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.

Acetosolv delignification of marabou (Dichrostachys cinerea) wood with and without acid prehydrolysis

The chemical composition of marabou（Dichrostachys cinerea） wood and its treatment with acetic acid were investigated.Two different treatment approaches,direct acetosolv and combined acid prehydrolysis/acetosolv,were evaluated.The effects of acetic acid concentration（50%,70% and 90%） and temperature（normal boiling temperature and 121°C） on yield of solids,solubilization of lignin and hemicelluloses and recovery of cellulose were evaluated for both treatments.High solubilization of marabou components was observed in the direct acetosolv treatment at 121°C,especially at the highest acetic acid concentration,where around 84.8% of lignin and 78% of hemicelluloses were removed.When the material was subjected to acid prehydrolysis prior to acetosolv treatment,lignin solubilization was improved,especially at low acetic acid concentrations.Above 80% of the solubilized lignin was recovered from the liquors in the direct acetosolv treatment,but the recovery was lower in the combined treatment.Cellulose was well preserved in all the treatment schemes.

Regulation of Superoxide Anion Radical During the Oxygen Delignification Process

In this study, the superoxide anion radicals were generated by the auto-oxidation of 1,2,3-trihydroxybenzene and determined by UV spectrophotometry, and the reaction was found to be facilitated by anthraquinone-2-sulfonic acid sodium salt. The bamboo kraft pulps were treated by the 1,2,3-trihydroxybenzene auto-oxidation method or the 1,2,3-trihydroxybenzene auto-oxidation combined with anthraquinone-2-sulfonic acid sodium salt to show the ef-fect of the superoxide anion radicals during the oxygen delignification of bamboo kraft pulp and the enhancing af-fect of anthraquinone compounds as an additive on delignification. The results indicated that the superoxide anion radicals could react with lignin and remove it from pulp with negligible damage on cellulose, and the an-thraquinone-2-sulfonic acid sodium salt could facilitate the generation of superoxide anion radical to enhance delig-nification of pulps. The oxygen delignification selectivity could be improved using the 1,2,3-trihydroxybenzene auto-oxidation system combined with anthraquinone-2-sulfonic acid sodium salt.

PEROXYACID ENHANCED OXYGEN DELIGNIFICATION OF KRAFT PULP

Effect of peroxyacid (a mixture of peroxymonosulfuric acid and peroxyacetic acid) pretreatment on oxygen delignification of kraft pulp from eucalyptus was studied, and the conditions of pretreatment (e.g. DTPA charge, peroxyacid charge, pretreatment time, pretreatment temperature and pH value) were optimized. The results show that peroxyacid pretreatment prior to oxygen delignification could enhance oxygen delignification of kraft pulp, and result in selective delignification and increased delignified-pulp brightness. The optimum conditions of peroxyacid pretreatment were as follows: peroxyacid charge 3% (on peroxymonosulfuric acid), 60℃, 30min, 12% pulp consistency, pH5.0. Pretreatment with 0.5%DTPA was essential before peroxyacid pretreatment. Under the optimum conditions, the degree of delignification and brightness of final pulp were increased by 12.4% (from 44.9% to 57.3%) and 4.9%(ISO, from 54.0% to 58.9%) respectively while maintaining a similar viscosity of final pulps compared to single oxygen delignification.

INFLUENCE OF NON-PROCESS ELEMENTS ON REED PULP'S CHARACTERS DURING OXYGEN DELIGNIFICATION

A series of Reed Pulps were prepared in which the level of Non-Process Elements(NPEs), including calcium, manganese,copper,iron were seclectively enriched and depleted, these pulps were then oxygen delignification,and the pulps were characterized according to kappa number,viscosity,brightness. The results indicated that the enrichment of NPEs have an important effulence on delignification,pulp viscosity and brightness, iron is the most harmful during oxygen delignification but manganese is just like a kind of aid and can enhance brightness and delignification.

