A critical pathway towards enhancing pulp mill biorefineries is to integrate the extraction and utilization of hemicelluloses into the pulping processes.Hence,an industrial pre-extraction strategy for hemicelluloses t...A critical pathway towards enhancing pulp mill biorefineries is to integrate the extraction and utilization of hemicelluloses into the pulping processes.Hence,an industrial pre-extraction strategy for hemicelluloses targeting eucalyptus kraft pulping process was developed.Alkaline solution or pulping white liquor was used to pre-extract hemicelluloses before the actual pulping process.The response surface methodology(RSM)technique was applied to investigate the most suitable conditions to maximize the yield of these hemicelluloses while simultaneously minimizing the damage to pulp yields and properties.Temperature(105 to 155℃),alkali concentration(3%to 8%),sulfidity(20%to 30%)and retention time(19 to 221 min)were combined to evaluate their effects on hemicellulose yields and chemical structures.The optimal pre-extraction conditions identified in this work(5.75%NaOH concentration,25%sulfidity at 135℃for 60 min)successfully allowed recovering 4.8%of hemicelluloses(based on the wood dry mass)and limited damages to pulp yields and properties.The cellulose content in pulp can even be increased by about 10%.Hemicellulose emulsification properties were also evaluated,which were comparable to synthetic emulsifiers.This study provides an industrial pathway to effectively separate and utilize wood hemicelluloses from the pulping process,which has the potential to improve the economy and material utilization of pulp and paper mills.展开更多
The deterioration of recycled fibers especially unbleached kraft with high wet strength resin content due to the irreversible structural changes caused by drying and added chemicals makes the raw material difficult to...The deterioration of recycled fibers especially unbleached kraft with high wet strength resin content due to the irreversible structural changes caused by drying and added chemicals makes the raw material difficult to repulp.The mechanical effect in the pulper over time with chemical treatment has a negative impact on the recycled fibers.At lab scale,different compositions of enzymatic treatment C022L were under investigation to select the most efficient laccase Lacc1,Lacc2 or Lacc3 and to observe the impact of lipases during repulping at low and high consistencies.Pulp disintegration at different times was evaluated to define the level of rejects and to analyze the morphology of fibers after treatments.These results were more significant for Lacc2,by increasing the pulp consistency to 15%in the pulper.Combining lipases with CELODASE 022L appeared to decrease the efficiency of enzymes.The results showed a high reduction of energy power with the enzymatic treatment and a significant reduction of fines level in fibers’suspension.The most efficient version of C022L was used at industrial scale to compare directly with the standard conditions used in a paper mill.展开更多
Kraft lignin has the potential to replace traditional fossil resources for the preparation of high-value chemicals because it is rich in aromatic rings and active functional groups.An effective method for the pyrolysi...Kraft lignin has the potential to replace traditional fossil resources for the preparation of high-value chemicals because it is rich in aromatic rings and active functional groups.An effective method for the pyrolysis of kraft lignin into chemicals/fuels is microwave-assisted depolymerization.A simulation model is urgently needed to illustrate the coupling effect and mechanism of lignin conversion during the depolymerization process.In this study,COMSOL Multiphysics was used to simulate the microwave-assisted depolymerization process.The results showed that microwave power had a significant effect on the electric field and temperature distribution in the microwave cavity,while the reaction time had little effect on the electric field.The effect of the nitrogen flow rate on the electric field and temperature was negligible.The intensity of the electric field,heating rate of lignin,and final temperature of lignin depolymerization increased with increasing microwave power.展开更多
The present work evaluated the use of photo-Fenton process for the treatment of kraft pulp mill effluent. The photo-Fenton best operating conditions, such as pH, concentration, and H2O2: Fe2+ ratio were evaluated. The...The present work evaluated the use of photo-Fenton process for the treatment of kraft pulp mill effluent. The photo-Fenton best operating conditions, such as pH, concentration, and H2O2: Fe2+ ratio were evaluated. The efficiency of the treatment was measured by COD (chemical oxygen demand) removal. The results showed that the optimum pH for the photo-Fenton process was equal to 3. The increase in H2O2 application resulted in an efficiency increase of the photo-Fenton process, although this was not a directly proportional relation. For most cases, the H2O2: Fe2+ proportion of 100:1 yielded the best results for COD removal. Solar radiation was more efficient than artificial UV to the COD removal. During the treatment the organic matter of the effluent was more oxidized than mineralized, showing a higher removal of COD than BOD (biochemical oxygen demand) and TOC (total organic carbon), respectively. So, photo-Fenton process increased the BOD/ COD ration but decreased the BOD/TOC ratio.展开更多
