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.     

马尾松溶解浆的预水解硫酸盐法制浆

对制备马尾松溶解浆的预水解硫酸盐制浆工艺进行研究。实验结果表明:预水解硫酸盐纸浆的卡伯值随着预水解P因子的增加先降低后升高,聚戊糖含量不断降低,预水解P因子为700时聚戊糖含量低于3%;硫酸盐法蒸煮最佳用碱量为22%,硫化度为25%~30%,H因子为1500~1600;与普通硫酸盐马尾松浆比较,预水解硫酸盐浆的卡伯值、黏度及细浆得率低。     

用木材生产生物燃料与纸浆

杨木木片硫酸盐制浆前,进行缓和的碱抽提处理,抽提出半纤维素用作生物燃料(生物乙醇),在温度90℃,NaOH 1～2M,液比1∶4条件下进行碱处理,不需要高压设备,每吨木片得到半纤维素40～50kg,经碱抽提后木片进行硫酸盐蒸煮,与未经碱抽提木片参照对比,纸浆得率基本相同,但是需要很好地控制碱抽提与硫酸盐蒸煮工艺条件,能缩短蒸煮时间和节省化学品用量。碱预抽提木片得到的硫酸盐纸浆中纤维素/半纤维素的比率稍高,导致纸浆的抗张指数稍有降低(约10%),但是纸浆白度较高且筛渣含量低,为使硫酸盐纸浆的质量和得率保持较高水平,采用缓和的碱预抽提,使半纤维素得率较低,而回收的半纤维素的浓缩和离析比木片自水解或稀酸水解回收糠醛更加容易。     

APMP制浆废液中半纤维素的分离和应用

以XAPMP浆的废液中分离的半纤维素为原料,通过醚化反应制备不同取代度的季铵型半纤维素。主要讨论了醚化剂、催化剂用量、反应时间及温度对取代度的影响。结果表明,当醚化剂与半纤维素质量之比值为1．0,NaOH与半纤维素质量之比值为0．06时,反应时间为4h,温度为55℃时,可得到取代度为0．08的季铵型半纤维素。通过红外光谱对改性前后半纤维素的结构进行表征。改性后的季铵型半纤维素对阔叶木浆、针叶木浆以及OCC纸浆有明显的增强作用。研究表明取代度越高的半纤维素对纸浆的增强作用越显著。     

Some investigations on ASAM pulping and chlorine free bleaching of eucalyptus from spain

In ASAM pulping of eucalyptus important process variables, such as methanol content of the cooking liquor kind of additional alkali source and alkali ratio were investigated. The pulping results were compared to those of kraft cooks carried out with identical raw material. In the bleaching trials the attention was focused on chlorine free sequences. The most meaningful advantage of ASAM pulping in comparison to the kraft process is the easy bleachability of the pulps. The good bleaching response allows the application of an absolutely chlorine free bleaching sequence, without excessively impairing pulp strength.     

Upgrading Paper-grade Softwood Kraft Pulp to Dissolving Pulp by Cold Caustic Extraction

Cold caustic extraction has potential applications in the production of dissolving-grade pulps due to its ability to selectively remove hemicellulose from lignocellulosic materials. In this study,we demonstrate the conversion of paper-grade kraft pulp into dissolving pulp by a single-stage cold caustic extraction. Under the extraction conditions of 12 wt% NaOH lye,11% pulp consistency,a temperature of 35℃,and 2 h,a paper-grade softwood kraft pulp was purified to high-grade dissolving pulp with 97. 1% α-cellulose content,1. 2% pentosane content,and narrowed molecular weight distribution. The resulting extraction filtrate was concentrated by nano-filtration to obtain the hemicellulose content of 59. 0 g / L,while the permeate was a clear Na OH solution with 10. 9 wt% concentration. A process configuration was also proposed,integrating this cold caustic extraction process with existing pulp and paper production and multi-purpose utilization of the extraction filtrate.     

Effect of extraction conditions on hemicellulose yields and optimisation for industrial processes

Hemicellulose is a valuable component of agro‐food industrial wastes and used in various areas such as drug manufacture and food industry for encapsulation and emulsification. In this study, effects of raw material type, particle size, and extraction conditions (alkaline concentration, temperature, time) and methods (direct alkaline extraction, alkaline extraction after component removal and acidic extraction method) on hemicellulose yields were investigated. Sugar beet pulp and corn wastes were used as raw material. The alkaline method resulted in 40.2% pure extracts, while the acidic method gave only 27.4% purity in the same extraction conditions. The optimal extraction conditions were found as 30 °C temperature, 10% alkali (NaOH) and 24 h time (64.3%). It was also observed that removal of constituents such as fat, protein, starch and soluble sugar increased the purity of hemicellulose from 40.2% to 58.2% at the same conditions. The results indicated that using both low alkaline concentration and low temperature allows to recover higher‐quality extracts.     

