STUDY OF COORDINATED PRETREATMENT OF XYLANASE AND LACCASE ON SODA-AQ WHEAT STRAW PULP BEFORE CEH BLEACHING

Coordinated pretreatment of xylanase and laccase on Soda-AQ wheat straw pulp before CEH bleaching was studied. Results show: Pretreatment of xylanase and laccase has better effect than of sole xylanase and sole laccase; Coordination can increase pulp brightness and bleachability, improve pulp filterability of water, lighten degree of effluent pollution in bleaching workshop, and develop overall strength properties of bleached pulp.

Cleaner Production of Wheat Straw Pulp HUANG

A pulping method using NH4OH with less amount of KOH as cooking liquor on wheat straw was developed. KOH could reduce consumption of NH3 and cooking time for its strong alkalinity. The effects of various pulping conditions such as composition of cooking liquor, liquid-to-solid ratio, maximum temperature, cooking time to the maximum temperature and cooking time at the maximum temperature were studied. Experimental results indicated that the rate of delignification was 85.12% and the pulp yield was 49.65% under suitable pulping conditions. It looks promising to use black liquor containing nitrogen, phosphorus, potassium and organic substance as fertilizer resources for agricultural production. A new pattern of ecological cycling may be set up between paper industry and farming.

Pulping of Wheat Straw with Caustic Potash-Ammonia Aqueous Solutions and Its Kinetics

A pulping technology of wheat straw with aqueous ammonia and diluent caustic potash was investigated.Because its strong alkalinity, the addition of caustic potash not only reduced the quantity of NH3 consumed and cooking time, but also enriched the black liquor with nutrients such as potassium and nitrogen, which could be used as fertilizer for agriculture. Various pulping conditions including composition of cooking liquor, liquor-to-solid ratio,maximum cooking temperature, time to reach the maximum temperature and time at the maximum temperature were studied systematically to determine the suitable pulping conditions. Results of the cooking course showed that there were three distinct delignification phases, namely, the bulk delignification phase from the beginning of cooking to 100 ℃, the supplementary delignification phase from 100 ℃ to 155 ℃ for 45min and the third delignification phase till the end of cooking. The rate of delignification was found to be first order with respect to residual lignin and 0.34 order with respect to [OH-]. The activation energy of the delignification reaction was 29.75 kJ·mol-1 and the rate equation of delignification was also obtained.

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.

Pulping of Wheat Straw with Caustic Potash-Ammonia Aqueous Solutions and Its Kinetics

A pulping technology of wheat straw with aqueous ammonia and diluent caustic potash was investigated. Because its strong alkalinity, the addition of caustic potash not only reduced the quantity of NH3 consumed and cooking time, but also enriched the black liquor with nutrients such as potassium and nitrogen, which could be used as fertilizer for agriculture. Various pulping conditions including composition of cooking liquor, liquor-to-solid ratio, maximum cooking temperature, time to reach the maximum temperature and time at the maximum temperature were studied systematically to determine the suitable pulping conditions. Results of the cooking course showed that there were three distinct delignification phases, namely, the bulk delignification phase from the beginning of cook- ing to 100℃, the supplementary delignification phase from 100℃ to 155℃ for 45min and the third delignification phase till the end of cooking. The rate of delignification was found to be first order with respect to residual lignin and 0.34 order with respect to [OH - ]. The activation energy of the delignification reaction was 29.75kJ·mol-1 and the rate equation of delignification was also obtained.

BIOPULPING OF WHEAT STRAW WITH PHANEROCHAETE CHRYSOSPORIUM

Wheat straw was cut into a certain size range and treated with a strain of the white rot fungus Phanerochatete Chrysosporium for 5 days before subjected to a chemi-mechanical treatment. Chemical analyses revealed the effects of the white rot fungus on the wheat straw components. SEM was applied to observe the changes in fiber micromorphological structures. CODcr of the effluent from the sulfonation treatment of wheat straw was also discussed. Handsheets made from the treated and untreated wheat straw exhibited different optical and physical properties after chemi-mechanical pulping.

CHARACTERISTICS OF BENTONITE AND ITS SYNERGISTIC RETENTION EFFECT WITH CPAM ON WHEAT STRAW PULP

The various properties of bentonite samples with different sources and their synergistic retention effect with CPAM on wheat straw pulps were investigated. The investigated properties of bentonite included adsorptive capacity based on methylene blue, cation-exchange capacity, swelling volume, colloidal volume, particle size and charge properties. The results show that particle size is the most important properties of bentonite for its synergistic retention effect with CPAM. Using Wyoming type sodium bentonite without drying after modification can obtain the excellent furnishes retention.

