CN113563604B - Method for regulating and controlling industrial alkali lignin molecules - Google Patents
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- 229920005610 lignin Polymers 0.000 title claims abstract description 132
- 239000003513 alkali Substances 0.000 title claims abstract description 121
- 238000000034 method Methods 0.000 title claims abstract description 22
- 230000001105 regulatory effect Effects 0.000 title claims abstract description 21
- 230000001276 controlling effect Effects 0.000 title claims abstract description 10
- ZMXDDKWLCZADIW-UHFFFAOYSA-N N,N-Dimethylformamide Chemical compound CN(C)C=O ZMXDDKWLCZADIW-UHFFFAOYSA-N 0.000 claims abstract description 45
- SGRHVVLXEBNBDV-UHFFFAOYSA-N 1,6-dibromohexane Chemical compound BrCCCCCCBr SGRHVVLXEBNBDV-UHFFFAOYSA-N 0.000 claims abstract description 25
- 238000003916 acid precipitation Methods 0.000 claims abstract description 14
- 239000003960 organic solvent Substances 0.000 claims abstract description 12
- BWHMMNNQKKPAPP-UHFFFAOYSA-L potassium carbonate Chemical compound [K+].[K+].[O-]C([O-])=O BWHMMNNQKKPAPP-UHFFFAOYSA-L 0.000 claims abstract description 12
- 229910000027 potassium carbonate Inorganic materials 0.000 claims abstract description 6
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 claims description 48
- 239000002244 precipitate Substances 0.000 claims description 40
- 239000000243 solution Substances 0.000 claims description 31
- RYHBNJHYFVUHQT-UHFFFAOYSA-N 1,4-Dioxane Chemical compound C1COCCO1 RYHBNJHYFVUHQT-UHFFFAOYSA-N 0.000 claims description 23
- 239000002253 acid Substances 0.000 claims description 22
- 238000006243 chemical reaction Methods 0.000 claims description 20
- 239000000203 mixture Substances 0.000 claims description 18
- 239000006228 supernatant Substances 0.000 claims description 17
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims description 16
- 239000007787 solid Substances 0.000 claims description 16
- 238000000746 purification Methods 0.000 claims description 14
- 238000004108 freeze drying Methods 0.000 claims description 13
- 238000005804 alkylation reaction Methods 0.000 claims description 11
- 238000005119 centrifugation Methods 0.000 claims description 10
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 10
- 238000010438 heat treatment Methods 0.000 claims description 9
- 238000003756 stirring Methods 0.000 claims description 9
- 239000000126 substance Substances 0.000 claims description 9
- 230000002378 acidificating effect Effects 0.000 claims description 8
- 239000012190 activator Substances 0.000 claims description 8
- 239000011230 binding agent Substances 0.000 claims description 8
- DKAGJZJALZXOOV-UHFFFAOYSA-N hydrate;hydrochloride Chemical compound O.Cl DKAGJZJALZXOOV-UHFFFAOYSA-N 0.000 claims description 8
- 239000011259 mixed solution Substances 0.000 claims description 8
- 229910052757 nitrogen Inorganic materials 0.000 claims description 8
- 239000000843 powder Substances 0.000 claims description 8
- 238000005406 washing Methods 0.000 claims description 8
- 239000007864 aqueous solution Substances 0.000 claims description 6
- 239000006185 dispersion Substances 0.000 claims description 6
- 238000004043 dyeing Methods 0.000 claims description 3
- 239000003337 fertilizer Substances 0.000 claims description 3
- 229920001002 functional polymer Polymers 0.000 claims description 3
- 239000000463 material Substances 0.000 claims description 3
- 239000000575 pesticide Substances 0.000 claims description 3
- 239000002861 polymer material Substances 0.000 claims description 3
- 238000002360 preparation method Methods 0.000 claims description 3
- 230000009467 reduction Effects 0.000 claims description 3
- 239000011347 resin Substances 0.000 claims description 3
- 229920005989 resin Polymers 0.000 claims description 3
- 230000001376 precipitating effect Effects 0.000 claims description 2
- 230000008569 process Effects 0.000 claims description 2
- UIIMBOGNXHQVGW-DEQYMQKBSA-M Sodium bicarbonate-14C Chemical compound [Na+].O[14C]([O-])=O UIIMBOGNXHQVGW-DEQYMQKBSA-M 0.000 claims 1
- 230000003213 activating effect Effects 0.000 claims 1