热水抽提半纤维素在制浆造纸领域的应用研究进展

在传统的化学法制浆过程中,植物纤维原料中的半纤维素蒸煮时会降解到蒸煮废液中,得不到有效利用。结合生物质精炼理念,可以在蒸煮前提取出部分半纤维素,提取出的半纤维素可以用于生产生物质乙醇等化学品,提取后的植物纤维原料仍用于制浆造纸。热水抽提法是目前提取半纤维素的最有效方法之一。本文对热水抽提法提取半纤维素工艺的原理、研究进展及发展前景进行了分析与综述。     

混合竹材制备溶解浆的工艺试验

以混合竹片(慈竹、黄竹、西凤竹=1:1:1)为原料,对其化学成分进行分析,并采用预水解硫酸盐法蒸煮、OD0EPD1多段漂白工艺制备混合竹片溶解浆。试验发现:混合竹片的综纤维素74.52%、木素25.08%、戊糖20.67%、灰分2.25%,适用于溶解浆的制备原料;采用预水解硫酸盐法蒸煮、OD0EPD1工艺漂白能够生产出质量合格的竹纤维溶解浆。     

聚木糖酶在溶解浆制备中的应用研究

本文通过对毛竹预水解浆与非预水解浆的对比研究发现：预水解处理后浆料的灰分含量、铁离子含量高，锰酸钾值高，白度较低，不利于后续蒸煮和漂白。非预水解浆性能优于预水解浆，但聚戊糖含量偏高。实验在此前提下探索非预水解浆生物处理降低聚戊糖的可行性及其浆料性质，结果表明：细菌性聚木糖酶和真菌性木聚糖酶能降低聚戊糖含量18．8％左右，二者差异不显著（P〉0．05），但EDTA和Tween80的加入可以进一步降低聚木糖酶处理后浆料中聚戊糖含量、铁离子含量和灰分含量，同时可以提高溶解浆白度。     

毛竹阳离子半纤维素对纸浆性能的改善

利用碱法从南方毛竹原料中分离出半纤维素,并对其进行阳离子化改性.研究了阳离子化半纤维素作为阳离子造纸助剂对漂白桉木浆成纸性能的影响.结果表明:相对于添加半纤维素,在纸浆悬浮液中加入阳离子化半纤维素可使纸张的机械强度提高更大.当其用量为1%时,成纸的抗张指数和撕裂指数提高最多,可分别提高19.6%和30.6%;成纸的耐破指数在其用量为2%时提高幅度最大,达29.1%;添加该助剂后对成纸的白度无影响.当浆料打浆度在30～45°SR时,阳离子化半纤维素对成纸的抗张指数和撕裂指数提高较大,耐破指数在打浆度为30～50°SR时提高较大.     

水预水解提取半纤维素对碱法桉木浆H_2O_2漂白的影响

由水预水解提取半纤维素后的桉木片和原木片分别通过烧碱-蒽醌法和硫酸盐法蒸煮获得4组浆料,分析了浆料中铜、锰、铁含量,比较了不同条件H_2O_2漂白后的浆料白度及H_2O_2消耗.研究结果表明,水顶水解提取半纤维素的木片,其碱法浆在H_2O_2漂白中的可漂性明显提高,相同漂白条件下浆料白度提高了4-7个白度单位,漂至相同白度时H_2O_2的消耗量明显降低.木片的水预水解使其碱法浆中的Cu、Mn含量明显降低.对浆料进行漂前预处理使4种浆料样品中的金属元素含量处于相近水平,但相同条件下H_2O_2漂白后白度有明显差别.     

生物精炼在造纸工业中的应用模式和发展趋势

对生物精炼技术的概念和木材生物精炼工厂（IFBR）的路线进行了阐述。对传统硫酸盐法制浆造纸工厂如何转化为综合林业生物精炼工厂的原理进行了分析,总结出三种转化类型。详细介绍了近中性预抽提/制浆模式、酸性预水解/制浆模式和碱预处理纤维素糖化发酵生产乙醇模式。保留制浆造纸生产的综合林业生物精炼工厂将是近期主要的发展模式,可为传统造纸工厂带来额外的经济收益。在传统制浆之前进行预抽提,分离出的抽提液可以用来生产乙醇和乙酸及其它化学品,抽提后的木片进行制浆和漂白,对纸浆强度和光学指标没有不良影响,新增用于改造的投资回报率达到7.1%～13%。根据我国造纸工业特点,木材造纸工厂转化为IFBR工厂也将走保留制浆的发展模式;草类原料造纸工厂转化为生物精炼工厂具有一定的优势和可行性。     

Integrated Forest Biorefinery: Value-added Utilization of Dissolved Organics in the Prehydrolysis Liquor of Prehydrolysis Kraft (PHK) Dissolving Pulp Production Process

The concept of integrated forest biorefineries(IFBRs) has gained significant interest.The prehydrolysis kraft(PHK) dissolving pulp production process is a suitable example of IFBR concept for the production of dissolving pulp and utilization of dissolved hemicelluloses,acetic acid,and lignin in the prehydrolysis liquor(PHL).This review paper highlights recent progress related to the recovery and utilization of dissolved organics(e.g.,hemicelluloses,acetic acid,and lignin) in the PHL of the PHK dissolving pulp production process.Integrated multi-step recovery and separation processes have been developed for this purpose to accommodate the complex nature of the PHL.Potential products,including xylan-based compounds,acetic acid,and lignin,are also discussed in detail.     