XYLANASE PREBLEACHING ON NaOH-AQ WHEAT STRAW PULP

Before calcium hypochlorite bleaching (H) and chlorination,alkaline extraction, calcium hypochlorite three-stage-bleaching (CEH),we used a kind of hemicellulase, xylanase, to treat wheat straw pulp from Gaoyou Papermill. Xylanase pretreatment contained tow stages, the first stage was xylanase treatment, which was followed by alkaline extraction, the second stage. The xylanase could act on partial lignin and carbohydrate, chiefly xylan. The following alkaline extraction could dissolve something that could not be removed during the first stage. The result of pretreatment was to facilitate penetration of bleaching chemicals, to reduce effective chlorine consumption and to lower pollution loading of bleaching effluent. In the case of these two bleaching processes, the enzymatic pretreatment substantially enhanced the optical properties of the pulps. To calcium hypochlorite bleaching, strength properties of pulps were improved.

Mono Ethanol Amine (MEA) Pulping of Wheat Straw: An Environmentally Friendly Suggestion for the Fluff Pulp Production

This research aimed to investigate the effect of pulping conditions and refining intensities of wheat straw to be recommended for fluff pulp production.For this purpose,mono ethanol amine(MEA)was selected as a de-lignification agent at three levels of 50:50,25:75,and 15:85(MEA/water,W/V%),and soda-AQ 14 W/V%was used as a reference pulping.To investigate the optimal refining intensity,the obtained pulp was passed through a single disk laboratory refiner from 0 to 6 times and in two different consistencies(1.5 and 2.5 W/V%).Total yield,kappa number,ash content,and the Schopper-Riegler(SR°)freeness of the prepared pulps were investigated.Finally,hand sheets with a targeted basic weight of 70 g/m^(2) were made according to the related standards.The hand sheets were characterized using Fourier transform infrared(FTIR)spectroscopy and a field emission scanning electron microscope(FE-SEM).Sheet density,brightness,and mechanical properties such as burst,tensile,and tear indices were also investigated.The FE-SEM photographs showed that the texture of the hand sheet became denser as the refining intensity increased.External fibrillation on the surface of the fibers was also observed,especially on those refined with 2.5%consistency.The results of the chemical composition of wheat straw indicated that wheat straw containing a high percentage of holocellulose is an excellent candidate for the production of fluff pulp.The total yield and kappa number of MEA pulps increased with the decrease in MEA concentration.FTIR results indicated the presence of a peak related to amino groups in the pulp related to MEA pulp.The results also indicated that the mechanical properties of the papers,except for the tear index,were enhanced as the intensity of refining and the pulp consistency during refining increased.

Soda-AQ法麦草浆OA/QP_o漂白

对麦草Soda-AQ浆的OA/QPo漂白进行了研究。结果表明:Soda-AQ麦草浆在氧脱木素过程中,脱木素率为44.06%,粘度降低率为11.91%;A/Q预处理段的pH值对后续的漂白影响很大,选取A/Q预处理初始pH值在3.0～3.5之间比较合适;A/Q预处理能有效地控制浆中的金属离子分布,当Cu<30mg/kg和Mn<30mg/kg时,对氧漂和过氢化氢漂白有较好的效果,而Fe离子含量的控制相对来说没有那么重要;在压力H2O2漂白中,加压时间40min已经足够,纸浆的白度可达到81.59%ISO,纸浆的粘度为653.0mL/g。

麦草浆中木质素含量对防油剂作用效果的影响

在含氟防油剂经济用量范围内,针对麦草高得率浆抄造纸张防油效果不理想的问题,本研究对麦草高得率浆进行氧脱木质素处理,得到一系列不同卡伯值的麦草浆,探讨了麦草浆中木质素含量对防油剂作用效果的影响。结果表明,麦草浆中木质素含量对含氟防油剂的作用效果有明显影响,在防油剂质量分数1%(相对于绝干浆)的条件下,当麦草浆卡伯值降至<50.0时,麦草浆抄造纸张具有初步防油效果;当麦草浆卡伯值为30.0~50.0时,随着卡伯值降低,麦草浆抄造纸张的防油等级逐渐上升;当麦草浆卡伯值降至<30.0时,麦草浆抄造纸张防油等级达到最高等级(7级)。利用Owens-Wendt-Rabel-Kaelble (OWRK)法分析纸张的表面自由能,随着麦草浆中木质素的脱除,纸张的表面自由能不断降低,而极性比率不断升高,表明木质素的脱除有利于提高纸张防油效果。麦草浆中木质素含量也会影响防油剂用量,在一定防油等级要求下,麦草浆的卡伯值越低,所需防油剂用量越少。