- 239000003795 chemical substances by application Substances 0.000 claims 1
- 238000004537 pulping Methods 0.000 abstract description 14
- 125000002887 hydroxy group Chemical group [H]O* 0.000 abstract description 8
- ISWSIDIOOBJBQZ-UHFFFAOYSA-N phenol group Chemical group C1(=CC=CC=C1)O ISWSIDIOOBJBQZ-UHFFFAOYSA-N 0.000 abstract description 8
- 230000004048 modification Effects 0.000 abstract description 5
- 238000012986 modification Methods 0.000 abstract description 5
- 239000002994 raw material Substances 0.000 abstract description 4
- 238000005516 engineering process Methods 0.000 abstract description 2
- 230000035484 reaction time Effects 0.000 abstract description 2
- UIIMBOGNXHQVGW-UHFFFAOYSA-M Sodium bicarbonate Chemical compound [Na+].OC([O-])=O UIIMBOGNXHQVGW-UHFFFAOYSA-M 0.000 description 14
- 238000002390 rotary evaporation Methods 0.000 description 13
- 230000029936 alkylation Effects 0.000 description 8
- 229910000030 sodium bicarbonate Inorganic materials 0.000 description 7
- 235000017557 sodium bicarbonate Nutrition 0.000 description 7
- 239000010414 supernatant solution Substances 0.000 description 7
- 230000008859 change Effects 0.000 description 6
- 238000000926 separation method Methods 0.000 description 5
- 125000000524 functional group Chemical group 0.000 description 2
- 238000002156 mixing Methods 0.000 description 2
- 239000000047 product Substances 0.000 description 2
- 239000002028 Biomass Substances 0.000 description 1
- 241000196324 Embryophyta Species 0.000 description 1
- 241000592342 Tracheophyta Species 0.000 description 1
- 125000003118 aryl group Chemical group 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 239000006227 byproduct Substances 0.000 description 1
- 239000001913 cellulose Substances 0.000 description 1
- 229920002678 cellulose Polymers 0.000 description 1
- 239000003153 chemical reaction reagent Substances 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 230000003750 conditioning effect Effects 0.000 description 1
- 238000007599 discharging Methods 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 239000000446 fuel Substances 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 238000011031 large-scale manufacturing process Methods 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 229920000642 polymer Polymers 0.000 description 1
- 230000009257 reactivity Effects 0.000 description 1
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08H—DERIVATIVES OF NATURAL MACROMOLECULAR COMPOUNDS
- C08H6/00—Macromolecular compounds derived from lignin, e.g. tannins, humic acids
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Abstract
The invention belongs to the field of alkali lignin utilization in pulping and papermaking industries, and relates to a method for regulating and controlling industrial alkali lignin molecules, which comprises the following steps: alkali lignin in pulping and papermaking industry is used as a raw material, and the alkali lignin is purified by an organic solvent and an acid precipitation method. The purified alkali lignin reacts in a 1, 6-dibromohexane/dimethylformamide/potassium carbonate system to obtain the alkali lignin regulated and controlled by molecules. The novel technology developed by the application improves the molecular weight of the alkali lignin, reduces the polydispersity of partial fractions, regulates the content of phenolic hydroxyl groups, changes the color depth of the alkali lignin and lays a foundation for subsequent modification and application of the alkali lignin. By controlling the adding amount, the reaction time and the temperature of the 1, 6-dibromohexane, the molecular weight of the alkali lignin can be improved by 353-1643 percent, the polydispersity of partial fractions is reduced, the content of the phenolic hydroxyl group is regulated and controlled to be reduced by 2-80 percent, and the color of the alkali lignin can be changed.
Description
Technical Field
The invention belongs to the field of alkali lignin utilization in the pulping and papermaking industry, and particularly relates to a method for regulating and controlling the molecular weight and main functional groups of alkali lignin.
