CN109653012B - Method for preparing dissolving pulp by using straws or energy plants - Google Patents
Method for preparing dissolving pulp by using straws or energy plants Download PDFInfo
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- CN109653012B CN109653012B CN201710947155.XA CN201710947155A CN109653012B CN 109653012 B CN109653012 B CN 109653012B CN 201710947155 A CN201710947155 A CN 201710947155A CN 109653012 B CN109653012 B CN 109653012B
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- dissolving pulp
- straws
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- 229920000875 Dissolving pulp Polymers 0.000 title claims abstract description 59
- 239000010902 straw Substances 0.000 title claims abstract description 47
- 238000000034 method Methods 0.000 title claims abstract description 35
- 238000011282 treatment Methods 0.000 claims abstract description 123
- 239000002994 raw material Substances 0.000 claims abstract description 77
- 239000007788 liquid Substances 0.000 claims abstract description 59
- 229920002678 cellulose Polymers 0.000 claims abstract description 41
- 239000001913 cellulose Substances 0.000 claims abstract description 41
- 239000003513 alkali Substances 0.000 claims abstract description 32
- 238000002360 preparation method Methods 0.000 claims abstract description 27
- 238000010335 hydrothermal treatment Methods 0.000 claims abstract description 21
- 238000006243 chemical reaction Methods 0.000 claims abstract description 14
- 239000002699 waste material Substances 0.000 claims abstract description 11
- 238000007598 dipping method Methods 0.000 claims abstract description 6
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 57
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 claims description 54
- KRKNYBCHXYNGOX-UHFFFAOYSA-N citric acid Chemical compound OC(=O)CC(O)(C(O)=O)CC(O)=O KRKNYBCHXYNGOX-UHFFFAOYSA-N 0.000 claims description 51
- BDAGIHXWWSANSR-UHFFFAOYSA-N methanoic acid Natural products OC=O BDAGIHXWWSANSR-UHFFFAOYSA-N 0.000 claims description 50
- 239000000835 fiber Substances 0.000 claims description 33
- 239000000047 product Substances 0.000 claims description 32
- 238000004061 bleaching Methods 0.000 claims description 31
- MHAJPDPJQMAIIY-UHFFFAOYSA-N Hydrogen peroxide Chemical compound OO MHAJPDPJQMAIIY-UHFFFAOYSA-N 0.000 claims description 30
- OSVXSBDYLRYLIG-UHFFFAOYSA-N dioxidochlorine(.) Chemical compound O=Cl=O OSVXSBDYLRYLIG-UHFFFAOYSA-N 0.000 claims description 30
- 238000005470 impregnation Methods 0.000 claims description 30
- 238000005406 washing Methods 0.000 claims description 30
- 239000004094 surface-active agent Substances 0.000 claims description 27
- OSWFIVFLDKOXQC-UHFFFAOYSA-N 4-(3-methoxyphenyl)aniline Chemical compound COC1=CC=CC(C=2C=CC(N)=CC=2)=C1 OSWFIVFLDKOXQC-UHFFFAOYSA-N 0.000 claims description 25
- 235000019253 formic acid Nutrition 0.000 claims description 25
- 239000007787 solid Substances 0.000 claims description 25
- 239000000463 material Substances 0.000 claims description 24
- 239000012752 auxiliary agent Substances 0.000 claims description 23
- 241000196324 Embryophyta Species 0.000 claims description 21
- 238000000605 extraction Methods 0.000 claims description 19
- SRBFZHDQGSBBOR-IOVATXLUSA-N D-xylopyranose Chemical compound O[C@@H]1COC(O)[C@H](O)[C@H]1O SRBFZHDQGSBBOR-IOVATXLUSA-N 0.000 claims description 18
- 230000007935 neutral effect Effects 0.000 claims description 18
- BJEPYKJPYRNKOW-REOHCLBHSA-N (S)-malic acid Chemical compound OC(=O)[C@@H](O)CC(O)=O BJEPYKJPYRNKOW-REOHCLBHSA-N 0.000 claims description 17
- BJEPYKJPYRNKOW-UHFFFAOYSA-N alpha-hydroxysuccinic acid Natural products OC(=O)C(O)CC(O)=O BJEPYKJPYRNKOW-UHFFFAOYSA-N 0.000 claims description 17
- 239000001630 malic acid Substances 0.000 claims description 17
- 235000011090 malic acid Nutrition 0.000 claims description 17
- CSNNHWWHGAXBCP-UHFFFAOYSA-L Magnesium sulfate Chemical compound [Mg+2].[O-][S+2]([O-])([O-])[O-] CSNNHWWHGAXBCP-UHFFFAOYSA-L 0.000 claims description 16
- 239000004155 Chlorine dioxide Substances 0.000 claims description 15
- 235000019398 chlorine dioxide Nutrition 0.000 claims description 15
- 239000000413 hydrolysate Substances 0.000 claims description 15
- 238000004140 cleaning Methods 0.000 claims description 14
- 150000001875 compounds Chemical group 0.000 claims description 14
- 239000003223 protective agent Substances 0.000 claims description 13
- 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
- 229960001484 edetic acid Drugs 0.000 claims description 12
- 239000002245 particle Substances 0.000 claims description 12
- 239000002738 chelating agent Substances 0.000 claims description 11
- 239000012265 solid product Substances 0.000 claims description 10
- DBMJMQXJHONAFJ-UHFFFAOYSA-M Sodium laurylsulphate Chemical compound [Na+].CCCCCCCCCCCCOS([O-])(=O)=O DBMJMQXJHONAFJ-UHFFFAOYSA-M 0.000 claims description 9
- PYMYPHUHKUWMLA-UHFFFAOYSA-N arabinose Natural products OCC(O)C(O)C(O)C=O PYMYPHUHKUWMLA-UHFFFAOYSA-N 0.000 claims description 9
- SRBFZHDQGSBBOR-UHFFFAOYSA-N beta-D-Pyranose-Lyxose Natural products OC1COC(O)C(O)C1O SRBFZHDQGSBBOR-UHFFFAOYSA-N 0.000 claims description 9
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 claims description 8
- IGFHQQFPSIBGKE-UHFFFAOYSA-N Nonylphenol Natural products CCCCCCCCCC1=CC=C(O)C=C1 IGFHQQFPSIBGKE-UHFFFAOYSA-N 0.000 claims description 8
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 claims description 8
- 240000008042 Zea mays Species 0.000 claims description 8
- 235000005824 Zea mays ssp. parviglumis Nutrition 0.000 claims description 8
- 235000002017 Zea mays subsp mays Nutrition 0.000 claims description 8
- 235000005822 corn Nutrition 0.000 claims description 8
- 229910052943 magnesium sulfate Inorganic materials 0.000 claims description 8
- 235000019341 magnesium sulphate Nutrition 0.000 claims description 8
- 229910021645 metal ion Inorganic materials 0.000 claims description 8
- SNQQPOLDUKLAAF-UHFFFAOYSA-N nonylphenol Chemical compound CCCCCCCCCC1=CC=CC=C1O SNQQPOLDUKLAAF-UHFFFAOYSA-N 0.000 claims description 8
- 229940051841 polyoxyethylene ether Drugs 0.000 claims description 8
- 229920000056 polyoxyethylene ether Polymers 0.000 claims description 8
- 241001520808 Panicum virgatum Species 0.000 claims description 7
- 239000002202 Polyethylene glycol Substances 0.000 claims description 7
