CN109653009B - Preparation method for producing dissolving pulp from xylose residues - Google Patents
Preparation method for producing dissolving pulp from xylose residues Download PDFInfo
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- CN109653009B CN109653009B CN201710946817.1A CN201710946817A CN109653009B CN 109653009 B CN109653009 B CN 109653009B CN 201710946817 A CN201710946817 A CN 201710946817A CN 109653009 B CN109653009 B CN 109653009B
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- xylose
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- 125000000969 xylosyl group Chemical group C1([C@H](O)[C@@H](O)[C@H](O)CO1)* 0.000 title claims abstract description 97
- 229920000875 Dissolving pulp Polymers 0.000 title claims abstract description 67
- 238000002360 preparation method Methods 0.000 title claims abstract description 37
- 238000011282 treatment Methods 0.000 claims abstract description 80
- 239000007788 liquid Substances 0.000 claims abstract description 55
- 238000000034 method Methods 0.000 claims abstract description 50
- 229920002678 cellulose Polymers 0.000 claims abstract description 45
- 239000001913 cellulose Substances 0.000 claims abstract description 45
- 239000003513 alkali Substances 0.000 claims abstract description 30
- 239000002994 raw material Substances 0.000 claims abstract description 29
- 238000010411 cooking Methods 0.000 claims abstract description 19
- 239000002699 waste material Substances 0.000 claims abstract description 11
- 238000006243 chemical reaction Methods 0.000 claims abstract description 9
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 claims description 57
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 54
- 238000005406 washing Methods 0.000 claims description 44
- 239000000047 product Substances 0.000 claims description 39
- 239000000835 fiber Substances 0.000 claims description 38
- 239000004094 surface-active agent Substances 0.000 claims description 35
- OSVXSBDYLRYLIG-UHFFFAOYSA-N dioxidochlorine(.) Chemical compound O=Cl=O OSVXSBDYLRYLIG-UHFFFAOYSA-N 0.000 claims description 32
- MHAJPDPJQMAIIY-UHFFFAOYSA-N Hydrogen peroxide Chemical compound OO MHAJPDPJQMAIIY-UHFFFAOYSA-N 0.000 claims description 30
- 238000004061 bleaching Methods 0.000 claims description 28
- 238000010438 heat treatment Methods 0.000 claims description 25
- 239000007787 solid Substances 0.000 claims description 25
- 238000000605 extraction Methods 0.000 claims description 24
- 230000007935 neutral effect Effects 0.000 claims description 21
- 238000005470 impregnation Methods 0.000 claims description 17
- 239000004155 Chlorine dioxide Substances 0.000 claims description 16
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 claims description 16
- 235000019398 chlorine dioxide Nutrition 0.000 claims description 16
- 239000003223 protective agent Substances 0.000 claims description 16
- 239000002738 chelating agent Substances 0.000 claims description 15
- 239000012752 auxiliary agent Substances 0.000 claims description 14
- KCXVZYZYPLLWCC-UHFFFAOYSA-N EDTA Chemical group OC(=O)CN(CC(O)=O)CCN(CC(O)=O)CC(O)=O KCXVZYZYPLLWCC-UHFFFAOYSA-N 0.000 claims description 12
- 238000000227 grinding Methods 0.000 claims description 11
- 238000007670 refining Methods 0.000 claims description 10
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 claims description 8
- CSNNHWWHGAXBCP-UHFFFAOYSA-L Magnesium sulfate Chemical compound [Mg+2].[O-][S+2]([O-])([O-])[O-] CSNNHWWHGAXBCP-UHFFFAOYSA-L 0.000 claims description 8
- DBMJMQXJHONAFJ-UHFFFAOYSA-M Sodium laurylsulphate Chemical compound [Na+].CCCCCCCCCCCCOS([O-])(=O)=O DBMJMQXJHONAFJ-UHFFFAOYSA-M 0.000 claims description 8
- 229910021645 metal ion Inorganic materials 0.000 claims description 8
- 239000000203 mixture Substances 0.000 claims description 8
- 235000010482 polyoxyethylene sorbitan monooleate Nutrition 0.000 claims description 8
- 229920000053 polysorbate 80 Polymers 0.000 claims description 8
- 239000002202 Polyethylene glycol Substances 0.000 claims description 7
- LWZFANDGMFTDAV-WYDSMHRWSA-N [2-[(2r,3r,4s)-3,4-dihydroxyoxolan-2-yl]-2-hydroxyethyl] dodecanoate Chemical compound CCCCCCCCCCCC(=O)OCC(O)[C@H]1OC[C@H](O)[C@H]1O LWZFANDGMFTDAV-WYDSMHRWSA-N 0.000 claims description 7
- GVGUFUZHNYFZLC-UHFFFAOYSA-N dodecyl benzenesulfonate;sodium Chemical compound [Na].CCCCCCCCCCCCOS(=O)(=O)C1=CC=CC=C1 GVGUFUZHNYFZLC-UHFFFAOYSA-N 0.000 claims description 7
- 229920001223 polyethylene glycol Polymers 0.000 claims description 7
- 229940080264 sodium dodecylbenzenesulfonate Drugs 0.000 claims description 7
- 229920005552 sodium lignosulfonate Polymers 0.000 claims description 7
- 235000011067 sorbitan monolaureate Nutrition 0.000 claims description 7
- IGFHQQFPSIBGKE-UHFFFAOYSA-N Nonylphenol Natural products CCCCCCCCCC1=CC=C(O)C=C1 IGFHQQFPSIBGKE-UHFFFAOYSA-N 0.000 claims description 6
- 238000009897 hydrogen peroxide bleaching Methods 0.000 claims description 6
- SNQQPOLDUKLAAF-UHFFFAOYSA-N nonylphenol Chemical compound CCCCCCCCCC1=CC=CC=C1O SNQQPOLDUKLAAF-UHFFFAOYSA-N 0.000 claims description 6
- 229940051841 polyoxyethylene ether Drugs 0.000 claims description 6
- 229920000056 polyoxyethylene ether Polymers 0.000 claims description 6
- 238000004140 cleaning Methods 0.000 claims description 5
- 238000007598 dipping method Methods 0.000 claims description 5
- 238000003756 stirring Methods 0.000 claims description 5
- PYKYMHQGRFAEBM-UHFFFAOYSA-N anthraquinone Natural products CCC(=O)c1c(O)c2C(=O)C3C(C=CC=C3O)C(=O)c2cc1CC(=O)OC PYKYMHQGRFAEBM-UHFFFAOYSA-N 0.000 claims description 4
- 150000004056 anthraquinones Chemical class 0.000 claims description 4
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims description 4
- 239000000395 magnesium oxide Substances 0.000 claims description 4
- CPLXHLVBOLITMK-UHFFFAOYSA-N magnesium oxide Inorganic materials [Mg]=O CPLXHLVBOLITMK-UHFFFAOYSA-N 0.000 claims description 4
- 229910052943 magnesium sulfate Inorganic materials 0.000 claims description 4
- 235000019341 magnesium sulphate Nutrition 0.000 claims description 4
- AXZKOIWUVFPNLO-UHFFFAOYSA-N magnesium;oxygen(2-) Chemical compound [O-2].[Mg+2] AXZKOIWUVFPNLO-UHFFFAOYSA-N 0.000 claims description 4
- 239000000463 material Substances 0.000 claims description 4
- 239000001301 oxygen Substances 0.000 claims description 4
- 229910052760 oxygen Inorganic materials 0.000 claims description 4
- DVEKCXOJTLDBFE-UHFFFAOYSA-N n-dodecyl-n,n-dimethylglycinate Chemical compound CCCCCCCCCCCC[N+](C)(C)CC([O-])=O DVEKCXOJTLDBFE-UHFFFAOYSA-N 0.000 claims description 3
- 239000012265 solid product Substances 0.000 claims description 3