Background
Lignin, a generic term for a class of substances with common properties found in woody, herbaceous and all vascular plants, is the second largest biomass resource in the plant kingdom that reserves only the second to cellulose. Meanwhile, the lignin is the only reproducible aromatic polymer compound, can be used for preparing resin materials and functional polymer materials, and plays an important role in the fields of oil exploitation, building concrete water reduction, printing and dyeing dye dispersion, pesticide slow-release dispersion, fertilizer slow release and the like. Currently only about 2% of lignin is used to produce high value added products, most of which are used only as cheap fuels. The lignin is mainly from the pulping and paper-making industry, and as a pulping byproduct, the annual production amount of the lignin is about 5000 ten thousand tons, wherein about 1500 ten thousand tons in China are not separated or utilized, and 95 percent of the lignin is treated in a direct discharging or burning mode, so that a serious environmental problem is caused. Today, most pulp and paper mills in the world use alkaline pulping, and the lignin produced is mainly alkali lignin. Therefore, the alkali lignin resources are fully utilized to produce the alkali lignin-based product with high added value, and the method has more economic, social and ecological significance. The small molecular weight, high polydispersity, low reactivity, etc. of alkali lignin severely limit its applications.
Disclosure of Invention
In order to overcome the problems, the invention uses alkali lignin in pulping and papermaking industries as a raw material, adopts a novel alkylation system of 1, 6-dibromohexane/dimethylformamide/potassium carbonate, and efficiently improves the molecular weight of the alkali lignin, adjusts the polydispersity, and adjusts and controls functional groups such as phenolic hydroxyl groups. By controlling the adding amount of the 1, 6-dibromohexane, the reaction time and the temperature, the molecular weight of the alkali lignin can be increased by 353-1643 percent, the polydispersity of partial fractions is reduced, the content of phenolic hydroxyl is regulated and controlled to be reduced by 2-80 percent, and the color of the alkali lignin can be changed.
In order to achieve the technical purpose, the invention adopts the following technical scheme:
in a first aspect of the invention, a method for regulating an industrial alkali lignin molecule is provided, which comprises the following steps:
purifying the industrial alkali lignin to obtain purified alkali lignin;
and (3) carrying out alkylation reaction on the purified alkali lignin in a 1, 6-dibromohexane/dimethylformamide/potassium carbonate system to obtain the alkali lignin subjected to molecular regulation.
The novel technology developed by the application improves the molecular weight of the alkali lignin, reduces the polydispersity of partial fractions, regulates the content of phenolic hydroxyl groups, changes the color depth of the alkali lignin and lays a foundation for subsequent modification and application of the alkali lignin.
In a second aspect of the invention, there is provided a molecularly imprinted alkali lignin prepared by any of the above methods.
The third aspect of the invention provides the application of the alkali lignin subjected to molecular regulation and control in the fields of preparation of resin materials, functional polymer materials, oil exploitation, water reduction of building concrete, dye dispersion for printing and dyeing, slow-release dispersion of pesticides and slow release of fertilizers.
The invention has the beneficial effects that:
(1) In the whole alkali lignin molecule regulation and control process, the alkali lignin and a 1, 6-dibromohexane/dimethylformamide/potassium carbonate novel alkylation system are purified by adopting an organic solvent and an acid precipitation method, the molecular weight of the alkali lignin can be regulated and controlled according to different application requirements of different alkali lignin, the polydispersity of partial fractions is reduced, the content of phenolic hydroxyl groups is regulated and controlled, the color depth of the alkali lignin is changed, and the alkali lignin molecule regulation and control method has important significance for subsequent modification and application of the alkali lignin.
(2) The operation method is simple, low in cost, high in efficiency, universal and easy for large-scale production.
Drawings
The accompanying drawings, which are incorporated in and constitute a part of this specification, are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification, illustrate exemplary embodiments of the invention and together with the description serve to explain the invention and not to limit the invention.
FIG. 1 shows the change in color of alkali lignin before and after conditioning in example 1 of the present invention.
FIG. 2 shows the color change of alkali lignin before and after the control in example 2 of the present invention.
FIG. 3 shows the color change of alkali lignin before and after the control in example 3 of the present invention.
FIG. 4 shows the color change of alkali lignin before and after the control in example 4 of the present invention.
Detailed Description
It is to be understood that the following detailed description is exemplary and is intended to provide further explanation of the invention as claimed. 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.