- 241000209140 Triticum Species 0.000 claims description 7
- 235000021307 Triticum Nutrition 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
- 239000002253 acid Substances 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
- 239000000203 mixture Substances 0.000 claims description 7
- 229920001223 polyethylene glycol Polymers 0.000 claims description 7
- 235000010482 polyoxyethylene sorbitan monooleate Nutrition 0.000 claims description 7
- 229920000053 polysorbate 80 Polymers 0.000 claims description 7
- 238000007670 refining Methods 0.000 claims description 7
- 229940080264 sodium dodecylbenzenesulfonate Drugs 0.000 claims description 7
- 235000011067 sorbitan monolaureate Nutrition 0.000 claims description 7
- 238000009897 hydrogen peroxide bleaching Methods 0.000 claims description 6
- 229920005552 sodium lignosulfonate Polymers 0.000 claims description 6
- 238000003756 stirring Methods 0.000 claims description 5
- 240000007594 Oryza sativa Species 0.000 claims description 4
- 235000007164 Oryza sativa Nutrition 0.000 claims description 4
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims description 4
- 239000001301 oxygen Substances 0.000 claims description 4
- 229910052760 oxygen Inorganic materials 0.000 claims description 4
- 235000009566 rice Nutrition 0.000 claims description 4
- 240000003433 Miscanthus floridulus Species 0.000 claims description 3
- 108010009736 Protein Hydrolysates Proteins 0.000 claims description 3
- 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 3
- 150000004056 anthraquinones Chemical class 0.000 claims description 3
- 238000001027 hydrothermal synthesis Methods 0.000 claims description 3
- 239000000395 magnesium oxide Substances 0.000 claims description 3
- CPLXHLVBOLITMK-UHFFFAOYSA-N magnesium oxide Inorganic materials [Mg]=O CPLXHLVBOLITMK-UHFFFAOYSA-N 0.000 claims description 3
- AXZKOIWUVFPNLO-UHFFFAOYSA-N magnesium;oxygen(2-) Chemical compound [O-2].[Mg+2] AXZKOIWUVFPNLO-UHFFFAOYSA-N 0.000 claims description 3
- 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
- 235000015165 citric acid Nutrition 0.000 claims 1
- YDEXUEFDPVHGHE-GGMCWBHBSA-L disodium;(2r)-3-(2-hydroxy-3-methoxyphenyl)-2-[2-methoxy-4-(3-sulfonatopropyl)phenoxy]propane-1-sulfonate Chemical compound [Na+].[Na+].COC1=CC=CC(C[C@H](CS([O-])(=O)=O)OC=2C(=CC(CCCS([O-])(=O)=O)=CC=2)OC)=C1O YDEXUEFDPVHGHE-GGMCWBHBSA-L 0.000 claims 1
- 238000004519 manufacturing process Methods 0.000 abstract description 16
- 230000008569 process Effects 0.000 abstract description 15
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 abstract description 8
- 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 4
- 238000006731 degradation reaction Methods 0.000 abstract description 4
- 238000005265 energy consumption Methods 0.000 abstract description 2
- 238000000746 purification Methods 0.000 abstract description 2
- 230000000087 stabilizing effect Effects 0.000 abstract description 2
- 239000002002 slurry Substances 0.000 description 26
- 239000000284 extract Substances 0.000 description 18
- 229920000297 Rayon Polymers 0.000 description 14
- 229920005610 lignin Polymers 0.000 description 14
- 229920002488 Hemicellulose Polymers 0.000 description 13
- 238000010438 heat treatment Methods 0.000 description 12
- XEEYBQQBJWHFJM-UHFFFAOYSA-N iron Substances [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 11
- 229920000433 Lyocell Polymers 0.000 description 10
- 238000001125 extrusion Methods 0.000 description 6
- 150000002500 ions Chemical class 0.000 description 6
- 239000011343 solid material Substances 0.000 description 6
- 239000012467 final product 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
- 229920001131 Pulp (paper) Polymers 0.000 description 4
- 235000017166 Bambusa arundinacea Nutrition 0.000 description 3
- 235000017491 Bambusa tulda Nutrition 0.000 description 3
- 241001330002 Bambuseae Species 0.000 description 3
- 235000015334 Phyllostachys viridis Nutrition 0.000 description 3
- 239000011425 bamboo Substances 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 230000009467 reduction Effects 0.000 description 3
- 239000002023 wood Substances 0.000 description 3
- QAOWNCQODCNURD-UHFFFAOYSA-L Sulfate Chemical compound [O-]S([O-])(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-L 0.000 description 2
- 230000000052 comparative effect Effects 0.000 description 2
- 238000010411 cooking Methods 0.000 description 2
- 238000004090 dissolution Methods 0.000 description 2
- 230000007062 hydrolysis Effects 0.000 description 2
- 238000006460 hydrolysis reaction Methods 0.000 description 2
- 230000008676 import Effects 0.000 description 2
- 239000012535 impurity Substances 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 239000010908 plant waste Substances 0.000 description 2
- 238000002791 soaking Methods 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- LSNNMFCWUKXFEE-UHFFFAOYSA-L sulfite Chemical compound [O-]S([O-])=O LSNNMFCWUKXFEE-UHFFFAOYSA-L 0.000 description 2
- 241000609240 Ambelania acida Species 0.000 description 1
- 239000002028 Biomass Substances 0.000 description 1
- 241001349804 Juncus alpinoarticulatus Species 0.000 description 1
- 239000000020 Nitrocellulose Substances 0.000 description 1
- LSNNMFCWUKXFEE-UHFFFAOYSA-N Sulfurous acid Chemical compound OS(O)=O LSNNMFCWUKXFEE-UHFFFAOYSA-N 0.000 description 1
- 229920006221 acetate fiber Polymers 0.000 description 1
- 238000005903 acid hydrolysis reaction Methods 0.000 description 1
- 239000010905 bagasse Substances 0.000 description 1
- 239000002585 base Substances 0.000 description 1
- 239000002551 biofuel Substances 0.000 description 1
- 159000000007 calcium salts Chemical class 0.000 description 1
- 229920003086 cellulose ether Polymers 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 239000011248 coating agent Substances 0.000 description 1
- 238000000576 coating method Methods 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 230000002349 favourable effect Effects 0.000 description 1
- 239000010419 fine particle Substances 0.000 description 1
- 235000013305 food Nutrition 0.000 description 1
- 238000000227 grinding Methods 0.000 description 1
- 238000007654 immersion Methods 0.000 description 1
- 239000013067 intermediate product Substances 0.000 description 1
- 229920001220 nitrocellulos Polymers 0.000 description 1