- QPCDCPDFJACHGM-UHFFFAOYSA-N N,N-bis{2-[bis(carboxymethyl)amino]ethyl}glycine Chemical compound OC(=O)CN(CC(O)=O)CCN(CC(=O)O)CCN(CC(O)=O)CC(O)=O QPCDCPDFJACHGM-UHFFFAOYSA-N 0.000 claims 2
- 230000008569 process Effects 0.000 abstract description 28
- 238000004519 manufacturing process Methods 0.000 abstract description 11
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 abstract description 9
- 238000006116 polymerization reaction Methods 0.000 abstract description 8
- 239000003153 chemical reaction reagent Substances 0.000 abstract description 5
- 230000015556 catabolic process Effects 0.000 abstract description 3
- 238000006731 degradation reaction Methods 0.000 abstract description 3
- 239000002440 industrial waste Substances 0.000 abstract description 3
- 238000000746 purification Methods 0.000 abstract description 3
- 238000005265 energy consumption Methods 0.000 abstract description 2
- 230000000087 stabilizing effect Effects 0.000 abstract description 2
- SRBFZHDQGSBBOR-IOVATXLUSA-N D-xylopyranose Chemical compound O[C@@H]1COC(O)[C@H](O)[C@H]1O SRBFZHDQGSBBOR-IOVATXLUSA-N 0.000 description 30
- 239000000284 extract Substances 0.000 description 24
- 239000002002 slurry Substances 0.000 description 22
- 229920005610 lignin Polymers 0.000 description 18
- 235000011121 sodium hydroxide Nutrition 0.000 description 18
- PYMYPHUHKUWMLA-UHFFFAOYSA-N arabinose Natural products OCC(O)C(O)C(O)C=O PYMYPHUHKUWMLA-UHFFFAOYSA-N 0.000 description 15
- SRBFZHDQGSBBOR-UHFFFAOYSA-N beta-D-Pyranose-Lyxose Natural products OC1COC(O)C(O)C1O SRBFZHDQGSBBOR-UHFFFAOYSA-N 0.000 description 15
- XEEYBQQBJWHFJM-UHFFFAOYSA-N iron Substances [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 11
- 229960001484 edetic acid Drugs 0.000 description 10
- 238000004537 pulping Methods 0.000 description 9
- 229920000433 Lyocell Polymers 0.000 description 8
- 229920000297 Rayon Polymers 0.000 description 8
- QAOWNCQODCNURD-UHFFFAOYSA-L Sulfate Chemical compound [O-]S([O-])(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-L 0.000 description 8
- 150000002500 ions Chemical class 0.000 description 6
- 239000002023 wood Substances 0.000 description 6
- 235000017166 Bambusa arundinacea Nutrition 0.000 description 5
- 235000017491 Bambusa tulda Nutrition 0.000 description 5
- 241001330002 Bambuseae Species 0.000 description 5
- 235000015334 Phyllostachys viridis Nutrition 0.000 description 5
- 239000011425 bamboo Substances 0.000 description 5
- 229910052742 iron Inorganic materials 0.000 description 5
- -1 iron ions Chemical class 0.000 description 5
- 229920000742 Cotton Polymers 0.000 description 4
- LSNNMFCWUKXFEE-UHFFFAOYSA-N Sulfurous acid Chemical compound OS(O)=O LSNNMFCWUKXFEE-UHFFFAOYSA-N 0.000 description 4
- 230000000694 effects Effects 0.000 description 4
- 239000002245 particle Substances 0.000 description 4
- 239000012467 final product Substances 0.000 description 3
- 238000004321 preservation Methods 0.000 description 3
- 239000011343 solid material Substances 0.000 description 3
- 229920002522 Wood fibre Polymers 0.000 description 2
- 239000002253 acid Substances 0.000 description 2
- 238000005903 acid hydrolysis reaction Methods 0.000 description 2
- 239000000654 additive Substances 0.000 description 2
- 230000000996 additive effect Effects 0.000 description 2
- 239000002585 base Substances 0.000 description 2
- 229920002301 cellulose acetate Polymers 0.000 description 2
- 230000000052 comparative effect Effects 0.000 description 2
- 230000007547 defect Effects 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 239000002025 wood fiber Substances 0.000 description 2
- QTBSBXVTEAMEQO-UHFFFAOYSA-M Acetate Chemical compound CC([O-])=O QTBSBXVTEAMEQO-UHFFFAOYSA-M 0.000 description 1
- 241000609240 Ambelania acida Species 0.000 description 1
- 239000002028 Biomass Substances 0.000 description 1
- LSNNMFCWUKXFEE-UHFFFAOYSA-M Bisulfite Chemical compound OS([O-])=O LSNNMFCWUKXFEE-UHFFFAOYSA-M 0.000 description 1
- 229920000298 Cellophane Polymers 0.000 description 1
- 102000004190 Enzymes Human genes 0.000 description 1
- 108090000790 Enzymes Proteins 0.000 description 1
- 229920002488 Hemicellulose Polymers 0.000 description 1
- 239000000020 Nitrocellulose Substances 0.000 description 1
- 229920001131 Pulp (paper) Polymers 0.000 description 1
- 239000010905 bagasse Substances 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 230000002950 deficient Effects 0.000 description 1
- 238000004090 dissolution Methods 0.000 description 1
- 230000002349 favourable effect Effects 0.000 description 1
- 239000010419 fine particle Substances 0.000 description 1
- 239000011121 hardwood Substances 0.000 description 1
- 230000008676 import Effects 0.000 description 1
- 229920001220 nitrocellulos Polymers 0.000 description 1
- 230000001737 promoting effect Effects 0.000 description 1
- 238000004064 recycling Methods 0.000 description 1
- 239000011347 resin Substances 0.000 description 1
- 229920005989 resin Polymers 0.000 description 1
- 239000002893 slag Substances 0.000 description 1
- 239000011122 softwood Substances 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
Classifications
-
- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21B—FIBROUS RAW MATERIALS OR THEIR MECHANICAL TREATMENT
- D21B1/00—Fibrous raw materials or their mechanical treatment
- D21B1/02—Pretreatment of the raw materials by chemical or physical means
- D21B1/021—Pretreatment of the raw materials by chemical or physical means by chemical means
-
- 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
-
- 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
- D21C9/16—Bleaching ; Apparatus therefor with per compounds
- D21C9/163—Bleaching ; Apparatus therefor with per compounds with peroxides
Abstract
The invention discloses a preparation method for producing dissolving pulp by using xylose residues, which comprises the steps of 1) raw material pretreatment and 2) preimpregnation treatment; 3) alkali cooking treatment; 4) a purification treatment step, and the like. According to the preparation method, a whole set of dissolving pulp preparation process is designed for the industrial waste xylose residue, so that more choices are provided for high-value utilization of the dissolving pulp; the invention has simple process steps and low equipment and factory management cost; the treatment condition is relatively mild, the dosage of chemical reagents is small, and the production energy consumption, the chemical reagent cost and the waste liquid treatment difficulty are low; simple treatment process and mild reaction conditions, and reduces the excessive degradation of cellulose, thereby improving or stabilizing the content of alpha-cellulose, the polymerization degree of cellulose, the purity and the product yield.