A method for regulating and controlling industrial alkali lignin molecules, which takes the pulping and papermaking industrial alkali lignin as a raw material, comprises the following steps:
the dry crude alkali lignin was added to an aqueous acidic dioxane solution (dioxane/water = 9: 1, v: v, pH = 2). The mixture was stirred at 87-90 ℃ for 2-2.5 hours and then centrifuged to remove the precipitate. The supernatant solution of sodium bicarbonate was added and kept stirring for 3 to 4 hours to neutralize the acid in the solution. After centrifugation again to remove the precipitate, the supernatant was subjected to vacuum rotary evaporation at 55 ℃ to remove and recover dioxane. The supernatant after vacuum rotary evaporation was added to a hydrochloric acid solution of pH =2, followed by centrifugation to obtain a precipitate. Freeze drying the precipitate to obtain solid powdered Purified Alkali Lignin (PAL). PAL was dissolved in dimethylformamide in a ratio of 1: 20 to 25. In the above-mentioned mixed liquorAdding K with the mass 0.6 to 08 times of that of the purified alkali lignin 2 CO 3 As an acid-binding agent to absorb the acid generated in the reaction, and a trace amount of KI was added as an activator of 1, 6-dibromohexane. Under the protection of nitrogen, heating the mixture to a specified temperature (60-90 ℃), adding 1, 6-dibromohexane, keeping the temperature for reaction for 1-4 hours, and then adding 2mol/L hydrochloric acid aqueous solution to finish the reaction. The alkali lignin after the reaction was precipitated with aqueous hydrochloric acid (pH = 2). Centrifuging to obtain precipitate, washing with hydrochloric acid water solution (pH = 2), and lyophilizing to obtain solid powdered substance, i.e. alkali lignin (CAL) regulated by molecules.
In some embodiments, the alkali lignin is crude alkali lignin, in powder or cake form, isolated from alkaline pulping black liquor.
The chemical reagent grades used in the patent of the invention are all chemically pure.
The invention takes alkali lignin in pulping and papermaking industry as raw material, purifies the alkali lignin by using organic solvent and acid precipitation method, adopts a novel alkylation system 1, 6-dibromohexane/dimethylformamide/potassium carbonate to regulate and control alkali lignin molecules, and comprises the following detailed steps:
(1) Organic solvent purification of crude alkali lignin: the dry crude alkali lignin was added to an aqueous acidic dioxane solution (dioxane/water = 9: 1, v: v, pH = 2). The mixture was stirred at 87-90 ℃ for 2-2.5 hours and then centrifuged to remove the precipitate. The supernatant solution of sodium bicarbonate was added and kept stirring for 3 to 4 hours to neutralize the acid in the solution. After centrifugation again to remove the precipitate, the supernatant was subjected to vacuum rotary evaporation at 55 ℃ to remove and recover dioxane.
(2) Acid precipitation, separation and purification of alkali lignin: the supernatant after vacuum rotary evaporation was added to a hydrochloric acid solution of pH =2, followed by centrifugation to obtain a precipitate. Freeze drying the precipitate to obtain solid powder of Purified Alkali Lignin (PAL).
(3) Alkylation of PAL: PAL was dissolved in dimethylformamide in a ratio of 1: 20 to 25. Adding K which is 0.6 to 08 times of the mass of the purified alkali lignin into the mixed solution 2 CO 3 As acidsA binder to absorb the acid produced in the reaction and adding a trace amount of KI as an activator for 1, 6-dibromohexane. Under the protection of nitrogen, heating the mixture to a specified temperature (60-90 ℃), adding 1, 6-dibromohexane, keeping the temperature for reaction for 1-4 hours, and then adding 2mol/L hydrochloric acid aqueous solution to finish the reaction.
(4) Acid precipitation of CAL: the reacted alkali lignin was precipitated with aqueous hydrochloric acid (pH = 2). Centrifuging to obtain precipitate, washing with hydrochloric acid water solution (pH = 2), and freeze drying to obtain solid powdered substance, i.e. alkali lignin (CAL) regulated by molecules.
The method specifically comprises the following steps:
(1) The dry crude alkali lignin was added to an aqueous acidic dioxane solution (dioxane/water = 9: 1, v: v, pH = 2). The mixture was stirred at 87-90 ℃ for 2-2.5 hours and then centrifuged to remove the precipitate. The supernatant solution of sodium bicarbonate was added and kept stirring for 3 to 4 hours to neutralize the acid in the solution. After centrifugation again to remove the precipitate, the supernatant was subjected to vacuum rotary evaporation at 55 ℃ to remove and recover dioxane.
