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
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
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
Bamboo was used as raw material for unbleached pulp production.An acetic acid prehydrolysis process was employed before the pulping process.The effect of acetic acid prehydrolysis on pulp properties was investigated.T...Bamboo was used as raw material for unbleached pulp production.An acetic acid prehydrolysis process was employed before the pulping process.The effect of acetic acid prehydrolysis on pulp properties was investigated.The results showed that some components,such as hemicellulose and extractives,were degraded or dissolved in the prehydrolysis process prior to kraft pulping.SEM images of the substrate after treatment indicated that the parenchyma cell wall was thinner,and the size of pores between fiber bundle cell walls was larger.The pulping results showed that acetic acid prehydrolysis could improve the pulp quality and make the pulp easier to bleach.The brightness of the pulp reached 59.6%ISO with a single oxygen delignification step.The acetic acid prehydrolysis decreased pulp viscosity and fiber length,but not significantly.The amount of parenchyma cells in the pulp was reduced,which was beneficial for papermaking and improving mechanical strength of paper.This procedure has good potential for unbleached pulp production.展开更多
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financial support from the National Natural Science Foundation of China (31570569)
文摘Bamboo was used as raw material for unbleached pulp production.An acetic acid prehydrolysis process was employed before the pulping process.The effect of acetic acid prehydrolysis on pulp properties was investigated.The results showed that some components,such as hemicellulose and extractives,were degraded or dissolved in the prehydrolysis process prior to kraft pulping.SEM images of the substrate after treatment indicated that the parenchyma cell wall was thinner,and the size of pores between fiber bundle cell walls was larger.The pulping results showed that acetic acid prehydrolysis could improve the pulp quality and make the pulp easier to bleach.The brightness of the pulp reached 59.6%ISO with a single oxygen delignification step.The acetic acid prehydrolysis decreased pulp viscosity and fiber length,but not significantly.The amount of parenchyma cells in the pulp was reduced,which was beneficial for papermaking and improving mechanical strength of paper.This procedure has good potential for unbleached pulp production.