Description
Technical Field
The invention relates to the field of biomass recycling, in particular to a preparation method for producing xylose residue dissolving pulp (high-purity cellulose) by utilizing xylose residue produced by a xylose extraction process.
Background
The dissolving pulp is special chemical pulp, consists of high-purity high-quality cellulose, can be used for producing products with high added value, and is mainly used for producing viscose, nitrocellulose, acetate, cellophane and other products. The world dissolving pulp is mainly produced in America, south Africa, Canada, Brazil and the like, and China is the largest consumer of the world dissolving pulp and accounts for 40 percent of the world total amount. At present, the import amount of the dissolving pulp in China is very large, the dependency is about 60 percent, and the demand and the yield of the dissolving pulp in China in the future are still expected to keep higher growth speed.
At present, the main raw materials of dissolving pulp are wood, cotton linter and the like, and in recent years, bamboo has also become an important raw material of dissolving pulp. However, different raw materials need different processes to produce dissolving pulp, two main processes are used for preparing the dissolving pulp at home and abroad, and generally, the raw material with low hemicellulose content can adopt an acid sulfite method; the raw materials with high resin content must be subjected to a prehydrolysis sulfate process. Wood raw materials mainly use sulfite process and prehydrolysis sulfate process, while cotton linters mainly use alkali process (Sixta, Handbook of Pulp, 2006). The sulfite process is a process containing free SO2The bisulfite cooking process of (a) is carried out at elevated temperatures, which has been used in the past for most softwood dissolving pulps and some hardwood dissolving pulps. However, the method has strict requirements on raw materials and complicated waste liquid treatment, and is gradually replaced by a prehydrolysis sulfate method. The production of dissolving pulp in China gradually changes from a wood mixture sulfite cooking process to a sulfate cooking process taking broadleaf wood and bamboo as raw materials, and most of the existing devices used in the sulfate cooking process use imported devices.
The cotton linter is a better raw material of dissolving pulp, and the alkali method treatment condition is generally 150-175 ℃, and the alkali consumption is 14-18%. The prehydrolysis process of the prehydrolysis sulfate method generally adopts 100-125 ℃ inorganic strong acid hydrolysis or 140-180 ℃ non-acid hydrolysis, and the subsequent sulfate treatment process is similar to the treatment conditions of the cooking, bleaching and other processes of the traditional paper-making and pulping industry. The method for preparing bamboo dissolving pulp is similar to that for preparing wood dissolving pulp, and a prehydrolysis sulfate method and a prehydrolysis caustic soda method can be adopted.
Dissolving pulp production develops rapidly in China, but the existing production process still has many problems and defects. Firstly, the process conditions are similar to those of the traditional pulping industry, the treatment conditions are generally severe, the reaction temperature is higher than 150 ℃, the alkali consumption is more than 20 percent, and the like; secondly, in order to obtain high quality dissolving pulp, a complicated treatment process is usually introduced, which increases the process cost, such as: enzyme treatment, low-temperature extraction technology and the like; and thirdly, wood and bamboo resources in China are deficient, the raw materials are high in price, and the shortage of the cotton linter sources cannot meet the existing industrial requirements.
The xylose residue is waste residue obtained by taking lignocellulose such as corncobs and the like as raw materials and performing an industrial xylose extraction process, and the annual xylose residue waste of China is about 1.3 multiplied by 108Ton. Many studies have been made on resource utilization of xylose residues, but there are few parts to be utilized in actual production. The xylose pulp cellulose is obviously different from the traditional pulp fiber and bamboo pulp fiber, and the shape of the main cellulose is micron-sized particles (about 100 microns). Such particulate wood fibers have not been well utilized in a high value, nor have they been used in the conventional paper industry. The microcosmic properties of the xylose residue fiber are different from those of the traditional wood fiber raw material, and the existing dissolving pulp preparation process is not suitable for the special fiber raw material.
Aiming at the special and cheap fiber raw material of the xylose residue, the invention aims to overcome the defects of severe treatment conditions, complex process steps and the like in the existing industrial process, and provides the preparation method of the xylose residue dissolving pulp, which has the advantages of cheap raw material source, mild treatment conditions and simple process. The dissolving pulp can be used for producing viscose fibers, Lyocell (Lyocell fibers) and other cellulose derivative products.
Disclosure of Invention
Aiming at the technical problems of resource utilization of the xylose residues and the prior process for preparing the dissolving pulp, the invention provides a mild preparation method for producing the dissolving pulp from the xylose residues according to one aspect of the invention.
In order to achieve the above object, the preparation method of the present invention comprises the steps of:
1) pretreatment of raw materials: since the raw material xylose slag often has a large amount of hard particles, the uniformity of the raw material can be increased by selectively performing a treatment such as mechanical grinding (e.g., a disc mill, a planetary ball mill, etc.).
