CN105777913B - A kind of efficient Cellulose nanocrystal preparation method - Google Patents
A kind of efficient Cellulose nanocrystal preparation method Download PDFInfo
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- CN105777913B CN105777913B CN201610236962.6A CN201610236962A CN105777913B CN 105777913 B CN105777913 B CN 105777913B CN 201610236962 A CN201610236962 A CN 201610236962A CN 105777913 B CN105777913 B CN 105777913B
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- cellulose
- cellulose nanocrystal
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08B—POLYSACCHARIDES; DERIVATIVES THEREOF
- C08B15/00—Preparation of other cellulose derivatives or modified cellulose, e.g. complexes
- C08B15/02—Oxycellulose; Hydrocellulose; Cellulosehydrate, e.g. microcrystalline cellulose
-
- 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
- D21C9/001—Modification of pulp properties
- D21C9/002—Modification of pulp properties by chemical means; preparation of dewatered pulp, e.g. in sheet or bulk form, containing special additives
- D21C9/004—Modification of pulp properties by chemical means; preparation of dewatered pulp, e.g. in sheet or bulk form, containing special additives inorganic compounds
-
- 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
Abstract
The present invention provides a kind of methods for efficiently, quickly preparing Cellulose nanocrystal.This method carries out acidolysis again after pre-processing first with aqueous slkali to cellulosic material, the inorganic salts that metal ion is added in acid hemolysis process assist promoting acidolysis reaction as co-catalyst.The method applied in the present invention reaction condition is mild, easily controllable, and raw materials required for the reaction is simple and easy to get, can be widely applied to all kinds of cellulosic material preparation Cellulose nanocrystals.
Description
[technical field]
The invention belongs to field of nano material preparation, also belong to the field of polymers, in particular to a kind of Cellulose nanocrystal
Preparation method.
[background technique]
Native cellulose is that the maximum biological material of amount, annual output can achieve 1.5 × 10 in nature12
Ton.By the available Cellulose nanocrystal with nano-scale in crystal region for extracting cellulose.Cellulose nanocrystal has
Numerous good characteristics, if it has big draw ratio, length is from hundreds of nanometers to several microns etc.；It has high machinery
Intensity, Young's modulus it is similar to aramid fibre and be higher than steel, tensile strength it is similar to aluminium；Cellulose nanocrystal
Thermal stability it is good, thermal expansion coefficient with carbon fiber generally in 0.1ppm/K hereinafter, can compare favourably.Cellulose nanocrystal is one
Under fixed condition can orientations, so that the characteristic of liquid crystal be presented.In addition, Cellulose nanocrystal also has biocompatibility, can give birth to
Object degradation, reactive surface, high crystalline, low-density (be less than inorfil), it is cheap the advantages that, keep it high in manufacture
Performance composite science field obtains extensive concern, especially today earth resource it is increasingly depleted, people are to environment
Under the background that the craving of protection is increasingly urgent to, there is greatly theoretical and reality to anticipate the research and development of Cellulose nanocrystal
Justice.
Currently, the method for preparation Cellulose nanocrystal mainly has acid hydrolyzation, enzymatic isolation method and physical mechanical facture etc., wherein
Enzymatic isolation method is complicated, time-consuming, at high cost；Physicomechanical processes need special installation and using high pressures, and energy consumption is higher, the cellulose of preparation
Nano Particle distribution is wide.Most common is exactly the method for sulfuric acid solution, and this method results from nineteen forty-seven earliest, by
Cellulose nanocrystal suspension has been made using sulphuric acid hydrolysis timber and cotton-wool in Nickerson and Habrle, and this method raw material is easy
, the Cellulose nanocrystal suspension stability of preparation is high.But the yield of sulfuric acid solution preparation Cellulose nanocrystal needs into one
Step improves, and the yield of usual sulfuric acid solution method is lower than 30%, and Cellulose nanocrystal particle diameter distribution is wider, and gained is nanocrystalline
From several nanometers to several microns, its performance in subsequent use has been seriously affected, it is therefore necessary to be further improved
This method makes its more simple and effective.In patent CN104711305A, using enzymatic isolation method prepared by cellulose to bacteria cellulose
Nanocrystalline, yield is up to 50-85%, and it is higher up to 70% or more that this is mainly due to bacteria cellulose crystallinity itself, significantly
Higher than plant cellulose, so nanocrystalline yield is also higher, but the method is not particularly suited for preparing nanometer using plant cellulose
It is brilliant.Cellulosic material is directly handled in the above-mentioned various methods of preparation Cellulose nanocrystal, there are no pretreatment
The step of.This patent uses alkali process during having used for reference the biomass materials such as stalk, timber production cellulose to remove wherein
Hemicellulose and lignin method, using to cellulosic material carry out oxygenation pretreatment, while during the preparation process be added urge
The method of agent, improves the yield of Cellulose nanocrystal, while shortening the reaction time and making the nanocrystalline particle diameter distribution of gained more
Uniformly.
