CN103485228B - The method of carbohydrate is protected in a kind of oxygen bleaching of pulp process - Google Patents
The method of carbohydrate is protected in a kind of oxygen bleaching of pulp process Download PDFInfo
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- CN103485228B CN103485228B CN201310487569.0A CN201310487569A CN103485228B CN 103485228 B CN103485228 B CN 103485228B CN 201310487569 A CN201310487569 A CN 201310487569A CN 103485228 B CN103485228 B CN 103485228B
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Abstract
The present invention relates to a kind of method protecting carbohydrate in oxygen bleaching of pulp process.The method adds one of shitosan or chitosan oligosaccharide or combination when being included in oxygen bleaching of pulp, consumption is 0.3-5.0kg/ ton slurry, also add NaOH 20-60kg/ ton slurry, magnesium salts 0-6.0kg/ ton is starched, pulp density 10-30% mass ratio, bleaching temperature 80-130 DEG C, bleaching time 20-80min, oxygen pressure 0.2-1.0MPa.The viscosity that the present invention adds shitosan, chitosan oligosaccharide protective agent can significantly improve oxygen bleaching paper pulp and association with pulp bleaching yield, and do not reduce oxygen bleaching of pulp effect.
Description
Technical field
The present invention relates to a kind of method protecting carbohydrate in oxygen bleaching of pulp process, belong to Bleaching Technology field.
Background technology
In bleaching of chemical pulp, oxygen bleaching is a kind of conventional method.Oxygen bleaching significantly can reduce the residual lignin in paper pulp.But because transition metal ions in paper pulp is as the existence of copper ion, manganese ion and iron ion, a large amount of hydroxyl radical free radicals is produced in oxygen bleaching process, the existence of hydroxyl radical free radical causes in oxygen bleaching process, while delignification, carbohydrate can be degraded, and the viscosity showing as paper pulp declines.The degraded of carbohydrate causes the reduction of the physical strength of paper pulp, affects the quality of paper pulp.So the generation of hydroxyl radical free radical will be controlled in oxygen bleaching, reduce the degraded of carbohydrate in bleaching process.
In oxygen bleaching process, the concentration controlling hydroxyl radical free radical will control the concentration of transition metal ions; Two is add free radical scavenger.It is acid treatment that the method for control transition metal ions mainly contains three kinds: one, as adopted sulfuric acid treatment before oxygen delignification, can reduce the concentration of transition metal ions; Two is chelation treatment, adopts chelating agent as EDTA and DTPA pulp treatment in acid condition, also can reduce the concentration of transition metal ions.But no matter be that acid treatment or chelation treatment all will increase by one section of process separately, make bleaching process complicated; Three is add magnesium ion and various salt thereof in oxygen delignification process, and this is also the method for most widely used protection carbohydrate in current oxygen delignification process.
The people such as Kang Ben add methyl alcohol in oxygen bleaching, and result shows the degraded can protecting carbohydrate, see Kang Ben etc., the effect of peroxide ion (free radical) in oxygen bleaching process: the 1. factor affecting the reaction selectivity of carbohydrate and lignin model, wood chemistry and technology, 16 (1): 95, 1996(Yasumoto M, Matsumoto Y, Ishizu A.The roleof peroxide species in the carbohydrate degradation during oxygen bleaching.1.Factorsinfluencing the reaction selectivity between carbohydrate and lignin model compounds.Journalof Wood Chemistry and Technology, 16 (1): 95, 1996).Methyl alcohol as the possible scavenger of hydroxyl free radical, decreases the concentration of hydroxyl free radical in oxygen delignification process, improves the selective of oxygen delignification.
Chinese patent document CN102444047A discloses the method that high viscosity bagasse pulp is prepared in the bleaching of a kind of oxygen alkali cooking, the bagasse after marrow is sent into boiling vessel, adds NaOH, magnesium sulfate, anthraquinone, Na
2sO
3, the digestant such as surfactant and water mix, pass into oxygen after airtight digesting apparatus to certain pressure, then heat temperature raising, oxygen alkali cooking carried out to bagasse and obtains oxonium base slurry; Add low molecular organic acids and/or alcohol protection auxiliary agent again, at a certain temperature ozone bleaching is carried out to oxonium base slurry, obtain ozone bleaching slurry; Carry out P bleaching or Eop bleaching by further using hydrogen peroxide, the bagasse pulp of high viscosity, high whiteness can be obtained.The present invention introduces environment-friendly type oxygen alkali pulping and substitutes traditional soda pulping process, has gained pulp viscosity and the advantage such as whiteness is high, bleaching process is short, energy-efficient, low stain, significant to the commercial Application of ozone bleaching.
