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1.
Our previous paper showed tobacco stalks to posses the characteristics of a raw material for pulp and paper application. It contains the major biomass constituents and cell components common to wood species. In this study, preparation and characterization of tobacco stalk pulp by steam explosion (SE) pulping at two chemical pretreatments were attempted. Chemical pretreatment prior to SE pulping improved the brightness, yield, and strength properties of the resulting tobacco SE pulps in the order: 6% Na2SO3 + 1% NaOH > 6% Na2SO3 > control (untreated). The 6% Na2SO3 + 1% NaOH-impregnated tobacco stalks produced SE pulps of good fiber length distribution and considerable properties that compare well with pulps from other raw materials obtained from previous studies, and the nonimpregnated ones showed strength properties superior to those of their poplar counterpart. Prior to bleaching, pretreating the tobacco stalk SE pulps with two stages, 2% NaOH at 90°C, improved the initial pulp brightness by about 5 points. Two-stage 6% H2O2 bleaching gave a comparable effect with hypochlorite bleaching for both tobacco and poplar, giving a 29–34 brightness point increase for tobacco SE pulp and 61 for the poplar samples. The differences in the bleaching responses for untreated tobacco and poplar SE pulps were attributed to the differences in their lignin structure, as shown in the total yield of their respective nitrobenzene oxidation products and FT-IR spectra. Tobacco SE pulps contain more of the guaiacyl-type lignin and poplar the syringyl-type lignin.This paper was presented in part during the 1998 CORESTA (Cooperation Centre for Scientific Research Relative to Tobacco) Congress, Brighton, UK, October 1998  相似文献   

2.
Summary High-yield pulps have been obtained by means of steam explosion pulping. This process was carried out as follows: 1) chips soak impregnation (60 °C, 24 h, L/C = 6) in solutions containing 8% Na2SO3 and a variable concentration of either Na2CO3 or NaHCO3, ranging from 0 to 2%; 2) cooking at high temperature (190–200 °C) for short time (2-1 min); 3) rapid pressure release. This work shows that mechanical properties were substantially improved when adding a second chemical to the Na2SO3 impregnation solution. Moreover, refining energy requirement was significantly reduced. However, the higher chemical charge used made the optical properties drop. In this paper, mathematical models have been proposed in order to accurately predict specific refining energy and paper properties from sulfonate content and pulp yield. In addition, the relative importance of these two parameters has been studied.Thanks are due to the Natural Science and Engineering Council of Canada (NSERC) and Fonds pour la Formation de chercheurs et l'aide à la recherche of Quebec (FCAR) for their financial support.  相似文献   

3.
The steam explosion (SE) pretreatment associated with the organosolv process was investigated to produce dissolving pulp from eucalyptus. Prehydrolysis Kraft (PHK) pulping was also done to produce viscose and acetate grade pulps as reference. The organosolv pulps were delignified in two steps with sodium chlorite. Viscose and acetate grade PHK pulps were bleached by OD0(EH)D1P and OD0(EP)D1PCCE sequences, respectively. Dilute acid-catalyzed (with acid addition) SE pretreatment dissolved more xylan than auto-catalyzed (no acid addition) SE pretreatment. Steam-exploded unbleached organosolv pulps showed lower residual lignin content and screened yield than unbleached organosolv pulps without SE pretreatment. Steam explosion pretreatment helped to decrease lignin content and damaged fiber length of unbleached organosolv pulps. The 1.0% H2SO4 organosolv pulp (organosolv dissolving pulp at bioconversion conditions) showed the highest reactivity. Even showing low viscosity for some applications, in general, the organosolv dissolving pulps produced in this study can be used for making lyocell fibers.  相似文献   