绿液预处理改进硫酸盐法制浆研究进展

介绍了绿液预处理技术改进传统硫酸盐法制浆的研究进展,包括绿液预处理对硫酸盐浆成浆质量的影响,对硫酸盐制浆过程化学品消耗的影响,以及添加蒽醌(AQ)对预处理效果的影响.介绍了对绿液预处理过程中各化学组分的反应行为的分析.     

桉木RDH硫酸盐法制浆性能的研究

研究了桉木RDH（快速置换加热）硫酸盐浆的制浆性能，对桉木RDH硫酸盐法制浆时，用碱量、H－因子、白液的硫化度以及在温黑液预处理段温黑液的活性碱浓度和硫化度等蒸煮条件，对最终制浆结果的影响进行了研究。结果表明：与常规硫酸盐法制浆相比，RDH硫酸盐法制浆时的用碱量相对较高（常规KP法和RDH法的用碱量分别为14％和15％，Na2O计），但RDH纸浆的硬度较低（分别为17．0和11．7）；在纸浆达到相似或较低硬度的情况下，RDH法制浆可以缩短蒸煮时间，或在相同的H－因子下，降低纸浆的卡伯值；在一定的范围内提高白液蒸煮段白液的硫化度，可以降低RDH纸浆的卡伯值或提高纸浆的得率，在温黑液预处理段，温黑液的活性碱浓度和硫化度会对RDH纸浆的最终结果产生较大的影响，对纸浆物理性能的分析结果表明，RDH纸浆在低卡伯值条件下也具有较高的强度性能，但与常规硫酸盐浆相比，RDH纸浆的撕裂强度相对较高耐抗张强度相对较低。     

HACCP体系在热风干制荔枝果肉加工中的应用

为了确保热风干制荔枝果肉的品质和安全,应用危害分析与关键控制点(HACCP)原理对荔枝果肉热风干制加工过程中各工序及其潜在危害进行分析,确定了原料、热烫、护色、热风干燥、检验、包装、运输销售7个工序为关键控制点,建立了相应工序的关键控制临界值,并制定了危害分析表和HACCP工作表。     

玉米芯半纤维素提取、乙酰化改性及结构表征

以玉米芯为原料提取半纤维素,并对所提取的玉米芯半纤维素进行乙酰化改性。采用超声辅助碱法提取玉米芯半纤维素,浓硫酸（H₂SO₄）和单质碘（I₂）共催化玉米芯半纤维素进行乙酰化改性;采用红外光谱（IR）、热重分析（TGA）和核磁共振光谱（NMR）对玉米芯半纤维素及其乙酰化产物进行表征。玉米芯半纤维素得率和提取率分别为33.7%和81.0%,其中半纤维素含量为85.3wt%,乙酰化产物产率和取代度（DS）分别为84.6%和1.27。超声辅助有效缩短了碱法提取玉米芯半纤维素的时间,且玉米芯半纤维素得率和提取率均得到提高。H₂SO₄和I₂是半纤维素乙酰化改性的高效共催化体系,IR和NMR结果表明半纤维素被成功改性,改性产物中存在乙酰基,TGA分析表明乙酰化产物热稳定性增加,且DS值适中,有望进一步用于制备可生物降解的食品包装材料。     

半纤维素热水预提取及其沉积对竹浆性能的影响

本论文以南方混合竹片为原料,考察了半纤维素热水预提取及其沉积对竹子制浆造纸性能的影响.结果表明:半纤维素热水预提取降低了蒸煮后纸浆的卡伯值,得率和耐破强度也相应降低,但纸页的撕裂强度提高;相对于未沉积半纤维素的纸浆,预处理后竹片制得的纸浆沉积半纤维素后,得率、卡伯值和机械强度均升高.在本实验条件下,热水预提取较佳的工艺条件为升温时间30min、保温时间30min、最高温度150℃;后续蒸煮的较佳工艺条件为用碱量16%,硫化度25%,最高温度165℃,升温90min,保温60min.     

思茅松硫酸盐漂白浆纤维细胞加填技术研究

以思茅松硫酸盐漂白浆为原料,探讨了加填操作参数对思茅松硫酸盐漂白浆纤维细胞内加填效果的影响。结果表明：“现场加填法”是适宜于思茅松硫酸盐漂白浆细胞内加填的方法,实验条件下,经加填的纸浆灰分含量可达16．45％～25．15％．