- 239000003960 organic solvent Substances 0.000 description 1
- 229920001282 polysaccharide Polymers 0.000 description 1
- 238000001556 precipitation Methods 0.000 description 1
- 230000001737 promoting effect Effects 0.000 description 1
- 238000004064 recycling Methods 0.000 description 1
- 230000000717 retained effect Effects 0.000 description 1
- 229910021653 sulphate ion Inorganic materials 0.000 description 1
- 239000004753 textile Substances 0.000 description 1
Classifications
-
- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21C—PRODUCTION OF CELLULOSE BY REMOVING NON-CELLULOSE SUBSTANCES FROM CELLULOSE-CONTAINING MATERIALS; REGENERATION OF PULPING LIQUORS; APPARATUS THEREFOR
- D21C3/00—Pulping cellulose-containing materials
- D21C3/003—Pulping cellulose-containing materials with organic 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
- D21C1/00—Pretreatment of the finely-divided materials before digesting
-
- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21C—PRODUCTION OF CELLULOSE BY REMOVING NON-CELLULOSE SUBSTANCES FROM CELLULOSE-CONTAINING MATERIALS; REGENERATION OF PULPING LIQUORS; APPARATUS THEREFOR
- D21C3/00—Pulping cellulose-containing materials
- D21C3/02—Pulping cellulose-containing materials with inorganic bases or alkaline reacting compounds, e.g. sulfate processes
-
- 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
- D21C3/00—Pulping cellulose-containing materials
- D21C3/02—Pulping cellulose-containing materials with inorganic bases or alkaline reacting compounds, e.g. sulfate processes
- D21C3/022—Pulping cellulose-containing materials with inorganic bases or alkaline reacting compounds, e.g. sulfate processes in presence of S-containing 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
- D21C3/00—Pulping cellulose-containing materials
- D21C3/22—Other features of pulping processes
- D21C3/26—Multistage processes
-
- 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
- D21C9/12—Bleaching ; Apparatus therefor with halogens or halogen-containing compounds
- D21C9/14—Bleaching ; Apparatus therefor with halogens or halogen-containing compounds with ClO2 or chlorites
- D21C9/142—Bleaching ; Apparatus therefor with halogens or halogen-containing compounds with ClO2 or chlorites with ClO2/Cl2 in a multistage process involving ClO2/Cl2 exclusively
-
- 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
Landscapes
- Life Sciences & Earth Sciences (AREA)
- Engineering & Computer Science (AREA)
- Wood Science & Technology (AREA)
- Chemical & Material Sciences (AREA)
- Inorganic Chemistry (AREA)
- Paper (AREA)
- Polysaccharides And Polysaccharide Derivatives (AREA)
Abstract
The invention discloses a method for preparing dissolving pulp by utilizing straws and energy plants, which comprises the following steps: 1) pretreating raw materials; 2) pre-dipping treatment; 3) carrying out hydrothermal treatment; 4) mild alkali treatment; 5) purification treatment, and the like. According to the preparation method, a set of novel dissolving pulp preparation process is designed according to the characteristics of the crop straw raw materials and the raw materials of energy plants, 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 of dissolving pulp (high-purity cellulose) for producing viscose fibers, Lyocell (Lyocell fibers) and other cellulose derivative products.
Background
The dissolving pulp is high-purity cellulose, is an important intermediate product for producing viscose fiber, acetate fiber, nitrocellulose, cellulose ether and other products, and has wide application markets in the fields of textile, military industry, food, coating, chemical industry and the like. The raw materials for producing viscose fiber in China mainly are dissolving pulp from cotton pulp and wood pulp, and also comprise a small amount of bamboo pulp dissolving pulp. In recent years, due to the reduction of the planting area of cotton, the use amount of wood pulp is increased year by year, and the demand of China for dissolving pulp is also increased year by year. In 2015, the import of the dissolving pulp in China exceeds 200 ten thousand tons, and in recent years, the import quantity is increased at a speed of 14-17% per year. The imported dissolving pulp has high quality and low price, and the monthly mean price difference between the domestic dissolving pulp and the imported dissolving pulp in the last four years is about 850 yuan/ton. Therefore, related domestic backbone enterprises strive to improve the quality of domestic dissolving pulp, and seek other cheap raw materials for producing the dissolving pulp so as to reduce the production cost and improve the enterprise competitiveness.
As for the production technique of dissolving Pulp, there are mainly two kinds, i.e., an acid sulfite method and a prehydrolysis sulfate method (Sixta, Handbook of Pulp, 2006). In the past, dissolving pulp was produced mainly by the acid sulphite process (US5139617), but for environmental and other reasons, the production lines newly built in recent years have basically adopted the prehydrolysis sulphate process, resulting in a gradual reduction in the proportion of the acid sulphite process. In addition, a small amount of pulp making processes such as organic solvents are also used to prepare dissolving pulp. The raw materials used are mainly cotton linters, wood chips and bamboo chips. Due to the lack of cotton and the reduction of planting area in recent years, the usage amount of wood chips is gradually increased, and a new process for producing dissolving pulp by directly using commercial bleached wood pulp as a raw material and removing hemicellulose through alkaline impregnation is also adopted by various viscose factories (Zhang et al, Carbohydrate Polymers,2016,141, 238-. Non-wood raw materials, bagasse, chinese alpine rush, etc. can be used to produce dissolving pulp, in addition to the utilization of bamboo chips, but have not been used in large quantities due to geographical limitations and the like (Yuan et al, Biotechnology for Biofuels,2017,10(1), 38). Therefore, other cheap and easily available raw materials are sought by related enterprises and scientific research institutions to replace expensive wood pulp so as to produce high-purity cellulose products for viscose fibers.