[summary of the invention]
[technical problems to be solved]
The purpose of the present invention is the deficiencies for existing sulfuric acid solution preparation Cellulose nanocrystal technology, provide one kind more
Easy, efficient preparation method, so that the yield of Cellulose nanocrystal significantly improves, and particle diameter distribution is more uniform.
[technical solution of the present invention]
The present invention is by carrying out aqueous slkali pretreatment to cellulosic material and metal ion conduct being added in acid hemolysis process
Co-catalyst, to improve the yield of Cellulose nanocrystal and improve particle diameter distribution.
The present invention is achieved by the following technical solutions:
(1) it pre-processes: cellulosic material being stirred and is crushed, with aqueous slkali soaking 1-120h, preferably 5-80 hours, more preferably
8-48 hours, then with deionized water filtering and washing to neutrality；
(2) by treated obtained by (1), cellulose is dispersed in mass percentage concentration as 45%-69%, preferably 55-69%；
In the aqueous sulfuric acid of more preferable 60-65%, while co-catalyst is added, under Elevated Temperature Conditions, stirs above-mentioned reactant aqueous solution
Certain time obtains hydrolyzate；
(3) post-process: deionized water be added in hydrolyzate obtained by (2) and is reacted with terminating, then by the hydrolyzate after dilution into
Row centrifuge separation takes upper layer suspension dialysed, filtered, ultrasonic wave dispersion, obtains the rod-like fibre element nanometer of stable dispersion
Crystalline suspension liquid.
Cellulosic material is plant fiber, paper pulp fiber, microcrystalline cellulose and alpha-cellulose in the step (1)；Certainly
Or common natural fiber in nature, for fiber type in the present invention there is no limit.
It is 1%-10% that aqueous slkali used in pre-processing in the step (1), which is mass percentage, and preferably 3-8% is more excellent
Select sodium hydroxide, lithium hydroxide, potassium hydroxide or the ammonia spirit of 4-6%.
Cellulosic material is soaked in aqueous slkali in the step (1), raw material and aqueous slkali
Amount ratio is 10-100g:1L.
The soaking time of cellulosic material is 8-120 hours in the step (1).
Content of the cellulose in sulfuric acid solution is 10-80g/l in the step (2).
Temperature reaction required temperature is 40-80 DEG C in the step (2), and the reaction time is 20-200 minutes.
Step (2) co-catalyst is the salt containing metal ion.
The co-catalyst is the salt containing iron ion, calcium ion, magnesium ion, aluminium ion or copper ion.
Co-catalyst used is to contain iron ion, calcium ion, magnesium ion, aluminium ion or copper ion in the step (2)
Inorganic salts.Preferably one or more of ferrous chloride, ferric trichloride, calcium chloride, magnesium sulfate, aluminum sulfate and copper sulphate.
The mass ratio of co-catalyst dosage and cellulosic material is 1:100-10:100 in the step (2).
When diluted hydrolyzate is centrifuged in the step (3), centrifuge speed 6000-10000rpm, from
Heart number is 2-5 times.
[beneficial effect]
The present invention has the advantage that due to taking above-mentioned technical proposal
(1) cellulosic material is soaked in aqueous slkali and carries out using aqueous slkali to the swelling action of cellulose by the present invention
Pretreatment destroys the hydrogen bond between cellulosic molecule, keeps cellulose molecular structure loose, and reaction accessibility improves, to improve
Acidolysis reaction efficiency, significantly improves reaction yield.