Effect of Glycerol Concentration and Heating Treatment on Delignification and Bioethanol Production of Sago Dregs

The purpose of this paper was to find the suitable condition between glycerol concentration and heating time treatment in the process of delignification and bioethanol production. The production of bioethanol consisted of 3 main stages： hydrolysis, fermentation, and distillation. The best result was obtained by a glycerol concentration of 90% and 15 minutes of heating time. It was used to delignify the lignocellulose biomass waste of the sago dregs originally containing 36.56% of lignin, 37.6% of or-cellulose and 39.51% of holocellulose. Then after being delignificated by 90% of glycerol concentration with 15 minutes heating time, the lignin content decreased to 19.3%, while a-cellulose increased to 39.64% and holocellulose also increased to 62.18%. After the delignification was successful, it was followed by the bioethanol production to produce 25% of bioethanol. This research is expected to overcome the problem of the energy crisis, food crisis, and environmental pollution by the sago dregs.

Ethyl Levulinate Obtained from Lignocellulosic Waste Material with Previous Delignification by Ultrasonic-Assisted Technique

Ultrasound-assisted pretreatment under mild operating conditions has been investigated for intensification of delignification to facilitate the obtaining of ethyl levulinate from biomass. The effect of pH (2 - 12), temperature (30°C - 70°C) and pretreatment time (0 - 120 minutes) has been studied for different biomass samples. The most favorable conditions were basic pH, temperature of 70°C and pretreatment time of 2 h, obtaining values of delignification near 80 percent. The ethyl levulinate is obtained in microwave directly via from samples before and after delignification and analyzed for GC-MS. The results evidenced better yields for the delignified samples.

洗涤效果对桉木化学浆氧脱反应影响的研究

本研究以氧脱前广西桉木硫酸盐化学浆为原料,对不同洗涤情况的未漂浆进行氧脱反应,探讨了不同的洗涤效果对于氧脱浆白度、脱木质素率、降黏率、纸张强度等方面的影响。结果表明,洗涤效果对氧脱浆的黏度影响较大,洗涤更充分的氧脱浆抄造纸张强度,尤其是耐折度有较大提高。

预水解硫酸盐竹浆的漂白工艺研究

本研究以预水解硫酸盐未漂竹浆为原料,采用“氧脱木质素(O)-氯漂(D0)-氧和过氧化氢强化碱抽提(Eop)-氯漂(D_(1))”的漂白工艺制备可用作溶解浆的竹浆。通过优化各工段的处理条件(氧漂白段:氢氧化钠用量2.0%、氧压0.5 MPa、反应时间60 min、反应温度95℃;D0漂白段:二氧化氯用量3.5%、反应时间80 min、反应温度70℃、初始pH值4.0;Eop漂白段:过氧化氢用量1.4%、氧压0.2 MPa、反应时间90 min、反应温度90℃、初始pH值11.5;D1漂白段:二氧化氯用量1.5%、反应时间150 min、反应温度70℃、初始pH值4.0),最终制备白度82.7%、黏度440.0 mL/g、灰分含量0.24%、α-纤维素含量90.92%的竹浆。

低共熔溶剂预处理毛竹制备木质素微球和可发酵糖研究

针对现有木质素微球制备方法普遍存在的产物收率低、成本高和过程复杂等问题,本研究提出了一种多元醇基低共熔溶剂(DES)预处理方法,采用该方法在温和条件(110℃,1 h)下对毛竹进行预处理,木质素脱除率为69.7%,该部分脱除木质素可通过简单方法回收,其回收率可达97.1%。通过扫描电镜(SEM)、凝胶渗透色谱(GPC)、核磁共振(NMR)、X射线衍射(XRD)和Zeta-sizer进一步研究发现,采用该体系获得的木质素结构完整且均以微球形态存在,其粒径随预处理温度的升高而增大(1102~6187 nm)。SEM结果显示,经本研究DES预处理回收的木质素微球表面光滑,分散性好,不同于以往DES预处理体系获得的块状或片状木质素;GPC结果表明,该方法回收的木质素结构保存完整,且木质素微球的粒径与木质素分子量负相关。此外,不同预处理条件下,预处理物料纤维素回收率均达90%以上,聚合度显著下降,因而增加了纤维素酶与底物的接触面积,纤维素可消化性大幅提升。因此,氯化胆碱/1,4-丁二醇(BDO)/氯化铝三元DES预处理体系,在竹材木质素、纤维素和半纤维素分离的同时,得到了微米级球状的木质素,实现了木质素微球的一锅法制备,并联产可发酵糖。