Hemicellulose has a wide range of applications,including that as an emulsifier for the food industry and raw material for the synthesis of bioethanol/biochemicals and biodegradable films.Hemicellulose is usually prese...Hemicellulose has a wide range of applications,including that as an emulsifier for the food industry and raw material for the synthesis of bioethanol/biochemicals and biodegradable films.Hemicellulose is usually present as a spent liquor,such as the prehydrolysis liquor of the prehydrolysis kraft dissolving pulp production process and the alkali extraction liquor of the cold caustic extraction of pulp fibers.Due to its dilute nature,hemicellulose needs to be dried for practical utilization,and this is challenging.In this study,cellulose and hemicellulose in a bleached bamboo kraft pulp were separated using an alkali extraction process.Hemicellulose obtained from the extraction liquor was dried by an ammonium carbonate-assisted drying process.The effects of drying time and drying temperature were determined.Structure of the hemicellulose obtained by the ammonium carbonate-assisted drying process was similar to that of original hemicellulose,as revealed by detailed Fourier transform infrared and X-ray diffraction analyses.The novel drying method was more energy efficient and required a shorter drying time than the conventional freeze drying method,and the excellent solubility in alkaline solutions favored the chemical modification of hemicellulose.The dried hemicellulose can be used as a renewable raw material for the preparation of hydrogels and other substances such as bioethanol/biochemicals and biodegradable films.展开更多
It is known that large amounts of residual lignin are generated in the pulp and paper industry.A new alternative for Kraft lignin valorization,which consists of first a chemical modification using a diisocyanate and t...It is known that large amounts of residual lignin are generated in the pulp and paper industry.A new alternative for Kraft lignin valorization,which consists of first a chemical modification using a diisocyanate and then the efficient dispersion in castor oil to achieve stable gel-like systems,is proposed in this work.Rheological properties and microstructure of these materials were determined by means of small amplitude oscillatory shear tests and viscous flow measurements and atomic force microscopy observations,respectively.Moreover,both standardized penetration tests and tribological assays,usually performed in the lubricant industry,were carried out to evaluate the performance characteristics as lubricating greases.Linear viscoelasticity functions are affected by the lignin/diisocyanate ratio and thickener concentration.The thermorheological response evidenced a softening temperature of around 105°C.The microstructure of these gel-like dispersions is composed of interconnected thin fibers,homogeneously distributed in castor oil.Moreover,the NCO-functionalized lignin gel-like dispersions studied show lower friction coefficients than traditional lubricating greases.展开更多
Kraft lignin was liquefied using polyethylene glycol#400(PEG)and glycerol(G)in a weight ratio of 80/20(w/w)and sulphuric acid(SA)as catalyst under atmospheric pressure at 160ºC.The three independent variables:rea...Kraft lignin was liquefied using polyethylene glycol#400(PEG)and glycerol(G)in a weight ratio of 80/20(w/w)and sulphuric acid(SA)as catalyst under atmospheric pressure at 160ºC.The three independent variables:reaction time(60,80 and 100 min),percentage of lignin(15,20 and 25%,w/w),and catalyst concentration(0,3 and 6%,w/w),were varied resulting in 27 experimental runs.The effect of these reaction conditions on the properties of the polyols was evaluated.The statistical analysis showed that only“the percentage of lignin”did not influence the properties of the liquefied products,however,reaction time and catalyst load were important parameters.The resulting liquefied products were characterized by FTIR analysis.展开更多
By applying ultrasound at different stage of kraft pulping process, the properties of kraft pulp produced by ultrasonic treatment were studied and compared with those by conventional method. The results indicated that...By applying ultrasound at different stage of kraft pulping process, the properties of kraft pulp produced by ultrasonic treatment were studied and compared with those by conventional method. The results indicated that, while the performances of the pulp were close to conventional kraft pulp, the chemical-to-wood ratio decreased from 20% to 17.5%, cooking time was shortened from 140 to 120 rain, and the yield increased. When the ultrasound came into play at the 90th minute during pulping process, the properties of the produced bamboo fiber were the most desirable.展开更多
This study indicated that by applying an improved classification system to decayed large-diameter Norway spruce(Picea abies)wood,its use as raw material for kraft pulping without loss of pulp quality could be essentia...This study indicated that by applying an improved classification system to decayed large-diameter Norway spruce(Picea abies)wood,its use as raw material for kraft pulping without loss of pulp quality could be essentially increased.This is based on the fact that although the cooking yield of decayed spruce material which has been sorted according to these new recommendations is somewhat lower and Kappa number higher than those of sound wood material,the greatest part of the decayed stem(the outer part of the stem)contains long-fiber wood material which produces pulp of good quality.Therefore,large-diameter spruce logs can also be separately used,for example,in the manufacture of reinforcement pulp.展开更多