2) Pre-dipping treatment: adding water into the homogenized xylose residue obtained in the step 1) until the solid-to-liquid ratio is 1:5-1:15, then adding hydrochloric acid or sulfuric acid to adjust the pH value to 1-7, adding an auxiliary agent A, stirring uniformly, directly heating to 40-95 ℃ to perform pre-impregnation treatment for 20-90min, extruding pre-impregnation liquid after the pre-impregnation is finished, and cleaning the pre-impregnated xylose residue by using water with the weight 5-20 times that of the pre-impregnated xylose residue product;
wherein the addition amount of the additive A is 0.1-2 wt% relative to the oven-dried mass of the xylose residue. The auxiliary agent A consists of a chelating agent and a surfactant, the chelating agent is selected from EDTA (ethylene diamine tetraacetic acid) and/or DTPA (diethyltriamine pentaacetic acid), the surfactant is selected from one or a mixture of several of sodium dodecyl benzene sulfonate, sodium lignosulfonate, sodium dodecyl sulfate, polyethylene glycol, Tween80, Span20, dodecyl betaine, nonylphenol polyoxyethylene ether and other surfactants, and the mass ratio of the chelating agent to the surfactant is 1:10 to 1: 0.5;
3) alkali cooking treatment: adding water into the cleaned preimpregnated xylose residues obtained in the step 2) according to the solid-to-liquid ratio of 1:4-1:8, adding 3-12wt% of alkali and 0.1-4 wt% of auxiliary agent B into the absolute dry mass of the xylose residues, mechanically stirring for 2-15 minutes, premixing, and then reacting for 30-150 minutes at the temperature of 70-120 ℃; after the reaction is finished, extruding the waste liquid, cleaning the residual solid with water which is 5-20 times the weight of the solid product, wherein the cleaned product is crude fiber, and after the cooking is finished, washing the material for later use and recovering black liquor;
the auxiliary agent B is a mixture consisting of a cellulose protective agent and a surfactant, the cellulose protective agent is selected from one or more of green oxygen, anthraquinone, magnesium sulfate and magnesium oxide, the surfactant is selected from one or more of sodium dodecyl benzene sulfonate, sodium lignosulfonate, sodium dodecyl sulfate, polyethylene glycol, Tween80, Span20, nonylphenol polyoxyethylene ether and other surfactants, and the mass ratio of the cellulose protective agent to the surfactant is 1: 20-1: 2;
4) refining treatment: and (3) carrying out multi-stage bleaching and refining treatment on the crude fiber obtained in the step 3), wherein the multi-stage bleaching can be multi-stage hydrogen peroxide bleaching, the single-stage dosage of the hydrogen peroxide is 3-8wt%, the pH value is 8-11, the temperature is 70-90 ℃, preferably, 2-3 stages of hydrogen peroxide bleaching are carried out, the fiber pulp after each stage of bleaching is washed until the pH value is neutral, and the solid-liquid ratio is 1:6-1:12, and after the treatment is finished, the fiber pulp is washed to obtain a final dissolving pulp product (high-purity cellulose).
Preferably, the multi-stage bleaching in the step 4) can also adopt multi-stage bleaching alternately performed by chlorine dioxide and alkaline extraction, wherein the single-stage dosage of the chlorine dioxide is 0.1-1wt%, the pH value is 1-4, and the temperature is 60-100 ℃ relative to the oven dry mass of the fiber; relative to the oven dry mass of the fiber, the amount of NaOH in the alkali extraction is 0.5-4wt%, 0-4wt% of hydrogen peroxide can be selectively added in the alkali extraction, the pH value is adjusted to 9-12, the single-stage treatment time is 30-180min, and preferably, 3-4 stages of alternate treatment are adopted.
Alternatively, the preparation method according to the present invention may further include the steps of:
5) and (3) metal ion removal treatment: relative to the absolute dry mass of the fiber, adding water and 0.1-2 wt% of EDTA or DTPA, controlling the pH value to be 3-7, the temperature to be 70-90 ℃, the solid-to-liquid ratio to be 1:8-1:12, treating for 30-90 minutes, and washing the pulp until the pH value is neutral after treatment to obtain the final product of the xylose residue dissolving pulp (high-purity cellulose).
Preferably, hydrochloric acid or sulfuric acid is added to adjust the pH to 2-4 in step 2) of the preparation method according to the present invention; after completion of the pre-impregnation, the pre-impregnation liquid is extruded, and the pre-impregnated xylose residues are washed with water in an amount of 8 to 15 times the weight of the pre-impregnated xylose residue product.
Further preferably, after completion of the pre-impregnation in step 2) of the production method according to the present invention, the pre-impregnation liquid is extruded and the pre-impregnated xylose residue is washed with water in an amount of 10 times the weight of the pre-impregnated xylose residue product.
Further preferably, the mass ratio of the chelating agent to the surfactant in step 2) of the preparation method according to the present invention is 1:5 to 1: 0.8;
preferably, 5 to 12wt%, more preferably 10 to 12wt% of a base is added in step 3) of the preparation method according to the present invention;
preferably, the mass ratio of the cellulose protective agent and the surfactant constituting the auxiliary agent B in step 3) of the preparation method according to the present invention is 1:10 to 1: 5.
Further preferably, after the reaction in step 3) of the preparation method according to the present invention is completed, the waste liquid is squeezed out, and the remaining solid is washed with water in an amount of 8 to 15 times, most preferably 10 times, the weight of the pre-impregnated xylose residue product.
Advantageous effects
According to the preparation method, a whole set of dissolving pulp preparation process is designed for the industrial waste xylose residue, so that more choices are provided for high-value utilization of the dissolving pulp; the invention has simple process steps and low equipment and factory management cost; the treatment condition is relatively mild, the dosage of chemical reagents is small, and the production energy consumption, the chemical reagent cost and the waste liquid treatment difficulty are low; simple treatment process and mild reaction conditions, and reduces the excessive degradation of cellulose, thereby improving or stabilizing the content of alpha-cellulose, the polymerization degree of cellulose, the purity and the product yield.
Detailed Description
Hereinafter, the present invention will be described in detail. Before the description is made, it should be understood that the terms used in the present specification and the appended claims should not be construed as limited to general and dictionary meanings, but interpreted based on the meanings and concepts corresponding to technical aspects of the present invention on the basis of the principle that the inventor is allowed to define terms appropriately for the best explanation. Accordingly, the description proposed herein is just a preferable example for the purpose of illustrations only, not intended to limit the scope of the invention, so it should be understood that other equivalents and modifications could be made thereto without departing from the spirit and scope of the invention.
Due to the effects of instability in the xylose extraction process and the source of the feedstock, large amounts of hard clumped particles may be present in the xylose bagasse. The preparation method according to the present invention requires a raw material pretreatment step to increase the homogeneity of the raw material, wherein the homogeneity of the raw material can be increased by selectively performing a mechanical treatment or a chemical treatment, such as a mechanical grinding treatment of a disc mill, a planetary ball mill, or the like, or by adding an acid-base fluffing agent without affecting a subsequent treatment process.
The presoaking treatment in step 2) of the preparation method according to the invention can remove residual sugar, extract and ash in the xylose residue as much as possible by adding the assistant A consisting of the chelating agent and the surfactant, and reduce the pressure of subsequent purification of cellulose. Wherein the addition amount of the additive A is 0.1-2 wt% relative to the oven-dried mass of the xylose residue. The chelating agent is selected from EDTA and/or DTPA, the chelating agent can remove middle ash in raw materials, particularly metal ions, if excessive metal ions exist in a final product, the subsequent application is not facilitated, the surfactant is selected from one or a mixture of several of sodium dodecyl benzene sulfonate, sodium lignosulfonate, sodium dodecyl sulfate, polyethylene glycol, Tween80, Span20, dodecyl betaine, nonylphenol polyoxyethylene ether and the like, and the surfactant can promote the removal of extracts and is favorable for improving the purity of cellulose. The mass ratio of the chelating agent to the surfactant is 1:10 to 1:0.5, the dosage of the chelating agent is not too large, but if the ratio is less than 1:10, the ash removal effect is not obvious (particularly, the removal of iron ions is not obvious), and if the ratio is more than 1:0.5, the removal rate of extract is too low (less than 50%).
