Effects of Mg-based Alkaline Peroxide Bleaching on Physical Properties of Poplar Bleached Chemi-thermomechanical Pulp and Its Influence Mechanism

In this study,Mg O was partially used as an alkali source in the peroxide bleaching process of bleached chemi-thermomechanical pulp(BCTMP).The effects of substitution percentage of Mg O for Na OH on the bulk,optical,and physical properties of bleached pulp,and the main effluent characteristics were analyzed.In addition,the influencing mechanism of Mgbased alkali on the strength properties of the BCTMP was further investigated.Strength properties of the BCTMPs were investigated as a function of charge characteristics,fiber morphology,surface lignin content,relative bonding area,and hydrogen bonds of the BCTMP.The results showed that cationic demand(CD) and chemical oxygen demand(COD_(Cr)) of the bleaching effluent decreased as the substitution percentage of Mg O for Na OH increased; meanwhile,the bulk and optical properties of the BCTMP increased.Nevertheless,the strength properties(tensile,tear,and burst indices) of the bleached pulp decreased as the substitution percentage of Mg O for Na OH increased.The decrease in the fiber charge density and increase in the surface lignin content affected the fiber swelling,resulting in a decline in pulp interfibers bonding strength and further loss of the tensile and burst indices.

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.

THE OXYGEN-ALKALI BLEACHING OF THE STRAW PULP

The influences on the brightness, viscosity and Kappa of the straw pulp under the different oxygen-alkali bleaching conditions have been studied in this paper.

Lignin Extraction from Black Liquor and its Application Prospects in Pulp Mills

This paper summarizes the possible application of lignin extraction from black liquor and the development of lignin extraction technology.Lignin extraction from black liquor is an important,economical method to resolve the bottleneck associated with the recovery boiler and achieve the targeted capacity expansion in pulp mills.A few of key issues must be taken into cosideration when lignin extraction technology is adopted on the industrial scale.

玉米秸秆中还原糖的预提取及其对制浆性能的影响

本研究通过碱(NaOH)和酸(HCl)预处理以提取玉米秸秆中的还原糖,采用扫描电子显微镜观察玉米秸秆预处理前后的形态变化,探究了预处理前后玉米秸秆的制浆性能及纸张强度性能。结果表明,在150℃,NaOH和HCl用量分别为6%,预处理时间120 min条件下,玉米秸秆的酸、碱抽提的还原糖(Trs)得率分别为34.2%和14.5%。其中,酸预处理玉米秸秆在碱用量为12%蒸煮时,纸浆得率最高,为48.1%。此外,酸和碱预处理后纸张撕裂指数分别降低了18%和13%,抗张指数也呈现下降趋势,分别降低了28%和16%,耐破指数分别降低了60%和41%。因此,预处理过程中半纤维素的损失会导致纸张强度性能降低。

基于DPM模型的碱回收炉竹浆黑液雾化数值模拟研究

为高效回收高固含量竹浆黑液的化学品和热能,改善其雾化性能,本研究采用DPM(discrete phase model)模拟研究碱回收炉中高固含量竹浆黑液的雾化性能。通过建立的碱回收炉三维几何模型,采用Fluent软件对碱回收炉进行冷态流场模拟,研究了黑液黏度、雾化锥角及粒径范围对碱回收炉中黑液雾化效果、颗粒分布、熔融物垫层形成的影响。结果表明,增大黑液黏度对液滴破碎影响显著,而对于分散沉降的影响远不及雾化锥角及初始液滴尺寸;碱回收炉前墙上、下二次风之间区域存在结渣风险。液滴粒径大于0.5 mm时,黑液液滴主要受重力作用下沉至垫层,能有效减少气流的机械携带现象。