The invention develops a new dissolving pulp preparation method aiming at the characteristics of raw materials of a large amount of cheap and easily-obtained crop straws (such as corn straws, wheat straws, rice straws and the like) and energy plants (miscanthus, switchgrass and the like) which are being planted in a large amount.
Disclosure of Invention
Aiming at the comprehensive utilization of crop waste straws and energy plants and the technical problems in the existing dissolving pulp preparation process, the invention provides a novel method for preparing dissolving pulp by using straws and energy plants 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: the raw material is primarily crushed to ensure that the length of the raw material particles is not more than 3 cm,
the raw materials are straws or energy plants, the straws are selected from corn straws, wheat straws or rice straws and the like, and the energy plants are selected from miscanthus or switchgrass and the like.
2) Pre-dipping treatment: adding water into the raw material particles 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 be 1-7, then adding the auxiliary agent A, stirring uniformly, directly performing pre-impregnation treatment at 40-95 ℃ for 20-90min, extruding pre-impregnation liquid after the pre-impregnation is finished, and cleaning the pre-impregnation raw material by using water of which the weight is 5-20 times that of the pre-impregnation raw material product;
the addition amount of the auxiliary agent A is 0.1-2 wt% relative to the oven dry mass of the raw materials, 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) hydrothermal treatment: adding water into the cleaned preimpregnation raw material obtained in the step 2) according to the solid-liquid ratio of 1:9-1:12, adding 8-15 wt% of an auxiliary agent B relative to the absolute dry mass of the raw material, then carrying out hydrothermal reaction at 90-140 ℃ for 30-90 minutes, after the reaction is finished, extruding a hydrolysate, wherein the hydrolysate can be used for preparing a xylose product, and cleaning the residual solid with water of which the weight is 5-20 times that of the solid product;
the auxiliary agent B is a compound of citric acid and formic acid or a compound of malic acid and formic acid, and the mass ratio of the compound of citric acid (or malic acid) and formic acid is 1:10-1: 0.2.
4) Mild alkali treatment: adding water into the solid product subjected to hydrothermal treatment in the step 3) according to the solid-liquid ratio of 1:4-1:8, adding 3-12 wt% of alkali and 0.1-4 wt% of auxiliary agent C relative to the absolute dry mass of the solid product, mechanically stirring for 2-15 minutes, premixing, and then reacting for 30-150 minutes at 90-140 ℃; 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, washing the material for later use after mild alkali treatment, and recovering black liquor;
the auxiliary agent C 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.
5) Refining treatment: and (3) carrying out multi-stage bleaching and refining treatment on the washing material obtained in the step 4), wherein the multi-stage bleaching can be multi-stage hydrogen peroxide bleaching, the single-stage dosage of the hydrogen peroxide is 3-8 wt%, the pH value is 8-11, the temperature is 70-90 ℃, and 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 final dissolving pulp product (high-purity cellulose) is obtained by washing.
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 prepreg, the prepreg liquid is extruded and the prepreg is washed with water in an amount of 8 to 15 times, preferably 10 times, the weight of the prepreg.
Further preferably, after the reaction in step 3) of the production 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 obtained solid.
Further preferably, in step 3) of the preparation method, the assistant B is a compound of citric acid and formic acid or a compound of malic acid and formic acid, and the mass ratio of the compound of citric acid (or malic acid) and formic acid is 1:2-1: 0.5.
Further preferably, after the reaction in step 4) of the production 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 obtained solid.
Preferably, the multi-stage bleaching in the step 5) can also adopt multi-stage bleaching alternately performed by chlorine dioxide and alkaline extraction, wherein the single-stage dosage of the chlorine dioxide is 0.1-1 wt%, 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 0.5-4 wt%, 0-4 wt% 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:
6) 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 dissolving pulp (high-purity cellulose) product.
Advantageous effects
According to the preparation method, a set of novel dissolving pulp preparation process is designed according to the characteristics of the crop straw raw materials and the raw materials of energy plants, 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.
Because the raw materials adopted by the preparation method are crop waste straws and energy plants, the raw materials can be pretreated and primarily crushed to ensure that the particle length of the raw materials is not more than 3 cm for convenient application, or the preparation method of the invention needs a raw material pretreatment step to increase the uniformity of the raw materials, wherein the uniformity of the raw materials can be increased by selectively carrying out mechanical treatment or chemical treatment, such as mechanical grinding treatment of a disc mill, a planetary ball mill and the like, or modes of adding an acid-base defibering agent and the like on the premise of not influencing the subsequent treatment process.
In the pre-impregnation treatment in step 2) of the preparation method according to the invention, the extract and ash in the raw material can be removed as much as possible by adding the auxiliary agent A consisting of the chelating agent and the surfactant, so that the pressure for purifying the cellulose later is reduced. Wherein the addition amount of the auxiliary agent A is 0.1-2 wt% relative to the oven dry mass of the raw materials. 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%).
Adding water into the cleaned preimpregnation raw materials obtained in the step 2) in the hydrothermal treatment of the step 3) of the preparation method according to the invention according to the solid-liquid ratio of 1:9-1:12, adding 8-15 wt% of the auxiliary agent B relative to the absolute dry mass of the raw materials, then carrying out hydrothermal reaction treatment at 90-140 ℃ for 30-90 minutes, extruding hydrolysate after the reaction is finished, preparing xylose products from the hydrolysate, and cleaning the rest solid with 5-20 times, preferably 8-15 times, and most preferably 10 times of water by weight of the solid products;
compared with the absolute dry mass of the raw materials, the auxiliary agent B is a compound of citric acid and formic acid or a compound of malic acid and formic acid, wherein the formic acid is added to accelerate the degradation and dissolution of hemicellulose, so that the temperature of hydrothermal treatment is mild, but when the amount of formic acid is more than 8 wt%, equipment is corroded, and the equipment cost is increased; citric acid and malic acid are much safer, but if only citric acid or malic acid is used, the cost is much higher than that of formic acid under the same hydrolysis efficiency, so the citric acid and malic acid are selected to be used in combination. In addition, both citric acid and malic acid can be separated by calcium salt precipitation. The mass ratio of the citric acid (or malic acid) to the formic acid is 1:10-1:0.2, preferably 1:2-1: 0.5. If the ratio is less than 1:10, the equipment can be corroded under the condition that the ratio of formic acid is too large; if the ratio is more than 1:0.2, the hydrolysis efficiency is reduced under the condition that the ratio of formic acid is too small, the removal rate of hemicellulose in the raw material is low, the purity of subsequent cellulose products is influenced, and the cost of acid hydrolysis is increased. The mole number of effective acid radicals of the formic acid is larger than that of citric acid and malic acid with larger molecular weight in the same mass of acid.