Current oxygen bleaching is widely used in the bleaching process of chemical pulp, because the existence of transition metal ions can produce a large amount of hydroxyl radical free radicals in oxygen bleaching process, causes the degraded of carbohydrate.General employing is adding the method for magnesium salts to reduce the generation of hydroxyl free radical in oxygen bleaching of pulp process, protection carbohydrate.Even if but when magnesium salts exists, the degraded of more carbohydrate still can be there is, especially when in paper pulp, transition metal ions concentration is higher, situation can be more serious.
Summary of the invention
The present invention is directed to paper pulp in oxygen bleaching process, the hydroxyl radical free radical that transition metal ion catalyst produces causes the degraded of carbohydrate, causes the problem that pulp viscosity declines, provides a kind of method protecting carbohydrate in oxygen bleaching of pulp process.
Term illustrates:
Chemical pulp, comprises the paper pulp that timber or non-wood fibrous raw material adopt sulfate process, soda processes, caustic soda-anthraquinone method or sulphite process to obtain through boiling.Timber comprises leaf wood and needlebush, and non-timber comprises wheat straw, straw, bamboo, reed, bagasse etc.
Kappa value, be used to characterize the content remaining in lignin in paper pulp and other reducing substanceses after boiling, indirectly represent the size of delignified pulp lignin degree, kappa value is higher, and the residual lignin concentration in paper pulp is higher.
Technical scheme of the present invention is as follows:
A guard method for carbohydrate in oxygen bleaching of pulp process, comprise paper pulp passed in a kettle. oxygen, oxygen bleaching is carried out in heating, wherein:
Add one of shitosan or chitosan oligosaccharide or combination when oxygen bleaching of pulp, consumption is 0.3-5.0kg/ ton slurry, relative to the weight of absolute dried paper pulp;
Also add NaOH 20-60kg/ ton slurry, magnesium salts 0-6.0kg/ ton is starched, relative to the weight of absolute dried paper pulp;
Pulp density 10-30% mass ratio, bleaching temperature 80-130 DEG C, bleaching time 20-80min, oxygen pressure 0.2-1.0MPa.
Preferred according to the present invention, described magnesium salts is selected from magnesium sulfate or magnesium carbonate;
Preferred according to the present invention, described paper pulp is chemical pulp;
Preferred according to the present invention, deacetylation >=75% of described shitosan or chitosan oligosaccharide, shitosan particle mean size≤250 μm, the molecular weight of chitosan oligosaccharide is between 500-6000kDa.
Further preferably, described shitosan or chitosan oligosaccharide deacetylation 80-95%; Chitosan oligosaccharide molecular weight is between 1000-5000kDa; Particle mean size≤150 μm of shitosan.
Preferred according to the present invention, chitosan dosage is 0.5-5.0kg/ ton slurry, and chitosan oligosaccharide consumption is 0.3-3.0kg/ ton slurry.
Preferred according to the present invention, when shitosan and chitosan oligosaccharide combine, mass ratio is 1 ~ 2:1 is good.Preferably shitosan and chitosan oligosaccharide press the combination of 1:1 mass ratio further, and shitosan and chitosan oligosaccharide amount of mixture are that 0.3-5.0kg/ ton is starched.
Preferred according to the present invention, add NaOH 20-40kg/ ton slurry; Magnesium salts 0-3.0kg/ ton is starched;
Preferred according to the present invention, pulp density 20-30% mass ratio, bleaching temperature 90 DEG C-120 DEG C, oxygen pressure is 0.4-0.8MPa, bleaching time 30-60min.
According to the present invention, a preferred embodiment is as follows:
The guard method of carbohydrate in a kind of oxygen bleaching of pulp process, one of chitosan oligosaccharide of particle mean size 70-120 μm of shitosan or molecular weight 2000-5000kDa or combination is added when oxygen bleaching of pulp, consumption is 1.0-3.0kg/ ton slurry, relative to the weight of absolute dried paper pulp; Also add NaOH 20-40kg/ ton slurry, magnesium salts 0-3.0kg/ ton is starched, relative to the weight of absolute dried paper pulp; Pulp density 10-30% mass ratio, bleaching temperature 90 DEG C-120 DEG C, bleaching time 30-60min, oxygen pressure 0.4-0.8MPa.
