Green and Effective Ammonium Carbonate-assisted Process for Drying Hemicellulose Obtained through Alkali Extraction of Bleached Bamboo Kraft Pulp

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.

Effects of Ultrasonic Treatment on Kraft Pulping of Bamboo

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.

Behavior of Decayed Spruce (Picea abies) during Kraft Pulping

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.

Effect of Optical Brightening Agent(OBA)on Bleaching Process on Paper of Eucalyptus Kraft Pulp

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.

SYNERGISTIC EFFECTS BETWEEN BIRCH CHEMICAL MECHANICAL PULPS AND ASPEN BLEACHED KRAFT PULP

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.

THE COMPARISON OF STRENGTH PROPERTY BETWWEEN KRAFT PULP AND ALKALINE SULFITE-ANTHRAQUINONE PULP FOR THICKER CELL WALL FIBER MATERIALS

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.

Application of Photo-Fenton Process for the Treatment of Kraft Pulp Mill Effluent

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.

PEROXYACID ENHANCED OXYGEN DELIGNIFICATION OF KRAFT PULP

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.

STUDY ON THE ELEMENTAL CHLORINE FREE BLEACHING OF BAMBOO KRAFT PULP

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.

EXAMINATION OF POLYCHLORINATED DIBENZO-P-DIOXINS AND POLYCHLORINATED DIBENZOFURANS INTO PROCESS WATER OF KRAFT PULP BLEACHING MILL FROM ASPECT OF ENVIRONMENTAL WATER QUALITY

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.

Using Additives for the Removal of Extractives in Kraft Pulping and Bleaching of Hardwood

The effect of four additives (surfactants and dispersant) that were supplied by Hercules Chemicals Singapore Pte Ltd on kraft pulping and bleaching of Eucalyptus camaldulensis and Acacia mangium has been studied. The use of additives results in a more removal of extractives, and in a more uniform cook with lower screen rejects in eucalyptus, lower residual alkali, and in an improvement in brightness of eucalyptus pulps. At low additive charge level, a reduction of kappa number generated without clear loss of pulp yield in acacia cook.

Effects of a poly(hydroxyalkanoate)elastomer and kraft pulp fibres on biocomposite properties and three-dimensional(3D)printability of filaments for fused deposition modelling

Three-dimensional(3D)printing is a useful technique that allows the creation of objects with complex structures by deposition of successive layers of material.These materials are often from fossil origin.However,efforts are being made to produce environmentally friendly materials for 3D printing.The addition of lignocellulosic fibres to a polymer matrix is one of the alternatives to replace,for instance,glass fibres in composites as reinforcing materials.The fields of biocom-posites and 3D printing open innovative application areas for pulp fibres from the pulp and paper industry.In this work,biocomposites of poly(lactic acid)(PLA),poly(hydroxyalkanoate)(PHA)and kraft pulp fibres were prepared in order to find a suitable formulation for filaments for 3D printing.The effect of two different types of kraft fibres(bleached(B)and unbleached(U))and of PHA on the mechanical and thermal properties of the biocomposites was assessed.The addition of 30%kraft fibres to PLA resulted in an increase of the tensile modulus from 3074 to∼4800 MPa.In the case of biocomposites containing PHA(50%PLA/20%PHA/30%kraft)the increase in modulus was more moderate(PLA+PHA+U:3838 MPa,and PLA+PHA+B:3312 MPa).The tensile strength of PLA(66 MPa)increased to 77 MPa in PLA+kraft biocomposites,while a reduc-tion in strength was observed for PLA+PHA+U(43 MPa)and PLA+PHA+B(32 MPa).Filaments prepared with PLA,PHA and bleached and unbleached pulp fibres showed similar printability of complex geometries,demonstrating that unbleached pulp fibres could also be utilized in the preparation of biocomposites with good mechanical performance and 3D printing properties.

Recovery of calcium carbonate waste as paper filler in the causticizing process of bamboo kraft pulping

In this paper, calcium carbonate waste was recovered as paper filler from the causticizing process of bamboo kraft pulping. The effects of the causticizing process parameters on the filler qualities were investigated, in terms of the whiteness, tear strength, tensile strength and ash content of the filled paper. To investigate the effect of silica content on the qualities of the resultant calcium carbonate filler, the green liquor was desiliconized with aluminum salt modified bentonite prior to the causticizing process to obtain calcium carbonate of various silicon contents, particle size and brightness, and different crystal morphology. It was found that the ionic strength and silicate concentration were the two key factors in affecting the size and shape of the calcium carbonate particles formed in the causticizing process.

