Totally chlorine‐free bleaching of Acetosolv pulps: a clean approach to dissolving pulp manufacture

Eucalyptus globulus wood samples were delignified in media containing concentrated acetic acid, water and hydrochloric acid (Acetosolv process) under optimized conditions, and the pulps were subjected to totally chlorine‐free (TCF) bleaching. Alkaline extractions, oxygen delignification, ozone treatment, enzymatic xylan removal and hydrogen peroxide oxidation in alkaline media were investigated as individual steps in selected bleaching sequences. Under the best conditions, fully bleached pulps with favourable characteristics for dissolving pulp manufacture were obtained. © 2001 Society of Chemical Industry     

马尾松预水解硫酸盐法制人造纤维浆粕工艺的研究

对马尾松制人造纤维浆粕过程中的预水解工艺进行研究,比较了不同液比、最高温度及保温时间的处理效果。研究结果表明:预水解最佳工艺条件为液比1:6;最高温度170℃;保温时间90min。蒸煮工艺采用常规硫酸盐法蒸煮,漂白采用全无氯(TCF)漂白。在此条件下,可获得性能优良的浆粕。     

Extractive Profiles in the Production of Sulfite Dissolving Pulp from Eucalyptus Globulus WOOD

The profile of major families of extractives soluble in acetone and dichloromethane during the production of acid sulfite dissolving pulp from Eucalyptus globulus wood was assessed. Nearly 85% of total extractives were removed from wood during pulping and nearly 11% in the course of E-O-P pulp bleaching and secondary pulp screening. Unlike extractives of polyphenolic origin that were almost completely removed after the alkaline extraction stage (E), fatty acids were the main retained component in fully bleached pulp followed by sterols and fatty alcohols. Throughout the bleaching steps, the profiles of extractives were not necessarily decreasing and depended on their reactions with bleaching reagents and the presence of auxiliary chemicals (e.g. antifoams). In this context, the content of fatty acids and fatty alcohols was mostly vulnerable. It has been suggested that Fock reactivity of dissolving pulps is unaffected by extractives at concentrations up to 0.3%.     

TCF BLEACHED PULPS FROM MISCANTHUS SINENSIS BY THE IMPREGNATION RAPID STEAM PULPING (IRSP) PROCESS

ABSTRACT

The production of bleached cellulose pulps from elephant grass (Miscanthus sinensis) via a two-stage soda pulping process and a TCF bleaching sequence is evaluated in this work. The impregnation rapid steam pulping process (IRSP) involves impregnating of the lignocellulosic material with the pulping liquor, withdrawing the excess liquor and rapidly steaming the impregnated material at 180–200°C for a short time. In this paper the process variables and their effect on the kappa number, yield and viscosity of the unbleached pulps are discussed. Bleaching by an ozone-based TCF sequence was tested, and the papermaking properties of the bleached pulp were determined. A kappa number of 19 was obtained by impregnating at an alkali charge of 30 + 0.1% anthraquinone carboxylic acid (AQCA) and pulping at 180°C for only 15 min. Kappa was reduced to 16 by extending pulping time to 26 min. The alkali consumption during impregnation and pulping was 10.2 g NaOH/100 g of dry Miscanthus. Screened pulp yield, viscosity and brightness for this pulp were 54.6%, 913 mL/g and 37.3%, respectively. After bleaching, the pulp had an ISO brightness of 87.4% and a viscosity of 700 mL/g. Refining in a PFI mill provided optimal strength properties of the bleached pulp at 4500 revolutions (71°SR): breaking length 7.2 km, tensile index 72 N m/g, and burst index 4.3 kN/g. Tear index was 7.9 mN m²/g at this degree of refining.     

