CN116463872A - Method for preparing nanocellulose by using broad-leaved wood TEMPO method based on deep eutectic solvent pretreatment - Google Patents
Method for preparing nanocellulose by using broad-leaved wood TEMPO method based on deep eutectic solvent pretreatment Download PDFInfo
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- 238000000034 method Methods 0.000 title claims abstract description 44
- 229920001046 Nanocellulose Polymers 0.000 title claims abstract description 30
- 230000005496 eutectics Effects 0.000 title claims abstract description 29
- GDOPTJXRTPNYNR-UHFFFAOYSA-N methyl-cyclopentane Natural products CC1CCCC1 GDOPTJXRTPNYNR-UHFFFAOYSA-N 0.000 title claims abstract description 29
- 239000002904 solvent Substances 0.000 title claims abstract description 29
- 239000002023 wood Substances 0.000 title claims abstract description 20
- QNVNLUSHGRBCLO-UHFFFAOYSA-N 5-hydroxybenzene-1,3-dicarboxylic acid Chemical compound OC(=O)C1=CC(O)=CC(C(O)=O)=C1 QNVNLUSHGRBCLO-UHFFFAOYSA-N 0.000 claims abstract description 44
- 238000004061 bleaching Methods 0.000 claims abstract description 27
- 239000001763 2-hydroxyethyl(trimethyl)azanium Substances 0.000 claims abstract description 22
- 235000019743 Choline chloride Nutrition 0.000 claims abstract description 22
- 229960003178 choline chloride Drugs 0.000 claims abstract description 22
- SGMZJAMFUVOLNK-UHFFFAOYSA-M choline chloride Chemical compound [Cl-].C[N+](C)(C)CCO SGMZJAMFUVOLNK-UHFFFAOYSA-M 0.000 claims abstract description 22
- 230000003647 oxidation Effects 0.000 claims abstract description 19
- 238000007254 oxidation reaction Methods 0.000 claims abstract description 19
- 239000002994 raw material Substances 0.000 claims abstract description 17
- 238000001132 ultrasonic dispersion Methods 0.000 claims abstract description 5
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 claims description 30
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 claims description 27
- SUKJFIGYRHOWBL-UHFFFAOYSA-N sodium hypochlorite Chemical group [Na+].Cl[O-] SUKJFIGYRHOWBL-UHFFFAOYSA-N 0.000 claims description 23
- 238000003756 stirring Methods 0.000 claims description 16
- 238000005406 washing Methods 0.000 claims description 12
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 11
- JHJLBTNAGRQEKS-UHFFFAOYSA-M sodium bromide Chemical compound [Na+].[Br-] JHJLBTNAGRQEKS-UHFFFAOYSA-M 0.000 claims description 10
- QTBSBXVTEAMEQO-UHFFFAOYSA-N Acetic acid Chemical compound CC(O)=O QTBSBXVTEAMEQO-UHFFFAOYSA-N 0.000 claims description 8
- 239000012295 chemical reaction liquid Substances 0.000 claims description 8
- 238000010438 heat treatment Methods 0.000 claims description 8
- 238000006243 chemical reaction Methods 0.000 claims description 7
- 239000007788 liquid Substances 0.000 claims description 7
- 238000001035 drying Methods 0.000 claims description 5
- 238000007710 freezing Methods 0.000 claims description 5
- 230000008014 freezing Effects 0.000 claims description 5
- 230000007935 neutral effect Effects 0.000 claims description 5
- 230000035484 reaction time Effects 0.000 claims description 5
- 229960000583 acetic acid Drugs 0.000 claims description 4
- 239000012362 glacial acetic acid Substances 0.000 claims description 4
- 239000007844 bleaching agent Substances 0.000 claims description 3
- 238000009210 therapy by ultrasound Methods 0.000 claims description 2
- 235000013312 flour Nutrition 0.000 claims 1
- 239000011121 hardwood Substances 0.000 claims 1
- 229920002678 cellulose Polymers 0.000 abstract description 17
- 239000001913 cellulose Substances 0.000 abstract description 17
- 230000000694 effects Effects 0.000 abstract description 8
- 229920005610 lignin Polymers 0.000 abstract description 8