In integrated factories of pulp and paper, the bleaching control is made by kappa number and/or brightness. However, the product paper is evaluated and valued for its whiteness. The level of final brightness of pulp c...In integrated factories of pulp and paper, the bleaching control is made by kappa number and/or brightness. However, the product paper is evaluated and valued for its whiteness. The level of final brightness of pulp certainly affects the demand for optical brighteners in paper manufacturing, nevertheless, there is not a direct correlation between consumption of optical brightener and final brightness, being the method of bleaching pulp, especially from the final stage of bleaching, also important in relation to this demand. Therefore, this study aimed to evaluate the potential of using the parameter whiteness as a tool to control bleaching pulp, instead of the traditional brightness and evaluate the impacts of different methods of bleaching and the pulp final brightness level in action of optical brighteners, to improve their performance. It was observed that the whiteness and brightness of the pulp are highly correlated and that the control of the bleaching plant can be done by any one of these two parameters. It was also concluded that, considering current prices of bleaching reagents and of optical brighteners, it is better to bleach the pulp up to lower brightness values (e.g. 88% ISO) and use larger amounts of optical brighteners to brighten the mass until the whiteness of 130 CIE. This conclusion is valid for whiteness measured before the size press. Further studies are needed to validate this conclusion considering the finished product.展开更多
A newly isolated bacterium was screened out for its survival on medium with 6 000 mg/L kraft lignin as the sole carbon source and energy,and identified as Pandoraea sp.by 16S rRNA gene sequence analysis.The biodegrada...A newly isolated bacterium was screened out for its survival on medium with 6 000 mg/L kraft lignin as the sole carbon source and energy,and identified as Pandoraea sp.by 16S rRNA gene sequence analysis.The biodegradation experiment was carried out in mineral salt medium,containing 5 000 mg/L kraft lignin as only carbon and energy at pH 8.0 and 30 °C.Under these conditions,significant reduction in color and lignin content by the strain was observed after incubation for 5 d.The strain attains maximum reduction capability in color(44.6%) and lignin content(39.9%) within 5 d of incubation,and reduced chemical oxygen demand(COD) from initial concentration 7 399 to 3 980 mg/L at maximum reduction level of 46.2% on the 4th day.The total ion chromatograph(TIC) of compounds presented in the chloroform extract of control and bacterial treated samples shows the formation of several lignin-related aromatic compounds including some small molecular lignin fragments,indicating a strong destruction in the lignin structure.展开更多
The comparison of strength property between kraft pulp(KP)and Alkaline Sulfite-Anthraquinone(AS-AQ)pulp for thicker cell wall fiber materials Larch and Quercus as examples was studied. The average coefficient of flexi...The comparison of strength property between kraft pulp(KP)and Alkaline Sulfite-Anthraquinone(AS-AQ)pulp for thicker cell wall fiber materials Larch and Quercus as examples was studied. The average coefficient of flexibility of Larch and Quercus are 0.6-0.7 and 0.45-0.50, respectively. The results showed that the strength property of thicker cell wall pulp is some what different from those reported earlier. The strengths of AS-AQ are all higher than those of KP for Larch and Quercus. For Larch, under same beating degree the breaking length of AS-AQ is 8-16% higher than that of KP , burst index 3-14% higher, folding endurance 30% higher, tear index slightly higher. For Quercus, the breaking length of AS-AQ is 5-10% higher then that of KP, burst index 10-15% higher, folding endurance 30-50% higher, tear index 5-15% higher. Under the same breaking length the tear index of AS-AQ pulp is significantly higher than that of KP for both Larch and Quercus.展开更多
In this investigation, two different grades of birch chemical mechanical (P-RC APMP) pulps and aspen market bleached kraft pulp were compared by low consistency refining of the pulps separately and in different combin...In this investigation, two different grades of birch chemical mechanical (P-RC APMP) pulps and aspen market bleached kraft pulp were compared by low consistency refining of the pulps separately and in different combinations. In addition, the separately refined pulps were also combined to compare with the pulps from the co-refined pulp blend. The results showed that in both cases there were synergistic effects between the two types of pulps: adding the birch P-RC APMP pulp to the aspen kraft pulp improved pulp properties, and the resultant pulp blends had a higher fiber bonding strength (tensile and tensile energy absorption) than the sum of weighted contributions from the individual components. Understanding this synergistic effect between chemical mechanical (P-RC APMP) and kraft pulps can help to improve their applications and performances in various papermaking processes.The results also showed that introducing, at least up to certain percentage of, the birch P-RC APMP pulp into the aspen bleached kraft pulp not only improves optical and bulk properties, but also maintains or improves tensile strength, even though the P-RC APMP pulp used has lower tensile than the kraft pulp.展开更多
