Productive experiment of the best xylanase improvi

Productive experiment of xylanase improving the performance of rice straw pulp

key words: Bleached rice straw pulp; Xylanase; Whiteness; Chlorine consumption

1 test overview

Jinhu paper mill is an enterprise that produces toilet paper with straw as the main raw material. The pulping method is caustic soda method, and the bleaching process is hypochlorite one-stage bleaching. The biological bleaching test is carried out in a bleaching tank with a volume of 30m3, and the feeding amount is 1t absolute dry pulp. Xylanase used in biological bleaching is provided by the school run factory of the school of chemical engineering of our university. Jinan assaying hydraulic universal experimental machine for xylanase production has achieved great results after several experiments and the introduction of advanced technology. From Aspergillus niger, xylanase activity is 120iu/ml, cellulase activity (carboxymethyl cellulase activity) is 4iu/ml

2 results and discussion

2.1 comparison of enzyme treatment results of bleached rice straw pulp with the same amount of chlorine with the control

generally, the biological bleaching method is to pretreat the pulp with enzyme before bleaching. In this experiment, the enzyme treatment was carried out after pulp bleaching. That is, after the cooking of raw materials, the pulp is washed, screened, and then bleached. The chlorine amount used in bleaching is 8% (taking this pulp as the control pulp). After bleaching, the enzyme treatment is carried out to obtain the enzymatic hydrolysis pulp. See Table 1 for the results of enzyme treatment

Table 1 Comparison of enzymatic treatment results of bleached rice straw pulp with the control at the same chlorine dosage pulp type chlorine dosage% enzyme dosage iu/g whiteness%sbd yellowing value beating degree ° SR breaking length km bursting index kPa · m2/g tearing index Mn · m2/g embrittlement% control pulp

enzymatic hydrolysis pulp 8

80

464.9

68.23.77

3.4837

323.25

3.472.14 <./p>

2.274.78

5.2020.0

13.5 note: the enzyme treatment time is 60min, the temperature is 45 ℃, and the slurry concentration is 5%, The quantity of the tablets is 60g/m2

it can be seen from table 1 that after enzyme treatment, the whiteness of bleached rice straw pulp of grades B, C, D, e and F was increased by 3.3 percentage points compared with the control pulp, and the yellowing condition was improved. Due to the treatment of xylanase, some xylans on the fiber surface and fiber cell wall are degraded, resulting in pores on the fiber surface and cell wall, which increases the water filtration of the slurry. It can be seen from table 1 that the water filtration of the pulp treated by enzyme is increased, which is conducive to the washing, screening and dehydration of the pulp and the improvement of the speed of the paper machine. In addition, it is also found from table 1 that the strength and brittleness of the enzyme treated slurry are also slightly improved

2.2 comparison of the results of enzyme treatment between enzymatic hydrolysis pulp and control pulp at similar whiteness

the purpose of enzyme treatment is to reduce the pollution of chlorine containing bleaching agents to the environment. Therefore, the test of how much chlorine can be saved by enzyme treatment when enzymatic hydrolysis pulp and control pulp reach similar whiteness is carried out. The results are shown in Table 2

Table 2 results of enzymatic treatment when enzymatic hydrolysis pulp and control pulp have similar whiteness

pulp type chlorine content% enzyme dosage iu/g whiteness%sbd yellowing value beating degree ° SR breaking length km bursting index kPa · m2/g tearing index Mn · m2/g embrittlement% control pulp

enzymatic hydrolysis pulp 8

60

464.9

65.33.77

3.5237

323.25

3.722.14

2.584.78

4.9820.0

14.6 note: the enzyme treatment time is 60min, the temperature is 45 ℃, and the slurry concentration is 5%, The quantity of the tablets is 60g/m2

it can be seen from table 2 that when the whiteness of enzymatic hydrolysis pulp is similar to that of control pulp, the chlorine consumption of xylanase treated pulp is 6%, while the chlorine consumption of control pulp is 8%. 25% of the chlorine consumption can be saved through enzyme treatment. The hydraulic universal data testing machine is composed of measuring system, driving system, control system and computer (computer system tensile testing machine), which significantly reduces the pollution to the environment. In addition, the water filtration, strength and brittleness of the slurry have also been improved

3 conclusion

3.1 the whiteness of bleached rice straw pulp treated with xylanase can be increased by 3.3 percentage points compared with the control pulp at the same chlorine dosage; When the whiteness is similar, 25% chlorine consumption can be saved

3.2 the cost of xylanase treatment is about 20 ~ 30 yuan per ton of absolute dry pulp, which is lower than the chlorine consumption and wastewater treatment cost saved by the company, which has stable customer resources at present