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.

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.

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.

AS-AQ麦草浆压力高温H_2O_2漂白

研究了AS-AQ麦草浆压力高温H2O2漂白工艺,并对漂前预处理进行了探讨。结果表明:采用亚甲基磷酸型预处理剂X在压力高温H2O2漂白前对纸浆进行预处理,能够显著提高漂白效率,其预处理效果优于EDTA、DTPA等传统预处理方式;压力高温H2O2漂白最适宜的工艺条件为:浆浓10%,H2O2用量3%,NaOH用量3%,MgSO4用量0.5%,氧压0.3MPa,温度120℃,时间60min。在上述条件下所得漂浆白度为79.8%,黏度为941mL/g。再添加少量助剂活化H2O2,漂浆白度可达84.5%,同时保持了较高黏度。

AS-AQ麦草浆氧脱木素后的过氧化氢漂白

研究了氧脱木素后的AS-AQ麦草浆H2O2漂白工艺,并对漂前预处理进行了探讨。结果表明:采用预处理剂X对浆料进行H2O2漂前预处理能够显著提高漂浆白度;在提高H2O2漂白效率方面,预处理剂X预处理优于EDTA、DTPA等传统预处理方式;柠檬酸钠可以替代Na2SiO3用作H2O2漂白稳定剂。H2O2漂白最适宜的工艺条件为:浆浓12%,H2O23%,NaOH1.2%,柠檬酸钠1%,温度95℃,时间120min。在优化条件下,漂终白度达83.9%ISO。

麦草AS-AQ法浆亚硫酸化度的影响

研究了不同亚硫酸化度对麦草ＡＳＡＱ浆的影响。结果表明，在相同的蒸煮条件下随亚硫酸化度的降低，木素脱除率提高，碳水化合物的保留率提高，从而得率提高。蒸煮的反应活性在亚硫酸化度为０．３时最高，此时可获得最低硬度和最高木素脱除率。综合蒸煮反应活性及脱木素反应的选择性，麦草ＡＳＡＱ法蒸煮的最佳亚硫酸化度应为０．３～０．５。

均匀设计法优化麦草AS-AQ法蒸煮工艺

利用均匀设计和二次回归分析的方法对麦草AS-AQ法蒸煮工艺进行了优化。得到最佳工艺条件为:用碱量15%(以NaOH计),亚硫酸化度65%,最高温度160℃,保温时间65min。在上述条件下蒸煮得到的纸浆具有较高的细浆得率,较低的卡伯值,以及较高的黏度和白度。

低硬度AS-AQ麦草浆TCF漂白特性

研究了低硬度AS-AQ麦草浆的TCF漂白特性。结果表明,低硬度的AS-AQ麦草浆对氧系漂剂具有很好的可漂性,通过短程序TCF漂白即可达到较高的白度,且漂白选择性好。本实验条件下,漂白效果最好的TCF漂白程序是OXP和XPO,漂浆白度分别达到了84.1%ISO和82.8%ISO。

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。

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。

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。

An—76真菌木聚糖酶漂白NaOH一AQ麦草浆的研究

探讨了用Ａｎ—７６真菌木聚糖酶漂白ＮａＯＨ—ＡＱ麦草浆。结果表明，经酶处理后纸浆白度和聚合度提高，ＫＭｎＯ４值降低。酶处理浆的可漂性增加，尤其对过氧化氢漂白影响较大，白度提高３％～４％ＩＳＯ。酶处理浆的强度提高。

木聚糖酶在麦草浆漂白中的应用

对于单段次氨酸盐漂白，木聚糖酶处理（X）可明显改善麦草浆的漂白性能，纸浆白度提高约5％ISO或在相同的白度下减少用氯量28％左右，但与木浆相比处理麦草浆的酶用量较高（50IU／g浆）。采用XCH、CXH、CHX和CH／X漂序纸浆白度可达80％ISO以上，采用XCEH、CEHX或CEH／X漂序纸浆白度接近85％ISO，纸浆强度均有不同程序的提高。

热水和木聚糖酶预处理制备麦草碱法化机浆的研究

对热水和木聚糖酶预处理的麦草碱法化学机械制浆过程中热水和木聚糖酶预处理的效果进行了研究。结果表明 ,在适宜条件下 ,采用热水和木聚糖酶预处理原料可以有效改善麦草碱法化机浆的抗张指数和撕裂度、降低碱的消耗 ,虽然成浆的白度稍有降低 ,但可漂性增加 ,漂白浆白度增加。热水预处理适宜的温度是 90℃ ,酶预处理段较佳的木聚糖酶用量和处理时间分别为 1 5IU/g和 1 2 0min。