The invention uses glutaraldehyde as a crosslinking agent to carry out a crosslinking reaction between carboxymethyl cellulose and an amino group of a phenolic hydroxyl-terminated amino-group hyperbranched polymer having a branched network molecular chain. The obtained modified carboxymethyl cellulose adsorption material has a three-dimensional crosslinking network and a larger specific surface area, can increase more adsorption sites, contains a large number of phenolic hydroxyl groups, has a strong affinity with phenol and its derivatives, can form a π-π bond interaction between the two, and the phenolic hydroxyl group and the carboxyl group can form a hydrogen bond interaction with phenolic compounds, thereby significantly improving the adsorption performance of the adsorption material on phenol and 4-chlorophenol.

[0022] The modified carboxymethyl cellulose adsorbent material of the present invention contains a large number of functional groups such as carboxyl, amino, imino, and phenolic hydroxyl groups, which can react with Cu 2+ The strong coordination and chelation of metal ions further improves the adsorption of Cu 2+ Adsorption properties of metal ions. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is the adsorption curve of phenol by the adsorbent material.

[0024] Figure 2 It is the adsorption curve of 4-chlorophenol by the adsorbent material.

[0025] Figure 3 Is the adsorption material to Cu 2+ The adsorption curve. DETAILED DESCRIPTION

[0026] To better illustrate the purpose, technical solutions and advantages of the present invention, the present invention will be further described below in conjunction with specific embodiments. It should be understood by those skilled in the art that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0027] The carboxymethyl cellulose in the embodiment of the present invention has the following characteristics: model: FH7000; viscosity: 7000-9000 mPa·s; purity: 99.5%.

[0028] The preparation method of N,N'-bis(2-ethyl acrylate)ethylenediBoc amine is as follows:

[0029] In an ice water bath, add 50 mL of dichloromethane and 48 mmol of N,N'-bis(2-hydroxyethyl)ethylenediamine (structural formula: CAS No. 4439-20-7), 57mmol di-tert-butyl dicarbonate (CAS No. 24424-99-5), 57mmol triethylamine, then stirred at 25°C for 12h, distilled under reduced pressure, and the product was separated by silica gel column chromatography, with the eluent being a solution of dichloromethane and methanol in a volume ratio of 30:1, to obtain N,N'-bis(2-hydroxyethyl)ethylenediBocamine. The structural formula is

[0030]

[0031] In an ice-water bath, add 50 mL of dichloromethane, 77 mmol of acryloyl chloride, 77 mmol of triethylamine, and 38 mmol of N, N'-bis (2-hydroxyethyl) ethylenedi Boc amine to the flask, and then stir and react at 25 ° C for 12 hours. After filtering, the filtrate is distilled under reduced pressure, and the product is separated by silica gel column chromatography. The eluent is a solution of petroleum ether and ethyl acetate in a volume ratio of 3:1 to obtain N, N'-bis (2-ethyl acrylate) ethylenedi Boc amine. The structural formula is

[0032]

[0033] Example 1

[0034] (1) Add 200 mL of ethyl acetate and 40 mmol of N,N'-bis(2-ethyl acrylate)ethylenediBocamine to a flask, stir to dissolve, then drop 180 mL of ethyl acetate solution of hydrogen chloride with a molar concentration of 2 mol / L in an ice-water bath, then react at 30°C for 3 h, add saturated sodium bicarbonate solution, mix well, and stand to separate, separate the ethyl acetate organic phase, and distill under reduced pressure to obtain the intermediate. The preparation reaction formula is:

[0035]

[0036] (2) Add 80 mL of dichloromethane, 20 mmol of the intermediate, and 50 mmol of triethylamine to a flask, stir to dissolve, then add 46 mmol of 4-hydroxybenzyl chloride (CAS No. 35421-08-0), react at 20° C. for 18 h, and then distill under reduced pressure. After washing with water, the product is recrystallized in ethanol to obtain N,N'-bis(2-ethyl acrylate)ethylenedi(hydroxybenzyl)amine. The preparation reaction formula is:

[0037]

[0038] (3) Add 80 mL of chloroform solvent, 50 mmol of N,N'-bis(2-ethyl acrylate)ethylenedi(hydroxybenzyl)amine, and 52 mmol of diethylenetriamine to a flask, introduce nitrogen, stir and react at 45°C for 24 hours, distill under reduced pressure, wash with petroleum ether, and dry to obtain a phenolic hydroxyl-terminated amino-group hyperbranched polymer. The preparation reaction mechanism is:

[0039]

[0040] (4) Add 800 mL of distilled water and 10 g of carboxymethyl cellulose into a flask, stir to dissolve, add 8 g of phenolic hydroxyl-terminated amino hyperbranched polymer, stir to mix, then add 250 mL of 1% by mass glutaraldehyde aqueous solution, stir to react at 25° C. for 3 h, filter, wash with distilled water and ethanol in turn, and dry to obtain a modified carboxymethyl cellulose adsorption material.