Effect of peroxyacid (a mixture of peroxymonosulfuric acid and peroxyacetic acid) pretreatment on oxygen delignification of kraft pulp from eucalyptus was studied, and the conditions of pretreatment (e.g. DTPA charge,...Effect of peroxyacid (a mixture of peroxymonosulfuric acid and peroxyacetic acid) pretreatment on oxygen delignification of kraft pulp from eucalyptus was studied, and the conditions of pretreatment (e.g. DTPA charge, peroxyacid charge, pretreatment time, pretreatment temperature and pH value) were optimized. The results show that peroxyacid pretreatment prior to oxygen delignification could enhance oxygen delignification of kraft pulp, and result in selective delignification and increased delignified-pulp brightness. The optimum conditions of peroxyacid pretreatment were as follows: peroxyacid charge 3% (on peroxymonosulfuric acid), 60℃, 30min, 12% pulp consistency, pH5.0. Pretreatment with 0.5%DTPA was essential before peroxyacid pretreatment. Under the optimum conditions, the degree of delignification and brightness of final pulp were increased by 12.4% (from 44.9% to 57.3%) and 4.9%(ISO, from 54.0% to 58.9%) respectively while maintaining a similar viscosity of final pulps compared to single oxygen delignification.展开更多
The influential factors of DQP bleaching, chlorine dioxide bleaching, chelation and hydrogen peroxide bleaching, of bamboo kraft pulp were studied. The pH value in D stage, dosage of EDTA in Q stage and charge of MgSO...The influential factors of DQP bleaching, chlorine dioxide bleaching, chelation and hydrogen peroxide bleaching, of bamboo kraft pulp were studied. The pH value in D stage, dosage of EDTA in Q stage and charge of MgSO4 in P stage were optimized. The results indicated that good results of chlorine dioxide bleaching were obtained under the conditions of ClO2 2.0%,pH 4, and the highest final brightness(86.4%ISO) and the lowest final Kappa number(1.37) were attained when the charge of EDTA in Q stage was 0.4%, charge of MgSO4 in P stage was 0.2%, and the other conditions of P stage : pulp consistency 10%, H2O2 charge 2.5%, NaOH charge 1.4%, temperature 90℃ and time 120 min. A comparison of bleaching results, pulp strength and effluent characteristics of bamboo kraft pulp between DQP and CEH sequences was done. The results indicated that bamboo kraft pulp could be bleached to brightness of above 83%ISO by both DQP and CEH sequences. Compared with CEH bleached pulp, DQP bleached pulp had slightly lower brightness, better brightness stability, higher pulp viscosity, better strength properties and lower pollution loads.展开更多
Process water of a pulp mill with kraft cooking, oxygen delignification and chlorine bleaching or chlorine dioxide (ECF) bleaching was examined from an aspect of a new level for environmental water quality in Japan. A...Process water of a pulp mill with kraft cooking, oxygen delignification and chlorine bleaching or chlorine dioxide (ECF) bleaching was examined from an aspect of a new level for environmental water quality in Japan. According to the new level, a concentration of dioxins consisting of polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs) and coplanar polychlorinated biphenyls (PCBs) in environmental water is restricted to less than 1 pg- TEQ/L. We clarified that the 2,3,7,8-tetrachlorodibenzofuran (TCDF) concentrations were 0.5 pg/L or less. In addition, a main source of 1,3,6,8- and 1,3,7,9-tetrachlorodibenzo-p-dioxins in the process water seemed to be an agrochemical in water supplied from a river.展开更多
The flow curvesshear-rate rangeby using theof bagasse Kraft black liquor over aof 10-1 s- 1-103s- 1 were investigatedRheometric RFSII rheometerExperimental results show that Bagasse black liquorsare non-Newtonian flui...The flow curvesshear-rate rangeby using theof bagasse Kraft black liquor over aof 10-1 s- 1-103s- 1 were investigatedRheometric RFSII rheometerExperimental results show that Bagasse black liquorsare non-Newtonian fluids instead of Newtonian fluidsat higher solids contents, and the viscosities of blackliquor would decrease about 2-3 orders of magnitudewith an increase in the shear rates. The apparentviscosity and flow behavior of bagasse black liquorare also affected by its solids content, and the highersolids content the more shear-thinning bagasse blackliquor fluid is. In addition, the power-law equationwas utilized to fit these flow curves at differentconditions. Finally, the significances ofshear-thinning properties of bagasse black liquor inthe chemical recovery system, such as frictioncalculation of pipe and design optimization of thewhole recovery system, were presented.展开更多
基金supported by the Natural Science Foundation of Guangdong Province(2023A1515030211)the National Natural Science Foundation of China(22278157)Guangzhou Science and Technology Program(2023B03J1365).