(2) present invention is not particularly limited the inorganic salts of co-catalyst, as long as it includes following cations；In this hair
Bright middle Fe2+、Fe3+、Ca2+、Mg2+、Al3+、Cu2+Equal metal ions have positive charge, can destroy the charge between cellulose hydrogen bond
Balance, facilitates the fracture of hydrogen bond, accelerates the hydrolysis of cellulose, and the present invention uses the inorganic salts containing above-mentioned metal ion
As co-catalyst, the reaction time is shortened, improves reaction efficiency and yield, effectively improves the grain of Cellulose nanocrystal
Diameter distributing homogeneity.
(3) inorganic salts used in reaction are used mainly as co-catalyst, and dosage is few and is easy to by dialysis
It removes, product is not influenced.
(4) for the Cellulose nanocrystal for using the method for the present invention to prepare to be rodlike, average grain diameter is about 100-200nm, grain
Diameter distribution is narrower compared to common sulfuric acid solution method, i.e., particle diameter distribution more evenly, nanocrystalline grain obtained by usual sulfuric acid solution method
Diameter profile exponent (PDI) is 2.0 or so, and the nanocrystalline PDI of present invention gained is 1.0-1.6.The yield of Cellulose nanocrystal is
70-90%.
(5) reaction condition of present invention preparation Cellulose nanocrystal is mild, and easily controllable, raw materials required for the reaction is simply easy
, the method applied in the present invention can be widely applied to all kinds of cellulosic materials existing in the prior art, including natural plants
Fiber and the higher paper cellulose of molecular weight and the higher microcrystalline cellulose of crystallinity, alpha-cellulose etc. prepare cellulose
It is nanocrystalline.
[Detailed description of the invention]
Fig. 1 is the atomic force microscopy of the made Cellulose nanocrystal of the embodiment of the present invention 1
Fig. 2 is the grading curve of the made Cellulose nanocrystal of the embodiment of the present invention 1.
[specific embodiment]
The present invention is further described below with reference to embodiment, but protection scope of the present invention is not limited to that.
Embodiment 1.
5 grams of paper celluloses are broken into flocculence with blender, the NaOH solution of 250ml, 4wt% is added, impregnates 24
After hour, with deionized water by its filtering and washing to neutrality, this cellulose by oxygenation pretreatment is taken, is added 0.078 gram
CuSO4·5H2O adds the sulfuric acid of 90 milliliters of 64wt%, after stirring 40min at 50 DEG C, deionized water is added and terminates reaction,
After solution left standstill, divided again with the revolving speed centrifugation 10min of 8000rpm/min then by washing of precipitate with supercentrifuge
From until supernatant becomes cloudy.By gained Cellulose nanocrystal suspension ultrasound, stable Cellulose nanocrystal suspension is obtained,
It is about 160nm, yield 77%, PDI 1.5 through measurement gained cellulose crystal size average-size.
Embodiment 2.
Raw materials used type, dosage and process flow are with embodiment 1, the difference is that by paper cellulose in NaOH solution
Soaking time extend to 72h, obtain stable Cellulose nanocrystal suspension, through measurement gained cellulose crystal size average-size
About 150nm, yield 81%, PDI 1.4.
Embodiment 3.
After 5g alpha-cellulose is impregnated 48 hours with the NaOH solution of 250ml, 4wt%, extremely with deionized water filtration washing
Neutrality takes this cellulose by oxygenation pretreatment, and 0.078 gram of CuSO is added4·5H2O adds the sulphur of 100 milliliters of 64wt%
Acid, at 50 DEG C stir 1.5h after, be added deionized water terminate reaction, after solution left standstill, with supercentrifuge with
The revolving speed centrifugation 10min of 8000rpm/min is separated again then by washing of precipitate, until supernatant becomes cloudy.By gained fibre
Plain nanocrystal suspension ultrasound is tieed up, obtains stable Cellulose nanocrystal suspension, partial size average-size is about 200nm, and yield is
83%, PDI 1.5.
Embodiment 4.