[0041] Example 2

[0042] (1) Add 300 mL of ethyl acetate and 40 mmol of N,N'-bis(2-ethyl acrylate)ethylenediBocamine to a flask, stir to dissolve, then dropwise add 100 mL of 3.5 mol / L hydrogen chloride in ethyl acetate solution in an ice-water bath, then react at 20°C for 4 h, add saturated sodium bicarbonate solution, mix well, and allow to stand to separate, separate the ethyl acetate organic phase, and distill under reduced pressure to obtain an intermediate.

[0043] (2) Add 70 mL of dichloromethane, 20 mmol of the intermediate, and 40 mmol of triethylamine into a flask, stir to dissolve, then add 40 mmol of 4-hydroxybenzyl chloride, react at 35° C. for 18 h, and then distill under reduced pressure. After washing with water, the product is recrystallized in ethanol to obtain N,N'-bis(2-ethyl acrylate)ethylenedi(hydroxybenzyl)amine.

[0044] (3) Add 100 mL of chloroform solvent, 50 mmol of N,N'-bis(2-ethyl acrylate)ethylenedi(hydroxybenzyl)amine, and 55 mmol of diethylenetriamine into a flask, introduce nitrogen, stir and react at 60°C for 12 h, evaporate under reduced pressure, wash with petroleum ether, and dry to obtain a phenolic hydroxyl-terminated amino group hyperbranched polymer.

[0045] (4) Add 1200 mL of distilled water and 10 g of carboxymethyl cellulose into a flask, stir to dissolve, add 18 g of phenolic hydroxyl-terminated amino hyperbranched polymer, stir to mix, then add 150 mL of a 3% by mass glutaraldehyde aqueous solution, stir to react at 20° C. for 8 h, filter, wash with distilled water and ethanol in turn, and dry to obtain a modified carboxymethyl cellulose adsorption material.

[0046] Example 3

[0047] (1) Add 300 mL of ethyl acetate and 40 mmol of N,N'-bis(2-ethyl acrylate)ethylenediBocamine to a flask, stir to dissolve, then dropwise add 150 mL of 3 mol / L hydrogen chloride in ethyl acetate solution in an ice-water bath, then react at 30°C for 2 h, add saturated sodium bicarbonate solution, mix well, and allow to stand to separate, separate the ethyl acetate organic phase, and distill under reduced pressure to obtain an intermediate.

[0048] (2) Add 60 mL of dichloromethane, 20 mmol of the intermediate, and 44 mmol of triethylamine into a flask, stir to dissolve, then add 44 mmol of 4-hydroxybenzyl chloride, react at 30° C. for 24 h, and then distill under reduced pressure. After washing with water, the product is recrystallized in ethanol to obtain N,N'-bis(2-ethyl acrylate)ethylenedi(hydroxybenzyl)amine.

[0049] (3) Add 100 mL of chloroform solvent, 50 mmol of N,N'-bis(2-ethyl acrylate)ethylenedi(hydroxybenzyl)amine, and 50 mmol of diethylenetriamine into a flask, introduce nitrogen, stir and react at 60°C for 18 h, distill under reduced pressure, wash with petroleum ether, and dry to obtain a phenolic hydroxyl-terminated amino group hyperbranched polymer.

[0050] (4) Add 1200 mL of distilled water and 10 g of carboxymethyl cellulose into a flask, stir to dissolve, add 30 g of phenolic hydroxyl-terminated amino hyperbranched polymer, stir to mix, and then add 300 mL of a 3% by mass aqueous solution of glutaraldehyde, stir to react at 30° C. for 3 h, filter, wash with distilled water and ethanol in turn, and dry to obtain a modified carboxymethyl cellulose adsorption material.

[0051] Comparative Example 1

[0052] Add 800 mL of distilled water and 10 g of carboxymethyl cellulose into a flask, stir to dissolve, add 250 mL of an aqueous solution of 1% glutaraldehyde, stir to react at 25°C for 3 h, filter, wash with distilled water and ethanol in turn, and dry to obtain a modified carboxymethyl cellulose adsorption material.

[0053] Comparative Example 2

[0054] Add 800 mL of distilled water and 8 g of phenolic hydroxyl-terminated amino-group hyperbranched polymer (prepared according to the method of Example 1) into a flask, stir to mix, then add 250 mL of a 1% by mass aqueous solution of glutaraldehyde, stir to react at 25° C. for 3 h, filter, wash with distilled water and ethanol in turn, and dry to obtain an adsorbent material.

