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.

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.

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.

NaOH-AQ麦草浆二氧化氯漂白工艺的研究

对NaOH—AQ麦草浆的ClO2漂白工艺(CEHD)条件进行了优化,并对含ClO2漂白段(D段)的工艺流程进行了探讨。结果表明,NaOH-AQ麦草浆ClO2漂白的条件为:初始pH值4.0,温度70℃,时间150min,用量不超过1.0％;用次氯酸盐和ClO2结合进行两段漂,浆料可以达到与CEH相近的白度,并且在提高强度的基础上可以降低用水量和漂白废水的CODCr量。

麦草NaOH-AQ浆ECF漂白

对NaOHAQ麦草浆的DP高白度漂白进行了研究。结果表明,DP漂白浆白度可达81.6%ISO,强度性能良好。在DP漂白中的P段之前进行不同处理,可以改善漂白浆的性能。不同木聚糖酶处理都能够提高DP漂白麦草浆的白度,其适宜处理流程为DXP和DPX。

多金属氧酸盐为催化剂的麦草NaOH-AQ浆氧脱木素的研究

以多金属氧酸盐(POM-5)为催化剂,对烧碱蒽醌麦草浆氧脱木素进行了研究。结果表明,POM-5作为催化剂能有效地脱除木素,而浆的粘度损失不大。POM-5催化氧脱木素的最佳工艺条件是:温度90℃,浆浓5%,氧压0.5MPa,时间2h,POM-5用量2mmol/L,pH值为4.0。在最佳工艺条件下,采取不同的漂白流程对纸浆进行研究,结果表明:以O(POM+助剂)P漂白流程最好。

木聚糖酶处理对NaOH-AQ麦草浆HD漂白的影响

探讨了木聚糖酶处理对NaOH-AQ麦草浆HD漂白的影响。结果表明,AU-PE89木聚糖酶处理可以有效改善NaOH-AQ麦草浆HD漂白效果,在本实验条件下,当酶用量为7.5 U/g时,漂白效果最理想,白度增值为3.3%ISO;同时,AU-PE89木聚糖酶处理还可以降低HD漂白废液的CODCr,减少漂白污染。通过扫描电镜观察发现,经木聚糖酶处理后纸浆的纤维结构变得更疏松,纤维更加润胀柔软。

白腐菌与酶生物预处理对麦草NaOH-AQ制浆性能的影响

研究了麦草白腐菌预处理条件的优选以及白腐菌、木聚糖酶、漆酶生物预处理对麦草蒸煮性能的影响。结果表明:白腐菌预处理半个月优于一个月,漆酶生物预处理脱木素的选择性优于白腐菌、木聚糖酶。麦草经生物预处理后,均能改善后续蒸煮性能,改善程度漆酶好于木聚糖酶、白腐菌。在提高蒸煮得率、浆料强度方面漆酶优于木聚糖酶、白腐菌,与未处理浆和白腐菌生物化学浆相比,实际得率分别提高4.39、3.49个百分点;裂断长分别提高33.39%、16.03%;耐破指数分别提高42.86%、19.48%;撕裂指数分别提高43.91%、9.57%。木聚糖酶预处理对浆料白度的改善程度优于漆酶、白腐菌,与未处理浆和漆酶生物化学浆相比白度分别提高4.2和2.0SBD。

NaOH-AQ麦草浆二氧化氯漂白的工业生产试验

在实验室研究的基础上,对ClO2漂白NaOHAQ麦草浆进行了工业生产试验。试验结果表明,用次氯酸盐和ClO2结合对NaOHAQ麦草浆进行两段漂白,浆料白度可以达到与用CEH漂白相近的白度,该漂白程序不仅能提高浆料强度,还可明显降低用水量和漂白废水的化学需氧量(COD)。

V_2O_5在NaOH-AQ麦草浆ClO_2漂白中的应用

对V_2O_5在NaOH-AQ麦草浆ClO2漂白中的助漂作用进行了研究,主要探讨了使其催化效果明显的影响因素。实验结果表明,V_2O_5是一种良好的漂白催化剂,具有降低氯酸盐的生成、提高ClO_2漂白能力的作用,当V_2O_5用量为0.14%,温度70℃,反应时间120 min.终点pH值4.0左右时,催化效果最为理想。

木聚糖酶预处理对NaOH-AQ法麦草浆H_2O_2漂白效果的影响

探讨了木聚糖酶预处理对麦草化学浆 H2 O2 漂白可漂性等的影响。结果表明 :与对照浆漂至相近白度 ,木聚糖酶预处理后可节省 H2 O2 用量 4 0 %以上 ,且浆的强度变化不大 ;酶预处理还可以改善 H2 O2 漂后浆的滤水性能 ,提高漂白浆的白度稳定性。

NaOH-AQ麦草浆木聚糖酶漂前预处理工艺的研究

用法国马赛大学提供的一种木聚糖酶对 Na OH-AQ麦草浆进行了漂前预处理 ,对预处理的条件进行了探讨 ,优选出了最佳的工艺参数。

G6-2细菌木聚糖酶漂白NaOH-AQ麦草浆的研究

从土壤中分离得到一株耐碱性木聚糖酶高产细菌 ,经鉴定属假单胞菌属。探讨了用其所产木聚糖酶处理NaOH AQ麦草浆的工艺参数及酶处理对后续漂白的影响。结果表明 ,用该木聚糖酶漂白NaOH AQ麦草浆的最佳条件为 :酶用量 5 0IU/g浆 ,pH 7 5 ,纸浆浓度 5 %～ 10 % ,温度 40～ 5 0℃ ,时间 90～ 12 0min。

绿色糖单孢菌胞外酶漂白麦草NaOH-AQ浆的研究

用绿色糖单孢菌胞外酶的粗酶液对麦草NaOH-AQ浆进行生物预处理及后续漂白,摸索出生物预处理最佳条件为:酶用量20IU/g浆;浆浓10%;温度60℃;时间120min;pH值7.0。该酶具有一定的热稳定性和耐碱性,对纸浆漂白十分有利。若再接后续漂白段,可进一步提高纸浆白度和粘度,降低卡伯值,改善纸浆的可漂性。