文摘A critical pathway towards enhancing pulp mill biorefineries is to integrate the extraction and utilization of hemicelluloses into the pulping processes.Hence,an industrial pre-extraction strategy for hemicelluloses targeting eucalyptus kraft pulping process was developed.Alkaline solution or pulping white liquor was used to pre-extract hemicelluloses before the actual pulping process.The response surface methodology(RSM)technique was applied to investigate the most suitable conditions to maximize the yield of these hemicelluloses while simultaneously minimizing the damage to pulp yields and properties.Temperature(105 to 155℃),alkali concentration(3%to 8%),sulfidity(20%to 30%)and retention time(19 to 221 min)were combined to evaluate their effects on hemicellulose yields and chemical structures.The optimal pre-extraction conditions identified in this work(5.75%NaOH concentration,25%sulfidity at 135℃for 60 min)successfully allowed recovering 4.8%of hemicelluloses(based on the wood dry mass)and limited damages to pulp yields and properties.The cellulose content in pulp can even be increased by about 10%.Hemicellulose emulsification properties were also evaluated,which were comparable to synthetic emulsifiers.This study provides an industrial pathway to effectively separate and utilize wood hemicelluloses from the pulping process,which has the potential to improve the economy and material utilization of pulp and paper mills.
文摘The deterioration of recycled fibers especially unbleached kraft with high wet strength resin content due to the irreversible structural changes caused by drying and added chemicals makes the raw material difficult to repulp.The mechanical effect in the pulper over time with chemical treatment has a negative impact on the recycled fibers.At lab scale,different compositions of enzymatic treatment C022L were under investigation to select the most efficient laccase Lacc1,Lacc2 or Lacc3 and to observe the impact of lipases during repulping at low and high consistencies.Pulp disintegration at different times was evaluated to define the level of rejects and to analyze the morphology of fibers after treatments.These results were more significant for Lacc2,by increasing the pulp consistency to 15%in the pulper.Combining lipases with CELODASE 022L appeared to decrease the efficiency of enzymes.The results showed a high reduction of energy power with the enzymatic treatment and a significant reduction of fines level in fibers’suspension.The most efficient version of C022L was used at industrial scale to compare directly with the standard conditions used in a paper mill.
基金This work was supported by the Foundation of Key Laboratory of Pulp and Paper Science and Technology of the Ministry of Education of China(No.KF201917)the National Natural Science Foundation of China(31800497).
文摘Kraft lignin has the potential to replace traditional fossil resources for the preparation of high-value chemicals because it is rich in aromatic rings and active functional groups.An effective method for the pyrolysis of kraft lignin into chemicals/fuels is microwave-assisted depolymerization.A simulation model is urgently needed to illustrate the coupling effect and mechanism of lignin conversion during the depolymerization process.In this study,COMSOL Multiphysics was used to simulate the microwave-assisted depolymerization process.The results showed that microwave power had a significant effect on the electric field and temperature distribution in the microwave cavity,while the reaction time had little effect on the electric field.The effect of the nitrogen flow rate on the electric field and temperature was negligible.The intensity of the electric field,heating rate of lignin,and final temperature of lignin depolymerization increased with increasing microwave power.