竹浆碱回收锅炉烟气污染物排放影响因素探析

根据四台竹浆碱回收锅炉的实际运行情况,分析碱回收锅炉污染物排放的影响因素。

福建某金矿选矿尾渣的无害化处置工艺

为切实推进福建某金矿山的可持续发展,本研究在充分结合上游选矿工艺流程及指标的基础上,对选矿尾渣(炭浸尾浆及堆浸渣)处置进行了详细的实验研究。结果表明:对于炭浸尾浆中的含氰废液,采用碱氯化(漂白粉)法破氰工艺,可有效去除其中氰化物,CN-浓度从250 mg/L下降至0.217 mg/L,去除率达99.90%。实验指标成功应用于生产实践,效果同样显著。开发的选矿尾渣无害化处置工艺,即固体废渣(炭浸废渣和堆浸渣)混排用于生态修复,炭浸废水破氰达标后视生产实际回用或外排,极大地节约了矿区尾矿库库容,减少了排土场的占用。生产实践可为同类型金矿山选矿尾渣的末端处置提供基础依据。

综合法二氧化氯和离子膜法氯碱工厂含氯废气处理工艺

结合大型制浆企业化学品工厂的生产特点,重点研究了一种含氯尾气的处理工艺与改造升级。

碱预浸低温硫酸盐法制备竹浆粕及其抗菌性的研究

为了保留竹子的天然抗菌性,以四川慈竹为原料,利用碱预浸低温硫酸盐法和常规硫酸盐法制备竹浆,对两种工艺条件下的浆料性质进行对比,探讨了碱预浸低温硫酸盐法蒸煮的最佳工艺条件。结果表明,最佳碱预浸条件为:预浸温度120℃,NaOH用量12%,渗透剂用量1.75%,预浸时间30 min;预浸后的蒸煮条件:用碱量(以Na2O计)20%,硫化度18%。碱预浸低温硫酸盐法浆粕中α-纤维素含量能够达到91%以上,且较常规硫酸盐法有更好的抗菌性。

我国的木浆和麦草浆黑液碱回收现状

简述了我国制浆黑液碱回收的现状,全面分析了我国木浆与麦草浆碱回收的不同。以我国木浆、麦草浆黑液典型碱回收为实例,对蒸发、燃烧、苛化系统的能耗进行了计算,并分析了碱回收产生的主要产品和副产品。我国木浆黑液碱回收处在世界领先的水平,麦草浆黑液的碱回收具有中国特色,在回收热能治理污染方面虽然发挥了巨大的作用,但与先进的木浆黑液碱回收相比,还有很大的差距,还需要继续努力,不断提高。

碱处理芦苇浆纳米纤维素制备工艺条件优化

采用质量分数55%硫酸水解碱处理芦苇浆制备纳米纤维素,研究反应时间、反应温度和碱处理时间对纳米纤维素得率及其平均粒径变化的影响。单因素试验最优制备条件为碱处理时间1.0 h,反应温度60℃,反应时间2.0 h,纳米纤维素得率为54.50%,平均粒径为156.9 nm;通过傅里叶红外和X射线衍射分析,结果表明碱处理芦苇浆制备纳米纤维素为纤维素Ⅱ型。在单因素试验基础上进行正交优化试验,对纳米纤维素得率而言,正交优化最佳工艺条件为碱处理时间1.0 h,反应温度60℃,反应时间3.0 h,此条件下纳米纤维素得率最高,为55.64%,平均粒径为166.3 nm。

麦草氧碱两段蒸煮黑液性能的研究

对麦草进行NaOH +AQ/NaOH +O2 两段蒸煮 ,研究了氧碱蒸煮段用碱量、最高温度。

棉短绒制绒毛浆H_2O_2-氧碱蒸煮工艺

介绍了棉短绒制绒毛浆的H2O2-氧碱制浆工艺,对比研究了原料预处理及添加Na2CO3对棉绒 制浆得率、纸浆白度及吸水高度的影响。

GC-MS分析碱法草浆造纸废水中的有机污染物组成

碱法草浆造纸废水在酸性条件下经乙醚萃取———K_D浓缩器浓缩 ,采用气相色谱_质谱 (GC_MS)联用仪对其有机污染物进行了分析研究。结果表明 ,该废水中共含有 2 9种有机物 ,其中主要为有机酸类 ,占有机物总量的 5 0 84%。其次为难降解的呋喃类和毒性较大的苯环类有机物 ,它们分别占有机物总量的 2 5 1 2 %和 1 3 5 3 %。