(2) The supernatant after the vacuum rotary evaporation in step (1) was added to a hydrochloric acid solution of pH =2, and then centrifuged to obtain a precipitate. Freeze drying the precipitate to obtain solid powder of Purified Alkali Lignin (PAL).
(3) The PAL in step (2) was dissolved in dimethylformamide in a ratio of 1: 20. Adding K which is 0.6 to 08 times of the mass of the purified alkali lignin into the mixed solution 2 CO 3 As an acid-binding agent to absorb the acid generated in the reaction, and a trace amount of KI was added as an activator of 1, 6-dibromohexane. Under the protection of nitrogen, heating the mixture to a specified temperature (60-90 ℃), adding 1, 6-dibromohexane, keeping the temperature for reaction for 1-4 hours, and then adding 2mol/L hydrochloric acid aqueous solution to finish the reaction.
(4) Precipitating the reacted alkali lignin from the mixture of step (3) with aqueous hydrochloric acid (pH = 2). Centrifuging to obtain precipitate, washing with hydrochloric acid water solution (pH = 2), and lyophilizing to obtain solid powdered substance, i.e. alkali lignin (CAL) regulated by molecules.
The present invention is described in further detail below with reference to specific examples, which should be construed as illustrative rather than restrictive.
Example 1: the alkali lignin molecule regulation and control in pulping and papermaking industry is prepared by the following steps.
(1) Organic solvent purification of crude alkali lignin: to the dried crude alkali lignin was added an aqueous acidic dioxane solution at a ratio of 1 (w: v) (dioxane/water = 9: 1, v: v, pH = 2). The mixture was stirred at 87 ℃ for 2 hours and then centrifuged to remove the precipitate. The supernatant solution of sodium bicarbonate was added and kept stirring for 3 hours to neutralize the acid in the solution. After centrifugation again to remove the precipitate, the supernatant was subjected to vacuum rotary evaporation at 55 ℃ to remove and recover dioxane.
(2) Acid precipitation, separation and purification of alkali lignin: the supernatant after vacuum rotary evaporation was added to 2000mL of hydrochloric acid solution (pH = 2), and then centrifuged to obtain a precipitate. Freeze drying the precipitate to obtain solid powder of Purified Alkali Lignin (PAL).
(3) Alkylation of PAL: PAL was dissolved in dimethylformamide in a ratio of 1: 20. Adding K with the mass 0.6 times of that of the purified alkali lignin into the mixed solution 2 CO 3 As an acid-binding agent to absorb the acid generated in the reaction, and a trace amount of KI was added as an activator of 1, 6-dibromohexane. Heating the mixture to 70 ℃ under the protection of nitrogen, and then adding 0.05g/g Lignin 1, 6-dibromohexane was added, the temperature was maintained, and the reaction was terminated by adding 2mol/L aqueous hydrochloric acid.
(4) Acid precipitation of CAL: the reacted alkali lignin was precipitated with aqueous hydrochloric acid (pH = 2). Centrifuging to obtain precipitate, washing with hydrochloric acid water solution (pH = 2), and freeze drying to obtain solid powdery substance, i.e. alkali lignin (CAL) regulated by molecules. The resulting CAL molecular weight and phenolic hydroxyl content were varied as shown in Table 1, and the color was varied as shown in FIG. 1.
TABLE 1 variation of alkali lignin molecular weight and phenolic hydroxyl group content before and after control
Example 2: the alkali lignin molecule regulation and control in the pulping and papermaking industry is prepared by the following steps.
(1) Organic solvent purification of crude alkali lignin: to the dried crude alkali lignin was added an aqueous acidic dioxane solution at a ratio of 1 (w: v) (dioxane/water = 9: 1, v: v, pH = 2). The mixture was stirred at 87 ℃ for 2 hours and then centrifuged to remove the precipitate. The supernatant solution of sodium bicarbonate was added and kept stirring for 3 hours to neutralize the acid in the solution. After centrifugation again to remove the precipitate, the supernatant was subjected to vacuum rotary evaporation at 55 ℃ to remove and recover dioxane.
(2) Acid precipitation, separation and purification of alkali lignin: the supernatant after vacuum rotary evaporation was added to 2000mL of hydrochloric acid solution (pH = 2), and then centrifuged to obtain a precipitate. Freeze drying the precipitate to obtain solid powder of Purified Alkali Lignin (PAL).