Paper cellulose is replaced with microcrystalline cellulose, proportion and operation in embodiment 1 is repeated, obtains stable cellulose
Nanocrystal suspension, partial size 150nm, yield 87%, PDI 1.4.
Embodiment 5.
5g paper cellulose is broken into flocculence with blender, is impregnated 24 hours with the NaOH solution of 250ml, 4wt%
Afterwards, with deionized water filtration washing to neutrality, this 5 grams celluloses by oxygenation pretreatment is taken, 0.085 gram of FeCl is added3·
6H2O adds the sulfuric acid of 90 milliliters of 64wt%, after stirring 40min at 50 DEG C, deionized water is added and terminates reaction, by solution
After standing, separated again with the revolving speed centrifugation 10min of 8000rpm/min then by washing of precipitate with supercentrifuge, until
Supernatant becomes cloudy.By gained Cellulose nanocrystal suspension ultrasound, stable Cellulose nanocrystal suspension is obtained, partial size is
180nm, yield 75%, PDI 1.5.
Embodiment 6.
Raw materials used type, dosage and process flow are with embodiment 6, the difference is that with 0.078 gram of MgSO4As co-catalysis
Agent obtains stable Cellulose nanocrystal suspension, partial size 190nm, yield 73%, PDI 1.6.
Comparative example 1.
Paper cellulose is repeated into the proportion and operation in embodiment 1, but is added without co-catalyst, through fiber obtained by acidolysis
The nanocrystalline size of element is 260nm, is greater than the nanocrystalline size of gained in embodiment 1, and the yield of Cellulose nanocrystal is 38% remote
Lower than the yield in embodiment 1, and its particle diameter distribution is also wider, PDI 2.2.
Comparative example 2.
Paper cellulose is repeated into the proportion and operation in embodiment 1, but is pre-processed without aqueous slkali, through obtained by acidolysis
The size of Cellulose nanocrystal is 350nm, is greater than the nanocrystalline size of gained, the yield of Cellulose nanocrystal in embodiment 1 and is
43% far below the yield in embodiment 1, PDI 2.1.
Claims (4)
1. a kind of Cellulose nanocrystal preparation method, it is characterised in that method includes the following steps:
(1) it pre-processes: will be washed after cellulosic material aqueous slkali soaking；
(2) gained cellulose in step (1) is dispersed in the sulfuric acid solution that mass percentage concentration is 45%-69%, is added simultaneously
Enter co-catalyst, heating reaction obtains cellulosic hydrolysate；
(3) post-process: cellulosic hydrolysate obtained by (2) added into deionized water termination acidolysis reaction, after by diluted hydrolyzate into
Row centrifuge separation takes the dialysis of upper layer suspension, filtering, dispersion, obtains Cellulose nanocrystal suspension；
Step (1) pre-process aqueous slkali used be mass percentage be 1%-6% sodium hydroxide, lithium hydroxide, hydroxide
Potassium or ammonia spirit；The amount ratio of the cellulosic material and aqueous slkali is 10-100g:1L；
Content of the cellulose in sulfuric acid solution is 10-80g/l；
The co-catalyst is the salt containing iron ion, calcium ion, magnesium ion, aluminium ion or copper ion；Co-catalyst and fiber
The mass ratio of plain raw material is 1:100-1:10；
Step (1) soaking time is 8-120 hours；
The reaction temperature of step (2) is 40-50 DEG C, and the reaction time is 20-200 minutes；
The particle diameter distribution index for the Cellulose nanocrystal that this method obtains is 1.0-1.6.
2. the preparation method of Cellulose nanocrystal according to claim 1, it is characterised in that the cellulosic material is plant
One or more of fiber, paper pulp fiber, microcrystalline cellulose or alpha-cellulose.
3. the preparation method of Cellulose nanocrystal according to claim 1, it is characterised in that: step (2) described co-catalyst
For one or more of ferrous chloride, ferric trichloride, calcium chloride, magnesium sulfate, aluminum sulfate or copper sulphate.
4. the preparation method of Cellulose nanocrystal according to claim 1, it is characterised in that: step (3) the diluted water
When solution liquid is centrifuged, centrifuge speed 6000-10000rpm, centrifugation number is 2-5 times.
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