低卡伯值麦草浆无氯漂白的研究

采用麦草硫酸盐法(KP法)一级蒸煮深度脱木素技术,制取低卡伯值麦草浆,并对其进行两种不同方式的无氯漂白。结果表明:AQ(PN)P流程可将浆料漂至白度86.2%(SBD),粘度为938mL/g。QZEYP流程能漂至86.9%(SBD),粘度为851mL/g。无氯漂白的粘度和白度稳定性均优于CEH三段漂。预处理对保护浆料有着重要作用。在过氧化氢漂白中,高温高压是脱木素和提高白度的必要条件。臭氧漂白是一种重要又经济的无氯漂白方法。     

木浆制备钻井液用低黏羧甲基纤维素钠盐

低黏羧甲基纤维素钠盐是一种优异的降滤失剂,国内大多以精制棉为原料、选用溶媒法工艺生产该产品。本文选用造纸木浆为原料,采用工艺简单的水媒法制备钻井液用低黏羧甲基纤维素钠盐。通过纤维浆的优选、醚化剂制备工艺的确定、设计取代度的确定、水量的确定以及降解剂用量的确定,进行工艺条件调整,最终确定了产品的配方。     

Optimization of beech wood pulping in catalyzed acetic acid media

Fagus sylvatica wood samples were treated in HCl‐catalyzed, acetic acid solutions. The effects of selected operational variables (catalyst concentration, reaction time and liquor to wood ratio) on pulp yield, composition of pulps and composition of pulping liquors were assessed using incomplete, second‐order, centred, factorial designs. Pulp composition was measured by the contents in cellulose, xylan and lignin. The concentrations of glucose, xylose and furfural in pulping liquors were also considered as experimental variables. Under selected conditions, pulps with 5.8% to 7.5% Klason lignin (kappa numbers in the range 25 to 33), 77.2% to 85.3% cellulose and 3.3% to 6.1% xylan were obtained at 45.8% to 50.0% pulp yield. The selected pulps showed good SCAN viscosity (723 to 814 mL/g) and alkaline resistances which were affected by the acetyl group content of samples (6.6 to 7.6 weight percent).     

杨水漂白浆和未漂浆水解反应动力学的研究

本文研究了木素含量为0．23％山杨漂白浆和1．05％速生杨未漂浆稀酸低温多相水解降解反应动力学特性。研究结果表明,该过程与棉浆、桦木和针叶材浆具有类似的特点,即纤维素多相水解过程分为快速降解和缓慢降解两个明显的阶段,而最终降至极限聚合度（山杨漂白浆为180,速生杨未漂浆为206）。根据试验数据计算了反应速度常数,山杨漂白浆为KAB＝2.5×10-4／min,速生杨未漂浆为KPu＝1．6×10－4／min,前者明显高于后者。随着水解时间的延长,水解残渣得率下降,其最终结果为83％～84％。     

黏胶纤维用落叶松溶解浆的清洁漂白

引言近年来,随着棉花价格的总体上涨和消费者对纺织材料舒适度的要求,给黏胶纤维带来了需求增长空间。作为黏胶纤维的原材料,国内目前的溶解浆产能难以满足客户需求。据统计,国内溶解浆存     

Cellulose triacetate prepared from low-grade hardwood dissolving pulp and its insoluble residues in acetylation mediums

As cellulose triacetate is prepared from low-grade hardwood dissolving pulp, a considerable amount of the insoluble residue was present in the acetylation medium of the acetic acid/acetic anhydride/sulfuric acid system. The characterization of this residue indicated that the insoluble residue is composed of cellulose triacetate and xylan diacetate, retaining a fiber structure of swollen form. To reduce the insoluble residues, reaction conditions for acetylation were investigated. As one of the remedies of reducing the insoluble residues, 17 different solvents were selected to add to the acetylation medium, and among these, dichloroacetic acid was found to be very effective for its reduction. The obtained cellulose triacetate could then reveal good thermal properties similar to that from high-grade dissolving pulps. Therefore, acetylation systems with an addition of an appropriate solvent can have a potential to industrially manufacture a high-quality cellulose triacetate from even low-grade hardwood-dissolving pulps, as observed in low-grade softwood-dissolving pulps. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 67: 289–297, 1998     

Effect of xylanase on ozone bleaching kinetics and properties of Eucalyptus kraft pulp