[0055] Comparative Example 3

[0056] (1) Add 80 mL of chloroform solvent and 50 mmol of the intermediate (structural formula: Prepared according to the method of Example 1), 52 mmol of diethylenetriamine, introduced nitrogen, stirred and reacted at 45°C for 24 hours, distilled under reduced pressure, washed with petroleum ether, and dried to obtain an amino-terminated hyperbranched polymer.

[0057] (2) Add 800 mL of distilled water and 10 g of carboxymethyl cellulose into a flask, stir to dissolve, add 8 g of amino-terminated hyperbranched polymer, stir to mix, then add 250 mL of 1% by mass glutaraldehyde aqueous solution, stir to react at 25° C. for 3 h, filter, wash with distilled water and ethanol in turn, and dry to obtain a modified carboxymethyl cellulose adsorption material.

[0058] Comparative Example 4

[0059] (1) Add 80 mL of chloroform solvent and 50 mmol of ethylene glycol dimethacrylate (structural formula: CAS No. 97-90-5), 52 mmol of diethylenetriamine, nitrogen was introduced, the mixture was stirred at 45°C for 24 hours, and the mixture was distilled under reduced pressure, washed with petroleum ether, and dried to obtain an amino-terminated hyperbranched polymer.

[0060] (2) Add 800 mL of distilled water and 10 g of carboxymethyl cellulose into a flask, stir to dissolve, add 8 g of amino-terminated hyperbranched polymer, stir to mix, then add 250 mL of 1% by mass glutaraldehyde aqueous solution, stir to react at 25° C. for 3 h, filter, wash with distilled water and ethanol in turn, and dry to obtain a modified carboxymethyl cellulose adsorption material.

[0061] Weigh 2g of adsorption material and add it to 1000mL of aqueous solution containing phenolic compounds, the concentration of phenolic compounds in the solution is 500mg / L, stir and adsorb at 25℃, remove the supernatant at different adsorption times, detect the concentration of phenolic compounds by UV-visible spectrophotometry, and calculate the adsorption rate W. C0 is the initial concentration of phenolic compounds, and C is the concentration of phenolic compounds after adsorption. Phenolic compounds are phenol or 4-chlorophenol.

[0062] Weigh 100 mg of adsorbent material and add it to 500 mL of copper nitrate aqueous solution. 2+ The concentration of Cu was 20 mg / L, dilute nitric acid was added to adjust the solution pH to 5, and the solution was stirred and adsorbed at 25°C. The supernatant was removed at different adsorption times, and the Cu was detected by atomic absorption spectrophotometry. 2+ The concentration of , calculate the adsorption rate W, C0 is Cu 2+ The initial concentration of the solution, C is the Cu after adsorption 2+ Solution concentration.

[0063] In Examples 1-3, glutaraldehyde is used as a crosslinking agent to crosslink carboxymethyl cellulose with the amino group of the phenolic hydroxyl-terminated amino-terminated hyperbranched polymer having a branched network molecular chain. The obtained modified carboxymethyl cellulose adsorbent material has a three-dimensional crosslinked network, a larger specific surface area, can increase more adsorption sites, and contains a large number of phenolic hydroxyl groups, has a strong affinity with phenol and its derivatives, and can form a π-π bond interaction between the two, and the phenolic hydroxyl group and the carboxyl group can form a hydrogen bond interaction with phenolic compounds, which significantly improves the adsorption performance of the adsorbent material for phenol and 4-chlorophenol. In addition, the adsorbent material contains a large number of functional groups such as carboxyl groups, amino groups, imino groups, and phenolic hydroxyl groups, which can interact with Cu 2+ The strong coordination and chelation of metal ions further improves the adsorption of Cu 2+ The adsorption performance of metal ions such as Figure 1-3 It can be seen that the adsorption rate of the adsorbent of Example 2 for phenol and 4-chlorophenol reached 97.1% and 94.6% respectively. 2+ The adsorption rate reached 93.8%.

[0064] Compared with Example 1, the adsorption material of Comparative Example 1 does not undergo crosslinking reaction with the phenolic hydroxyl-terminated amino-terminated hyperbranched polymer, and is difficult to form a three-dimensional crosslinked network with a high specific surface area. It has fewer adsorption sites and does not contain functional groups such as amino, imino, and phenolic hydroxyl groups. The adsorption rate for phenol is only 29.2%, the adsorption rate for 4-chlorophenol is only 25.9%, and the adsorption rate for Cu is only 0.04. 2+ The adsorption rate is only 39.9%.