In the mild alkali treatment in step 4) of the preparation method according to the invention, 3-12 wt% of alkali and 0.1-4 wt% of auxiliary agent C are added relative to the absolute dry mass of the raw material, and the cooking of the raw material is realized under relatively mild conditions, so that the lignin in the raw material is removed as much as possible, but at the same time the cellulose is retained as much as possible, and the high yield of the cellulose is ensured. 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 liquor, 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 standby and recovering black liquor.
Wherein, relative to the absolute dry mass of the raw materials, 3 to 12 weight percent of alkali and 0.1 to 4 weight percent of auxiliary agent C are added, and the auxiliary agent C is a mixture of a cellulose protective agent and a 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. The auxiliary agent C 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. 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.
In the refining treatment of the step 5) of the preparation method, the washing material obtained in the step 4) is subjected to multi-stage bleaching refining treatment, the multi-stage bleaching can be multi-stage hydrogen peroxide bleaching, the single-stage dosage of the hydrogen peroxide is 3-8 wt% relative to the absolute dry mass of the crude fiber, the pH value is 8-11, the temperature is 70-90 ℃, preferably, 2-3 stages of hydrogen peroxide bleaching are needed, 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 final dissolving pulp product (high-purity cellulose) is obtained through washing.
Preferably, the multi-stage bleaching in step 5) 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 1 wt%, 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 0.5-4 wt%, 0-4 wt% 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:
6) 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 dissolving pulp (high-purity cellulose) product.
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.
Example 1
A preparation method of dissolving pulp for viscose fibers comprises the following specific steps:
A. and (3) primarily crushing the air-dried corn straws to enable the particle size length of the crushed straws to be less than 3 cm for later use.
B. Pre-impregnating the crushed corn straws under the following treatment conditions: the solid-liquid ratio is 1:9, the temperature is 70 ℃, the dosage of EDTA is 0.3 wt%, the dosage of sodium dodecyl sulfate is 0.9 wt% and the immersion time is 70 minutes based on the dry weight of the corn stalks. After the completion of the treatment, the impregnation solution was recovered by extrusion, and the raw material was washed with 10 times the weight of water. After treatment under these conditions, the extract removal rate was 86% and the ash removal rate was 69%.
C. Carrying out improved hydrothermal treatment on the materials after the preimpregnation and cleaning, wherein the treatment conditions are as follows: the solid-liquid ratio is 1:9, the temperature is 115 ℃, the citric acid content is 8 wt%, the formic acid content is 4 wt% and the processing time is 60 minutes based on the dry weight of the material. After the completion of the treatment, the hydrolysate was extruded and recovered, and then the raw material was washed with 10 times by weight of water. After treatment under these conditions, the hemicellulose removal rate was 87%. The hydrolysate can be used for preparing xylose.
D. Carrying out mild alkali treatment on the material subjected to the improved hydrothermal treatment and washed, wherein the treatment conditions are as follows: the solid-liquid ratio is 1:5, based on the dry weight of the materials, the using amount of NaOH is 10 wt%, the using amount of magnesium sulfate is 0.7 wt%, the using amount of nonylphenol polyoxyethylene ether is 1.2 wt%, and the temperature is 120 ℃, and the treatment is carried out for 50 minutes. After the treatment, the black liquor was squeezed out and recovered, and then the raw material was washed with 10 times the weight of water. After treatment under these conditions, the removal rate of lignin was 84% and the yield of cellulose was 96%.
E. Adding 8 wt% of hydrogen peroxide (relative to the absolute dry weight of the solid materials) into the solid slurry obtained in the step D, 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 slurry yield of the obtained dissolving pulp product is 53 percent, the polymerization degree is 531, the Fe ion content is 35ppm, and relative to the absolute dry weight of the original raw materials, the pentosan content is 0.1 percent, the extract content is 0.11 percent, the alpha-cellulose content is 92.7 percent, and the production requirement of viscose fiber is completely met.
Example 2
A preparation method of dissolving pulp for viscose fibers comprises the following specific steps:
A. and (3) primarily crushing the air-dried wheat straws to enable the particle size length of the crushed wheat straws to be less than 3 cm for later use.
B. Pre-impregnating the crushed wheat straws under the following treatment conditions: the solid-liquid ratio is 1:10, the temperature is 85 ℃, the amount of EDTA is 0.35 wt%, the amount of Span20 is 1.2 wt% and the impregnation time is 80 minutes based on the dry weight of the material. After the completion of the treatment, the impregnation solution was recovered by extrusion, and the raw material was washed with 10 times the weight of water. After treatment under these conditions, the extract removal rate was 87%, and the ash removal rate was 67%.
C. Carrying out improved hydrothermal treatment on the materials after the preimpregnation and cleaning, wherein the treatment conditions are as follows: the solid-liquid ratio is 1:10, the temperature is 125 ℃, the malic acid content is 5 wt%, the formic acid content is 5 wt% and the processing time is 70 minutes based on the dry weight of the material. After the completion of the treatment, the hydrolysate was extruded and recovered, and then the raw material was washed with 10 times by weight of water. After treatment under these conditions, the hemicellulose removal rate was 85%. The hydrolysate can be used for preparing xylose.
D. Carrying out mild alkali treatment on the slurry subjected to the improved hydrothermal treatment and washed, wherein the treatment conditions are as follows: the solid-liquid ratio is 1:7, based on the dry weight of the materials, the using amount of NaOH is 11 wt%, the using amount of green oxygen is 0.2 wt%, the using amount of Tween80 is 1 wt%, and the temperature is 110 ℃, and the treatment is carried out for 70 minutes. After the treatment, the black liquor was squeezed out and recovered, and then the raw material was washed with 10 times the weight of water. After treatment under these conditions, the removal rate of lignin was 87%, and the yield of cellulose was 98%.
