Sulfite-Formaldehyde Pulping and Oxygen Delignification of Wheat Straw

In this study,wheat straw pulp was prepared by sulfiteformaldehyde(SF) pulping combined with oxygen delignification to develop a sustainable methodology for chemical pulping of straw materials.The bleachability of oxygen-delignified SF pulp was also evaluated by hypochlorite bleaching.The results indicated that the Na_2SO_3 charge played an important role in lignin removal during SF pulping as well as oxygen delignification.The efficiency of oxygen delignification of wheat straw SF pulp was markedly high.After the oxygenation stage,the Kappa number decreased by over 50%(the original Kappa number of SF pulp was lower than 30) when the Na OH charge was in the range of 3%~5%.The optimal conditions for preparing bleached pulp via combined SF pulping and oxygen delignification involved the use of 12% of Na_2SO_3 and 3% of Na OH,respectively.Pulp with relatively high brightness,a low Kappa number,as well as an acceptable viscosity could be obtained when oxygen-delignified SF pulp was bleached with hypochlorite under a low active chlorine dosage.

Oxidation inhibition of sulfite in dual alkali flue gas desulfurization system

A laboratory-scale well-mixed thermostatic reactor with continuously blasting air was used to investigate the oxidation inhibition of sulfite in dual alkali flue gas desulfurization （FGD） system. The effects of operating parameters such as pH value and catalyst concentration on the oxidation were studied. Sodium thiosulfate was used in the system, and was found that it significantly inhabited the sulfite oxidation. In the absence of catalyst, sodium thiosulfate at 12.67 mmol/L had an inhibition efficiency of approximately 98%. While in the presence of catalyst, sodium thiosulfate at 26.72 mmol/L had an inhibition efficiency less than 85.0%. The oxidation reaction order of sulfite in the sodium thiosulfate was determined to be -1.90 and 4）.55 in the absence and presence of the catalyst, respectively. Apparent activation energy of oxidation inhibition was calculated to be 53.9 kJ/mol. Pilot tests showed that the consumption rate of thiosulfate agreed well with the laboratory-scale experimental results.

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.

Effect of cooking conditions and oxygen-delignification on Bambusa tulda kraft pulping using experimental design and regression models

This study was concerned on the influence of cooking liquor parameters i.e. active alkali （AA） and sulfidity, on the properties of pulp produced from Thai bamboo by means of multivariate analysis. The investigated pulp properties were cooking yield and viscosity. The experiments were performed according to a face centered cube experimental design. Then, multiple linear regression （MLR） of independent and dependent variables were conducted with SPSS software using least square method. In order to optimize process, Pareto-Optimality method was employed. The obtained regression models were characterized by both descriptive and predictive ability （R^2 ≥ 95% and Rcv^2 ≥ 93%） and allowed the kraft pulping process with an acceptable viscosity （ 1110- 1 190 ml/g） and a total yield about 50% at a sulfidity level of 20-30% with 18% AA. Results indicated that high sulfidity at a lower AA could get high viscosity and relatively low kappa number for pulps. Also oxygen delignification was studied in this research.

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.

针叶木浆制备莱赛尔级溶解浆工艺探究

实验以针叶木浆为原料,针对标莱赛尔纤维专用溶解浆性能指标,探究了冷碱抽提、纤维素酶处理及两者联合预处理对浆料特性的影响,优选出针叶木浆制备Lyocell级溶解浆的工艺。结果表明,采用先碱处理后纤维素酶处理两步法,可以显著提升浆料的性能,最优条件下所得溶解浆中α-纤维素含量达到97.1%、聚合度为663.2、灰分含量0.03%、铜离子含量1.2mg/kg、白度90.2%ISO。

烧碱法协同乙酸钠制浆及其碱回收实验研究

在传统烧碱法制浆的基础上添加乙酸钠进行制浆,探究不同乙酸钠用量、氢氧化钠用量、蒸煮温度和保温时间对成浆效果的影响,得到了乙酸钠制浆的最佳工艺参数,从而开发了一种得率高、成浆效果良好的新型制浆工艺。研究结果表明,氢氧化钠和乙酸钠用量分别为木片质量的20%和10%时,并在165℃下保温3 h,纸浆得率为51.49%,比传统的烧碱法制浆的纸浆得率(40.12%~43.41%)提高了8.08%~11.37%;将所得纸浆进行抄纸后,其纸张具有良好的力学性能;同时,其蒸煮后所得黑液经过燃烧和石灰碱化处理后,碱回收率较高。这证明了烧碱法协同乙酸钠制浆工艺的可行性,从而促进制浆造纸的技术进步。

化机浆碱回收工艺设备的研发与应用

根据化机浆生产线大型化趋势和环保政策导向,化机浆污水生化处理已不能满足排放要求,需要适用的碱回收工艺设备满足化机浆污水处理需求,汶瑞机械(山东)有限公司研发的碱回收蒸发和苛化工艺设备,历经多个项目实际使用和不断完善,成为经济实用、成熟可靠的化机浆污水处理碱回收系统技术设备。