(3) Alkylation of PAL: PAL was dissolved in dimethylformamide in a ratio of 1: 20. Adding K with the mass 0.6 times of that of the purified alkali lignin into the mixed solution 2 CO 3 As an acid binder to absorb the acid generated in the reaction, and a trace amount of KI was added as an activator of 1, 6-dibromohexane. Heating the mixture to 70 deg.C under nitrogen protection, and mixing at a ratio of 0.60g/g Lignin 1, 6-dibromohexane was added, the temperature was maintained, and the reaction was terminated by adding 2mol/L aqueous hydrochloric acid.
(4) Acid-out of CAL: the reacted alkali lignin was precipitated with aqueous hydrochloric acid (pH = 2). Centrifuging to obtain precipitate, washing with hydrochloric acid water solution (pH = 2), and freeze drying to obtain solid powdery substance, i.e. alkali lignin (CAL) regulated by molecules. The resulting CAL molecular weight and phenolic hydroxyl content were varied as shown in Table 2, and the color change was shown in FIG. 2.
TABLE 2 variation of alkali lignin molecular weight and phenolic hydroxyl group content before and after control
Example 3: the alkali lignin molecule regulation and control in the pulping and papermaking industry is prepared by the following steps.
(1) Organic solvent purification of crude alkali lignin: to the dried crude alkali lignin was added an aqueous acidic dioxane solution at a ratio of 1 (w: v) (dioxane/water = 9: 1, v: v, pH = 2). The mixture was stirred at 87 ℃ for 2 hours and then centrifuged to remove the precipitate. The supernatant solution of sodium bicarbonate was added and kept stirring for 3 hours to neutralize the acid in the solution. After centrifugation again to remove the precipitate, the supernatant was vacuum rotary evaporated at 55 ℃ to remove and recover dioxane.
(2) Acid precipitation, separation and purification of alkali lignin: the supernatant after vacuum rotary evaporation was added to 2000mL of hydrochloric acid solution (pH = 2), and then centrifuged to obtain a precipitate. Freeze drying the precipitate to obtain solid powder of Purified Alkali Lignin (PAL).
(3) Alkylation of PAL: PAL was dissolved in dimethylformamide in a ratio of 1: 20. Adding K with the mass 0.6 times of that of the purified alkali lignin into the mixed solution 2 CO 3 As an acid-binding agent to absorb the acid generated in the reaction, and a trace amount of KI was added as an activator of 1, 6-dibromohexane. Heating the mixture to 70 ℃ under the protection of nitrogen, and then heating the mixture to 0.60g/g Lignin 1, 6-dibromohexane was added, the temperature was maintained, and the reaction was terminated by adding 2mol/L aqueous hydrochloric acid.
(4) Acid precipitation of CAL: the reacted alkali lignin was precipitated with aqueous hydrochloric acid (pH = 2). Centrifuging to obtain precipitate, washing with hydrochloric acid water solution (pH = 2), and lyophilizing to obtain solid powdered substance, i.e. molecular-Controlled Alkali Lignin (CAL). The resulting CAL molecular weight and phenolic hydroxyl content were varied as shown in Table 3, and the color was varied as shown in FIG. 3.
TABLE 3 variation of alkali lignin molecular weight and phenolic hydroxyl group content before and after control
Example 4: the alkali lignin molecule regulation and control in the pulping and papermaking industry is prepared by the following steps.
(1) Organic solvent purification of crude alkali lignin: to the dried crude alkali lignin was added an aqueous acidic dioxane solution at a ratio of 1 (w: v) (dioxane/water = 9: 1, v: v, pH = 2). The mixture was stirred at 87 ℃ for 2 hours and then centrifuged to remove the precipitate. The supernatant solution of sodium bicarbonate was added and kept stirring for 3 hours to neutralize the acid in the solution. After centrifugation again to remove the precipitate, the supernatant was subjected to vacuum rotary evaporation at 55 ℃ to remove and recover dioxane.
(2) Acid precipitation, separation and purification of alkali lignin: the supernatant after vacuum rotary evaporation was added to 2000mL of hydrochloric acid solution (pH = 2), and then centrifuged to obtain a precipitate. Freeze drying the precipitate to obtain solid powder of Purified Alkali Lignin (PAL).