In the alkali cooking treatment in step 3) of the preparation method, 3-12wt% of alkali and 0.1-4 wt% of auxiliary agent B are added relative to the absolute dry mass of the xylose residue, and the cooking of the xylose residue is realized under relatively mild conditions, so that the lignin in the xylose residue is removed as much as possible, but the cellulose is kept as much as possible, and the high yield of the cellulose is ensured.
Wherein, relative to the absolute dry mass of the xylose residue, 3 to 12 weight percent of alkali and 0.1 to 4 weight percent of auxiliary agent B are added, and the auxiliary agent B is a mixture of cellulose protective agent and surfactant. The fiber protective agent mainly protects cellulose to avoid the transitional degradation of alkali to the cellulose; the surfactant has the functions of promoting the cellulose protective agent to be well dispersed and permeated and facilitating the dissolution of lignin.
If the dosage of the cellulose protective agent and the surfactant is less than the above range, the yield of cellulose is reduced, the loss is too large, the lignin removal is insufficient, and the further purification effect is affected. Mechanically stirring for 2-15 min, premixing, and reacting at 70-120 deg.C for 30-150 min; after the reaction is finished, extruding the waste liquid, cleaning the residual solid by using water with the weight 5-20 times, preferably 8-15 times and most preferably 10 times that of the solid product, wherein the cleaned product is crude fiber, and after the cooking is finished, washing the material for later use and recovering black liquor;
the auxiliary agent B is a mixture consisting of a cellulose protective agent and a surfactant, the cellulose protective agent is selected from one or more of green oxygen, anthraquinone, magnesium sulfate and magnesium oxide, the surfactant is selected from one or more of sodium dodecyl benzene sulfonate, sodium lignosulfonate, sodium dodecyl sulfate, polyethylene glycol, Tween80, Span20, nonylphenol polyoxyethylene ether and other surfactants, and the mass ratio of the cellulose protective agent to the surfactant is 1: 20-1: 2.
4) Refining treatment: and (3) carrying out multi-stage bleaching and refining treatment on the crude fiber obtained in the step 3), wherein the multi-stage bleaching can be multi-stage hydrogen peroxide bleaching, the single-stage dosage of the hydrogen peroxide is 3-8wt%, the pH value is 8-11, the temperature is 70-90 ℃, preferably, 2-3 stages of hydrogen peroxide bleaching are carried out, the fiber pulp after each stage of bleaching is washed until the pH value is neutral, and the solid-liquid ratio is 1:6-1:12, and after the treatment is finished, the fiber pulp is washed to obtain a final dissolving pulp product (high-purity cellulose).
Preferably, the multi-stage bleaching in step 4) of the preparation method according to the present invention may also be multi-stage bleaching in which chlorine dioxide and alkaline extraction are alternately performed, wherein the single-stage amount of chlorine dioxide is 0.1 to 1wt%, the pH is 1 to 4, and the temperature is 60 to 100 ℃ relative to the oven-dried mass of the fiber; relative to the oven dry mass of the fiber, the amount of NaOH in the alkali extraction is 0.5-4wt%, 0-4wt% of hydrogen peroxide can be selectively added in the alkali extraction, the pH value is adjusted to 9-12, the single-stage treatment time is 30-180min, and preferably, 3-4 stages of alternate treatment are adopted.
Alternatively, the preparation method according to the present invention may further include the steps of:
5) and (3) metal ion removal treatment: relative to the absolute dry mass of the fiber, adding water and 0.1-2 wt% of EDTA or DTPA, controlling the pH value to be 3-7, the temperature to be 70-90 ℃, the solid-to-liquid ratio to be 1:8-1:12, treating for 30-90 minutes, and washing the pulp until the pH value is neutral after treatment to obtain the final product of the xylose residue dissolving pulp (high-purity cellulose).
Specifically, which bleaching process is used can be selected according to the residual amount and properties of the lignin in the material. In principle, multi-stage pure hydrogen peroxide bleaching is used for samples with less residual lignin, less ash and fine particles; the combined process of chlorine dioxide and alkali extraction is suitable for samples with high metal ion and lignin residual quantity and large particles. If further preparation of a higher purity cellulose product is desired, the number of chlorine dioxide bleaching and alkaline extraction treatments can be increased appropriately.
The crude fiber refining treatment process can only comprise multi-stage bleaching treatment, and also can comprise multi-stage bleaching treatment and treatment process for removing metal ions, so as to further remove lignin and metal ions (particularly iron ions) and improve the fiber purity.
The following examples are given by way of illustration of embodiments of the invention and are not to be construed as limiting the invention, and it will be understood by those skilled in the art that modifications may be made without departing from the spirit and scope of the invention. Unless otherwise specified, reagents and equipment used in the following examples are commercially available products.
The xylose residue used in the examples is from Futian pharmaceutical Co Ltd for producing xylose from corncob, and is an industrial waste after xylose extraction.
Example 1:
a preparation method of xylose residue dissolving pulp for viscose fiber comprises the following specific steps:
1) adding water into the xylose residues until the solid-liquid ratio is 1:9, and then adding the xylose residues into a PFI pulping machine for grinding, wherein the rotating speed of the pulping machine is 1460rpm, the pulping clearance is 0.24mm, and the pulping revolution is 1000 revolutions.
2) Adding water into the xylose residue until the solid-to-liquid ratio is 1:10, wherein the pH value is about 2.7; heating for 15min, wherein the temperature reaches 75 ℃, and adding 0.5 wt% of sodium dodecyl benzene sulfonate and 0.2 wt% of EDTA (ethylene diamine tetraacetic acid) relative to the weight of the raw material xylose residue, and keeping the temperature for 60 min; after the completion of the pre-dipping treatment, washing was carried out (the amount of water used was 10 times the mass of the solid matter, and washing was carried out in two times). Residual sugar, partial ash and extract in the xylose residue are removed. After the treatment under the condition, the removal rate of the extract can reach 86 percent, and the removal rate of ash content is 67 percent.
3) Adding 10 wt% of NaOH, 0.2 wt% of anthraquinone and 2wt% of sodium lignosulfonate into the xylose residue obtained in the step 2) relative to the absolute dry weight of the xylose residue, and adding water to adjust the solid-liquid ratio to 1: 5; heating for 18min to 90 deg.C, and keeping the temperature for 100 min; after the cooking is finished, washing and recovering black liquor and solid slurry. Under the condition, the removal rate of lignin is 87%, and the yield of cellulose is 95%.