E. Adding 7 wt% of hydrogen peroxide (relative to the absolute dry weight of the solid material) into the solid material obtained in the step D, adding water until the solid-liquid ratio is 1:10, and adjusting the pH value to 10.5 by using NaOH; heating for 18min to 90 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 slurry yield of the obtained dissolving pulp product is 55%, the polymerization degree 563 and the Fe ion content are 21ppm, relative to the absolute dry weight of the original raw materials, the pentosan content is 0.3 wt%, the extract content is 0.2 wt%, and the alpha-cellulose content is 93.2 wt%, so that the production requirement of viscose fibers is completely met.
Example 3
A preparation method of dissolving pulp for viscose fibers comprises the following specific steps:
A. and (3) primarily crushing the air-dried rice straws to enable the particle size length of the crushed straws to be less than 3 cm for later use.
B. Pre-impregnating the crushed wheat straws under the following treatment conditions: the solid-liquid ratio is 1:10, the temperature is 90 ℃, based on the dry weight of the materials, the dosage of DTPA is 0.6 wt%, the dosage of sodium dodecyl benzene sulfonate is 1 wt%, and the dipping time is 66 minutes. After the completion of the treatment, the impregnation solution was recovered by extrusion, and the raw material was washed with 10 times the weight of water. After treatment under these conditions, the extract removal rate was 91% and the ash removal rate was 73%.
C. Carrying out improved hydrothermal treatment on the slurry after the preimpregnation and cleaning, wherein the treatment conditions are as follows: the solid-liquid ratio is 1:12, the temperature is 130 ℃, the malic acid content is 3 wt%, the formic acid content is 5 wt% and the processing time is 75 minutes based on the dry weight of the material. After the completion of the treatment, the hydrolysate was extruded and recovered, and then the raw material was washed with 10 times by weight of water. After treatment under these conditions, the hemicellulose removal rate was 87%. The hydrolysate can be used for preparing xylose.
D. Carrying out mild alkali treatment on the slurry subjected to the improved hydrothermal treatment and washed, wherein the treatment conditions are as follows: the solid-liquid ratio is 1:8, based on the dry weight of the materials, the amount of NaOH is 12 wt%, the amount of magnesium sulfate is 0.4 wt%, the amount of sodium lignosulfonate is 2 wt%, and the temperature is 140 ℃, and the treatment is carried out for 40 minutes. After the treatment, the black liquor was squeezed out and recovered, and then the raw material was washed with 10 times the weight of water. After the treatment under the conditions, the removal rate of lignin is 88 percent, and the yield of cellulose is 97 percent.
E. Adding 0.6 wt% of chlorine dioxide (relative to the absolute dry weight of the solid material) into the solid material obtained in the step D, 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, adding 2 wt% of NaOH and 2 wt% of hydrogen peroxide relative to the absolute dry weight of the solid material, 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 2 wt% of NaOH and 2 wt% of hydrogen peroxide to repeat the alkali extraction once, and obtaining a dissolving pulp product after washing after the treatment is finished.
The total pulp yield of the obtained dissolving pulp product is 51%, the polymerization degree is 519, the Fe ion content is 39ppm, and relative to the absolute dry weight of the original raw materials, the pentosan content is 0.5 wt%, the extract content is 0.4 wt%, and the alpha-cellulose content is 92 wt%, so that the production requirement of viscose fibers is completely met.
Example 4
A preparation method of dissolving pulp for tencel (Lyocell fiber) comprises the following specific steps:
A. preliminarily crushing the air-dried switchgrass to ensure that the particle size length of the crushed straw is less than 3 cm for later use.
B. Pre-soaking the crushed switchgrass under the following conditions: the solid-liquid ratio was 1:11, the temperature was 95 ℃, the amount of DTPA was 0.7 wt%, the amount of polyethylene glycol was 1.2 wt%, and the impregnation time was 55 minutes, based on the dry weight of the material. After the completion of the treatment, the impregnation solution was recovered by extrusion, and the raw material was washed with 10 times the weight of water. After treatment under these conditions, the extract removal rate was 89%, and the ash removal rate was 71%.
C. Carrying out improved hydrothermal treatment on the slurry after the preimpregnation and cleaning, wherein the treatment conditions are as follows: the solid-liquid ratio is 1:11, the temperature is 135 ℃, the citric acid content is 5 wt%, the formic acid content is 7 wt% and the processing time is 60 minutes based on the dry weight of the material. After the completion of the treatment, the hydrolysate was extruded and recovered, and then the raw material was washed with 10 times by weight of water. After treatment under these conditions, the hemicellulose removal rate was 90%. The hydrolysate can be used for preparing xylose.
D. Carrying out mild alkali treatment on the slurry subjected to the improved hydrothermal treatment and washed, wherein the treatment conditions are as follows: the solid-liquid ratio is 1:7, based on the dry weight of the materials, the amount of NaOH is 10 wt%, the amount of magnesium sulfate is 0.5 wt%, the amount of sodium dodecyl sulfate is 2 wt%, and the temperature is 140 ℃, and the treatment is carried out for 45 minutes. After the treatment, the black liquor was squeezed out and recovered, and then the raw material was washed with 10 times the weight of water. After treatment under these conditions, the removal rate of lignin was 84% and the yield of cellulose was 95%.
E. Adding 0.7 wt% of chlorine dioxide (relative to the absolute dry weight of the solid slurry) into the solid slurry obtained in the step D, adding water until the solid-liquid ratio is 1:10, 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 2 wt% of NaOH and 1 wt% of hydrogen peroxide, adding water until the solid-to-liquid ratio is 1:10, 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 until the solid-to-liquid ratio is 1:10, and adjusting the pH value to be 2.0; rapidly heating to 70 ℃, keeping the temperature for 120min, and washing to be neutral; then adding 2 wt% of NaOH and 1 wt% of hydrogen peroxide to repeat the alkali extraction once; and finally, carrying out iron ion removal treatment, wherein the use amount of EDTA is 1 wt%, the temperature is 85 ℃, the treatment time is 1 hour, the solid-to-liquid ratio is 1:10, and washing is carried out after the treatment is finished to obtain a dissolving pulp product.