- 239000000463 material Substances 0.000 abstract description 6
- 229920002488 Hemicellulose Polymers 0.000 abstract description 4
- 230000009471 action Effects 0.000 abstract description 2
- 239000000203 mixture Substances 0.000 description 11
- 239000007787 solid Substances 0.000 description 9
- 239000000835 fiber Substances 0.000 description 8
- 239000013078 crystal Substances 0.000 description 7
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 6
- 235000019441 ethanol Nutrition 0.000 description 6
- PEDCQBHIVMGVHV-UHFFFAOYSA-N Glycerol Natural products OCC(O)CO PEDCQBHIVMGVHV-UHFFFAOYSA-N 0.000 description 5
- 230000004048 modification Effects 0.000 description 5
- 238000012986 modification Methods 0.000 description 5
- 238000002360 preparation method Methods 0.000 description 5
- 230000008569 process Effects 0.000 description 5
- MHAJPDPJQMAIIY-UHFFFAOYSA-N Hydrogen peroxide Chemical compound OO MHAJPDPJQMAIIY-UHFFFAOYSA-N 0.000 description 4
- 125000003178 carboxy group Chemical group [H]OC(*)=O 0.000 description 4
- 229910052739 hydrogen Inorganic materials 0.000 description 4
- 239000001257 hydrogen Substances 0.000 description 4
- 239000000843 powder Substances 0.000 description 4
- LYCAIKOWRPUZTN-UHFFFAOYSA-N Ethylene glycol Chemical compound OCCO LYCAIKOWRPUZTN-UHFFFAOYSA-N 0.000 description 3
- 238000001914 filtration Methods 0.000 description 3
- UKLNMMHNWFDKNT-UHFFFAOYSA-M sodium chlorite Chemical compound [Na+].[O-]Cl=O UKLNMMHNWFDKNT-UHFFFAOYSA-M 0.000 description 3
- 229960002218 sodium chlorite Drugs 0.000 description 3
- 239000000725 suspension Substances 0.000 description 3
- 239000002028 Biomass Substances 0.000 description 2
- CBENFWSGALASAD-UHFFFAOYSA-N Ozone Chemical compound [O-][O+]=O CBENFWSGALASAD-UHFFFAOYSA-N 0.000 description 2
- 235000011187 glycerol Nutrition 0.000 description 2
- JVTAAEKCZFNVCJ-UHFFFAOYSA-N lactic acid Chemical compound CC(O)C(O)=O JVTAAEKCZFNVCJ-UHFFFAOYSA-N 0.000 description 2
- 238000007781 pre-processing Methods 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- 241000196324 Embryophyta Species 0.000 description 1
- 244000166124 Eucalyptus globulus Species 0.000 description 1
- 240000007472 Leucaena leucocephala Species 0.000 description 1
- 235000010643 Leucaena leucocephala Nutrition 0.000 description 1
- 229920002201 Oxidized cellulose Polymers 0.000 description 1
- 241000219000 Populus Species 0.000 description 1
- CDBYLPFSWZWCQE-UHFFFAOYSA-L Sodium Carbonate Chemical compound [Na+].[Na+].[O-]C([O-])=O CDBYLPFSWZWCQE-UHFFFAOYSA-L 0.000 description 1
- 241001625808 Trona Species 0.000 description 1
- 239000000370 acceptor Substances 0.000 description 1
- 150000001408 amides Chemical class 0.000 description 1
- 125000003118 aryl group Chemical group 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000010170 biological method Methods 0.000 description 1
- 150000001720 carbohydrates Chemical class 0.000 description 1
- 230000015556 catabolic process Effects 0.000 description 1
- 230000003749 cleanliness Effects 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000006731 degradation reaction Methods 0.000 description 1
- 238000004090 dissolution Methods 0.000 description 1
- 239000000374 eutectic mixture Substances 0.000 description 1
- 238000000605 extraction Methods 0.000 description 1
- 150000004676 glycans Chemical class 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 239000002608 ionic liquid Substances 0.000 description 1
- 239000004310 lactic acid Substances 0.000 description 1
- 235000014655 lactic acid Nutrition 0.000 description 1
- 239000002029 lignocellulosic biomass Substances 0.000 description 1
- 238000002844 melting Methods 0.000 description 1
- 230000008018 melting Effects 0.000 description 1