NaOH-AQ法蒸煮过程中用碱量对剑麻浆纤维力学性能的影响

本研究对烧碱-蒽醌(NaOH-AQ)法蒸煮过程中不同用碱量下的剑麻浆纤维力学性能差异进行了系统分析。同时,对其纤维形态、微纤丝角、结晶度以及木质素含量进行研究,以探究其与单根纤维力学性能的协同效应。结果表明,随着用碱量从12%升至30%,剑麻浆单根纤维的弹性模量由12.60 GPa降至6.99 GPa;柔软度指数由0.54×10^(17)/(N·m^(2))增至3.15×10^(17)/(N·m^(2));细胞壁硬度在用碱量18%时达到最大值449.20 MPa,纸张的零距抗张指数在用碱量15%时达到最大值177 N·m/g。

云杉预水解硫酸盐法制备Lyocell纤维用溶解浆

针对目前国产Lyocell纤维用溶解浆质量不高、来源不稳定等问题,以俄罗斯云杉为原料,采用预水解硫酸盐蒸煮工艺制备了高品质Lyocell纤维用溶解浆粕。考察了预水解、硫酸盐蒸煮、二氧化氯、过氧化氢漂白及酸处理等工艺对溶解浆粕关键技术指标(如α-纤维素含量、聚合度、白度、灰分以及金属离子含量)的影响。试验结果显示,保温时间90 min、温度150℃、固液比1∶4为最佳预水解条件,碱用量24%、硫化度30%、保温时间180 min为最佳蒸煮条件。在最佳预水解和蒸煮条件下制备的浆料经过二氧化氯质量分数1.5%漂白、冷碱质量分数12%抽提、过氧化氢质量分数5%漂白和乙酸质量分数6%处理后,所得浆粕的α-纤维素含量为96%,白度为85%,聚合度为647,灰分为0.06%,铁离子含量为6 mg/kg,铜离子含量为3 mg/kg。偏光显微镜观察显示,该浆料在90℃的N-甲基吗啉-N-氧化物(含水率为13.3%)中30 s即可完全溶解。

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。

基于常温干燥法的纤维素基泡沫制备及性能分析

传统的石油基泡沫难以降解,因而带来环境污染和安全问题。纤维素基泡沫借助其可生物降解的天然特性,逐渐成为研究热点。然而,目前的成型技术在很大程度上依赖于干燥条件(如冷冻干燥和超临界干燥),存在干燥耗时长、成本高的问题,因而难以实现泡沫的规模化生产。为解决此问题,提出一种常温干燥制备可再生纤维素基泡沫的新方法。以纸浆纤维为主料、纳米纤维素为黏结剂、聚乙烯醇作为纤维分散剂和泡沫助剂,经过充分混合、发泡、排水和干燥后,制成纤维素基泡沫。最后,测试泡沫密度、孔隙率,分析导热性能、力学性能。结果表明:制备的纤维素基泡沫具有密度低((0.015±0.002)~(0.028±0.004)g/cm^(3))、孔隙率高(>98%)、热导率低((0.060±0.003)~(0.069±0.003)W/(m·K))等特点。纤维素基泡沫在80%应变下的最大应力值为59.366 kPa,比其他文献报道的类似纳米纤维素基泡沫高37.1%。未来,纤维素基泡沫有望替代石油基泡沫,在冷链运输过程中对产品进行缓冲保护和隔热保温。

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。

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。

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。

亚硫酸盐蔗渣浆的纤维素酶水解及其机理研究

研究了影响纤维素酶水解亚硫酸盐蔗渣浆的一些影响因素,采用离子色谱、X射线衍射(XRD)、傅里叶红外光谱(FT-IR)和原子力显微镜(AFM)对水解液成分、纤维素超分子结构及纤维形态的变化进行了分析。结果表明,在最适条件下,未漂浆和漂白浆的水解得率分别为74.89%和70.67%,漂白浆的水解得率低于未漂浆。水解产生的纤维二糖的质量浓度随反应进行逐渐降低,其中未漂浆的纤维二糖质量浓度由6 h时的7.95 g/L降到了72 h时的2.44 g/L,漂白浆的纤维二糖质量浓度由6 h时的6.59 g/L降到了72 h时的3.11 g/L。酶解使纤维素结晶度升高,但没有改变晶型。

碱性和中性亚硫酸盐法制浆废液合成木素铁铬盐的研究

对中性亚硫酸钠 -蒽醌法杨木浆废液 (NS L)和碱性亚硫酸钠 -蒽醌法落叶松废液 (AS L)及二者的混合液 (体积比 4∶1 ) (M L) ,作了合成木质素铁铬盐的研究。并与酸性亚硫酸盐法木浆废液 (Ca L)及亚硫酸氢镁法苇浆废液 (Mg L)的合成木质素铁铬盐进行了比较。结果表明 ,浓H2 SO4 用量、反应温度和反应时间是反应的主要影响因素。NS L的适宜反应条件是 :反应温度 :40℃ ;反应时间 :60min ;浓H2 SO4用量 3/ 50 (对 50 %固含量的废液 )。AS L的适宜反应条件是 :反应温度 :50℃ ,反应时间 :70min ,浓H2 SO4 用量 4/ 4 0。M L的适宜反应条件是 :反应温度 :50℃ ;反应时间 :70min ;浓H2 SO4 用量 3/ 4 0。在各自的适宜反应条件下 ,实验用各种废液合成的木质素铁铬盐 ,其全铁和全铬含量 ,都符合国家行业标准的要求 ,络合度的测定值为 :NS L 93 4,AS L 93 0 ,Mg L 90 0 ,M L 86 0 ,Ca L 75 0。