4) Adding 8wt% of hydrogen peroxide into the solid slurry obtained in the step 3) relative to the absolute dry weight of the solid slurry, adding water until the solid-liquid ratio is 1:9, and adjusting the pH value to 10.5 by using NaOH; heating for 18min to 95 deg.C, and maintaining for 120 min; after bleaching, washing the pulp to be neutral, then continuously repeating the bleaching process twice, and finally washing to obtain a dissolving pulp product.
The total pulp yield of the obtained dissolving pulp product is 51 percent (relative to the absolute dry weight of the original xylose residue), the polymerization degree is 551, the Fe ion content is 38.5ppm, the pentosan content is 0.2 percent, the extract content is 0.15 percent, and the alpha-cellulose content is 93.2 percent, thereby completely meeting the production requirement of viscose fibers.
Example 2:
a preparation process of dissolving pulp for tencel (Lyocell fiber) comprises the following specific steps:
1) adding water into the xylose residues until the solid-liquid ratio is 1:9, and then adding the xylose residues into a single-disc refiner for grinding, wherein the rotation speed of the refiner is 1500rpm, and the refining gap is 0.2 mm.
2) After the xylose residues are treated by single-stage disc grinding, adding water until the solid-to-liquid ratio is 1:10, and adjusting the pH value to 2.0 by using sulfuric acid; the temperature is raised for 15min, the temperature reaches 80 ℃, the heat preservation time is 60min, and 0.1 wt% of DTPA and 0.5 wt% of Tween80 are added relative to the weight of the raw material xylose residues. After the pre-impregnation treatment is finished, residual sugar, partial ash and extract in the xylose residue are removed by washing (the amount of water is 10 times of the mass of the solid material, and the washing is carried out twice). The extract removal rate can reach 88 percent, and the ash removal rate is 70 percent.
3) Adding 11 wt% of NaOH, 0.2 wt% of green oxygen and 1wt% of sodium dodecyl sulfate into the xylose residue obtained in the step 2) relative to the absolute dry weight of the xylose residue, adding water to adjust the solid-liquid ratio to 1:6, heating for 18min, keeping the temperature at 95 ℃ for 100 min; after the cooking is finished, washing and recovering black liquor and solid slurry. After the treatment is finished, the removal rate of lignin can reach 90 percent, and the yield of cellulose is 97 percent.
4) Adding 0.6 wt% of chlorine dioxide into the solid slurry obtained in the step 3) relative to the absolute dry weight of the solid slurry, adding water until the solid-liquid ratio is 1:9, and adjusting the pH value to 2.5; rapidly heating to 75 deg.C, and maintaining the temperature for 60 min; after bleaching, washing the pulp to be neutral, then adding 2wt% of NaOH and 2wt% of hydrogen peroxide, adding water until the solid-to-liquid ratio is 1:9, quickly heating to 80 ℃, and preserving heat for 60 min; after alkali extraction, washing the slurry to be neutral, adding 0.2 wt% of chlorine dioxide, adding water to a solid-to-liquid ratio of 1:9, and adjusting the pH value to 2.0; rapidly heating to 70 ℃, keeping the temperature for 120min, and washing to be neutral; then adding 2wt% of NaOH and 2wt% of hydrogen peroxide to repeat the alkali extraction once; and finally, carrying out iron ion removal treatment, wherein the use amount of EDTA is 1wt%, the temperature is 85 ℃, the treatment time is 1 hour, and washing after the treatment is finished to obtain the xylose residue dissolving pulp product.
The total pulp yield of the dissolving pulp product is 45% (relative to the absolute dry weight of the original xylose residue), the polymerization degree is 538, the Fe ion content is 4.5ppm, the pentosan content is 0 wt%, the extract content is 0.05 wt%, and the alpha-cellulose content is 96.4 wt%, thus completely meeting the quality requirements of dissolving pulp for tencel.
Example 3:
a preparation process of dissolving pulp for viscose fibers comprises the following specific steps:
1) adding water into the xylose residue until the solid-liquid ratio is 1:9, and then adding into a PFI pulping machine for grinding, wherein the speed of the pulping machine is 1460rpm, the pulping clearance is 0.21mm, and the number is 800 revolutions.
2) Adding water into the ground xylose residue until the solid-to-liquid ratio is 1:10, and adjusting the pH value to 1.5 by using sulfuric acid; the temperature is raised for 15min, the temperature reaches 70 ℃, the heat preservation time is 90min, the dosage of EDTA is 0.7 wt% and the dosage of polyethylene glycol is 0.6 wt% relative to the weight of the raw material xylose residue, and after the pre-impregnation treatment is finished, residual sugar, partial ash and extract in the xylose residue are removed through washing (the dosage of water is 10 times of the mass of the solid material, and the washing is carried out twice). Under the condition, the extract removal rate is 84%, and the ash removal rate is 67%.
3) Adding 12wt% of NaOH, 0.6 wt% of magnesium sulfate and 2wt% of Span20 into the xylose residue obtained in the step 2) relative to the absolute dry weight of the xylose residue, adding water to adjust the solid-liquid ratio to 1:6, heating for 18min, keeping the temperature at 90 ℃ for 100 min; after the cooking is finished, washing and recovering black liquor and solid slurry. After treatment under the conditions, the removal rate of lignin is 86%, and the yield of cellulose is 98%.
4) Adding 0.3 wt% of chlorine dioxide into the solid slurry obtained in the step 3) relative to the absolute dry weight of the solid slurry, adding water until the solid-liquid ratio is 1:8, and adjusting the pH value to 2; rapidly heating to 75 deg.C, and maintaining the temperature for 60 min; after bleaching, washing the pulp to be neutral, then adding 3 wt% of NaOH and 1wt% of hydrogen peroxide, adding water until the solid-to-liquid ratio is 1:8, quickly heating to 80 ℃, and preserving heat for 60 min; after alkali extraction, washing the slurry to be neutral, adding 0.3 wt% of chlorine dioxide, adding water to a solid-to-liquid ratio of 1:8, and adjusting the pH value to 2.0; quickly heating to 70 ℃, preserving heat for 120min, and washing to be neutral to obtain a dissolving pulp product.
The total pulp yield of the dissolving pulp product is 48% (relative to the absolute dry weight of the original xylose residue), the polymerization degree is 543, the Fe ion content is 41.7ppm, the pentosan content is 0.1 wt%, the extract content is 0.1 wt%, the alpha-cellulose content is 94.4 wt%, and the quality of the fiber product meets the quality requirement of producing viscose fiber.
Example 4:
a preparation process of dissolving pulp for preparing cellulose acetate comprises the following specific steps:
1) adding water into the xylose residues until the solid-to-liquid ratio is 1: and 8, adding a single-disc refiner for grinding, wherein the rotation speed of the refiner is 1500rpm, and the refining gap is 0.2 mm.
