Efficient extraction of bagasse hemicelluloses and characterization of solid remainder.pdf (original) (raw)
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Carbohydrate Polymers, 2014
Developing optimum treatment and separation procedures for hemicellulose components of lignocellulosic biomass could be useful in ethanol fermentation processes and obtaining pure hemicelluloses as biopolymers. Sugarcane bagasse analyses indicate that xylose is the major hemicellulose component constituting 17.7% of dry bagasse weight. In this study the effects of treatment conditions such as time, temperature and pressure on the yields of extracted hemicelluloses were studied. The optimum conditions were achieved at 180 • C for 30 min and 1 MPa pressure, with the yield of xylose reaching to 85% and the concentrations of sugar degradation products such as HMF and furfural remaining minimal at 0.95 and 0.07 g/L, respectively. Further, isolation of hemicelluloses from extracted hemicelluloses solutions was performed using Alfa Laval M20 membrane filtration system in two steps: (1) concentration of high molar mass hemicelluloses by ultrafiltration; and (2) separation of low molar mass hemicelluloses and oligomeric sugars by nanofiltration. The isolated hemicelluloses with the optimum pretreatment conditions were characterized by FT-IR and 13 C NMR techniques, resulting in agreement with typical spectra of xylan-type hemicelluloses.
Search for optimum conditions of sugarcane bagasse hemicellulose extraction
A process has been elaborated for one-step low lignin content sugarcane bagasse hemicellulose extraction using alkaline solution of hydrogen peroxide. To maximize the hemicellulose yields several extraction conditions were examined applying the 2 4 factorial design: H 2 O 2 concentration from 2 to 6% (w/v), reaction time from 4 to 16 h, temperature from 20 to 60 • C, and magnesium sulfate absence or presence (0.5%, w/v). This approach allowed selection of conditions for the extraction of low and high lignin content hemicellulose. At midpoint the yield of hemicellulose was 94.5% with more than 88% of lignin removed. Lignin removal is suppressed at low extraction temperatures and in the absence of magnesium sulfate. Hemicellulose in 86% yield with low lignin content (5.9%) was obtained with 6% H 2 O 2 treatment for 4 h and 20 • C. This hemicellulose is much lighter in color than samples obtained at the midpoint condition and was found suitable for subsequent enzymatic hydrolysis.
Industrial Crops and Products, 2013
The aim of this study was to further evaluate the viability of the integrated pulp mill biorefinery concept. On one side the properties of hot-water pre-extractions were studied, in order to determine the effect of extraction on soda pulping and bleachability. On the other side, the performance of two dry-strength agents on the paper properties obtained from extracted and un-extracted (control) samples were investigated. It was found that hemicelluloses removal of the depithed bagasse chips was 24.6% at 140 • C for 10 min with a solid to liquor ratio (S:L) of 1:8 (w/w), and that mass removal increased with extraction time and temperature. The hemicelluloses removal reached 65.5% at 170 • C for 30 min. The residual extracted bagasse were subjected to soda pulping at 160 • C for 1 h with 11, 14 and 17% active alkali charge and a S:L of 1:5 (w/w). Conventional elemental chlorine free bleaching (D 0 ED 1 ) sequence was also used to compare the results with the un-extracted ones. Compared with the control sample, the overall pulp yield for extracted bagasse increased considerably while Kappa number and rejects decreased moderately. In addition, yield and Kappa number of the pulps improved with increasing alkali charge from 11% to 17%. After pre-extraction, better brightness compared with the control pulp was also shown. However, hot-water extraction was found to negatively impact some pulp properties including decreases in burst and tensile indices while addition of chitosan and cationic starch could improve the strength properties. Overall, papers treated with chitosan gave superior mechanical properties compared to the papers treated with cationic starch.
The aim of this study was to further evaluate the viability of the integrated pulp mill biorefinery concept. On one side the properties of hot-water pre-extractions were studied, in order to determine the effect of extraction on soda pulping and bleachability. On the other side, the performance of two dry-strength agents on the paper properties obtained from extracted and un-extracted (control) samples were investigated. It was found that hemicelluloses removal of the depithed bagasse chips was 24.6% at 140 • C for 10 min with a solid to liquor ratio (S:L) of 1:8 (w/w), and that mass removal increased with extraction time and temperature. The hemicelluloses removal reached 65.5% at 170 • C for 30 min. The residual extracted bagasse were subjected to soda pulping at 160 • C for 1 h with 11, 14 and 17% active alkali charge and a S:L of 1:5 (w/w). Conventional elemental chlorine free bleaching (D 0 ED 1 ) sequence was also used to compare the results with the un-extracted ones. Compared with the control sample, the overall pulp yield for extracted bagasse increased considerably while Kappa number and rejects decreased moderately. In addition, yield and Kappa number of the pulps improved with increasing alkali charge from 11% to 17%. After pre-extraction, better brightness compared with the control pulp was also shown. However, hot-water extraction was found to negatively impact some pulp properties including decreases in burst and tensile indices while addition of chitosan and cationic starch could improve the strength properties. Overall, papers treated with chitosan gave superior mechanical properties compared to the papers treated with cationic starch.