4.
The extraction of phenolic compounds from eucalyptus (Eucalyptus globulus) bark was examined with the aim of analyzing the potential of the extracts as natural antioxidants. Experiments were planned according to a 23 factorial design to analyze the influence of temperature and Na2SO3 and NaOH concentrations in aqueous solutions on extraction yield, extract total phenols content, ferric reducing antioxidant power (FRAP), and number- and weight-average molecular weights. Extract total phenols content and FRAP antioxidant activity in the ranges 0.91–2.58?g gallic acid equivalent (GAE)/100?g oven-dried bark and 4.70–11.96?mmol ascorbic acid equivalent (AAE)/100?g oven-dried bark, respectively, demonstrated the potential of eucalyptus bark as a source of antioxidant compounds. Extraction at the highest temperature (100°C), the lowest Na2SO3 concentration (1.5% on oven-dried bark), and without NaOH provided the highest extract total phenols content and FRAP antioxidant activity. Those eucalyptus bark extracts with lower molecular weight showed higher antioxidant activity. Matrix-assisted laser desorption ionization time-of-flight and reverse-phase high-performance liquid chromatography electrospray ionization time-of-flight mass spectrometry revealed the presence of polygalloyl glucoses, catechin, epicatechin, ellagic acid, quercetin-3-o-rhamnoside, and isorhamnetin in eucalyptus bark aqueous extracts.  相似文献   

5.
Summary The surface composition of explosion pulp and conventional CMP and CTMP underwent ESCA spectroscopy. Explosion pulps exhibited a higher oxygen-to-carbon ratio and less C1 peak areas compared to conventional CMP/CTMP. Based on the theoretical O/C ratios and C1 contents for the main components of wood fibers (i.e., carbohydrates, lignin and extractives), a triangular graph was used to illustrate the relative amounts of the three components on the surface. This analysis indicated that explosion pulps had more carbohydrates exposed on their fiber surface, which may explain their high physical strength. A bulk analysis indicated that these differences could not depend on their bulk compositions, since the latter were similar.  相似文献   

6.
渗透剂对桉木化学机械法制浆性能的影响   总被引：1，自引：0，他引：1  
研究了不同渗透剂对桉木化学机械法制浆性能的影响,结果表明:不同类型的渗透剂对桉木浸渍性能的影响差异较大,其中磺化琥珀酸二辛酯钠盐类渗透剂S4对桉木浸渍性能改善程度最高,渗透剂用量为0.4%时,可以使木片的吸液量和Na OH吸收率分别比对照样提高7.34%和9.97%。渗透剂对桉木化学机械浆的性能影响如下:浸渍段添加0.4%渗透剂S4,制取加拿大游离度(CSF)为300 m L的纸浆,可以使磨浆电耗降低10%以上,浆中的细小组分减少9个百分点以上,纤维束减少46%;纸浆的抗张强度、耐破强度及撕裂强度均有不同程度的提高,可分别提高11.4%、14.3%和15.6%,但对纸浆的白度无明显影响。  相似文献   

7.
应用正交试验设计方法分析预浸时间、预浸温度、NaOH用量、Na2SO3用量对尾巨桉CTMP制浆性能的影响并选取最优方案,在此基础上,对4年生和6年生尾巨桉分别进行制浆抄纸,并对纸张物理性能进行测定。研究表明,适当的预浸时间、预浸温度、NaOH用量、Na2SO3用量可制得质量较好的CTMP。  相似文献   

8.
MALDI-TOF, HPLC-ESI-TOF and 13C-NMR techniques were used to analyse the structure of non-purified aqueous chestnut shell tannin extracts. In addition, the influence of the extraction agent (water or aqueous solutions of Na2SO3 and/or NaOH) on tannin structure was analysed by MALDI-TOF in order to select the extract with the best properties for wood adhesives. Using HPLC-ESI-TOF, catechin/epicatechin, gallocatechin/epigallocatechin, dicatechin structures, dicatechin structures without a hydroxyl group, galloyl-glucoses and ellagic acid were identified as the main monomeric components in the aqueous extract. 13C-NMR and MALDI-TOF spectra revealed that extracts are mostly composed of procyanidin and prodelphinidin structures although prorobinetidins might be also present. MALDI-TOF spectrometry was used to identify the extract oligomeric components. Extractions with Na2SO3 and/or NaOH produced changes in the predominant structures in the extracts and on the amount of sugar units linked to the flavonoid structures, which decreased in the presence of Na2SO3. Extract obtained using low Na2SO3 and NaOH concentrations (1.5 and 0.75 %, respectively) was selected as more suitable for wood adhesive preparation.  相似文献   