文摘The present work evaluated the use of photo-Fenton process for the treatment of kraft pulp mill effluent. The photo-Fenton best operating conditions, such as pH, concentration, and H2O2: Fe2+ ratio were evaluated. The efficiency of the treatment was measured by COD (chemical oxygen demand) removal. The results showed that the optimum pH for the photo-Fenton process was equal to 3. The increase in H2O2 application resulted in an efficiency increase of the photo-Fenton process, although this was not a directly proportional relation. For most cases, the H2O2: Fe2+ proportion of 100:1 yielded the best results for COD removal. Solar radiation was more efficient than artificial UV to the COD removal. During the treatment the organic matter of the effluent was more oxidized than mineralized, showing a higher removal of COD than BOD (biochemical oxygen demand) and TOC (total organic carbon), respectively. So, photo-Fenton process increased the BOD/ COD ration but decreased the BOD/TOC ratio.
基金the National Key Research and Development Program of China(2017YFB0307900,2019YFC1905903)the National Natural Science Foundation of China(31700507)the Major Project on the Integration of Industry-Education-Research of Fujian Provincial Department of Science and Technology(2018H6003).
文摘Hemicellulose has a wide range of applications,including that as an emulsifier for the food industry and raw material for the synthesis of bioethanol/biochemicals and biodegradable films.Hemicellulose is usually present as a spent liquor,such as the prehydrolysis liquor of the prehydrolysis kraft dissolving pulp production process and the alkali extraction liquor of the cold caustic extraction of pulp fibers.Due to its dilute nature,hemicellulose needs to be dried for practical utilization,and this is challenging.In this study,cellulose and hemicellulose in a bleached bamboo kraft pulp were separated using an alkali extraction process.Hemicellulose obtained from the extraction liquor was dried by an ammonium carbonate-assisted drying process.The effects of drying time and drying temperature were determined.Structure of the hemicellulose obtained by the ammonium carbonate-assisted drying process was similar to that of original hemicellulose,as revealed by detailed Fourier transform infrared and X-ray diffraction analyses.The novel drying method was more energy efficient and required a shorter drying time than the conventional freeze drying method,and the excellent solubility in alkaline solutions favored the chemical modification of hemicellulose.The dried hemicellulose can be used as a renewable raw material for the preparation of hydrogels and other substances such as bioethanol/biochemicals and biodegradable films.
文摘It is known that large amounts of residual lignin are generated in the pulp and paper industry.A new alternative for Kraft lignin valorization,which consists of first a chemical modification using a diisocyanate and then the efficient dispersion in castor oil to achieve stable gel-like systems,is proposed in this work.Rheological properties and microstructure of these materials were determined by means of small amplitude oscillatory shear tests and viscous flow measurements and atomic force microscopy observations,respectively.Moreover,both standardized penetration tests and tribological assays,usually performed in the lubricant industry,were carried out to evaluate the performance characteristics as lubricating greases.Linear viscoelasticity functions are affected by the lignin/diisocyanate ratio and thickener concentration.The thermorheological response evidenced a softening temperature of around 105°C.The microstructure of these gel-like dispersions is composed of interconnected thin fibers,homogeneously distributed in castor oil.Moreover,the NCO-functionalized lignin gel-like dispersions studied show lower friction coefficients than traditional lubricating greases.
文摘Kraft lignin was liquefied using polyethylene glycol#400(PEG)and glycerol(G)in a weight ratio of 80/20(w/w)and sulphuric acid(SA)as catalyst under atmospheric pressure at 160ºC.The three independent variables:reaction time(60,80 and 100 min),percentage of lignin(15,20 and 25%,w/w),and catalyst concentration(0,3 and 6%,w/w),were varied resulting in 27 experimental runs.The effect of these reaction conditions on the properties of the polyols was evaluated.The statistical analysis showed that only“the percentage of lignin”did not influence the properties of the liquefied products,however,reaction time and catalyst load were important parameters.The resulting liquefied products were characterized by FTIR analysis.
文摘By applying ultrasound at different stage of kraft pulping process, the properties of kraft pulp produced by ultrasonic treatment were studied and compared with those by conventional method. The results indicated that, while the performances of the pulp were close to conventional kraft pulp, the chemical-to-wood ratio decreased from 20% to 17.5%, cooking time was shortened from 140 to 120 rain, and the yield increased. When the ultrasound came into play at the 90th minute during pulping process, the properties of the produced bamboo fiber were the most desirable.