IMPACT OF HEMICELLULOSES PRE-EXTRACTION ON PULP PROPERTIES OF SUGARCANE BAGASSE
The extraction of hemicelluloses, which otherwise would be wasted in the black liquor, can be integrated with chemical pulping processes in a biorefinery approach that will generate a sugar-rich feedstock for production of fuels and chemicals. Extractions of hemicelluloses from sugarcane bagasse under dilute sulphuric acid or mild alkaline conditions were performed, using a central composite experimental design. Selected solid residues obtained after dilute acid, hot water (zero acid) or mild alkaline pre-extractions were subjected to soda or soda-AQ pulping, and kraft pulping of the dilute acid pre-extracted solid residue was also performed. The integration of hemicelluloses pre-extraction by alkaline methods into a soda-AQ-based pulping process was preferred for sugarcane bagasse as feedstock, since it enabled xylan recovery of 69.1%, while providing pulps with superior tear strength and brightness.
An integrated approach for hemicellulose extraction from forest residue
BioResources, 2021
An alkali-mediated hydrothermal approach was optimized for partial extraction of high-purity hemicellulose (xylan) from a timber waste product (unbleached eucalyptus sawdust). The extraction process was: a) extractives removal using sequential solvent extraction; b) alkali-mediated hydrothermal extraction of hemicellulose; and c) purification of the isolated hemicellulose fraction. Biomass was extracted in an autoclave at a fixed temperature of 121 °C while varying the extraction time (1 h to 2.5 h) and alkali concentration (10%, 15%, and 20% w/v). Using this simple approach, high purity polymeric hemicellulose with molecular mass (21 to 30 kDa) was recovered in yields of 35 to 37%. The isolated hemicellulose can be chemically transformed into high-value commercial products such as prebiotics (xylooligosaccharides), surfactants, hydrogels, and food packaging materials. The purified residue can be utilized in existing kraft pulping processes. The integration of hemicellulose extracti...
1973
Almost all studies on isolation and characterization of hemicelluloses have been carried out on plant raw material and not on pulps. This requires grinding of the plant and the use of expensive delignifying agents. The cellulosic residue becomes useless as potential fiber source. The present study is concerned with isolation and characterization of hemicelluloses from paper pulps. The isolation is easy, relatively cheap, and the fibrous cellulosic residue can be utilized e.g. as dissolving pulp. Hemicelluloses were isolated from bleached hardwood and rice straw paper pulps. The pentosan contents of the whole hemicellulose fractions isolated from both straw and wood pulps were similar and amounted lo about 80 %- The IR spectra of both wood and straw hemicelluloses showed great similarity except that the 1600 cm- 1 absorption band was more intense in the case of wood hemicellulose indicating its higher content of ionized carboxyl groups. This was also confirmed by analytical chemical determination. Hemicellulose fraction A constituted 33.5 % of the whole hemicellulose isolated from the rice straw pulp, while fraction B constituted l6.5 %. The present results represent the first information on hemicelluloses isolated from rice straw pulp.
Extraction of Cellulose from Sugarcane Bagasse Optimization and Characterization
Advances in Materials Science and Engineering
In this study, cellulose was extracted from sugarcane bagasse (SCB) through a convenient five-step treatment, and procedures were performed. During the alkaline curing process of the extraction of cellulose, NaOH has a concentration of (0.5, 1.5, 2.75, and 4%) and the extraction time (15, 30, and 45 min) at a constant temperature of 120°C were taken as variables and perfectly optimized by response surface methodology (RSM) for cellulose with the highest product. The optimum conditions were found to be 2.75% NaOH, 120°C, and 45 min with a cellulose yield of 73.71 ± 0.67% cellulose, 17.22 ± 0.82% hemicellulose, and 9.07 ± 0.95% lignin. Though most of the lignin was eliminated during the alkaline and dilute acid pretreatment process, the remaining lignin was removed by a solution treatment of 4% NaOH, and 21.92% H2O2 at 121°C for 44.97 min where the cellulose yield was found as 89.75 ± 0.64%, hemicellulose was 6.15 ± 0.83%, and lignin was 2.65 ± 0.66%. Morphological analysis revealed t...