9.
High-density polyethylene (HDPE), bagasse fibers treated by four pulping processes (AS-AQ (alkaline sulfite anthraquinone), SODA-AQ (soda anthraquinone), MEA (monoethanolamine) and chemical–mechanical pulping (CMP)), three levels of nano-SiO2 (0, 2, and 5?wt%), and maleic anhydride polyethylene as coupling agent were used to produce pulp–plastic composites (PPCs) by injection molding. The physical and mechanical properties of corresponding composites were evaluated according to ASTM standards. The results showed that compared to untreated bagasse/HDPE composite, the addition of bagasse pulp fibers increased significantly the mechanical properties such as tensile strength and modulus, flexural strength and modulus, and hardness. The chemical pulps-reinforced composites showed better mechanical strengths than that of CMP-reinforced composites, but in some properties, CMP pulp composites have comparable results to the chemical pulp-reinforced composites. Natural fibers (untreated and treated) increased water absorption and thickness swelling of composites compared to pure HDPE. The addition of nano-SiO2 particles showed both increasing and decreasing trends on physical and mechanical properties ofPPCs.  相似文献   

10.
为探究碱性离子液体四丁基氢氧化铵(TBAH)在桉木预处理中作用机理,采用响应面分析法设计模型,得到离子液体TBAH预处理桉木的最佳条件为:预处理时间57.19 min,预处理温度71.98℃,TBAH质量分数11.78％,并验证了模型的科学性、准确性和有效性.通过对比未处理、NaOH、四丁基氟化铵(TBAF)和TBAH...  相似文献   

11.
To investigate the possibility of decontaminating 137Cs-contaminated Cryptomeria japonica wood, kraft pulping was conducted and the Cs behavior in the reaction process was examined. 133Cs-treated or 137Cs-contaminated bark, sapwood, and heartwood chips of Cryptomeria japonica were digested using an aqueous solution of NaOH and Na2S. The pulp was washed with ultrapure water and filtered, after which the filtrate (black liquor) was collected. The black liquor was acidified to separate the supernatant and precipitation. The Cs (133Cs and 137Cs) concentrations in the chip and reaction products were measured. As for wood samples, the majority of Cs was present in black liquor, while only a minor amount of Cs was retained in the pulp (<1%). In the case of bark, although the majority of Cs was present in the black liquor, the proportion of Cs in the pulp was much higher than that in the wood pulp. In addition, the Cs in the precipitation of the bark was higher than that in the wood, possibly because the Cs in the bark was combined with some components, which is insoluble in alkaline solution. Our results suggest that 137Cs-contaminated Cryptomeria japonica wood can be used in the pulp and paper industries.  相似文献   

12.
Handsheets were prepared with aluminum sulfate under various conditions of pulp suspension, and factors influencing retention behavior of aluminum components on the handsheets were studied on the basis of their aluminum contents. When deionized water was used in the handsheet-making process, aluminum contents in the handsheets had a plateau level of 0.7mg/g in the range of 1%–8% Al2(SO4)3 addition levels on dry weight of pulp. On the other hand, when tap water was used aluminum contents increased up to 5.6 mg/g, increasing the Al2(SO4)3 addition levels to 8%. The high aluminum contents in the handsheets are explained in terms of pH and the presence of calcium ions from the tap water used. Cationic aluminum species, which are formed from aluminum sulfate added to pulp suspensions, are primarily adsorbed on pulp fibers by electrostatic interactions with carboxyl groups in the pulp, competing with OH– ions in water. These aluminum components, once adsorbed on pulp fibers by ionic interactions, are not removed from the fibers by extending the stirring time of the pulp suspensions.This research was presented in part at the 48th annual meeting of the Japan Wood Research Society in Shizuoka, April 1998  相似文献   