脱木素方法对木材吸附亚甲基蓝的影响

【目的】以巴沙木(Ochroma pyramidale)为原材料,使用不同试剂对其进行脱木素处理,探讨不同脱木素木材对亚甲基蓝(MB)的吸附性能。【方法】采用单因素分析方法,考察了初始质量浓度、接触时间、环境温度、初始pH值对3种脱木素木材吸附亚甲基性能的影响,并对其吸附动力学进行了研究。【结果】脱木素提高了木材的孔隙率和表面活性官能团含量。按照方法1得到的脱木素木材(DW1)和方法2得到的脱木素木材(DW2)对亚甲基蓝的吸附效果均明显优于方法3得到的脱木素木材(DW3),这说明脱木质素方法对木材吸附亚甲基蓝具有显著影响。在35℃、MB溶液质量浓度30 mg·L^(-1)、pH=10条件下,DW1对亚甲基蓝的吸附效果最好,最大吸附容量为12.47 mg·g^(-1)。脱木素木材对亚甲基蓝的吸附过程更符合准二级动力学模型和Langmuir吸附等温方程。【结论】与天然木材相比,脱木素木块可以提高对亚甲基蓝的吸附量,且不同脱木素方法得到的木块对亚甲基蓝的吸附效果有所不同。低价、简单处理的脱木素木块在水处理方面具有很大的潜在价值。

Structure and mechanical properties of windmill palm fiber with different delignification treatments

The removal of lignin from natural cellulose fibers is a crucial step in preparing high-performance materials,such as compressed high-toughness composites.This process can eliminate non-cellulosic impurities,create abundant compressible pores,and expose a greater number of active functional groups.In this study,biomass waste windmill palm fiber was used as the raw mate-rial to prepare holocellulose fibers through various chemical treatments.The structure,chemical composition,Fourier transform infrared spectroscopy analysis,X-ray diffraction analysis,ther-mal properties,and mechanical properties,particularly fatigue performance,were studied.The sodium chlorite treated fiber had the highest crystallinity index(61.3%)and the most complete appearance structure.The sodium sulfite treated fiber had the highest tensile strength(227.34±52.27)MPa.Hydroxide peroxide treatment removed most of the lignin and hemicellulose,increas-ing the cellulose content to 68.83%±0.65%.However,all the chemical treatments decreased the thermal property of the fibers.

Flame Retardant Material Based on Cellulose Scaffold Mineralized by Calcium Carbonate

Wood-based functional materials have developed rapidly.But the flammability significantly limits its further application.To improve the flame retardancy,the balsa wood was delignified by NaClO2 solution to create a cellulose scaffold,and then alternately immersed in CaCl_(2) ethanol solution and NaHCO3 aqueous solution under vacuum.The high porosity and wettability resulting from delignification benefited the following mineralization process,changing the thermal properties of balsa wood significantly.The organic-inorganic wood composite showed abundant CaCO_(3) spherical particles under scanning electron microscopy.The peak of the heat release rate of delignified balsa-CaCO_(3) was reduced by 33%compared to the native balsa,according to the cone calorimetric characterization.The flame test demonstrated that the mineralized wood was flame retardant and selfextinguish.Additionally,the mineralized wood also displayed lower thermal conductivity.This study developed a feasible way to fabricate a lightweight,fire-retardant,self-extinguishing,and heat-insulating wood composite,providing a promising route for the valuable application of cellulosic biomass.

Optimization and Characterization of Cellulose Extraction from Grevillea robusta (Silky Oak) Leaves by Soda-Anthraquinone Pulping Using Response Surface Methodology