The total slurry yield of the obtained dissolving slurry product is 49%, the polymerization degree is 609, the Fe ion content is 3ppm, and relative to the absolute dry weight of the original raw materials, the pentosan content is 0.2 wt%, the extract content is 0.1 wt%, and the alpha-cellulose content is 94 wt%, so that the production requirement of tencel is completely met.
Comparative example 1
A preparation method of dissolving pulp for viscose fibers comprises the following specific steps:
A. and (3) primarily crushing the air-dried corn straws to enable the particle size length of the crushed straws to be less than 3 cm for later use.
B. Pre-impregnating the crushed corn straws under the following treatment conditions: the solid-liquid ratio is 1:9, the temperature is 70 ℃, the amount of EDTA is 0.3 wt% based on the dry weight of the material, and the dipping time is 70 minutes. After the completion of the treatment, the impregnation solution was recovered by extrusion, and the raw material was washed with 10 times the weight of water. After treatment under these conditions, the extract removal rate was 71% and the ash removal rate was 60%, which were significantly lower than the 86% extract removal rate and the 69% ash removal rate in example 1.
C. Carrying out improved hydrothermal treatment on the slurry after the preimpregnation and cleaning, wherein the treatment conditions are as follows: the solid-liquid ratio is 1:9, the temperature is 115 ℃, and the treatment time is 60 minutes. After the completion of the treatment, the hydrolysate was extruded and recovered, and then the raw material was washed with 10 times by weight of water. After treatment under these conditions, the hemicellulose removal rate was 69%, which is significantly lower than the 87% hemicellulose removal rate in example 1. The hydrolysate can be used for preparing xylose.
D. Carrying out mild alkali treatment on the slurry subjected to the improved hydrothermal treatment and washed, wherein the treatment conditions are as follows: the solid-liquid ratio is 1:5, based on the dry weight of the materials, the using amount of NaOH is 10 wt%, the using amount of magnesium sulfate is 0.7 wt%, the using amount of nonylphenol polyoxyethylene ether is 1.2 wt%, and the temperature is 120 ℃, and the treatment is carried out for 50 minutes. After the treatment, the black liquor was squeezed out and recovered, and then the raw material was washed with 10 times the weight of water. After treatment under these conditions, the removal rate of lignin was 82% and the yield of cellulose was 94%.
E. Adding 8 wt% of hydrogen peroxide (relative to the absolute dry weight of the solid slurry) into the solid slurry obtained in the step D, 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 slurry yield of the obtained dissolving pulp product is 56%, the polymerization degree is 564, the Fe ion content is 65ppm, and relative to the absolute dry weight of the original raw materials, the pentosan content is 5.1 wt%, the extract content is 2.1 wt%, the lignin content is 1 wt%, and the alpha-cellulose content is 86.7 wt%, so that the production requirement of viscose fibers cannot be met. The reason is that the extraction, ash content and hemicellulose are not fully removed by the pre-impregnation and hydrothermal treatment, and the final product is treated by the subsequent treatment conditions of the embodiment 1, so that the impurity content of the final product is higher, and the production requirement of viscose fibers cannot be met.
Comparative example 2
A preparation method of dissolving pulp for tencel (Lyocell fiber) comprises the following specific steps:
A. preliminarily crushing the air-dried switchgrass to ensure that the particle size length of the crushed straw is less than 3 cm for later use.
B. Pre-soaking the crushed switchgrass under the following conditions: the solid-liquid ratio is 1:11, the temperature is 95 ℃, and the dipping time is 55 minutes. After the completion of the treatment, the impregnation solution was recovered by extrusion, and the raw material was washed with 10 times the weight of water. After treatment under these conditions, the extract removal rate was 66% and the ash removal rate was 58%, which are significantly lower than the 89% extract removal rate and the 71% ash removal rate in example 4.
C. Carrying out improved hydrothermal treatment on the slurry after the preimpregnation and cleaning, wherein the treatment conditions are as follows: the solid-liquid ratio is 1:11, the temperature is 135 ℃, and the treatment time is 60 minutes. After the completion of the treatment, the hydrolysate was extruded and recovered, and then the raw material was washed with 10 times by weight of water. After treatment under these conditions, the hemicellulose removal rate was 69%, which is significantly lower than the 90% hemicellulose removal rate in example 4. The hydrolysate can be used for preparing xylose.
D. Carrying out mild alkali treatment on the slurry subjected to the improved hydrothermal treatment and washed, wherein the treatment conditions are as follows: the solid-liquid ratio is 1:7, based on the dry weight of the materials, the amount of NaOH is 10 wt%, the amount of magnesium sulfate is 0.5 wt%, the amount of sodium dodecyl sulfate is 2 wt%, and the temperature is 140 ℃, and the treatment is carried out for 45 minutes. After the treatment, the black liquor was squeezed out and recovered, and then the raw material was washed with 10 times the weight of water. After treatment under these conditions, the removal rate of lignin was 81% and the yield of cellulose was 96%.
E. Adding 0.7 wt% of chlorine dioxide (relative to the absolute dry weight of the solid slurry) into the solid slurry obtained in the step D, adding water until the solid-liquid ratio is 1:10, 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 2 wt% of NaOH and 1 wt% of hydrogen peroxide, adding water until the solid-to-liquid ratio is 1:10, 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 until the solid-to-liquid ratio is 1:10, and adjusting the pH value to be 2.0; rapidly heating to 70 ℃, keeping the temperature for 120min, and washing to be neutral; then adding 2 wt% of NaOH and 1 wt% of hydrogen peroxide to repeat the alkali extraction once, and obtaining a dissolving pulp product after washing after the treatment is finished.
The total slurry yield of the obtained dissolving slurry product is 56%, the polymerization degree is 634, the Fe ion content is 37ppm, and relative to the absolute dry weight of the original raw materials, the pentosan content is 2.3 wt%, the extract content is 1.8 wt%, and the alpha-cellulose content is 89 wt%, so that the requirement of tencel production cannot be met. The reason is that the extract, ash content and hemicellulose are not fully removed by pre-impregnation and hydrothermal treatment, and then the final product is treated by the subsequent treatment conditions of the embodiment 1, so that the impurity content of the final product is higher, and the requirement of tencel production cannot be met. Moreover, no further iron ion removal treatment is carried out after bleaching, so that the iron ion content is too high (more than 5ppm), and the subsequent tencel production cannot be carried out.