13.
To examine why green liquor (GL) pretreatment of lignocellulosic materials effectively facilitates enzymatic saccharification under conditions milder than those of a common alkaline cooking process, dimeric β-O-4 type lignin model compounds with and without free phenolic hydroxyl group were reacted in several alkaline solutions including a model solution of GL, which mainly contains Na2CO3 and Na2S. The β-O-4 bond of the phenolic model compound was cleaved with a sufficient rate in the model solution of GL. The β-O-4 bond cleavage of the non-phenolic model compound was more frequent in the model solution of GL than in other alkaline solutions. These results suggest that β-O-4 bonds present in lignocellulosic materials are effectively cleaved in a GL pretreatment. It was also suggested that HS? and CO3 2? synergistically contribute to the β-O-4 bond cleavage of the non-phenolic model compound under GL pretreatment conditions.  相似文献   

14.
The effects of water potential, NaCl and Na2SO4 on germination and radicle growth of two riparian tree species, Populus euphratica Oliv. and P. pruinosa Schrenk (Salicaceae), were tested. Growth chamber studies revealed an optimum temperature range for seed germination of both species between 15-35℃. The final germination percentage of both species decreases with decreasing water potential in all types of solution applied in the experiments. P. pruinosa was less tolerant to low ψw stress than P. euphratica, especially in salt solutions. Germination percentages fell below 20% for P. pruinosa at -0.6 MPa (NaCl) or -0.4 MPa (Na2SO4) and for P. euphratica at -1.2 MPa (NaCl) or-0.6 MPa (Na2SO4). Radicle growth of both species was inhibited by high concentrations of PEQ NaCl and Na2SO4. However, growth was enhanced at -0.13 and -0.29 MPa in PEG or at -0.13 MPa in NaCl solutions compared to distilled water. Radicle growth of P. euphratica was higher than that of P. pruinosa. Germination and radicle growth of both species exhibited ion toxicity. Na2SO4 was more toxic than iso-osmotic solutions of NaCl. Radicle growth proved to be more sensitive than seed germination. Thus, flooding does not only yield the necessary soil moisture for germination but also favors seedling establishment of both species through leaching of salts from the soil surface. The different sensitivity of the species during their early growth stages might, moreover, contribute to the observed differences in their distribution in the Talim Basin (northwest China).  相似文献   

15.
Naturally occurring camptothecin(CPT) is an important source of chemotherapeutic agents.The extraction from Camptotheca acuminata is still the main approach to obtain CPT compared with total synthesis.In the present study,ultrasound-assisted extractions(UAE) of CPT from C.acuminata seeds with alkaline solutions were investigated and CPT yield were determined by High Performance Liquid Chromatography.The conditions of alkaline species and concentrations,extraction time,extraction temperature and ultrasonic power were optimized.Results show that both Na3PO4 and Na2CO3 solutions gain good extraction yields,whereas Na3PO4 solution has stronger basicity and need higher concentration than Na2CO3 solution does,thus aqueous Na2CO3 is more beneficial for the extraction.The optimal condition was ultrasonically extracted with 0.5% aqueous Na2CO3 at 50°C and ultrasonic power of 400 W for 60 min.Comparing with UAE with ethanol,the extraction with 0.5% Na2CO3 solution achieves higher yield.Moreover,aqueous Na2CO3 as a solvent has various advantages including non-toxicity,inflammable,non-corrosive and low cost,which ensure this UAE method is a superior method with high utilizing prospect.  相似文献   

16.
Antibodies recognizing galacturonan were used in immunoassays for industrial unbleached and hydrogen peroxide-bleached chemithermomechanical pulp (CTMP). The assays were based on a colorimetric method using specific monoclonal antibody recognition of acidic and methylated homogalacturonan, respectively, on the pulp fiber surfaces. Alkaline phosphatase-conjugated antibodies were linked to the galacturonan specific antibodies, and an alkaline phosphatase substrate (p-nitrophenylphosphate) was used to develop a yellow reaction product that can be followed spectrophotometrically. Together the newly developed immunoassays were able to describe the deesterification, specifically, of surface-localized galacturonan on CTMP, induced by alkaline hydrogen peroxide bleaching. Unbleached CTMP showed relatively more labeling by methylated galacturonan recognizing antibodies, whereas bleached CTMP was relatively more labeled for acidic galacturonan. The increase in negative charge of the bleached pulp was also shown by polyelectrolyte titration; the negative surface charge was 9.3 μeq g−1 in unbleached CTMP and 21.7 μeq g−1 in bleached pulp.  相似文献   