基于制浆废液和麦草废渣的生物质颗粒燃料预测模型的建立及分析

以麦草制浆备料工段中产生的麦草废渣和制浆过程产生的制浆废液为原料,通过混合压缩成型工艺制备麦草废渣颗粒燃料,以期提高制浆造纸工业废弃物的利用价值。为探究制浆废液对生物质颗粒燃料成型的影响机制,参照麦草废渣组分,将粉末状商业纯纤维素和半纤维素在质量比10.17∶7.62下与制浆废液混合,制备生物质颗粒燃料模型,并通过曲线拟合建立生物质颗粒燃料预测模型,探究制浆废液中固形物含量对颗粒燃料成型性能及其物理性能的影响机制。结果表明:制浆废液可以提高燃料颗粒间的黏结力,有利于颗粒燃料成型,改善了麦草废渣颗粒燃料的物理性能。当制浆废液固形物含量为10.28%时,麦草废渣颗粒燃料显示出较好的物理性能,其抗渗水性为84.90%,压缩应力为1.45 MPa。生物质颗粒燃料预测模型对麦草废渣颗粒燃料物理性能的预测结果误差小于5%,显示出较高的预测精度。研究结果可为生物质颗粒燃料的制备技术提供理论参考,同时为制浆造纸工业废弃物的综合利用提供新思路。

生物化学机械法制浆过程麦草废渣基棒状颗粒燃料的性能分析

为提高农业废弃物麦草全组分资源化利用效率,本研究将生物化学机械法制浆过程产生的麦草废渣和制浆废液进行混合,利用液压成形技术制备了麦草废渣基棒状颗粒燃料(简称颗粒燃料),探讨了麦渣粒径和废液添加量对颗粒燃料形貌、稳定性、物理性能和燃烧性能的影响。结果表明,颗粒燃料制备的较优工艺条件为:麦渣粒径范围[0.22,0.90)mm,制浆废液添加量36.31%。该条件下制备的颗粒燃料具有较好的稳定性、物理性能和燃烧性能,其松弛密度为1.50 g/cm^(3),抗跌碎性为99.94%,抗渗水性时间为105 min,横向抗压强度为75.1 MPa,径向抗压强度为1.53 MPa,热值为11 715 J/g,燃烧时间可达99 s。

麦草Soda-AQ浆的过氧化尿素漂白

对过氧化尿素用于麦草Soda-AQ浆漂白的影响因素和反应动力学进行了研究,并与H2O2漂白进行了比较。结果表明,过氧化尿素可以作为H2O2的替代品用于纸浆漂白,其漂白效果略优于H2O2。麦草浆过氧化尿素漂白在适宜的工艺条件下白度增值可达20%ISO。

不同松厚度P-RC APMP与漂白麦草Soda-AQ纸浆共磨浆特性

为合理高效利用麦草纸浆和高得率纸浆,通过合理配浆及其共磨浆,以获得所需纸性。以漂白麦草Soda-AQ纸浆为主,添加不同比例、不同松厚度的P-RC APMP纸浆,形成系列混合纸浆,对混合浆进行共磨浆、抄造成纸;研究不同系列配浆的共磨浆特性,探讨了高得率浆的松厚度及配浆比例对磨浆能耗、成纸松厚度、强度以及光学性能的影响。研究结果表明:1)高松厚度P-RC APMP纸浆(HB)和中等松厚度P-RC APMP纸浆(MB)与麦草浆共磨浆均能显著降低磨浆能耗,而MB共磨浆的能耗略低于相应配比的HB共磨浆的能耗; 2) HB共磨浆与MB共磨浆均能明显改善共磨浆的松厚度,且HB作用效果更为明显; 3)高得率浆添加量在10%左右时,HB共磨浆的抗张指数、耐破指数与MB共磨浆的相近,并接近或高于纯麦草浆,随着配比量的提高,MB共磨浆的抗张指数、耐破指数略高于HB; 4) HB共磨浆与MB共磨浆均能显著改善撕裂度和脆裂度,且均明显优于3种单一纸浆的撕裂度和脆裂度; 5)共磨浆可以显著改变光散射系数。试验证明,高得率浆与麦草浆共磨浆两者之间具有良好的协同作用,其中,HB与麦草浆的共磨浆能更好地改善浆料松厚度、光学性能和物理强度,更具有应用价值。