Of the present invention to be intended to shitosan, the deficiency of chitosan oligosaccharide to existing magnesium salt protective agent make up, synergy, or completely substitute magnesium salts as carbohydrate protective agent; Find that the molecular weight of shitosan affects very little in the present invention according to research, therefore the molecular weight of shitosan is not particularly limited to, the shitosan of the high, normal, basic different molecular weight of 5-70 ten thousand.And the granularity of shitosan is a key factor of influence technique effect, therefore the present invention limits shitosan particle mean size≤250 μm.
Technical characterstic of the present invention and excellent results as follows:
In chemical pulp oxygen bleaching process, the hydroxyl radical free radical produced to reduce transition metal ion catalyst causes the degraded of carbohydrate, what extensively adopt in prior art is that the method adding the magnesium salts such as magnesium sulfate in oxygen bleaching process carrys out passivation transition metal ions, but after oxygen bleaching, the viscosity of paper pulp still has more reduction.The present invention adds shitosan or chitosan oligosaccharide or both mixtures protective agent as carbohydrate in oxygen bleaching of pulp process, also can add the magnesium salts such as magnesium sulfate simultaneously, obviously can reduce the degraded of carbohydrate in paper pulp, the viscosity of protection paper pulp.The great amount of hydroxy group, the amino that exist in shitosan and chitosan oligosaccharide strand, they can adsorb transition metal ions, has stable chelation to transition metal ions.In addition; shitosan can be degraded generation chitosan oligosaccharide in oxygen bleaching process; the chitosan oligosaccharide added or shitosan degrade in oxygen bleaching process produce chitosan oligosaccharide; the effect of free radical quenchant can also be served as; reduce the hydroxyl radical free radical in bleach system, therefore can reduce the degraded of carbohydrate in oxygen bleaching process significantly, the viscosity of protection paper pulp; improve association with pulp bleaching yield, and do not reduce oxygen bleaching effect.With adopt at present only magnesium salts as compared with protectant oxygen bleaching method; under the prerequisite reaching identical or close delignification degree and bleached pulp whiteness, adopt method of the present invention, after oxygen bleaching of pulp, pulp viscosity significantly improves; association with pulp bleaching loss reduces, and bleached stlck chest yield improves.
Detailed description of the invention
Below in conjunction with embodiment, the present invention is described further, but be not limited thereto.
Pulp density in embodiment is mass percent concentration.Ton slurry refers to the weight of oven dry stock.
After the viscosity of paper pulp refers to that the cupri-ethylene diamine solution of employing standard dissolves, the viscosity of the paper pulp adopting capillary tube method to measure, unit is ml/g.
After association with pulp bleaching yield refers to oxygen bleaching, gained pulp quality accounts for the percentage of the front pulp quality of bleaching.
Embodiment 1:
Poplar sulfate brown stock, kappa value 25, viscosity 1100ml/g, whiteness 40%ISO, carry out oxygen bleaching in a kettle., add shitosan (deacetylation 90%, particle mean size 85 μm) 3.0kg/ ton slurry, NaOH 30kg/ ton is starched, magnesium sulfate 2.0kg/ ton is starched, pulp density 20%, bleaching temperature 105 DEG C, oxygen pressure 0.5MPa, bleaching time 30min.Gained bleached pulp viscosity is 910ml/g, whiteness 47.5%ISO, kappa value 14.0, and association with pulp bleaching yield is 94.1%.
Control experiment 1: as described in Example 1, difference does not add shitosan in bleaching process, and other conditions are all identical, and gained bleached pulp viscosity is 840ml/g, and whiteness is 47.0%ISO, kappa value is 14.2, and association with pulp bleaching yield is 92.3%.