Response surface methodology (RSM) using the central composite design (CCD) was applied to examine the impact of soda-anthraquinone pulping conditions on Grevillea robusta fall leaves. The pulping factors studied were: NaOH charge 5% to 20% w/v, pulping time 30 to 180 minutes, and the anthraquinone charge 0.1 to 0.5% w/w based on the oven-dried leaves. The responses evaluated were the pulp yield, cellulose content, and the degree of delignification. Various regression models were used to evaluate the effects of varying the pulping conditions. The optimum conditions attained were;NaOH charge of 14.63%, 0.1% anthraquinone, and a pulping period of 154 minutes, corresponding to 20.68% pulp yield, 80.56% cellulose content, and 70.34% lignin removal. Analysis of variance (ANOVA), was used to determine the most important variables that improve the extraction process of cellulose. The experiment outcomes matched those predicted by the model (Predicted R2 = 0.9980, Adjusted R2 = 0.9994), demonstrating the adequacy of the model used. FTIR analysis confirmed the elimination of the non-cellulosic fiber constituents. The lignin and hemicellulose-related bands (around 1514 cm−1, 1604 cm−1, 1239 cm−1, and 1734 cm−1) decreased with chemical treatment, indicating effective cellulose extraction by the soda-anthraquinone method. Similar results were obtained by XRD, SEM and thermogravimetric analysis of the extracted cellulose. Therefore, Grevillea robusta fall leaves are suitable renewable, cost-effective, and environmentally friendly non-wood biomass for cellulose extraction.

Isolation and Characterization of Cellulose Nanofiber(CNF)from Kenaf(Hibiscus cannabinus)Bast through the Chemo-Mechanical Process

The present work emphasizes the isolation of cellulose nanofiber(CNF)from the kenaf(Hibiscus cannabinus)bast through a chemo-mechanical process.In order to develop high CNF yield with superior properties of CNF for improving compatibility in varied applications this method is proposed.The fiber purification involved pulping and bleaching treatments,whereas mechanical treatment was performed by grinding and high-pressure treatments.The kraft pulping as a delignification method followed by bleaching has successfully removed almost 99%lignin in the fiber with high pulp yield and delignification selectivity.The morphology of the fibers was characterized by scanning electron microscopy,which showed a smooth surface,fiber bundles,gel-shaped nanofiber,and an average size of 94.05 nm with 69%of CNF in 34–100 nm size.The chemo-mechanical process exhibited a more crystalline nature in CNF than pulp kenaf.The low zeta potential values exhibit the distribution of fibrils and colloidal suspension stability without any further agglomeration.A lower concentration of CNF is less stable exhibiting the product agglomeration.Therefore,the chemo-mechanical process for the isolation of CNF(Hibiscus cannabinus)from kenaf involves sustainable,low-cost,non-toxic,and cheap alternatives than other traditional methods.

慈竹硫酸盐法蒸煮历程的研究

本研究以慈竹为研究对象,对其进行化学组分分析,研究了其在硫酸盐法蒸煮过程中木质素含量、综纤维素含量和聚戊糖含量的变化规律,揭示蒸煮历程。结果表明,慈竹中纤维素、木质素和半纤维素的含量分别为44.35%、25.88%和28.27%,是一种优良的非木材造纸纤维原料。慈竹硫酸盐法蒸煮的脱木质素过程分为3个阶段,分别为大量脱木质素阶段、补充脱木质素阶段、残余脱木质素阶段。在大量脱木质素阶段,木质素脱除率达46.40%,碳水化合物降解率为28.11%,聚戊糖溶出率为48.63%;在补充脱木质素阶段,木质素脱除率达89.72%,碳水化合物降解率为38.71%,聚戊糖溶出率为97.93%;残余脱木质素阶段,木质素脱除率为96.14%,碳水化合物降解率达38.82%,聚戊糖溶出率94.39%。

不同溶剂辅助碱性过氧化氢脱除木质素的研究

为了探究木质纤维原料在不同有机溶剂辅助碱性过氧化氢条件下脱除木质素的效果,以碱性过氧化氢体系(AHP)为参照,考察了乙醇碱性过氧化氢(EAHP)、二氧六环碱性过氧化氢(DAHP)对杨木机械浆脱除木质素后的组分变化。通过高效液相色谱(HPLC)、傅里叶变换红外光谱(FI-IR)、凝胶渗透色谱(GPC)、核磁共振磷谱(^(31)P NMR)表征分析了碱木质素(AL)、碱性过氧化氢木质素(AHPL)、乙醇碱性过氧化氢木质素(EAHPL)和二氧六环碱性过氧化氢木质素(DAHPL)的化学结构、分子质量和羟基含量的变化。研究结果表明:3种反应体系均导致脱木质素后物料得率不同程度降低,并导致了大量半纤维素的溶出。与AHP、DAHP相比,EAHP更有利于保存纤维素和溶出较多的木质素,木质素脱除率最高达65%。与AL相比,AHPL、EAHPL、DAHPL红外光谱峰型基本一致,均属于GS型。制备的木质素数均分子质量(M_(n))最小为4672 g/mol,分散性较好,酚羟基的量较少,但是脂肪族羟基和羧基羟基的量较高,最高值分别为14.95和1.25 mmol/g。