- 230000004660 morphological change Effects 0.000 description 1
- 239000002121 nanofiber Substances 0.000 description 1
- 239000002086 nanomaterial Substances 0.000 description 1
- 150000007524 organic acids Chemical class 0.000 description 1
- 230000001590 oxidative effect Effects 0.000 description 1
- 229940107304 oxidized cellulose Drugs 0.000 description 1
- 238000000053 physical method Methods 0.000 description 1
- 238000006116 polymerization reaction Methods 0.000 description 1
- 229920001282 polysaccharide Polymers 0.000 description 1
- 239000005017 polysaccharide Substances 0.000 description 1
- 238000004537 pulping Methods 0.000 description 1
- 150000003242 quaternary ammonium salts Chemical class 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 238000000926 separation method Methods 0.000 description 1
Classifications
-
- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21C—PRODUCTION OF CELLULOSE BY REMOVING NON-CELLULOSE SUBSTANCES FROM CELLULOSE-CONTAINING MATERIALS; REGENERATION OF PULPING LIQUORS; APPARATUS THEREFOR
- D21C1/00—Pretreatment of the finely-divided materials before digesting
-
- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21C—PRODUCTION OF CELLULOSE BY REMOVING NON-CELLULOSE SUBSTANCES FROM CELLULOSE-CONTAINING MATERIALS; REGENERATION OF PULPING LIQUORS; APPARATUS THEREFOR
- D21C9/00—After-treatment of cellulose pulp, e.g. of wood pulp, or cotton linters ; Treatment of dilute or dewatered pulp or process improvement taking place after obtaining the raw cellulosic material and not provided for elsewhere
- D21C9/02—Washing ; Displacing cooking or pulp-treating liquors contained in the pulp by fluids, e.g. wash water or other pulp-treating agents
-
- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21C—PRODUCTION OF CELLULOSE BY REMOVING NON-CELLULOSE SUBSTANCES FROM CELLULOSE-CONTAINING MATERIALS; REGENERATION OF PULPING LIQUORS; APPARATUS THEREFOR
- D21C9/00—After-treatment of cellulose pulp, e.g. of wood pulp, or cotton linters ; Treatment of dilute or dewatered pulp or process improvement taking place after obtaining the raw cellulosic material and not provided for elsewhere
- D21C9/10—Bleaching ; Apparatus therefor
- D21C9/12—Bleaching ; Apparatus therefor with halogens or halogen-containing compounds
- D21C9/14—Bleaching ; Apparatus therefor with halogens or halogen-containing compounds with ClO2 or chlorites
Landscapes
- Life Sciences & Earth Sciences (AREA)
- Engineering & Computer Science (AREA)
- Wood Science & Technology (AREA)
- Polysaccharides And Polysaccharide Derivatives (AREA)
Abstract
The invention discloses a method for preparing nanocellulose by a broadleaf wood TEMPO method based on deep eutectic solvent pretreatment, and belongs to the field of cellulose materials. The method comprises the following steps: pretreating raw materials by using a choline chloride/5-hydroxy isophthalic acid deep eutectic solvent system; bleaching the pretreated raw materials; and (3) carrying out ultrasonic dispersion on the raw material subjected to TEMPO oxidation bleaching to obtain the nanocellulose. Wherein, the mol ratio of the choline chloride to the 5-hydroxy isophthalic acid in the choline chloride/5-hydroxy isophthalic acid deep eutectic solvent system is 1:0.5-1. The method is formulated according to the action characteristics of the choline chloride/5-hydroxyisophthalic acid deep eutectic solvent on broadleaf wood, the deep eutectic solvent can selectively hydrolyze hemicellulose, has strong affinity to lignin, can effectively extract high-activity lignin, is environment-friendly, and is easy to recycle. The nano cellulose prepared by the method has high yield, crystallinity and aspect ratio and excellent performance.
