Method for removing stickies in waste paper pulp by using compound enzyme preparation
Patent Publication Number: CN 106318930 A
Applicant: South China University of Technology
Inventor: Wang Yonghua Lan Dongming Zhang Zedong Yang Bo Zhou Pengfei
Provided is a method for removing stickies in waste paper pulp by a composite enzyme preparation mainly based on high temperature esterase TTEST.
Proceed as follows:
(1) Preparation of high temperature esterase TTEST:
Inoculate the esterase TTEST strain into the seed liquid culture medium for shaking culture, and then inoculate the strain into the fermentation medium for shaking culture to prepare the high temperature esterase TTEST crude enzyme solution, purify the high temperature esterase TTEST crude enzyme solution, and use The phenol colorimetric method was used to determine the enzyme activity of high temperature esterase TTEST.
The coding gene of TTEST esterase obtained by whole gene synthesis method was cloned into the expression vector pET23a-CBD vector to obtain a recombinant expression vector. Using the CaCl2 transformation method, the expression plasmid containing the TTEST esterase encoding gene was transformed into BL21 (DE3) strains to obtain genetically engineered bacteria. The strain of esterase TTEST was connected to LB seed medium containing Amp (100ug / ml) to expand the culture. When the OD value reached 0.6-0.8, the bacterial solution was inoculated into the Amp containing (100ug / 100) at a ratio of 1: 100. ml) of LB fermentation medium, when shaken to an OD value of 0.6-0.8, I PTG (20mmol / L) inducer was added to induce expression, and bacteria were harvested after 18-24 hours. The bacterial solution was centrifuged at 12000r / min for 10 minutes, and the cell wall cells were collected for ultrasonic disruption, and then centrifuged at 12000r / min for 10 minutes, and the supernatant was taken to obtain the crude enzyme solution. Cellulose and esterase are used for specific binding, and then 3C protease is used for enzyme digestion to obtain pure enzyme. 1L of bacterial solution corresponds to 1g of cellulose, and the crude enzyme solution is combined with cellulose at room temperature for 30min, and stirred at an appropriate time. After binding, centrifuge at high speed for 10 min, discard the supernatant, and wash the adsorbed protein twice with PBS buffer. The 3C protease was centrifuged before use, the supernatant was discarded, and washed twice with PBS buffer. Add an appropriate amount of PBS to the adsorbed protein, mix according to the ratio of 1L of bacterial solution to 1ml of 3C protease, and then digest it for 4h or overnight. After enzyme digestion, high-speed centrifugation, the supernatant is pure enzyme. Afterwards, the enzyme activity of the prepared high-temperature esterase TTEST was measured by p-nitrophenol colorimetry, and the enzyme activity was measured to be 3500 U / g. Lipase CALB is a commercial lipase with an enzyme activity of 150.0 U / ml.
(2) According to the mass percentage, the high temperature esterase TTEST (45% -50%) and amylase (15% -20%), pectinase (10% -15%), xylanase (10% ～ 15%), glycerin (5%), polyethylene glycol (5%), water (5% ~ 10%) compounded into a compound enzyme preparation.
(3) Weigh 100g of OCC dry pulp, dilute to the corresponding pulp concentration, add a certain amount of enzyme, under a certain processing temperature, pH value, processing time, stirring speed (as shown in Table 1), according to TAPPIT-277 adhesive In the substance determination method, the slurry is screened using a Pulmac-MasterScreen sieve analyzer, and then the screened stickies are dyed and compressed, and finally analyzed and scanned with a scanning software, and then the content of the stickies after enzyme treatment is measured.
In the absence of enzymes, the waste paper pulp was treated with the same remaining conditions. The results of the experiment determined the content of stickies in the blank group.
The added amount of the compound enzyme preparation is 0.1% to 1.0% of the quality of the waste paper pulp absolute dry pulp, the processing temperature is 40 to 80 ° C, the processing time is 45 to 120 min, the pH is 6.0 to 9.0, and the stirring speed is 100 to 150 r / min.
The temperature of the composite enzyme-treated waste paper pulp is 50-55 ° C, the stirring condition of the composite enzyme-treated waste paper pulp is 120 r / min, and the reaction time is 60 min. The amount of compound enzyme added is 0.3% to 0.5% of the quality of the waste paper pulp dry pulp. The pH of the composite enzyme-treated waste paper pulp is 7.0-8.0. The pulp concentration of waste paper pulp is 4% to 6%.
The enzyme activity of the high-temperature esterase is 3500 U / g. The amylase activity is 5000U / g, the pectinase activity is 5000U / g, and the xylanase activity is 10000U / g.
It can be seen from Table 1 that under the condition of 40 ～ 55 ℃, the content of stickies in the waste paper pulp treated with compound enzymes is significantly reduced, and the removal rate of stickies can reach 60.8% -74.1%, which is significantly better than that of lipase CALB Removal. Even under the high temperature condition of 80 ℃, the treatment effect after adding the compound enzyme is also ideal. The removal rate of stickies in waste paper pulp reaches 58.5%, and the lipase CALB is basically inactivated under this condition, making it difficult to remove stickies. Considering that the temperature of different sections in the waste paper making process is not the same, the effect of esterase PCEST in removing waste paper in different sections of waste paper recovery is ideal.
Beneficial effects compared with existing technologies:
(1) The preparation of high temperature esterase TTEST is relatively easy and the effect is obvious.
(2) The compound enzyme preparation can cope with various high temperatures and acid-base environments in the waste paper recycling process, and can still maintain a good sticky substance removal effect under high temperature conditions.
(3) The method of removing waste paper stickies through a composite enzyme preparation mainly composed of high-temperature esterase can be directly carried out on the production line without adding any mechanical equipment, and the operation is simple and the cost is low.
Therefore, the method of controlling the stickies in the waste paper pulp by the high-temperature esterase-based complex enzyme preparation efficiently and reliably solves the problem of stickies in the past that has seriously affected product quality in the field of waste paper and papermaking, with simple operation and removal effect Significant, low production cost, no pollution and other advantages.
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