基金The authors wish to thank Mittaportti Oy for the log classification,Metsäteho Oy for the rot determinations,and Western Laboratories Inc.for the pulp strength analyses.
文摘This study indicated that by applying an improved classification system to decayed large-diameter Norway spruce(Picea abies)wood,its use as raw material for kraft pulping without loss of pulp quality could be essentially increased.This is based on the fact that although the cooking yield of decayed spruce material which has been sorted according to these new recommendations is somewhat lower and Kappa number higher than those of sound wood material,the greatest part of the decayed stem(the outer part of the stem)contains long-fiber wood material which produces pulp of good quality.Therefore,large-diameter spruce logs can also be separately used,for example,in the manufacture of reinforcement pulp.
基金Funding provided by the Minas Gerais State Research Foundation(FAPEMIG)from the Brazilian National Council for Science and Technology Development(CNPq)is greatly appreciated.
文摘In integrated factories of pulp and paper, the bleaching control is made by kappa number and/or brightness. However, the product paper is evaluated and valued for its whiteness. The level of final brightness of pulp certainly affects the demand for optical brighteners in paper manufacturing, nevertheless, there is not a direct correlation between consumption of optical brightener and final brightness, being the method of bleaching pulp, especially from the final stage of bleaching, also important in relation to this demand. Therefore, this study aimed to evaluate the potential of using the parameter whiteness as a tool to control bleaching pulp, instead of the traditional brightness and evaluate the impacts of different methods of bleaching and the pulp final brightness level in action of optical brighteners, to improve their performance. It was observed that the whiteness and brightness of the pulp are highly correlated and that the control of the bleaching plant can be done by any one of these two parameters. It was also concluded that, considering current prices of bleaching reagents and of optical brighteners, it is better to bleach the pulp up to lower brightness values (e.g. 88% ISO) and use larger amounts of optical brighteners to brighten the mass until the whiteness of 130 CIE. This conclusion is valid for whiteness measured before the size press. Further studies are needed to validate this conclusion considering the finished product.
基金Project(50925417) supported by the National Funds for Distinguished Young Scientists,ChinaProject(50830301) supported by the Key program of the National Natural Science Foundation of ChinaProject(2012BAC12B03) supported by the National 12th Five-year Plan for Science and Technology Support,China
文摘A newly isolated bacterium was screened out for its survival on medium with 6 000 mg/L kraft lignin as the sole carbon source and energy,and identified as Pandoraea sp.by 16S rRNA gene sequence analysis.The biodegradation experiment was carried out in mineral salt medium,containing 5 000 mg/L kraft lignin as only carbon and energy at pH 8.0 and 30 °C.Under these conditions,significant reduction in color and lignin content by the strain was observed after incubation for 5 d.The strain attains maximum reduction capability in color(44.6%) and lignin content(39.9%) within 5 d of incubation,and reduced chemical oxygen demand(COD) from initial concentration 7 399 to 3 980 mg/L at maximum reduction level of 46.2% on the 4th day.The total ion chromatograph(TIC) of compounds presented in the chloroform extract of control and bacterial treated samples shows the formation of several lignin-related aromatic compounds including some small molecular lignin fragments,indicating a strong destruction in the lignin structure.
文摘The comparison of strength property between kraft pulp(KP)and Alkaline Sulfite-Anthraquinone(AS-AQ)pulp for thicker cell wall fiber materials Larch and Quercus as examples was studied. The average coefficient of flexibility of Larch and Quercus are 0.6-0.7 and 0.45-0.50, respectively. The results showed that the strength property of thicker cell wall pulp is some what different from those reported earlier. The strengths of AS-AQ are all higher than those of KP for Larch and Quercus. For Larch, under same beating degree the breaking length of AS-AQ is 8-16% higher than that of KP , burst index 3-14% higher, folding endurance 30% higher, tear index slightly higher. For Quercus, the breaking length of AS-AQ is 5-10% higher then that of KP, burst index 10-15% higher, folding endurance 30-50% higher, tear index 5-15% higher. Under the same breaking length the tear index of AS-AQ pulp is significantly higher than that of KP for both Larch and Quercus.