麦草化机浆与废纸浆配抄制备瓦楞原纸

探究化学助剂对麦草化机浆纸张物理强度性能的影响,并与OCC浆配抄制备瓦楞原纸。结果表明:化学助剂可以明显提高麦草化机浆纸张的物理强度性能,在0.1%CPA M/0.1%H P555联用条件下可以获得性能较优的麦草化机浆。在此基础上与废纸浆配抄(配抄比例3∶7)可以制备瓦楞原纸,其抗张指数、裂断长、耐破指数以及环压指数分别为45.47 N.m/g、4.71 km、2.72 kPa.m^(2)/g、11.58 N.m/g,达到瓦楞原纸物理强度性能的要求。该研究拓展了麦草化机浆的应用,有助于缓解瓦楞原纸原料短缺问题。

Ca^(2+)交联羧基化麦草秸秆化机浆的制备及性能研究

本研究采用TEMPO氧化体系,转化麦草秸秆化机浆(SP)纤维素C6位上的羟基为羧基,制备羧基化麦草秸秆化机浆(CSP);对CSP进行Ca^(2+)交联,制备Ca^(2+)交联羧基化麦草秸秆化机浆(CSP@Ca^(2+)),探究其纸浆的物理强度性能。基于FT-IR、XPS等手段可以明显检测CSP纤维的羰基/羧基官能团:羧基化1 h麦草秸秆化机浆纤维(CSP1)的羧酸含量为0.27 mmol/g,其Zeta电位从SP的-21.7 mV变化为-29.2 mV,这为Ca^(2+)的交联提供作用位点。纸张物理强度结果表明,CSP1@Ca^(2+)0.5的抗张指数、耐破指数和撕裂指数分别较SP提高154.4%、170.8%和12.9%。最终,CSP1@Ca^(2+)0.5与SP配抄纸张(配抄比例为50∶50)的抗张指数、耐破指数和撕裂指数分别达27.1 N·m/g、2.28 kPa·m^(2)/g和3.68 mN·m^(2)/g,较SP分别提高83.4%、115.1%和8.3%。

麦草高得率浆的细小组分特性及其对纸浆性能的影响

针对两种不同打浆度的麦草高得率浆,分别采用100、200和350目的筛网筛分,对所得不同尺度细小组分的特性及其对麦草高得率浆性能的影响进行研究。通过Bauer-Mcnett筛分仪分析,麦草高得率浆中长纤维组分Rf30和细小组分Pf200是占比较大的两种筛分组分,高打浆度的纸浆中含有较多的细小组分。麦草高得率浆中不同尺度细小组分的含量、大小和外观不同,其中P350组分在纸浆中占比为10%左右,粒径为25μm左右,外观呈大小不一、形状不规则的片状或颗粒状。筛除P350组分可以显著改善纸浆性能。通过筛除P100细小组分得到的纤维组分,打浆度在20°SR以下,但保水值还高达250%左右。在麦草高得率制浆过程中,通过优化磨浆工艺、加强纸浆洗涤,控制P350细小组分含量,是改善麦草高得率浆性能的一条有效途径。

麦草化学机械浆湿部化学特性及造纸滤水性差、干燥能耗高原因分析

麦草化学机械浆不仅得率高、强度性能好,而且纸浆生产成本低。但在造纸过程中存在纸浆水化程度高、滤水性差及纸干燥能耗大等突出问题。研究结果表明:在草片磨成浆进行消潜-筛选净化-浓缩-贮浆过程中,由于制浆残碱和温度的作用,纸浆中的半纤维素一直在持续溶出,表现在水相中阴离子物质的阳离子需要量增大、纸浆纤维表面的羧基含量增加,导致水化程度上升;溶解进入水相的半纤维素分子片段通过高价金属离子能重新回吸到纤维表面,进一步增大了纸浆的水化程度。采用羧甲基淀粉模拟半纤维素,在钙离子环境下重现了半纤维素的回吸现象验证实验。因此,在麦草化学机械浆生产过程中,半纤维素溶出与回吸不仅导致纸浆的水化程度加重,而且导致了纸成形时滤水性变差、干燥能耗高的重要原因。

EDDHA-Na与Na_(2)SiO_(3)二元体系在麦草浆漂白中的应用

乙二胺二邻苯基乙酸钠EDDHA-Na无磷环保,在碱性条件对重金属离子锰、铁、铜螯合能力强,可以有效的络合纤维素和漂白用水的重金属离子,避免双氧水被金属离子过度激活与分解导致的黄变与白度下降。水玻璃Na_(2)SiO_(3)在碱性条件下会形成海绵状的胶体,可以吸附金属离子的同时也能吸附双氧水分解后的产物HOO-和O-等漂白因子,并在漂白进程中进行缓慢释放。EDDHA-Na与Na_(2)SiO_(3)对双氧水的漂白有明显的协同与互补作用,将EDDHA-Na与Na_(2)SiO_(3)二元体系应用于麦草浆的双氧水漂白中,可以获得良好的白度与较高的得浆率。