Environmental pressure has led the pulp and paper industry to develop new technologies in order to reduce or suppress the presence of various pollutants in effluents from bleaching plants. One of the choices for this purpose is enzyme‐based biotechnology. This study deals with the effect of using a xylanase‐based enzymatic pretreatment, in a TCF (Totally Chlorine Free) sequence, on the properties of the resulting paper pulps. The hexenuronic acid content in the pulp and the physical properties of the paper were also studied. The performance of the xylanase was analysed through kinetic studies on ozone bleaching. The enzymatic pretreatment results in easier bleaching and delignification of the pulp, causing a bleach‐boosting effect. The decreased consumption of reagent is related to a decreased content of hexenuronic groups. The physical properties of the treated pulp are similar to those of untreated pulps. Cellulose degradation, delignification and chromophores' removal show first‐order kinetics. Enzyme pretreatment leads to differences between the kinetic constants of cellulose degradation and chromophores' removal, due to an increased accessibility to bleaching agents. The xylanase treatment leads to a lower floor kappa number (IK_∞) during the ozone stage. Copyright © 2003 Society of Chemical Industry     

Strategies to reduce the brightness reversion of industrial ECF bleached Eucalyptus globulus kraft pulp

BACKGROUND: Brightness stability is a key property of bleached chemical pulps and is primarily determined by wood species and bleaching process conditions. Eucalyptus globulus is becoming a very important raw material for hardwood pulp production. In spite of this importance, there is a relative lack of systematic studies in the literature dealing with the subject. This research aims to study the effect of some of the foremost bleaching parameters of a DEDD bleaching sequence as well as the effect of a final P stage (DEDP instead of DEDD) in the brightness stability of bleached E. globulus kraft pulps. RESULTS: The increase of the D₀ stage temperature from 55 °C to 90 °C caused an increase in brightness stability. Increasing the ClO₂ charges from 2.8% to 3.2% also improved significantly the brightness stability. A high H₂SO₄ charge in the D₀ stage (10 kg tonne^?1 pulp) diminished the brightness stability. The combination of H₂O₂ addition to the E stage and ClO₂ reduction in the two final D stages does not affect brightness reversion. Raising the D₂ stage temperature from 65 °C to 82 °C decreased the brightness reversion, while an increase was obtained when the temperature rose above 82 °C. Substitution of the last ClO₂ stage in the DEDD sequence by a H₂O₂ stage (DEDP) significantly reduced the brightness reversion. CONCLUSION: For an existing pulp mill in which the implementation of new technologies to improve brightness reversion is considered, the results obtained showed that brightness stability can be improved without any significant capital investment. Copyright © 2007 Society of Chemical Industry     

Overview of the pulp and paper industry from a chemical industry perspective

The major processes of the pulp and paper industry are overviewed with particular emphasis given to existing chemical requirements; processing trends are identified which may affect future chemical requirements. The pulp and paper industry represents a vast market for chemicals. On the papermaking side, overall chemical usage will probably increase due to ever greater product sophistication and emphasis on value-added grades. On the pulping side, the pressing needs for fibre conservation and more effective utilization of fibre sources can only be achieved through continuing exploitation of chemical developments.     

Sustainable Production of Levulinic Acid from the Cellulosic Fraction of Pinus Pinaster Wood: Operation in Aqueous Media Under Microwave Irradiation

The fractionation of the structural components of lignocellulosic biomass (cellulose, hemicelluloses, and lignin) and the separate utilization of the resulting fractions for specific purposes, according to the philosophy of biorefineries, enables the development of sustainable processes for biomass utilization. In this work, Pinus pinaster wood was subjected to aqueous processing to remove water-soluble extractives and hemicelluloses, and the resulting solid was subjected to pulping with HCl-catalyzed acetic acid solutions (Acetosolv method). The pulp was employed as a substrate for levulinic acid manufacture by reaction in acidic media under microwave irradiation. The effects of the major operational variables (temperature, reaction time, and acid concentration) on the levulinic acid yield were established by statistical modeling of experimental data. Operating under the best reaction conditions (at 191.2°C for 18.9 min in aqueous media containing 1.10% HCl), the levulinic acid yield accounted for 56.4% of the stoichiometric value.     