文摘In this investigation, two different grades of birch chemical mechanical (P-RC APMP) pulps and aspen market bleached kraft pulp were compared by low consistency refining of the pulps separately and in different combinations. In addition, the separately refined pulps were also combined to compare with the pulps from the co-refined pulp blend. The results showed that in both cases there were synergistic effects between the two types of pulps: adding the birch P-RC APMP pulp to the aspen kraft pulp improved pulp properties, and the resultant pulp blends had a higher fiber bonding strength (tensile and tensile energy absorption) than the sum of weighted contributions from the individual components. Understanding this synergistic effect between chemical mechanical (P-RC APMP) and kraft pulps can help to improve their applications and performances in various papermaking processes.The results also showed that introducing, at least up to certain percentage of, the birch P-RC APMP pulp into the aspen bleached kraft pulp not only improves optical and bulk properties, but also maintains or improves tensile strength, even though the P-RC APMP pulp used has lower tensile than the kraft pulp.
文摘Effect of peroxyacid (a mixture of peroxymonosulfuric acid and peroxyacetic acid) pretreatment on oxygen delignification of kraft pulp from eucalyptus was studied, and the conditions of pretreatment (e.g. DTPA charge, peroxyacid charge, pretreatment time, pretreatment temperature and pH value) were optimized. The results show that peroxyacid pretreatment prior to oxygen delignification could enhance oxygen delignification of kraft pulp, and result in selective delignification and increased delignified-pulp brightness. The optimum conditions of peroxyacid pretreatment were as follows: peroxyacid charge 3% (on peroxymonosulfuric acid), 60℃, 30min, 12% pulp consistency, pH5.0. Pretreatment with 0.5%DTPA was essential before peroxyacid pretreatment. Under the optimum conditions, the degree of delignification and brightness of final pulp were increased by 12.4% (from 44.9% to 57.3%) and 4.9%(ISO, from 54.0% to 58.9%) respectively while maintaining a similar viscosity of final pulps compared to single oxygen delignification.
文摘The influential factors of DQP bleaching, chlorine dioxide bleaching, chelation and hydrogen peroxide bleaching, of bamboo kraft pulp were studied. The pH value in D stage, dosage of EDTA in Q stage and charge of MgSO4 in P stage were optimized. The results indicated that good results of chlorine dioxide bleaching were obtained under the conditions of ClO2 2.0%,pH 4, and the highest final brightness(86.4%ISO) and the lowest final Kappa number(1.37) were attained when the charge of EDTA in Q stage was 0.4%, charge of MgSO4 in P stage was 0.2%, and the other conditions of P stage : pulp consistency 10%, H2O2 charge 2.5%, NaOH charge 1.4%, temperature 90℃ and time 120 min. A comparison of bleaching results, pulp strength and effluent characteristics of bamboo kraft pulp between DQP and CEH sequences was done. The results indicated that bamboo kraft pulp could be bleached to brightness of above 83%ISO by both DQP and CEH sequences. Compared with CEH bleached pulp, DQP bleached pulp had slightly lower brightness, better brightness stability, higher pulp viscosity, better strength properties and lower pollution loads.
文摘Process water of a pulp mill with kraft cooking, oxygen delignification and chlorine bleaching or chlorine dioxide (ECF) bleaching was examined from an aspect of a new level for environmental water quality in Japan. According to the new level, a concentration of dioxins consisting of polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs) and coplanar polychlorinated biphenyls (PCBs) in environmental water is restricted to less than 1 pg- TEQ/L. We clarified that the 2,3,7,8-tetrachlorodibenzofuran (TCDF) concentrations were 0.5 pg/L or less. In addition, a main source of 1,3,6,8- and 1,3,7,9-tetrachlorodibenzo-p-dioxins in the process water seemed to be an agrochemical in water supplied from a river.
文摘The flow curvesshear-rate rangeby using theof bagasse Kraft black liquor over aof 10-1 s- 1-103s- 1 were investigatedRheometric RFSII rheometerExperimental results show that Bagasse black liquorsare non-Newtonian fluids instead of Newtonian fluidsat higher solids contents, and the viscosities of blackliquor would decrease about 2-3 orders of magnitudewith an increase in the shear rates. The apparentviscosity and flow behavior of bagasse black liquorare also affected by its solids content, and the highersolids content the more shear-thinning bagasse blackliquor fluid is. In addition, the power-law equationwas utilized to fit these flow curves at differentconditions. Finally, the significances ofshear-thinning properties of bagasse black liquor inthe chemical recovery system, such as frictioncalculation of pipe and design optimization of thewhole recovery system, were presented.