桉木硫酸盐浆DMD漂白工艺条件的研究

使用新漂剂二甲基二环氧乙烷（Dimethyldioxirane,简称DMD）漂白桉木硫酸盐浆时,应严格控制反应的pH值为7．0~7．5;过氧硫酸盐和丙酮用量增加,二甲基二环氧乙烷的漂白能力随之增强;5％用量的DMD漂浆经碱抽提后脱木素能力与氧脱水素相当,但前者漂浆得率高,脱木素选择性好。     

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。     

预水解强度对相思木硫酸盐法制浆黑液性质的影响

经水热预水解技术处理木质纤维素,木片的主要成分发生变化,对后续的化学制浆性能及制浆黑液性质带来影响。本实验采用不同预水解强度（P因子）处理相思木片,并对其硫酸盐制浆行为和黑液性质进行分析。研究结果表明,随着P因子的增大,粗浆得率和细浆得率逐渐降低;浆料的卡伯值逐渐升高。当P因子＜200时,水解后木片的黑液固形物含量由空白组的138.48 g/L升高到162.86 g/L;木素含量由58.57 g/L升高到72.68 g/L;残碱量由4.37 g/L迅速降低到2.07 g/L。当200＜P因子＜600时,黑液固形物含量由162.86 g/L降低到142.71 g/L;黑液中木素含量由72.41 g/L降低到59.16 g/L;残碱量由2.07 g/L降低到1.26 g/L。当P因子＞600时,黑液中固形物含量由142.71 g/L升高到156.95 g/L;木素含量由59.16 g/L升高到62.16 g/L;残碱量由1.26 g/L升高到1.37 g/L。不同条件下,黑液中无机物含量变化不大;黑液固形物的热值由对照组的13.71 MJ/kg提高到14.63~15.09 MJ/kg。     

速生桉木硫酸盐法制浆过程中甲醇生成量的预测模型

以速生桉木硫酸盐法制浆为研究对象,考察了制浆过程中有效碱浓度、H因子(时间和温度)对甲醇生成量以及残余有效碱浓度变化的影响,研究发现制浆过程残余有效碱浓度与蒸煮H因子的负指数呈线性关系,结合这一关系从动力学角度建立了引入碱浓动态变化的制浆过程中预测甲醇生成量的数学模型。结果表明该模型能很好地预测速生桉木硫酸盐法蒸煮过程中各工艺条件下的甲醇生成量(R² 0.990)。模型的预测效果表明,温度对甲醇生成量影响显著,而初始有效碱浓度对甲醇生成量影响较小。实际生产中,可根据该模型对各工艺条件对甲醇生成量影响程度的预测效果适当改变工艺条件,以控制制浆过程中单位木素脱除量的甲醇生成量。     

预水解硫酸盐法溶解浆水解液的利用

溶解浆的制造大体上可分为两种:一是亚硫酸法;另一种预水解硫酸盐法。亚硫酸法制造历史较久,要求原料条件较严,主要用含树脂量较少的白松或部分阔叶材,如杨木、桦木等,其它材种很难适应此种制造方法的要求。然而预水解硫酸盐法对原料选择适应性则较广,而且使产品含树脂量低、α-纤维素高、反应性能好等特点,至于白度低的问题,可采用氧漂、二氧化氯漂等方法解决。目前在我国森林资源比较紧缺的情况     

桉木枝桠材混合制浆性能实验

桉木是一种速生树种,其性能适合制浆造纸。实验将桉木按照一定比例均匀混入杨木枝桠材中进行磨浆,通过实验验证添加桉木后对制浆性能的影响。实验表明,桉木添加后浆料性能有所变化,消耗有所降低,桉木作为制浆原材料制浆能缓解制浆原料紧张,降低制浆成本,推广价值高,有很好的发展前途。     

桉木化机浆制浆过程中木素结构的变化

用付立叶变换红外光谱对桉水化机浆预处理和漂白过程中木素结构的变化进行了研究。结果表明，预处理过程中愈创木基易于磺化和溶出，木素中有新的共轭羰基和醌型结构产生。漂白过程中木素结构单元比例变化不大，木素中的碳基及醌型结构与纸浆白度有密切的关系。     

木聚糖酶NY—111对桉木KP浆漂白的研究

探讨了木浆糖酶ＮＹ－１１１用于桉木ＫＰ浆漂白预处理的最佳工艺条件及木聚糖酶预处理对桉木ＫＰ浆ＣＥＨ三段漂的影响。结果表明,用于漂白预处理的最佳工艺条件为酶 ５ＩＵ／ｇ,时间为２ｈ,对ＣＥＨ三段漂的影响为：与常规法１０％用氯量相比,达到相近白度且得率相近时,采用木聚糖酶预处理,可减少约５０％的用氯量、而强度未下降。     

桉木化学-热磨机械浆纤维的生物改性研究

采用白腐菌19-6对桉木化学-热磨机械浆(CTMP浆)进行了静置培养改性研究,探讨了附加营养物、pH、温度、培养时间和通氧方式等因素对处理效果的影响。结果表明,经白腐菌处理后的浆料二次磨浆能耗低于CTMP原浆,纸页的物理强度明显提高,在游离度约为330 mL时,抗张指数提高21.3%,撕裂指数提高27.4%,内结合强度提高33.1%。同时白腐菌处理使纸浆白度和光散射系数分别下降了25%和21%,而不透明度基本没有变化,通过Na2S2O4+H2O2两段漂后可以使白度达到70.3%ISO,接近相同漂白工艺下CTMP原浆的白度。     