Embodiment 2:
Larch sulfate brown stock, kappa value 35, whiteness 36%ISO, viscosity 1250ml/g.Carry out oxygen bleaching in a kettle., adding deacetylation is 95%, and particle mean size is the shitosan 2.0kg/ ton slurry of 100 μm, NaOH 40kg/ ton is starched, and magnesium sulfate 3.0kg/ ton is starched, pulp density 20%, bleaching temperature 120 DEG C, oxygen pressure 0.7MPa, bleaching time 50min.Gained bleached pulp viscosity is 1150ml/g, whiteness 45.0%ISO, kappa value 18.2, and association with pulp bleaching yield is 93.0%.
Control experiment 2: as described in Example 2, difference does not add shitosan in bleaching process, and other conditions are all identical, and gained bleached pulp viscosity is 905ml/g, and whiteness is 44.2%ISO, kappa value is 19.0, and association with pulp bleaching yield is 92.1%.
Embodiment 3:
Wheat straw soda-anthraquinone chemistry brown stock, whiteness 45.0%ISO, viscosity 1025ml/g.Carry out oxygen bleaching in a kettle., add deacetylation 90%, molecular weight is the chitosan oligosaccharide 2.0kg/ ton slurry of 5000kDa, NaOH 20kg/ ton is starched, and magnesium sulfate 3.0kg/ ton is starched, pulp density 25%, bleaching temperature 100 DEG C, oxygen pressure 0.4MPa, bleaching time 30min.Gained bleached pulp viscosity is 875ml/g, whiteness 52.5%ISO, kappa value 8.5, association with pulp bleaching yield 92.2%
Control experiment 3: as described in Example 3, difference does not add chitosan oligosaccharide in bleaching process, and other conditions are all identical, and gained bleached pulp viscosity is 795ml/g, and whiteness is 52.0%ISO, kappa value is 8.8, and association with pulp bleaching yield is 90.8%.
Embodiment 4:
Eucalyptus sulphite forensic chemistry brown stock, kappa value 20.5, whiteness 46.5%ISO, viscosity 1060ml/g.Carry out oxygen bleaching in a kettle., adding deacetylation is 85%, and particle mean size is the shitosan 2.0kg/ ton slurry of 105 μm, and NaOH 30kg/ ton is starched, pulp density 20%, bleaching temperature 115 DEG C, oxygen pressure 0.7MPa, bleaching time 40min.Gained bleached pulp viscosity is 925ml/g, whiteness 54.5%ISO, kappa value 14.5, and association with pulp bleaching yield is 94.2%.
Control experiment 4: as described in Example 4, difference does not add shitosan in bleaching process, and add magnesium sulfate 3.0kg/ ton slurry, other conditions are all identical, and gained bleached pulp viscosity is 885ml/g, and whiteness is 54.2%ISO, kappa value is 15.0, and association with pulp bleaching yield is 93.7%.
Contrast known, it is protectant more effective than adding separately magnesium sulfate that method of the present invention adds shitosan protective agent.
Embodiment 5:
As embodiment 1, difference is the paper pulp adopted is poplar sulfite pulp, kappa value 23, viscosity 1060ml/g, whiteness 43%ISO.The kappa value 13, viscosity 890ml/g, whiteness 51.2%ISO of paper pulp after oxygen bleaching, association with pulp bleaching yield is 92.7%.
Embodiment 6:
As embodiment 2, difference is the paper pulp adopted is Masson Pine Kraft Pulp, kappa value 30, whiteness 37%ISO, viscosity 1205ml/g.After oxygen bleaching, the kappa value of paper pulp is 17.5, viscosity 1100ml/g, whiteness 44.1%ISO, and association with pulp bleaching yield is 93.5%.
Embodiment 7:
As embodiment 3, when difference is oxygen bleaching, add the mixture 3.0kg/ ton slurry of shitosan (deacetylation 90%, particle mean size 80 μm) and chitosan oligosaccharide (deacetylation 90%, molecular weight 3000kDa) mass ratio 1:1.After oxygen bleaching paper pulp kappa value for viscosity be 885ml/g, whiteness 52.2%ISO, kappa value 8.7, association with pulp bleaching yield is 91.7%.
Embodiment 8:
As embodiment 4, difference is the deacetylation of the shitosan adopted is 90%.The kappa value 14.4, viscosity 930ml/g, whiteness 54.7%ISO of paper pulp after oxygen bleaching, association with pulp bleaching yield is 94.0%.