提高马尾松木纤维用浆粕中甲纤含量的研究

木材通过化学方法可制得用于生产木粘胶纤维用的浆粕，但制得的浆粕中甲纤含量较低，难以满足后续纺丝的要求。为了提高木浆粕中的甲纤含量，用漆酶对木浆粕进行处理，取得了一定的效果，木浆粕的甲纤台量由原来的83．2％提高到89．2％。     

再生木浆纤维素的制备及其稳定辛酸/癸酸甘油三酯乳液的性能研究

以高纯木浆板为原料制得再生木浆纤维素(W-RC),并用TEM、FT-IR和XRD对其进行表征,说明W-RC属于典型的纳米基纤维素Ⅱ型颗粒。以辛酸/癸酸甘油三酯(GTCC)为油相,W-RC为乳化剂,制得O/W型Pickering乳液,并通过光学显微镜、荧光显微镜、FE-SEM及流变仪对乳液进行表征。荧光显微镜与FE-SEM的结果显示W-RC吸附在油/水界面并在微球表面及微球间形成三维网状结构。流变学表明W-RC及由其稳定的乳液具有典型的剪切变稀特性。W-RC具有优良的乳化性能,在W-RC质量分数为0.6%、分散相体积分数高达60%时,也能得到稳定的乳液。     

单一态氧漂白甘蔗渣浆制备羧甲基纤维素研究

以甘蔗渣为原料,通过单一态氧漂白,进而成功地制备了羧甲基纤维素(CMC),不仅为甘蔗渣综合利用寻找出了一条途径,而且也会消除环境污染,为实现环境保护提供了一条较有效的漂白方式。     

纸浆漂白废水中可吸附有机氯化物的特性研究进展

纸浆漂白废水中含有的可吸附有机氯化物是国内外造纸工业严控的废物,是造纸环保界关注的重点。在查阅资料基础上,对目前关于纸浆漂白废水中可吸附有机氯化物的成分、分布、生成以及降解特性等方面的研究进行了述评,重点介绍了纸浆漂白废水中可吸附有机氯化物的生成及降解性能方面的研究成果,并在此基础上对今后的研究趋势进行了展望。     

Changes in supramolecular structure and improvement in reactivity of dissolving pulp via enzymatic pretreatment with processive endoglucanase EG1 from Volvaria volvacea

Abstract

Processive endoglucanase EG1 and its core domain, EG1(CD), were used to pretreat the commercial dissolving pulp to improve cellulose reactivity. The Fock reactivity of the pulp which was treated with EG1 and EG1 (CD) at 50?U/g enzyme loading increased from 74.3% of the control to 90.6% and 88.4%, respectively. Refining also improved the Fock reactivity of the pulp, but not as effective as EG1 or EG1(CD) treatment. Refining prior to EG1 or EG1(CD) treatment could slightly further improve the Fock reactivity, to 91.6% and 90.0%, respectively. After enzymatic treatment and (or) refining, the water retention value, differential scanning calorimetry and alkaline solubility analysis indicated that enzyme treatment, especially by EG1, significantly increased the accessibility of fibers to reaction reagents. Combined with the characteristics of soluble reducing sugar produced by EG1 treatment and the changes of degree of polymerization, it is inferred that a small fraction of cellulose crystallization regions are destroyed in the enzymatic hydrolysis process due to the processive acting ability of EG1, and some microchannels in the fiber cell wall were created, which is similar to the effect of “drilling holes”, so that the reaction reagent can reach the inside of the cell wall evenly, thus obviously improving the reactivity of the dissolved pulp.     

High‐quality cellulose triacetate prepared from bamboo dissolving pulp

Cellulose triacetate (CTA) was prepared from high‐grade bamboo dissolving pulp in general acetylation medium of acetic acid/acetic anhydride/sulfuric acid system. Despite its properties being improved compared with these of CTA prepared from viscose bamboo pulp, many insoluble residues still remained in its acetylation medium, which resulted in the decrease of the brightness and thermal stability of prepared CTA. Characterization of the insoluble residue indicated that its formation was associated with a higher content of xylan and ash in high‐grade bamboo pulp than in high‐grade hardwood pulp, in which insoluble residue was negligible. Because of the poor solubility of xylan diacetate (XDA) in acetylation medium, the insoluble residue formed through the aggregation of XDA and CTA by ultrastructural effects of the pulps during the precipitation of XDA. An addition to the good solvent of XDA, such as 1,2‐dichloroethane to acetylation medium of high‐grade bamboo pulp, could release the aggregation of XDA and CTA and dissolve the insoluble residue, which could lead to the improvement of the transmittance of reaction solution, as well as the properties of CTA prepared such as brightness and thermal stability. This study showed that high‐quality CTA could be prepared from high‐grade bamboo dissolving pulp in acetylation with an addition of solvent. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009