Description
Technical Field
The invention belongs to the field of cellulose materials, relates to a preparation method of nano cellulose crystals, and in particular relates to a method for preparing nano cellulose by a broad-leaved wood TEMPO method based on deep eutectic solvent pretreatment.
Background
The disclosure of this background section is only intended to increase the understanding of the general background of the invention and is not necessarily to be construed as an admission or any form of suggestion that this information forms the prior art already known to those of ordinary skill in the art.
Nanocellulose is defined as a cellulosic material having a nanometric width. They are prepared from abundant plant biomass resources. Nanocellulose is produced with as few characteristic or morphological changes as possible to meet the needs of industrial applications, a problem that needs to be solved when converting a variety of biomass materials into high-function materials. At present, the preparation method of the nano cellulose crystal mainly comprises a chemical method, a biological method and a physical method, and generally comprises auxiliary means such as pretreatment extraction of cellulose, nano cellulose preparation, mechanical treatment and the like. However, the conventional separation of pure oxidized cellulose nanostructures from raw wood generally requires multiple steps, and the wood is first subjected to multiple chemical treatment steps, such as pulping, bleaching and washing, which are complicated and have low yields, and the obtained nanocellulose has low crystallinity and low aspect ratio, which cannot meet the requirements of industrial applications.
The Deep Eutectic Solvent (DES) is a eutectic mixture composed of hydrogen bond acceptors such as quaternary ammonium salt and trona and hydrogen bond donors such as organic acid, amide, glycerin or carbohydrate, has the advantages of difficult volatilization, high thermal stability, strong dissolving capacity to various organic matters and inorganic matters, low melting point and the like, and also has designability. The current reports on DES for pretreatment of lignocellulosic biomass began to show, but there are not many, from the previous reports that their use in this respect has the potential to replace ionic liquids, but there are several drawbacks: the DES hydrogen bond donor with good pretreatment effect has single composition and is mainly concentrated on glycerol, ethylene glycol and lactic acid; there is no method to cope with DES composition with poor pretreatment effect to improve its effect.
Therefore, in order to obtain a method for preparing nanocellulose with high yield, cleanliness, and aspect ratio, it is necessary to continuously study the kind and proportion of DES components.
Disclosure of Invention
In order to solve the defects of the prior art, the invention aims to provide a method for preparing nanocellulose by a broad-leaved wood TEMPO method based on deep eutectic solvent pretreatment, wherein the choline chloride/5-hydroxy isophthalic acid deep eutectic solvent pretreatment can effectively remove hemicellulose and lignin in broad-leaved wood, cellulose is less in dissolution, a cellulose crystal structure is kept complete, and the preparation of nanocellulose is facilitated.
In order to achieve the above purpose, the technical scheme of the invention is as follows:
in a first aspect of the invention, a method for preparing nanocellulose by a broadleaf wood TEMPO method based on deep eutectic solvent pretreatment is provided, and the method comprises the following steps:
pretreating raw materials by using a choline chloride/5-hydroxy isophthalic acid deep eutectic solvent system; bleaching the pretreated raw materials; and (3) carrying out ultrasonic dispersion on the raw material subjected to TEMPO oxidation bleaching to obtain the nanocellulose.
Preferably, the raw material is 40-60 mesh broad-leaved wood powder.
Preferably, the molar ratio of the choline chloride to the 5-hydroxy isophthalic acid in the choline chloride/5-hydroxy isophthalic acid deep eutectic solvent system is 1:0.5-1, preferably 1:0.8.
preferably, the pretreatment device has the following treatment conditions: the solid-liquid ratio is 1:5-15, preferably 1:6-14; the treatment temperature is 100-150deg.C, preferably 130-150deg.C, and further preferably 140 deg.C; the treatment time is 1-10h, preferably 3-5h; the stirring speed is 100-1000rmp, preferably 300-500rmp.