Claims (11)
1. A method for preparing dissolving pulp by utilizing straws and energy plants comprises the following steps:
1) pretreatment of raw materials: the raw material is primarily crushed to ensure that the length of the raw material particles is not more than 3 cm,
wherein the raw material is straw or energy plant, the straw is selected from corn straw, wheat straw or rice straw, and the energy plant is selected from miscanthus or switchgrass;
2) pre-dipping treatment: adding water into the raw material particles 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 be 1-7, then adding the auxiliary agent A, stirring uniformly, directly performing pre-impregnation treatment at 40-95 ℃ for 20-90min, extruding pre-impregnation liquid after the pre-impregnation is completed, and cleaning the pre-impregnation raw material by using water of which the weight is 5-20 times that of the pre-impregnation raw material;
the addition amount of the auxiliary agent A is 0.1-2 wt% relative to the oven dry mass of the raw materials, 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 lignin sulfonate, 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 to 1: 0.5;
3) hydrothermal treatment: adding water into the cleaned preimpregnation raw material obtained in the step 2) according to the solid-liquid ratio of 1:9-1:12, adding 8-15 wt% of an auxiliary agent B relative to the absolute dry mass of the raw material, then carrying out hydrothermal reaction at 90-140 ℃ for 30-90 minutes, after the reaction is finished, extruding a hydrolysate, wherein the hydrolysate can be used for preparing a xylose product, and cleaning the residual solid with water of which the weight is 5-20 times that of the solid product;
the auxiliary agent B is a compound of citric acid and formic acid or a compound of malic acid and formic acid, and the mass ratio of the citric acid or the compound of malic acid and formic acid is 1:10-1: 0.2;
4) mild alkali treatment: adding water into the solid product subjected to hydrothermal treatment in the step 3) according to the solid-liquid ratio of 1:4-1:8, adding 3-12 wt% of alkali and 0.1-4 wt% of auxiliary agent C relative to the absolute dry mass of the solid product, mechanically stirring for 2-15 minutes, premixing, and then reacting for 30-150 minutes at 90-140 ℃; 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, washing the material for later use after mild alkali treatment, and recovering black liquor;
the auxiliary agent C 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;
5) refining treatment: and (3) carrying out multi-stage bleaching refining treatment on the washing material obtained in the step 4), wherein the multi-stage bleaching can be carried out by adopting multi-stage hydrogen peroxide bleaching, relative to the absolute dry mass of the crude fiber, the single-stage dosage of the hydrogen peroxide is 3-8 wt%, the pH value is 8-11, the temperature is 70-90 ℃, the fiber pulp after each stage of bleaching is washed until the pH value is neutral, the solid-to-liquid ratio is 1:6-1:12, and after the treatment is finished, the final dissolving pulp high-purity cellulose product is obtained by washing.
2. The method for preparing dissolving pulp by utilizing straws and energy plants as claimed in claim 1, wherein hydrochloric acid or sulfuric acid is added in the step 2) to adjust the pH to 2-4; after completion of the pre-impregnation, the pre-impregnation liquid is extruded and the pre-impregnation raw material is washed with water in an amount of 8 to 15 times the weight of the pre-impregnation raw material.
3. The method for preparing dissolving pulp by using straws and energy plants as claimed in claim 2, wherein the pre-impregnation liquid is extruded after the pre-impregnation is completed, and the pre-impregnation raw material is washed with water in an amount of 10 times the weight of the pre-impregnation raw material.
4. The method for preparing dissolving pulp by using straws and energy plants as claimed in claim 1, wherein after the reaction in step 3), the waste liquid is squeezed out, and the remaining solid is washed with water in an amount of 8-15 times the weight of the obtained solid.
5. The method for preparing dissolving pulp by using straws and energy plants as claimed in claim 1, wherein after the reaction in step 3), the waste liquid is squeezed out, and the remaining solid is washed with water in an amount of 10 times the weight of the obtained solid.
6. The method for preparing dissolving pulp by utilizing straws and energy plants according to claim 1, wherein the auxiliary agent B in the step 3) is a compound of citric acid and formic acid or a compound of malic acid and formic acid, and the mass ratio of the compound of citric acid or malic acid and formic acid is 1:2-1: 0.5.
7. The method for preparing dissolving pulp by using straws and energy plants as claimed in claim 1, wherein after the reaction in step 4), the waste liquid is squeezed out, and the remaining solid is washed with water 8-15 times the obtained solid.
8. The method for preparing dissolving pulp by using straws and energy plants as claimed in claim 5, wherein after the reaction in step 4), the waste liquid is squeezed out, and the remaining solid is washed with water in an amount of 10 times the weight of the obtained solid.
9. The method for preparing dissolving pulp by using straws and energy plants as claimed in claim 1, wherein the multi-stage bleaching in the step 5) can also adopt multi-stage bleaching alternately performed by chlorine dioxide and alkali extraction, wherein, relative to the absolute dry mass of the fiber, the single-stage dosage of the chlorine dioxide is 0.1-1 wt%, the pH value is 1-4, and the temperature is 60-100 ℃; relative to the oven dry mass of the fiber, the amount of NaOH in the alkali extraction is 0.5-4 wt%, 0-4 wt% of hydrogen peroxide can be selectively added in the alkali extraction, the pH value is adjusted to 9-12, and the single-stage treatment time is 30-180 min.
10. The method for preparing dissolving pulp by using straws and energy plants as claimed in claim 9, wherein the multi-stage bleaching in the step 5) can also adopt 3-4 stages of bleaching alternately performed by chlorine dioxide and alkali extraction.
11. The method for preparing dissolving pulp by using straws and energy plants according to claim 1, wherein the preparation method further comprises the following steps:
6) 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 after treatment until the pH value is neutral to obtain the final dissolving pulp high-purity cellulose product.
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| MX2023005250A (en) * | 2020-11-06 | 2023-07-18 | Kimberly Clark Co | Non-wood pulp having high brightness and low debris. |
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| CN112522985B (en) * | 2020-12-10 | 2023-03-17 | 齐鲁工业大学 | Micro-chemical pulping of agricultural straw and full-component refining method of biomass |
| CN112726249A (en) * | 2020-12-29 | 2021-04-30 | 陕西科技大学 | Dissolving pulp prepared from corn straw skins and method |
| CN113957736A (en) * | 2021-10-26 | 2022-01-21 | 福建农林大学 | High-drainability wheat straw chemi-mechanical pulp and preparation method and application thereof based on acid catalysis |
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