碱预处理对大麻秆浆纤维素性质的影响

采用氢氧化钠溶液对大麻秆浆进行预处理,研究了温度、氢氧化钠浓度、预处理时间对纤维得率、R-10值、聚合度、碘吸附值和纤维素晶型的影响。结果表明:低温下氢氧化钠溶液对分子质量较低的纤维素有较强的溶解能力,温度越低,纤维素可溶的分子质量分布越宽,且纤维素Ⅰ越易通过氢氧化钠溶液的润胀转变为纤维素Ⅱ。适当提高氢氧化钠溶液的浓度有助于浆料中半纤维素及低分子质量纤维素的溶解,有利于纤维素的充分润胀。当氢氧化钠质量分数超过9%时,纤维素的晶型开始明显由纤维素Ⅰ转变为纤维素Ⅱ,导致可及度降低。在预处理时间为1～3h时,预处理时间对纤维得率、R-10值、聚合度、碘吸附值及纤维素晶型等的影响不大。

麦草原料矿质元素在碱法制浆过程中的转移(Ⅰ)

用原子吸收光谱法、SEM-EDAX法研究了麦草原料灰分及矿质元素在碱法制浆过程中的脱除规律。结果表明,麦草原料灰分含量高达8.12%。在实验条件下,随温度升高、时间延长,原料相关成分的溶解,浆得率下降,黑液的固形物及其灰分含量均呈逐渐增加的趋势,保温后期则基本保持平衡;浆中的灰分含量及Ca、Mg、K、Si、Al、Fe等元素的含量则呈先降低而后稍有增加至基本稳定的趋势;上述元素大量转移至黑液中,将对黑液碱回收产生严重干扰。麦草Si的转移率仅为60%～70%,明显低于芦苇、竹子等原料Si的转移率,预示着麦草中Si的某些特殊性;也说明从预处理去除Si等矿质元素的角度来看,采用较低的用碱量、温度及较短时间较为合适。

纤维素酶酶解玉米秸秆新型蒸煮浆的工艺研究

本文以玉米秸秆活性氧固体碱蒸煮浆(木素脱除率82.1%)为原料,用国产纤维素酶(酶活为13.94 FPU/100 mL)进行酶解试验,探索酶解最佳工艺条件。结果显示:底物固液比为0.47%(m/V),酶解pH值为4.70,酶解温度为50℃,酶解时间为72 h时酶解液还原糖含量最大,即糖得率最大,达59.41%。本研究也进行玉米秸秆经不同方法预处理后的酶解实验,结果显示其纤维素酶解效果顺序为:活性氧固体碱蒸煮浆>硫酸盐浆>机械粉碎>未预处理玉米秸秆。

蒸煮助剂对低用碱量硫酸盐法预处理毛竹竹屑的影响

毛竹竹屑经10%低用碱量(以Na2O计)、20%硫化度、160℃下保温1 h预处理,木质素脱除率达到62.35%,预处理物料酶水解48 h葡萄糖和木糖得率分别为56.04%和53.47%。研究了硼氢化钠、三聚磷酸钠、2-蒽醌磺酸钠3种蒸煮助剂对毛竹竹屑10%用碱量硫酸盐预处理的成分以及糖化效果影响,其中2-蒽醌磺酸钠影响最大。在10%用碱量和20%硫化度的预处理液中添加0.15%的2-蒽醌磺酸时,160℃下保温1 h的葡聚糖回收率和木质素脱除率分别为94.93%和68.55%,与空白对比分别提高5.45%和9.94%;预处理物料酶解48 h葡萄糖和木糖得率分别为62.88%和58.97%,与空白对比分别提高12.21%和10.29%。