Preferably, before bleaching, the pretreated raw materials are added with absolute ethyl alcohol, heated and stirred, washed and filtered to be neutral.
It is further preferable that the amount of the anhydrous ethanol added is 2 to 6 times the volume of the reaction solution.
Further preferably, the stirring time of the heating and stirring is 10 to 50 minutes, preferably 10 to 30 minutes.
Further preferably, the washing liquid is absolute ethanol/water solution and the amount is 8-12 times of the volume of the reaction liquid.
Preferably, the bleaching agent is NaClO 2 Solution, sample and NaClO 2 The mass ratio of the solution is 1:40-60; the bleaching temperature is 70-100 ℃, preferably 70-80 ℃; bleaching time is 1-5h, preferably 3h; the stirring speed is 100-500rmp, preferably 300-500rmp. The bleaching effect of the present invention affects the subsequent oxidation effect. Good bleaching selectivity can promote oxidation effect. Other bleaching agents, such as ozone, hydrogen peroxide, etc., are not suitable for the bleaching process of the present invention because of the need for selective delignification, reduction of cellulose degradation, and the like in the bleaching process of the present invention, to obtain high performance cellulosic materials, ozone, hydrogen peroxide, etc., do not meet this requirement.
Further preferred, naClO 2 The solution contains sodium hydroxide and glacial acetic acid, preferably NaClO 2 NaClO in solution 2 The content of (2) is 0.5-1.0wt%, preferably 0.7wt%; the NaOH content is 1-5wt%, preferably 3.5wt%; the content of glacial acetic acid is 5-10wt%, preferably 7-8wt%.
Preferably, the bleached raw material is washed before TEMPO oxidation.
Preferably, the TEMPO oxidation is specifically: dissolving the sample, TEMPO and NaBr in water, stirring, and then dropwise adding NaClO solution; the total reaction time of the oxidation is 1 to 5 hours, preferably 2 hours; the reaction temperature was room temperature and the pH was 10.TEMPO oxidation is a method of oxidizing polysaccharides and introducing carboxyl groups on the surface of cellulose fibrils, allowing the natural cellulose to be completely dispersed in water at the level of individual nanofibers or base fibers. TEMPO oxidation causes electrostatic repulsion between cellulose fibrils, preventing strong hydrogen bonds from forming between the fibers, while cellulose crystals are not internally oxidized.
Further preferably, TEMPO is added in an amount of 0.1mmol/g sample.
Further preferably, naBr is added in an amount of 1mmol/g sample.
Further preferably, naClO is added in an amount of 10mol/g sample.
Further preferably, the NaClO solution is added over the first 20 minutes of TEMPO oxidation.
Preferably, the ultrasonic dispersion is specifically: and (5) carrying out ultrasonic treatment, washing, centrifuging the product at room temperature, freezing and drying the sample to obtain the product.
The beneficial effects of the invention are as follows:
the invention provides a preparation method of nanocellulose, which is characterized in that choline chloride/5-hydroxy isophthalic acid deep eutectic solvent is adopted to pretreat broadleaf wood, hemicellulose and most lignin are dissolved out, the whiteness is improved, residual lignin is removed through bleaching treatment, and then TEMPO oxidation is performed efficiently and energy-effectively, so that nanocellulose with excellent performance can be prepared. The method is formulated according to the action characteristics of the choline chloride/5-hydroxyisophthalic acid deep eutectic solvent on broadleaf wood, the deep eutectic solvent can selectively hydrolyze hemicellulose, has strong affinity to lignin, can effectively extract high-activity lignin, is environment-friendly, and is easy to recycle.
The nano cellulose prepared by the method has high yield, crystallinity and aspect ratio, wherein the crystallinity is as high as more than 90%, and the performance is excellent.
Detailed Description
In order to enable those skilled in the art to more clearly understand the technical scheme of the present invention, the technical scheme of the present invention will be described in detail with reference to specific embodiments.