Optimized Catalytic Bleaching Sequences for Eucalyptus Kraft Pulp

Contemporary multi-stage bleaching processes partially remove residual lignin and hexenuronic acid from cellulosic pulps. The reactions in the steps could be faster and consume smaller amounts of chemicals. Catalytic bleaching (H_cat), utilizing hypochlorite (H), triethylenediamine (DABCO) and its derivative N-carboxymethyl triethylenediamine (CM-DABCO), is a new discovery that has the potential to improve the chemical and energetic efficiency of bleaching processes in chemical pulp mills, e.g. through reducing the reaction time of the bleaching processes. The objective of this study was to clarify if new kraft pulp bleaching sequences with initial stage of chlorine dioxide (ClO₂; D) and an intermediate stage of H_cat could provide fully bleached pulps. The bleaching sequences of the studied eucalyptus pulps include D₀E_(OP)H_cat(Q)P and H_catZ/DP, which attained a final brightness of 88 and 89% ISO, respectively. H_catZ/DP showed to be the best sequence for the catalytic bleaching of eucalyptus kraft pulps. This study may open new doors to future bleaching of cellulose pulps with fewer towers and decreased use of chemicals.     

Effect of Alkaline Hemicellulose Extraction on Kraft Pulp Fibers from Eucalyptus Grandis

Abstract

The alkaline extraction of hemicelluloses from hardwoods prior to pulping, for further conversion to value-added products, seems to be a promising pathway for paper mills to increase profit and improve sustainability. However, the amount of hemicellulose extracted will be limited by the requirement to maintain pulp quality and pulp yield in comparison to existing pulping processes. The effects of NaOH concentration, temperature, and time on hemicellulose extraction of Eucalyptus grandis were studied using a statistical experimental design. Extracted wood chips were subjected to kraft pulping to evaluate the effect of the extraction on cooking chemicals, pulp quality, and handsheet paper strengths. The selective xylan recovery (12.4% dry mass) from E. grandis combined with low-cooking, active alkali charge, and less cooking time advantaged the xylan extraction and subsequent modified kraft pulping process under the studied conditions. Pulp viscosity, breaking strength, and tensile index of handsheets were slightly improved.     

Delignification of Kraft Pulp by Lipase

Fibre Chemistry - The influence of the preliminary enzymatic treatment of kraft pulp with lipase on the results of the subsequent chemical bleaching with hydrogen peroxide in the presence of alkali...     

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%.     

Determination of Mechanical and Optical Properties of Eucalyptus Kraft Pulp by NIR Spectrometry and Multivariate Calibration

Abstract

Multivariate data analysis and NIR spectrometry were used to determine the mechanical and optical properties of eucalyptus kraft pulps with different chemical compositions and refined to different levels. Tear (TrID), tensile (TsID), burst (BuID), and bending (BeID) indexes and elastic modulus (EM), stretch (ST), and breaking length (BL) were the mechanical properties measured. Measurement of beating degree (SR) was also achieved. Light scattering (LS) and light absorption (LA) coefficients were the optical properties measured. Mechanical and optical properties were modeled using NIR spectra obtained on pulp hand sheets by diffuse reflectance and application of the partial least squares (PLS) method. Models with two to seven PLS components and very good predictive ability were established after testing the first‐derivative, Kubelka‐Munk, or a combination of both as pre‐processing techniques. Models were validated by using cross‐validation methodology and a comparison of measurements using conventional methods for new samples. The predictive models can reduce time in traditional measurements in the pulp and paper industry and are suitable for direct application using “at‐line” conditions. As an additional benefit, improvements in process monitoring and paper quality can be achieved.     

溶解沉淀法制备高脱乙酰度壳聚糖

以乙醇为反应介质,采用溶解沉淀法制备了高脱乙酰壳聚糖。在反应温度８０℃,反应时间３ｈ,壳聚糖与氢氧化钠和乙醇的质量比为１∶３∶１６的条件下,获得了脱乙酰度达９０％的壳聚糖,而传统方法只有８０％。     

The Impact of Xylanase and Hot Acid Pretreatment on HexAs in Eucalyptus Kraft Pulp Bleaching

The influence of the presence of hexenuronic acid (HexA) in eucalyptus kraft pulp on the efficiency of D₀EpD₁ was investigated by separately using both commercial cellulase-free xylanase and hot acid pretreatments. In comparison to the xylanase pretreatment, the hot acid pretreatment was more than four-fold effective in removing the HexAs (61%) and concomitantly reduced the kappa number, but resulted in lower viscosity. After subsequent D₀EpD₁ bleaching, the final brightness and its stability were improved remarkably, especially under xylanase pretreatment. At the same brightness of 85% ISO, the xylanase pretreatment reduced the consumption of active chlorine (35.6%) more than the acid pretreatment did (27.5%). The total relative active chlorine savings for the xylanase pretreatment over the acid pretreatment was therefore nearly 23%. The HexA component can be removed considerably in both D₀ and D₁ stages during the D₀EpD₁ bleaching sequence, while only slightly in the Ep stage. The use of xylanase and acid pretreatment both resulted in insignificant physical strength losses for the bleached pulps.