2) After the xylose residues are treated by single-stage disc grinding, adding water until the solid-to-liquid ratio is 1:10, and adjusting the pH value to 1.5 by using sulfuric acid; the temperature rise time is 15min, the temperature reaches 90 ℃, the heat preservation time is 60min, relative to the weight of the raw material xylose residues, the use amount of DTPA is 0.5 wt%, the use amount of sodium dodecyl sulfate is 1wt%, and after the pre-impregnation treatment is finished, residual sugar, partial ash content and extract in the xylose residues are removed through washing (the use amount of water is 10 times of the mass of solid materials and washing is carried out twice). After treatment under these conditions, the removal rate of the extract was 89%, and the removal rate of the ash was 71%.
3) Adding 12wt% of NaOH, 0.2 wt% of magnesium oxide and 1wt% of Tween80 into the xylose residue obtained in the step 2) relative to the absolute dry weight of the xylose residue, and adding water to adjust the solid-liquid ratio to 1: 6; heating for 18min to 90 deg.C, and maintaining for 120 min; after the cooking is finished, washing and recovering black liquor and solid slurry. After treatment under these conditions, the removal rate of lignin was 91% and the yield of cellulose was 92%.
4) Adding 0.5 wt% of chlorine dioxide into the solid slurry obtained in the step 3) relative to the absolute dry weight of the solid slurry, adding water until the solid-liquid ratio is 1:9, and adjusting the pH value to 2.5; rapidly heating to 75 deg.C, and maintaining the temperature for 60 min; after bleaching, washing the pulp to be neutral, then adding 2wt% of NaOH and 1wt% of hydrogen peroxide, adding water until the solid-to-liquid ratio is 1:9, quickly heating to 80 ℃, and preserving heat for 60 min; after alkali extraction, washing the slurry to be neutral, adding 0.2 wt% of chlorine dioxide, adding water to a solid-to-liquid ratio of 1:9, and adjusting the pH value to 2.5; rapidly heating to 75 ℃, keeping the temperature for 60min, and washing to be neutral; and adding 2wt% of NaOH to repeat the alkali extraction once, adding 0.15 wt% of DTPA after washing, treating for 50 minutes at 75 ℃, and finally washing to be neutral to obtain a dissolving pulp product.
The total pulp yield of the dissolving pulp product is 42% (relative to the absolute dry weight of the original xylose residue), the polymerization degree is 658, the Fe ion content is 3.1ppm, the pentosan content is 0 wt%, the extract content is 0.06 wt%, the alpha-cellulose content is 96.1 wt%, and the product reaches the quality requirement of producing cellulose acetate.
Comparative example 1
A preparation method of xylose residue dissolving pulp for viscose fiber comprises the following specific steps:
1) adding water into the xylose residues until the solid-to-liquid ratio is 1:8, then adding a PFI refiner with 1460rpm, 0.22mm refining gap and 2000 revolutions for grinding.
2) Adding water into the ground xylose residue until the solid-to-liquid ratio is 1:10, wherein the pH value is about 2.7; heating for 15min, keeping the temperature at 75 deg.C for 60min, and adding no chelating agent and surfactant; after the completion of the pre-dipping treatment, residual sugar, part of ash and extract in the xylose residue are removed by washing. After treatment under these conditions, the extract removal rate was only 72%, and the ash removal rate was only 53%, which is significantly lower than the 86% extract removal rate and the 67% ash removal rate in example 1.
3) Adding 10 wt% of NaOH (relative to the absolute dry weight of the xylose residue) into the xylose residue obtained in the step 2), and adding water to adjust the solid-liquid ratio to 1: 5; heating for 18min, keeping the temperature at 90 deg.C for 100min, wherein no cellulose protectant and surfactant are added; after the cooking is finished, washing and recovering black liquor and solid slurry. Under the condition, the lignin removal rate is only 74 percent, and the cellulose yield is only 89 percent. Significantly lower than 87% lignin removal and 95% cellulose yield in example 1.
4) Adding 8wt% of hydrogen peroxide (relative to the absolute dry weight of the solid slurry) into the solid slurry obtained in the step 3), adding water until the solid-liquid ratio is 1:9, and adjusting the pH value to 10.5 by using NaOH; heating for 18min to 95 deg.C, and maintaining for 120 min; after bleaching, washing the pulp to be neutral, then continuously repeating the bleaching process twice, and finally washing to obtain a dissolving pulp product.
The total pulp yield of the obtained dissolving pulp product is 55 wt% (relative to the absolute dry weight of the original xylose residue), the polymerization degree is 521, the Fe ion content is 57ppm, the pentosan content is 1%, the extract content is 2.1%, and the alpha-cellulose content is 90.3 wt%, and the production requirement of viscose fibers cannot be met because the alpha-cellulose content is less than 92% and the iron ion content is more than 40 ppm. This is mainly because the extraction, ash and lignin removal at the front end is not sufficient, so the subsequent treatment is difficult to meet the target product requirements.
Comparative example 2
A preparation process of dissolving pulp for tencel (Lyocell fiber) comprises the following specific steps:
1) after the xylose residues are treated by single-stage disc grinding, adding water until the solid-to-liquid ratio is 1:10, and adjusting the pH value to 2.0 by using sulfuric acid; heating for 15min, keeping the temperature at 80 deg.C for 60min, and adding no chelating agent and surfactant; after the completion of the pre-dipping treatment, residual sugar, part of ash and extract in the xylose residue are removed by washing. The extract removal rate is only 76%, and the ash removal rate is only 57%, which is obviously lower than the 88% extract removal rate and the 70% ash removal rate in example 2.
2) Adding 11 wt% of NaOH into the xylose residue obtained in the step 1), and adding water to adjust the solid-liquid ratio to 1: 4; heating for 18min, keeping the temperature at 95 ℃ for 100min, wherein no cellulose protective agent or surfactant is added; after the cooking is finished, washing and recovering black liquor and solid slurry. After the treatment, the lignin removal rate is only 83%, and the cellulose yield is only 87%, which is obviously lower than the lignin removal rate of 90% and the cellulose yield of 97% in example 2.
3) Adding 0.6 percent of chlorine dioxide (relative to the absolute dry weight of the solid slurry) into the solid slurry obtained in the step 2), adding water until the solid-liquid ratio is 1:9, and adjusting the pH value to 2.5; rapidly heating to 75 deg.C, and maintaining the temperature for 60 min; after bleaching, washing the pulp to be neutral, then adding 2wt% of NaOH and 2wt% of hydrogen peroxide, adding water until the solid-to-liquid ratio is 1:9, quickly heating to 80 ℃, and preserving heat for 60 min; after alkali extraction, washing the slurry to be neutral, adding 0.2% of chlorine dioxide, adding water to a solid-to-liquid ratio of 1:9, and adjusting the pH value to 2.0; rapidly heating to 70 ℃, keeping the temperature for 120min, and washing to be neutral; then adding 2wt% of NaOH and 2wt% of hydrogen peroxide to repeat the alkali extraction once; and finally, carrying out iron ion removal treatment, wherein the use amount of EDTA is 1wt%, the temperature is 85 ℃, the treatment time is 1 hour, and washing after the treatment is finished to obtain the xylose residue dissolving pulp product.