[0065] Comparative Example 2: The cross-linking reaction of the phenolic hydroxyl-terminated amino-terminated hyperbranched polymer and glutaraldehyde was carried out to obtain an adsorbent material without cellulose matrix and carboxyl groups, and the adsorbent material was free of phenolic compounds and Cu 2+ The adsorption rate is significantly lower than that of Example 1.

[0066] Comparative Example 3 uses an intermediate (structural formula: ) and diethylenetriamine to undergo Michael addition reaction to obtain an amino-terminated hyperbranched polymer and a modified carboxymethyl cellulose adsorption material without phenolic hydroxyl groups. ) and diethylenetriamine to undergo Michael addition reaction, and the obtained amino-terminated hyperbranched polymer and modified carboxymethyl cellulose adsorption material do not contain phenolic hydroxyl groups. As a result, the adsorption rate of the two adsorption materials for phenolic compounds is significantly lower than that of Example 1. And for Cu 2+ The adsorption rate is also slightly lower than that of Example 1.

[0067] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the essence and scope of the technical solution of the present invention.

Claims

1. A method for preparing a modified carboxymethyl cellulose adsorbent material, characterized in that: The preparation method comprises the following steps: S1, adding chloroform solvent, N,N'-bis(2-ethyl acrylate)ethylenedi(hydroxybenzyl)amine and diethylenetriamine into a flask, introducing nitrogen, stirring for reaction, and then distilling under reduced pressure, washing, and drying to obtain a phenolic hydroxyl-terminated amino-group hyperbranched polymer; S2, add distilled water and carboxymethyl cellulose to a flask, stir to dissolve, add phenolic hydroxyl terminal amino hyperbranched polymer, stir to mix, then add glutaraldehyde aqueous solution, stir to react, filter, wash, and dry to obtain a modified carboxymethyl cellulose adsorption material; The structural formula of the N,N'-bis(2-ethyl acrylate)ethylenedi(hydroxybenzyl)amine is as follows: In the S2, the mass of the phenolic hydroxyl-terminated amino-group hyperbranched polymer is 80-300% of the mass of the carboxymethyl cellulose.

2. The method for preparing the modified carboxymethyl cellulose adsorbent material according to claim 1, characterized in that: In S1, the molar amount of diethylenetriamine is 100-110% of the molar amount of N,N'-bis(2-ethylacrylate)ethylenedi(hydroxybenzyl)amine.

3. The method for preparing the modified carboxymethyl cellulose adsorbent material according to claim 1, characterized in that: In S1, the reaction is carried out at 45-60° C. for 12-24 h.

4. The method for preparing the modified carboxymethyl cellulose adsorbent material according to claim 1, characterized in that: In the S2, the mass fraction of the aqueous solution of glutaraldehyde is 1-3%.

5. The method for preparing the modified carboxymethyl cellulose adsorbent material according to claim 1, characterized in that: In S2, the reaction is carried out at 20-30°C for 3-8h.

6. The method for preparing the modified carboxymethyl cellulose adsorbent material according to claim 2, characterized in that: The preparation method of N,N'-bis(2-ethyl acrylate)ethylenedi(hydroxybenzyl)amine is as follows: (1) adding ethyl acetate and N,N'-bis(2-ethyl acrylate)ethylenedi(Boc)amine into a flask, stirring to dissolve, then dripping a solution of hydrogen chloride in ethyl acetate under an ice-water bath, reacting at 20-30°C for 2-4h, and separating to obtain an intermediate; The structural formula of the N,N'-bis(2-ethyl acrylate)ethylenediBoc amine is (2) Add dichloromethane, the intermediate, and triethylamine into a flask, stir to dissolve, then add 4-hydroxybenzyl chloride, and after the reaction, distill under reduced pressure and recrystallize to obtain N,N'-bis(2-ethyl acrylate)ethylenedi(hydroxybenzyl)amine.

7. The method for preparing the modified carboxymethyl cellulose adsorbent material according to claim 6, characterized in that: The molar concentration of the ethyl acetate solution of hydrogen chloride in (1) is 2-3.5 mol / L.

8. The method for preparing the modified carboxymethyl cellulose adsorbent material according to claim 6, characterized in that: In the above (2), the molar amounts of triethylamine and 4-hydroxybenzyl chloride are 200-250% and 200-230% of the molar amount of the intermediate, respectively.

9. The method for preparing the modified carboxymethyl cellulose adsorbent material according to claim 6, characterized in that: In the step (2), the reaction is carried out at 20-35°C for 18-24 hours.

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