氧漂桉木硫酸盐浆臭氧漂白工艺研究

采用硫酸盐法制备桉木硫酸盐浆,经氧脱木质素处理后,对其进行臭氧漂白工艺的研究。探究臭氧漂白过程中浆浓、漂白时间、pH值、臭氧用量等对纸浆漂白性能及成纸性能的影响,得到较优的漂白工艺条件。结果表明,当浆浓为35%、漂白时间3 min、臭氧用量0.9%和pH值为2.0时,所得纸浆白度为76.9%ISO、纸浆黏度为535 mL/g、纸浆Kappa值为2.71,成纸抗张指数、耐破指数、撕裂指数和耐折度分别为57.4 N·m/g、4.77 kPa·m^(2)/g、7.95 mN·m^(2)/g和89次。

硫酸盐竹浆氧脱木质素强化的工艺研究

本研究通过改变HO·与O_(2)^(-)·的“平衡”状态,以提高氧脱木质素过程中酚盐阴离子数量,进而提高氧脱木质素的脱木质素效率及脱木质素选择性。合成了一种在氧脱木质素过程中使用的氧脱木质素强化助剂(S),并对助剂S与H_(2)O_(2)、NaNO_(3)、蒽醌(AQ)就氧脱木质素的强化效果进行了较为详实的对比研究。结果表明,助剂S、H_(2)O_(2)、NaNO_(3)对氧脱木质素的强化均有一定效果,其中助剂S强化效果最佳,AQ的添加对氧脱木质素没有显著的强化效果。当助剂S用量为1.0%时,脱木质素率达57.3%,脱木质素选择性可达4.2。

不同预处理方法对木材细胞壁孔隙结构影响

【目的】探究水分所引发的木材细胞壁孔隙结构变化,并与微波处理、脱木质素处理等预处理方法进行比较,为木材改性提供科学依据。【方法】将20 mm(径向)×20 mm(弦向)×5 mm(轴向)的杨木和杉木试材分别通过泡水1 h和1个月的方法进行水分处理,在500 W条件下微波处理18 min,在酸性条件下使用亚氯酸钠脱除试材中部分木质素。通过扫描电子显微镜和氮气吸附测试表征处理材的细胞壁微观形貌与孔隙结构,比较不同处理方法对细胞壁厚度、比表面积、孔径分布及孔体积等的影响。【结果】水分处理后,杨木和杉木的细胞壁增厚,水分处理1 h试材的比表面积分别从1.535和1.154 m^(2)/g增加到2.488和2.336 m^(2)/g,水分处理1个月的试材比表面积进一步增加到2.822和2.940 m^(2)/g。水分处理杨木试材在微、介孔范围内形成新的孔隙(造孔),且存在孔径增大(扩孔)现象。对于水分处理杉木试材,处理时间较短时其微孔范围内孔体积变化主要表现为扩孔效应,随着时间增加同时具有造孔和扩孔现象。在介孔范围中由于水溶性抽提物的脱除产生较大孔隙,并导致孔径的重新分布。微波处理杨木和杉木试材的细胞壁厚度和比表面积变化同与水分处理类似,处理后杨木试材中产生部分微孔,且杨木介孔及杉木孔径分布都表现为扩孔。脱木质素处理杨木和杉木的细胞壁厚度分别减少了1.79%和0.53%,但比表面积均增加,杉木试材中的微孔增加,其他孔径分布变化均因扩孔所致。【结论】水分处理能够改变木材细胞壁孔隙结构,杨木和杉木泡水1 h和1个月的作用效果与质量损失率分别为1.29%和3.33%的微波处理,以及脱除率分别为10.94%和8.06%的脱木质素处理相当,并且具有独特的孔径分布变化规律。3种处理方法由于作用机理不同,增大孔体积的方式在不同树种的不同孔径范围内不尽相同。本研究为选择科学高效的木材预处理方法提供了参考。