(3) Alkylation of PAL: PAL was dissolved in dimethylformamide in a ratio of 1: 20. Adding K with the mass 0.6 times of that of the purified alkali lignin into the mixed solution 2 CO 3 As an acid-binding agent to absorb the acid generated in the reaction, and a trace amount of KI was added as an activator of 1, 6-dibromohexane. Heating the mixture to 90 deg.C under nitrogen protection, and mixing at a ratio of 0.30g/g Lignin 1, 6-dibromohexane was added, the temperature was maintained, and the reaction was terminated by adding 2mol/L aqueous hydrochloric acid.
(4) Acid precipitation of CAL: the reacted alkali lignin was precipitated with aqueous hydrochloric acid (pH = 2). Centrifuging to obtain precipitate, washing with hydrochloric acid water solution (pH = 2), and freeze drying to obtain solid powdery substance, i.e. alkali lignin (CAL) regulated by molecules. The molecular weight and phenolic hydroxyl content of the obtained CAL varied as shown in Table 4, and the color change was shown in FIG. 4.
TABLE 4 variation of alkali lignin molecular weight and phenolic hydroxyl content before and after control
Finally, it should be noted that, although the present invention has been described in detail with reference to the foregoing embodiments, it will be apparent to those skilled in the art that modifications may be made to the embodiments described in the foregoing embodiments, or equivalents may be substituted for elements thereof. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (7)
1. A method for regulating and controlling industrial alkali lignin molecules is characterized by comprising the following steps:
purifying the industrial alkali lignin to obtain purified alkali lignin;
performing alkylation reaction on the purified alkali lignin in a 1, 6-dibromohexane/dimethylformamide/potassium carbonate system to obtain alkali lignin subjected to molecular regulation;
the purification comprises the following steps: purifying by organic solvent and acid precipitation;
adding a trace amount of KI as an activator of 1, 6-dibromohexane;
the alkylation reaction comprises the following specific steps: dissolving the purified alkali lignin in dimethylformamide to obtain a mixed solution; adding K to the mixed solution 2 CO 3 As an acid binding agent, and adding a trace amount of KI as an activating agent of the 1, 6-dibromohexane; under the protection of nitrogen, heating the mixture to 60-90 ℃, adding 1, 6-dibromohexane, keeping the temperature for reaction for 1-4 hours, and then adding hydrochloric acid aqueous solution to finish the reaction; precipitating by using a hydrochloric acid aqueous solution; washing the precipitate with hydrochloric acid water solution, and freeze drying to obtain solid powdery substance, i.e. alkali lignin regulated by molecules.
2. The method for regulating and controlling the industrial alkali lignin molecule according to claim 1, wherein the organic solvent purification comprises the following specific steps: the organic solvent purification treatment comprises the following specific steps: adding the dried alkali lignin into an acidic dioxane aqueous solution, stirring the mixture for 2-2.5 hours at 87-90 ℃, and then centrifuging to remove precipitates; adding the supernatant of sodium bicarbonate, keeping stirring for 3-4 hours to neutralize the acid in the solution; after centrifugation again to remove the precipitate, the supernatant was vacuum rotary evaporated to remove and recover dioxane.
3. The method for regulating the industrial alkali lignin molecule according to claim 1, wherein the acid precipitation comprises the following specific steps: adding a supernatant obtained after purifying an organic solvent into a hydrochloric acid solution with pH =2, and then centrifuging to obtain a precipitate; freeze drying the precipitate to obtain solid powder of purified alkali lignin.
4. The method for controlling the molecular weight of industrial alkali lignin according to claim 1, wherein the volume ratio of the purified alkali lignin to the dimethylformamide is 1: 20-25.
5. The method of claim 1, wherein the purification of alkali lignin and K is performed by a process that comprises reacting the purified alkali lignin with K 2 CO 3 The mass ratio of (1): 0.6 to 0.8.
6. A molecularly-modified alkali lignin prepared by the method of any one of claims 1 to 5.
7. The use of the molecularly imprinted alkali lignin of claim 6 in the fields of resin material preparation, functional polymer material preparation, oil exploitation, water reduction of building concrete, dye dispersion in printing and dyeing, slow release dispersion of pesticides and slow release of fertilizers.
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