Evaluating process of auto-hydrolysis prior to kraft pulping on production of chemical pulp for end used paper-grade products

The objective of this work is to systematically evaluate the performance of the hydrolysis-based kraft pulping process and associated pulp and black liquor characteristics.Acacia wood chips were auto-hydrolyzed under various severities,then the hydrolyzed wood chips were kraft pulping.The results indicated that the yield of pulp significantly dropped with intensifying the auto-hydrolysis severity.Meanwhile,the removal rate of pentosan reached 98.6%in the screened pulp at the P-factor of 1000.The fiber length,fines and fiber crimp of the screened pulp were not affected by the auto-hydrolysis treatment.Auto-hydrolyzed pulps deteriorated fibrillation and beating response of the pulp in a refining process.However,fiber length and fines changed obviously after beating treatment.After auto-hydrolysis,the tensile index of the paper matrices decreased,some particle substances were found on the surface of the pulp fiber,and the solid and organic content of the black liquor were improved.

Technical Evaluation of Hybrid Clones of Corymbia spp. to Produce Market Pulp

This study presents hybrid clones of Corymbia spp.developed by Aperam BioEnergia as potential substitutes for Eucalyptus wood in the pulp industry.The biomass of Eucalyptus spp.was compared with that of Corymbia spp.by performing modified kraft pulping and basic density analyses.Comparisons were made by analyzing their respective mean annual increments of cellulose(MAI_(cel))and specific wood consumption(SWC),estimated using a kappa number of(19±1).The results showed that one of the hybrid clones(Corymbia citriodora×Corymbia torelliana,ID 4)had higher basic wood density,higher screened yield,better MAI_(cel#k19),and lower SWC than the other samples,reaching values of 0.608 t/m^(3),54.1%,24.6 ADt/ha/year(i.e.,air dry ton/hectare/year),and 2.74 m^(3)/ADt,respectively.Consequently,clone ID 4 had the highest MAI_(cel)/SWC ratio score(8.98).Given its high forest productivity and low industrial cost compared with other samples,as well as its advantages over Eucalyptus spp.wood,we concluded that clone ID 4 has great potential as an alternative biomass for pulp production.

Effect of Acetic Acid Prehydrolysis on Unbleached Bamboo Pulp Production

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.

RELATIVE IMPORTANCE OF WOOD DENSITY AND CARBOHYDRATE CONTENT ON PULPING YIELD AND PRODUCT QUALITY

SUMMARYThe purpose of this study was to evaluate basic density, chemical composition and fiber dimensions of ten Eucalyptus sp wood samples and verify the impact of this set of parameters and their combination on the Kraft pulping process yield and on bleached pulp quality. Ten eucalypt woods of different species, with basic densities varying from 365 to 544 kg/m3 and total wood carbohydrate contents varying from 70.0 to 74.5%, were transformed into kraft pulp of kappa number 17-18 and bleached to 90% ISO brightness by the sequence OD(PO)D. Wood basic density showed stronger correlations with fiber dimensions, pulping yield and pulp quality than did chemical composition. Lighter woods resulted in higher yields. However, wood specific consumption was lower for denser woods, even though these demanded more drastic pulping conditions to achieve a given kappa number. The pulp quality results suggest that lower density woods should be directed towards fabrication of refined paper (printing and writing grades) while the denser woods be directed to the sanitary papers segment (tissue grades).

硫酸盐竹浆杂细胞含量对打浆过程纤维形态的影响

以硫酸盐竹浆为研究对象,利用纤维筛分仪分离竹纤维与杂细胞,对打浆过程中不同杂细胞含量竹浆的纤维形态和特性进行分析,探讨了杂细胞对竹纤维形态的影响。结果表明,杂细胞与竹纤维在打浆中形成的气球状结构相互摩擦,对竹浆性能产生影响。相同打浆转数下,杂细胞含量越高,竹浆滤水性能越差,纤维宽度越小。杂细胞在打浆过程中加剧了竹纤维的分丝帚化和细小纤维的产生,且易与竹纤维表面产生的细小纤维缠绕,使竹浆滤水性能降低。

氧漂桉木硫酸盐浆臭氧漂白工艺研究

采用硫酸盐法制备桉木硫酸盐浆,经氧脱木质素处理后,对其进行臭氧漂白工艺的研究。探究臭氧漂白过程中浆浓、漂白时间、pH值、臭氧用量等对纸浆漂白性能及成纸性能的影响,得到较优的漂白工艺条件。结果表明,当浆浓为35%、漂白时间3 min、臭氧用量0.9%和pH值为2.0时,所得纸浆白度为76.9%ISO、纸浆黏度为535 mL/g、纸浆Kappa值为2.71,成纸抗张指数、耐破指数、撕裂指数和耐折度分别为57.4 N·m/g、4.77 kPa·m^(2)/g、7.95 mN·m^(2)/g和89次。

大型硫酸盐木浆厂石灰窑碳排放及其减排路径分析

首先分析了大型硫酸盐木浆厂中石灰窑的温室气体排放特征,阐述其为硫酸盐木浆厂化石燃料最大消耗单元的主要原因,然后重点探讨石灰窑温室气体排放核算的路径,最后进一步提出石灰窑实现碳中和的可能技术途径,包括生物质燃料在石灰窑中的应用、石灰窑和碳捕获与封存(CCS)的集成技术以及石灰窑技术改造等。