The total pulp yield of the dissolving pulp product is 43 wt% (relative to the absolute dry weight of the original xylose residue), the polymerization degree is 503, the Fe ion content is 24.7ppm (more than 5ppm), the pentosan content is 0.8 wt%, the lignin content is 0.9 wt%, the extract content is 1.1 wt%, and the alpha-cellulose content is 87.2 wt% (less than 92%), and the quality requirement of dissolving pulp for tencel cannot be met. Due to insufficient removal of extract, ash and lignin in front-end treatment, the requirements of target products are difficult to meet in subsequent treatment.
Claims (11)
1. A preparation method for producing dissolving pulp from xylose residues comprises the following steps:
1) pretreatment of raw materials: the mechanical grinding treatment is carried out by selectively using a disc grinder or a planetary ball mill, so that the uniformity degree of the raw materials is increased;
2) pre-dipping treatment: adding water into the homogenized xylose residue obtained in the step 1) until the solid-to-liquid ratio is 1:5-1:15, then adding hydrochloric acid or sulfuric acid to adjust the pH value to 1-7, adding the auxiliary agent A, stirring uniformly, and directly heating to 40-95oC, performing pre-impregnation treatment for 20-90min, extruding pre-impregnation liquid after the pre-impregnation is finished, and cleaning the pre-impregnated xylose residues by using water with the weight 5-20 times that of the pre-impregnated xylose residue product;
the addition amount of the auxiliary agent A is 0.1-2 wt% relative to the oven-dry mass of the xylose residue, the auxiliary agent A is composed of a chelating agent and a surfactant, the chelating agent is selected from EDTA and/or DTPA, the surfactant is selected from one or a mixture of several of sodium dodecyl benzene sulfonate, sodium lignosulfonate, sodium dodecyl sulfate, polyethylene glycol, Tween80, Span20, dodecyl betaine and nonylphenol polyoxyethylene ether surfactant, and the mass ratio of the chelating agent to the surfactant is 1: 10-1: 0.5;
3) alkali cooking treatment: washing the obtained product in step 2)Adding water into the pre-impregnated xylose residue according to the solid-liquid ratio of 1:4-1:8, adding 3-12wt% of alkali and 0.1-4 wt% of auxiliary agent B into the pre-impregnated xylose residue according to the absolute dry mass of the xylose residue, mechanically stirring for 2-15 minutes, premixing, and then 70-120oC, reacting for 30-150 minutes; after the reaction is finished, extruding the waste liquid, cleaning the residual solid with water which is 5-20 times the weight of the solid product, wherein the cleaned product is crude fiber, and after the cooking is finished, washing the material for later use and recovering black liquor;
the auxiliary agent B is a mixture consisting of a cellulose protective agent and a surfactant, the cellulose protective agent is selected from one or more of green oxygen, anthraquinone, magnesium sulfate and magnesium oxide, the surfactant is selected from one or more of sodium dodecyl benzene sulfonate, sodium lignosulfonate, sodium dodecyl sulfate, polyethylene glycol, Tween80, Span20 and nonylphenol polyoxyethylene ether surfactant, and the mass ratio of the cellulose protective agent to the surfactant is 1: 20-1: 2;
4) refining treatment: subjecting the crude fiber obtained in the step 3) to multi-stage bleaching and refining treatment, wherein the multi-stage bleaching can be multi-stage hydrogen peroxide bleaching, and the single-stage dosage of the hydrogen peroxide is 3-8wt%, the pH value is 8-11, and the temperature is 70-90% relative to the oven dry mass of the crude fiberoAnd C, bleaching with hydrogen peroxide for 2-3 stages, washing the fiber pulp after each stage of bleaching until the pH is neutral, and washing to obtain the final dissolving pulp product after the treatment, wherein the solid-to-liquid ratio is 1:6-1: 12.
2. The method for preparing dissolving pulp from xylose residue according to claim 1, wherein the multi-stage bleaching in step 4) is performed by alternately performing chlorine dioxide and alkali extraction, wherein the single stage amount of chlorine dioxide is 0.1-1wt% relative to the absolute dry mass of the fiber, the pH is 1-4, and the temperature is 60-100oC; relative to the oven dry mass of the fiber, the amount of NaOH in the alkali extraction is 0.5-4wt%, 0-4wt% of hydrogen peroxide can be selectively added in the alkali extraction, the pH value is adjusted to 9-12, the single-stage treatment time is 30-180min, and the fiber is alternately treated by 3-4 stages.
3. The method for preparing dissolving pulp from xylose residues according to claim 1, characterized in that it may further comprise the following steps:
5) and (3) metal ion removal treatment: relative to the absolute dry mass of the fiber, adding water and 0.1-2 wt% of EDTA or DTPA, controlling the pH value to 3-7 and the temperature to 70-90oAnd C, the solid-liquid ratio is 1:8-1:12, the treatment time is 30-90 minutes, and the pulp is washed until the pH value is neutral after the treatment, so that the final xylose residue dissolving pulp product is obtained.
4. The method for preparing dissolving pulp from xylose residues according to claim 1, wherein hydrochloric acid or sulfuric acid is added in step 2) of the preparation method to adjust the pH to 2-4; after completion of the pre-impregnation, the pre-impregnation liquid is extruded, and the pre-impregnated xylose residues are washed with water in an amount of 8 to 15 times the weight of the pre-impregnated xylose residue product.
5. The method for preparing dissolving pulp from xylose residues according to claim 4, wherein after completion of the pre-impregnation in step 2), the pre-impregnation solution is extruded and the pre-impregnated xylose residues are washed with water in an amount of 10 times the weight of the pre-impregnated xylose residue product.
6. The method for preparing dissolving pulp from xylose residues according to claim 1, wherein the mass ratio of the chelating agent to the surfactant in step 2) of the preparation method is 1:5 to 1: 0.8.
7. The method for preparing dissolving pulp from xylose residues according to claim 1, wherein 5-12wt% of alkali is added in step 3) of the preparation method.
8. The method for preparing dissolving pulp from xylose residues according to claim 7, wherein 10-12wt% of alkali is added in step 3) of the preparation method.
9. The method for preparing dissolving pulp from xylose residues according to claim 1, wherein the mass ratio of the cellulose protective agent and the surfactant which constitute the aid B in step 3) of the preparation method is 1:10 to 1: 5.
10. The method for preparing dissolving pulp from xylose residues according to claim 1, wherein after the reaction in step 3) of the preparation method is completed, the waste liquid is squeezed out and the remaining solid is washed with water in an amount of 8 to 15 times the weight of the pre-impregnated xylose residue product.
11. The method for preparing dissolving pulp from xylose residues according to claim 10, wherein after the reaction in step 3) of the method, the waste liquid is squeezed out and the remaining solids are washed with water 10 times the weight of the pre-impregnated xylose residue product.
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| CN109653009A (en) | 2019-04-19 |
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