xxx大学

毕 业 论 文 设 计

      造纸黑液木素化学分离工艺
   
目 录

摘要………………………………………………………………………4
ABSTRACT…………………………………………………………………5
第1章  前言………………………………………………………7
1.1 制浆造纸工业的废水污染概况………………………7
1.2 制浆造纸工业废水的产生……………………………9
1.3 木质素的化学结构及其应用……………………………10
      1.3.1 木质素的化学结构…………………………………10
      1.3.2 木质素的应用………………………………………11
1.4 现有制浆造纸工业废水治理方法及研究进展…………13
      1.4.1 碱回收法…………………………………………13
      1.4.2 酸析法………………………………………………13
1.4.3 化学混凝法…………………………………………14
1.5 本设计的目的及意义…………………………………17
第2章  实验材料和方法………………………………………18
2.1 实验设计……………………………………………18
2.1.1 设计思路………………………………………18
2.1.2 设计实验……………………………………18
2.2 实验方法………………………………………………18
2.2.1 黑液性质测定……………………………………19
2.2.2 黑液滴定试验……………………………………19
2.2.3 黑液酸析实验……………………………………19
2.2.4 黑液混凝实验……………………………………19
2.3 实验仪器及药品……………………………………20
第3章  结果与讨论………………………………………………22
3.1 黑液性质测定结果……………………………………22
3.2 黑液滴定实验结果……………………………………22
3.3 黑液酸析试验结果………………………………23
3.4 黑液混凝试验结果……………………………………24
      3.4.1 有机高分子絮凝剂……………………………24
      3.4.2 无机絮凝剂+有机助凝剂…………………………25
      3.4.3 无机高分子絮凝剂……………………………27
a. PFSS（硅铁比1∶1）梯度实验……………………27
b. PFSS（硅铁比1∶2）梯度实验……………………28
3.5 讨论…………………………………………………30
第4章 结论与建议………………………………………………31
4.1 结论……………………………………………………31
4.2 建议……………………………………………………31
致谢………………………………………………………………32
参考文献…………………………………………………………33
毕业设计小结…………………………………………………………35

摘  要

造纸工业废水污染问题在我国已十分严重。当前我国造纸工业面临的最大难题是草浆造纸厂规模小、数量多、分布广、治污能力差。造纸工业废水中约有90%的有机污染物来自黑液，治理碱法制浆黑液是治理造纸废水的重中之重。黑液中约2/3为有机物，主要是木质素。碱回收法只适合大型木浆造纸厂，而传统的酸析工艺也存在着成本高等诸多弊端。因此，很有必要寻找一种处理效果好、成本低的新方法来解决黑液的污染问题。
本设计采用化学混凝法，选用不同的絮凝剂，试验不同的加药量，旨在寻找一条效率高、成本低的途径处理黑液。实验中采用了硫酸铁、氯化铁、阳离子聚丙烯酰胺、聚硅硫酸铁等多种絮凝剂，采取“先粗后细”的原则。首先，固定投加量，比较不同絮凝剂的效果。然后，选出效果较好的絮凝剂作梯度实验，絮凝后进行过滤，测滤液COD以及过滤速度，以确定最佳加药量。实验发现，聚硅硫酸铁对黑液的处理要好于其他絮凝剂，进一步的实验表明，每100ml黑液加入20ml聚硅硫酸铁（硅铁比1∶2）处理效果是最好的。该方法成本较传统酸析工艺要低，且处理效果优于酸析工艺，且过滤速度快，即易于分离木素。化学混凝法在处理黑液方面显示出了良好的前景。

关键词：黑液，木素，COD，絮凝剂

ABSTRACT

It has been already very serious in our country that papermaking industry abolished the water pollution problem. The greatest difficult problem our papermaking industry has to face is the paper mill of straw pulp which is in small scale, in large quantity, wide distributed and badly treatment of pollution. Nearly 90% of the organic pollution that comes from the black liquor in the industrial sewage of papermaking, it is the most important thing of managing the wastewater of papermaking to manage the black liquor of legal system of alkali. About 2/3 is the organic matter, is the lignin mainly in the black liquor. The alkali retrieving is only suitable for the large-scale wood pulp paper mill, and the traditional acid method has a great deal of high drawback, such as the high costs. However, It is very necessary to look for a kind of fine, with low costs new method that solves the pollution problems of black liquor.
Chemical coagulation method was used in the design. We select different flocculants, test different dosage to look for a method with high efficiency and low costs of black liquor treatment. Many flocculants, such as Ferric sulphate, Ferric Chloride, Cationic polyacrylamide were used, with the fundamental of “First cursory then being meticulous”. First, keep the same dosage, compare the effect of different flocculants. Then, the most efficient flocculants were selected to carry on the grads experiments. The black liquor was filtrated after flocculated. The COD of filtrate and the rate of filtration were measured to ascertain the best dosage. It is found that PFSS is better than other flocculants in the black liquor treatment. And, the best dosage is 20ml PFSS per 100ml black liquor. This method is more effective and economical than traditional acid method, and the rate of filtration is fast, in other words, the lignin can be easily separated. Chemical coagulation method has good perspective in the black liquor treatment.

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