17.
 The fiber separation step in refining is crucial for energy consumption in subsequent refining where the pulp properties are developed. The size reduction of chips during refining is dependent on refining intensity and chip strength. Factors affecting these two parameters are discussed in a literature review. The impact strength of chips and the break down of chips to separate fibers are also discussed. Specifically the effect of impact velocity on the fracture of wood has been studied by use of a falling weight impact tester. Samples were prepared from a freshly cut log of Norway spruce, Picea abies, and the impact strength was measured using an instrumented falling weight impact tester. An increase in impact velocity from about 2.7 to 4.8 m/s resulted in an increase in impact strength of about 50%. Received 23 August 1999  相似文献   

18.
Wettability changes of wheat straw treated with chemicals and enzymes   总被引：1，自引：0，他引：1  
A study was conducted to test wettability changes of the wheat straw treated with different methods for the preparation of wheat straw particle board. The wheat straws were separately sprayed with two chemicals (0.6% NaOH, 0.3% H2O2) and three enzymes (lipase, xylanase, cellulase). The contact angle between water and the surface of wheat straw was measured and the spreading-penetration parameters (K-values) were also calculated with wetting model. The surfaces of treated wheat straw and control sample were scanned by means of Micro-FTIR, and their peaks arrangements were analyzed. The surface morphologies of treated wheat straw and control sample were also observed by SEM. Chemical etching was found on the exterior surfaces of the straws treated separately with 0.6% NaOH and 0.3% H2O2; furthermore, the spreading-penetration parameters (K-values) of the distilled water on the exterior surfaces of the treated wheat straw along the grain were higher than that of control. The wettability of exterior surfaces of the wheat straws treated separately with lipase, xylanase and cellulose were improved after treating for seven days, and among the three enzymes treatments, the lipase treatment showed best result. The lipase treatment and NaOH treatment were determined as better methods for improving the wettability of wheat straw surfaces. However, in the economic aspect, NaOH treatment was more practical and easier in the pretreatment for the manufacture of straw particle board.  相似文献   

19.
Due to the variations in opacity and brightness of peroxide bleached pulp at Mazandaran Wood and Paper Industries Company (MWPI), empirical models were developed to predict chemimechanical pulp (CMP) brightness and opacity from peroxide bleaching conditions and to drive the optimum operating conditions. To overcome the inconsistency problem, a multi-variate regression analysis method was used for model building. The models were then validated using a new data set from the bleach plant at MWPI, assessing the models’ predictive ability and performance. The results show that there is a relationship between bleaching variables and such dependent variables as pulp brightness and opacity. In addition to the hydrogen peroxide charge and pulp initial brightness, the initial opacity had a significant reverse effect on the final CMP brightness. It was also found that the concentration of total Na+ in the CMP tower was the most important variable affecting the final pulp opacity. The validation results demonstrated that these models can be employed as useful tools for process optimization purposes.  相似文献   

20.
The process of peroxide bleaching of Populus tomentosa kraft pulp with H2O2 pretreatment under acid condition was studied. The variations of pulp characteristics such as brightness, Kappa number and viscosity during the peroxide bleaching process were discussed and the concept of the A/B value was presented for the first time. The results show that acid pretreatment with H2O2 is essential to improve pulp brightness and avoid viscosity loss. The conclusion is reached that the A/B value has great influence on pulp properties when the total amount of peroxide used in the bleaching process is 2%–5%. Pulp with a high viscosity and brightness can be obtained when A/B is about 0.15. [Supported by the National “863” Project (Grant No. 2002AA241071)]  相似文献   

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