Example 1
A method for preparing nanocellulose by a broadleaf wood TEMPO method based on deep eutectic solvent pretreatment comprises the following steps:
(1) Adding poplar 40-60 mesh wood powder into a choline chloride/5-hydroxyisophthalic acid deep eutectic solvent system (the molar ratio of the choline chloride to the 5-hydroxyisophthalic acid in the choline chloride/5-hydroxyisophthalic acid deep eutectic solvent system is 1:0.8), and pre-treating the raw materials under the following treatment conditions: the solid-liquid ratio of pretreatment is 1:6, the temperature is 140 ℃, the time is 3 hours, and the stirring speed is 300rmp;
(2) Adding absolute ethyl alcohol with the volume of 4 times of the reaction liquid, continuously heating and stirring for 10min, and then washing and filtering to be neutral by using an ethanol/water solution with the volume of 8 times of the reaction liquid;
(3) Bleaching the cellulose-rich solid obtained in the step (2) by using a sodium chlorite solution under the following treatment conditions: bleaching stage solution composition, sample: naClO 2 Solution = 2g:100g,100g naclo 2 The solution was prepared from 0.7wt% NaClO 2 3.5g NaOH and 7ml CH 3 COOH composition, bleaching temperature of 80 ℃, time of 3h and rotating speed of 300rmp;
(4) Washing the cellulose solid obtained in step (3) for 2-3 times;
(5) Heating the solid obtained in the step (4) by sulfuric acid to prepare nano cellulose crystals, wherein the treatment process comprises the following steps: a sample was added, TEMPO (0.1 mmol/g) and NaBr (1 mmol/g fiber) were dissolved in a volume of water and stirred at 700 rpm, and then NaClO solution (10 mol/g fiber) was added dropwise to the suspension to initiate surface modification. The addition of NaClO was completed in the first 20 minutes and the total reaction time for oxidation was 2 hours, the reaction was carried out at room temperature at pH 10 (adjusted by dropwise addition of 0.5M NaOH);
(6) Ultrasonic treating for 30min, adding ethanol with equal volume to wash the mixture, rapidly centrifuging at 3500rpm for 5min at room temperature, and repeating for 2-3 times;
(7) The sample was placed in a refrigerator for freezing and drying.
The yield of the prepared nanocellulose is 39.2%, the crystallinity is 90.2% and the aspect ratio is 48.1.
Example 2
A method for preparing nanocellulose by a broadleaf wood TEMPO method based on deep eutectic solvent pretreatment comprises the following steps:
(1) Adding acacia wood powder with 40-60 meshes into a choline chloride/5-hydroxy isophthalic acid deep eutectic solvent system (the molar ratio of the choline chloride to the 5-hydroxy isophthalic acid in the choline chloride/5-hydroxy isophthalic acid deep eutectic solvent system is 1:0.8), and preprocessing raw materials under the following processing conditions: the solid-liquid ratio of pretreatment is 1:14, the temperature is 140 ℃, the time is 3 hours, and the stirring speed is 300rmp;
(2) Adding absolute ethyl alcohol with the volume of 4 times of the reaction liquid, continuously heating and stirring for 10min, and then washing and filtering to be neutral by using an ethanol/water solution with the volume of 12 times of the reaction liquid;
(3) Bleaching the cellulose-rich solid obtained in the step (2) by using a sodium chlorite solution under the following treatment conditions: bleaching stage solution composition, sample: naClO 2 Solution = 2g:100g,100g naclo 2 The solution was prepared from 0.7wt% NaClO 2 3.5g NaOH and 7ml CH 3 COOH composition, bleaching temperature of 80 ℃, time of 3h and rotating speed of 300rmp;
(4) Washing the cellulose solid obtained in step (3) for 2-3 times;
(5) Heating the solid obtained in the step (4) by sulfuric acid to prepare nano cellulose crystals, wherein the treatment process comprises the following steps: a sample was added, TEMPO (0.1 mmol/g) and NaBr (1 mmol/g fiber) were dissolved in a volume of water and stirred at 700 rpm, and then NaClO solution (10 mol/g fiber) was added dropwise to the suspension to initiate surface modification. The addition of NaClO was completed in the first 20 minutes and the total reaction time for oxidation was 2 hours, the reaction was carried out at room temperature at pH 10 (adjusted by dropwise addition of 0.5M NaOH);
(6) Ultrasonic treating for 30min, adding ethanol with equal volume to wash the mixture, rapidly centrifuging at 3500rpm for 5min at room temperature, and repeating for 2-3 times;
(7) The sample was placed in a refrigerator for freezing and drying.