Embodiment 9:
As embodiment 1, when difference is oxygen bleaching, do not add magnesium sulfate.After oxygen bleaching, pulp viscosity is 870ml/g, kappa value 13.8, whiteness 47.6%ISO, and association with pulp bleaching yield is 93.0%.
Claims (7)
1. the guard method of carbohydrate in oxygen bleaching of pulp process, comprise paper pulp is passed into oxygen in a kettle., oxygen bleaching is carried out in heating, wherein:
Add one of shitosan or chitosan oligosaccharide or combination when oxygen bleaching of pulp, consumption is 0.3-5.0 kg/ ton slurry, relative to the weight of absolute dried paper pulp; Deacetylation >=75% of described shitosan or chitosan oligosaccharide, shitosan particle mean size≤250 μm, the molecular weight of chitosan oligosaccharide is between 500-6000 kDa;
Also add NaOH 20-60 kg/ ton slurry, magnesium salts 0-6.0 kg/ ton is starched, relative to the weight of absolute dried paper pulp;
Pulp density 20-30% mass ratio, bleaching temperature 90 DEG C-120 DEG C, oxygen pressure is 0.4-0.8 MPa, bleaching time 30-60 min.
2. the guard method of carbohydrate in oxygen bleaching of pulp process as claimed in claim 1, is characterized in that described magnesium salts is selected from magnesium sulfate or magnesium carbonate.
3. the guard method of carbohydrate in oxygen bleaching of pulp process as claimed in claim 1, is characterized in that described paper pulp is chemical pulp.
4. the guard method of carbohydrate in oxygen bleaching of pulp process as claimed in claim 1, is characterized in that described shitosan or chitosan oligosaccharide deacetylation 80-95%; Chitosan oligosaccharide molecular weight is between 1000-5000 kDa; Particle mean size≤150 μm of shitosan.
5. the guard method of carbohydrate in oxygen bleaching of pulp process as claimed in claim, is characterized in that mass ratio when described shitosan and chitosan oligosaccharide combine is 1 ~ 2:1.
6. the guard method of carbohydrate in oxygen bleaching of pulp process as claimed in claim 1, is characterized in that chitosan dosage be 0.5-5.0 kg/ ton slurry or chitosan oligosaccharide consumption is 0.3-3.0 kg/ ton slurry.
7. the guard method of carbohydrate in oxygen bleaching of pulp process as claimed in claim 1, is characterized in that adding NaOH 20-40 kg/ ton slurry; Magnesium salts 0-3.0 kg/ ton is starched.
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| CN107227643A (en) * | 2017-06-21 | 2017-10-03 | 昆明理工大学 | A kind of method that hydroxyl radical free radical agent for capturing improves oxygen alkali pulping effect |
| CN111287010A (en) * | 2020-02-29 | 2020-06-16 | 华南理工大学 | Application of chitosan as pulp ozone bleaching section viscosity protective agent |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6569286B1 (en) * | 1998-09-30 | 2003-05-27 | Warwick International Group Limited | Method for the alkaline bleaching of pulp with a peroxyacid based oxygen bleaching species using an agglomerated bleach activator |
| CN101082187A (en) * | 2007-08-03 | 2007-12-05 | 山东泉林纸业有限责任公司 | Oxygen delignify treating method for grass group unbleached chemical pulp |
| CN101200863A (en) * | 2006-12-11 | 2008-06-18 | 福建农林大学 | Use of sodium tripolyphosphate in oxygen delignification bleaching as protection additive |
| CN102505551A (en) * | 2011-11-22 | 2012-06-20 | 山东轻工业学院 | Method for alkaline hydrogen peroxide bleaching of paper pulp |
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Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6569286B1 (en) * | 1998-09-30 | 2003-05-27 | Warwick International Group Limited | Method for the alkaline bleaching of pulp with a peroxyacid based oxygen bleaching species using an agglomerated bleach activator |
| CN101200863A (en) * | 2006-12-11 | 2008-06-18 | 福建农林大学 | Use of sodium tripolyphosphate in oxygen delignification bleaching as protection additive |
| CN101082187A (en) * | 2007-08-03 | 2007-12-05 | 山东泉林纸业有限责任公司 | Oxygen delignify treating method for grass group unbleached chemical pulp |
| CN102505551A (en) * | 2011-11-22 | 2012-06-20 | 山东轻工业学院 | Method for alkaline hydrogen peroxide bleaching of paper pulp |
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