The yield of the prepared nano-cellulose is 40.3%, the crystallinity is 90.1%, the length-width ratio is 47.3, and the polymerization degree is up to 752.
Example 3
A method for preparing nanocellulose by a broadleaf wood TEMPO method based on deep eutectic solvent pretreatment comprises the following steps:
(1) Adding eucalyptus wood powder with 40-60 meshes into a choline chloride/5-hydroxyisophthalic acid deep eutectic solvent system (the molar ratio of the choline chloride to the 5-hydroxyisophthalic acid in the choline chloride/5-hydroxyisophthalic acid deep eutectic solvent system is 1:0.8), and preprocessing raw materials, wherein the processing conditions are as follows: the solid-liquid ratio of pretreatment is 1:6, the temperature is 140 ℃, the time is 5 hours, and the stirring speed is 300rmp;
(2) Adding absolute ethyl alcohol with the volume of 4 times of the reaction liquid, continuously heating and stirring for 10min, and then washing and filtering to be neutral by using an ethanol/water solution with the volume of 8 times of the reaction liquid;
(3) Bleaching the cellulose-rich solid obtained in the step (2) by using a sodium chlorite solution under the following treatment conditions: bleaching stage solution composition, sample: naClO 2 Solution = 2g:100g,100g naclo 2 The solution was prepared from 0.7wt% NaClO 2 3.5g NaOH and 7ml CH 3 COOH composition, bleaching temperature of 80 ℃, time of 3h and rotating speed of 300rmp;
(4) Washing the cellulose solid obtained in step (3) for 2-3 times;
(5) Heating the solid obtained in the step (4) by sulfuric acid to prepare nano cellulose crystals, wherein the treatment process comprises the following steps: a sample was added, TEMPO (0.1 mmol/g) and NaBr (1 mmol/g fiber) were dissolved in a volume of water and stirred at 700 rpm, and then NaClO solution (10 mol/g fiber) was added dropwise to the suspension to initiate surface modification. The addition of NaClO was completed in the first 20 minutes and the total reaction time for oxidation was 2 hours, the reaction was carried out at room temperature at pH 10 (adjusted by dropwise addition of 0.5M NaOH);
(6) Ultrasonic treating for 30min, adding ethanol with equal volume to wash the mixture, rapidly centrifuging at 3500rpm for 5min at room temperature, and repeating for 2-3 times;
(7) The sample was placed in a refrigerator for freezing and drying.
The yield of the prepared nanocellulose is 39.6%, the crystallinity is 89.6%, the length-width ratio is 51.1, and the lignin phenolic hydroxyl content is up to 0.65/aromatic ring.
The above description is only of the preferred embodiments of the present invention and is not intended to limit the present invention, but various modifications and variations can be made to the present invention by those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (10)
1. The method for preparing the nanocellulose by using the broad-leaved wood TEMPO method based on deep eutectic solvent pretreatment is characterized by comprising the following steps of:
pretreating raw materials by using a choline chloride/5-hydroxy isophthalic acid deep eutectic solvent system; bleaching the pretreated raw materials; and (3) carrying out ultrasonic dispersion on the raw material subjected to TEMPO oxidation bleaching to obtain the nanocellulose.
2. The method of claim 1, wherein the feedstock is 40-60 mesh hardwood flour.
3. The method according to claim 1, wherein the molar ratio of choline chloride to 5-hydroxyisophthalic acid in the choline chloride/5-hydroxyisophthalic acid deep eutectic solvent system is 1:0.5-1, preferably 1:0.8.
4. the method of claim 1, wherein the pretreatment tool is subjected to the following treatment conditions: the solid-liquid ratio is 1:5-15, preferably 1:6-14; the treatment temperature is 100-150deg.C, preferably 130-150deg.C, and further preferably 140 deg.C; the treatment time is 1-10h, preferably 3-5h; the stirring speed is 100-1000rmp, preferably 300-500rmp.
5. The method of claim 1, wherein the pretreated raw material is added with absolute ethyl alcohol, heated and stirred, washed and filtered to be neutral before bleaching;
preferably, the addition amount of the absolute ethyl alcohol is 2-6 times of the volume of the reaction solution;
preferably, the stirring time of heating and stirring is 10-50min, preferably 10-30min;
preferably, the washing liquid is absolute ethanol/water solution in the washing process, and the dosage is 8-12 times of the volume of the reaction liquid.
6. The method of claim 1, wherein the bleaching agent is NaClO 2 Solution, sample and NaClO 2 The mass ratio of the solution is 1:40-60; the bleaching temperature is 70-100 ℃, preferably 70-80 ℃; bleaching time is 1-5h, preferably 3h; the stirring speed is 100-500rmp, preferably 300-500rmp.
7. The method of claim 6, wherein NaClO 2 The solution contains sodium hydroxide and glacial acetic acid, preferably NaClO 2 NaClO in solution 2 The content of (2) is 0.5-1.0wt%, preferably 0.7wt%; the NaOH content is 1-5wt%, preferably 3.5wt%; the content of glacial acetic acid is 5-10wt%, preferably 7-8wt%.
8. The method of claim 1, wherein the bleached raw material is washed prior to TEMPO oxidation.
9. The method according to claim 1, wherein the TEMPO oxidation is in particular: dissolving the sample, TEMPO and NaBr in water, stirring, and then dropwise adding NaClO solution; the total reaction time of the oxidation is 1 to 5 hours, preferably 2 hours; the reaction temperature is room temperature, and the pH is 10;
preferably, TEMPO is added in an amount of 0.1mmol/g sample;
preferably, naBr is added in an amount of 1mmol/g sample;
preferably, the NaClO is added in an amount of 10mol/g sample;
further preferably, the NaClO solution is added over the first 20 minutes of TEMPO oxidation.
10. The method according to claim 1, characterized in that the ultrasonic dispersion is in particular: and (5) carrying out ultrasonic treatment, washing, centrifuging the product at room temperature, freezing and drying the sample to obtain the product.
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| Publication number | Priority date | Publication date | Assignee | Title |
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| JP2002060601A (en) * | 2000-06-08 | 2002-02-26 | Toray Ind Inc | Polyester resin composition |
| US20110152413A1 (en) * | 2009-12-21 | 2011-06-23 | Dawkins Bobby G | Polybenzimidazole solution in an ionic liquid |
| US20190374533A1 (en) * | 2008-12-31 | 2019-12-12 | Ardelyx, Inc. | Compounds and methods for inhibiting nhe-mediated antiport in the treatment of disorders associated with fluid retention or salt overload and gastrointestinal tract disorders |
| CN115197342A (en) * | 2022-08-01 | 2022-10-18 | 中国林业科学研究院林产化学工业研究所 | Deep eutectic solvent, preparation method thereof and application of deep eutectic solvent in depolymerization and separation of wood fiber raw material |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2002060601A (en) * | 2000-06-08 | 2002-02-26 | Toray Ind Inc | Polyester resin composition |
| US20190374533A1 (en) * | 2008-12-31 | 2019-12-12 | Ardelyx, Inc. | Compounds and methods for inhibiting nhe-mediated antiport in the treatment of disorders associated with fluid retention or salt overload and gastrointestinal tract disorders |
| US20110152413A1 (en) * | 2009-12-21 | 2011-06-23 | Dawkins Bobby G | Polybenzimidazole solution in an ionic liquid |
| CN115197342A (en) * | 2022-08-01 | 2022-10-18 | 中国林业科学研究院林产化学工业研究所 | Deep eutectic solvent, preparation method thereof and application of deep eutectic solvent in depolymerization and separation of wood fiber raw material |
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