Waste Newsprint Enzymatic Deinking (I)

● Shao Zhiyong Fu Yingjuan Qin Menghua (Shandong Institute of Light Industry, Jinan South 250100)
Gao Peiji Qu Yaobo (State Key Laboratory of Microbial Technology, Shandong University, Jinan South 250100)
● Dong Zhengquan Meng Qingxiang (Zhucheng Paper Co., Ltd., Zhucheng South 262200)
Abstract: Based on the laboratory research, the deinking cellulase preparation prepared by solid fermentation technology was used to conduct industrial production test on the deinking of waste newsprint paper, and 100% enzymatic deinking pulp was used to make qualified newsprint paper. Compared with chemical deinking, enzymatic deinking can further increase pulp whiteness and ink removal rate, and significantly reduce the pollution load of wastewater.
Key words: waste newsprint; enzymatic deinking; cellulase; fiber modification Author: Shao Zhiyong, Laboratory of Pulp and Paper, Shandong Institute of Light Industry.
The environmental and raw materials problems faced by the pulp and paper industry have led people to pay more attention to the recycling of waste paper. In recent years, the utilization rate of secondary fibers has grown significantly and has become an important fiber resource. For example, waste newsprint is an important raw material for the production of newsprint or other types of paper in China, and it is also one of the major waste papers imported by China. As a key technology for waste paper recycling, deinking is still performed using traditional alkaline chemical deinking. However, there are many drawbacks to traditional alkaline chemical deinking, so people hope to have better deinking and more environmentally friendly enzymatic deinking.
Based on the study of enzymatic deinking and fiber modification in waste newsprint, the research group conducted an industrial production test of enzymatic deinking of waste newsprint using a cellulase preparation prepared by solid fermentation technology.
1 Experimental Materials and Methods 1.1 Waste Newsprint #8 American Waste Paper. The composition of waste paper is: 70% black-and-white printing newsprint, 15% color printing newsprint and 15% drawing newspaper.
1.2 Aspergillus L22 was the cellulase-producing strain used in the experimental enzyme test. Batch deinking cellulase preparations were prepared under solid fermentation conditions. The active composition of the cellulase was CMCase 3.41 IU/ml, the xylanase activity was 6.44 IU/ml, and the FPA activity was 0.106 FPU/ml.
1.3 Experimental method The enzymatic deinking of the production test was carried out in a high-consistency pulper and bleaching was carried out in a bleaching tower.
1.4 Analytical Methods 1.4.1 Determination of Enzyme Activity Carboxymethyl Cellulase Activity (CMCase): Sodium carboxymethylcellulose is dissolved in NaAC buffer, pH 4.8, at a concentration of 0.5 mol/l, with a final concentration of 0.5% ( W/V). 2ml of the reaction solution, add 0.5ml of enzyme solution diluted appropriately, react at 50°C for 30min, add 2ml of DNS (3,5-dinitrosalicylic acid) reagent to terminate the reaction, boil for 10min, and bring to 15ml after cooling. Absorption was measured at 550 nm, with glucose as the standard.
Filter paper enzyme activity (FPA): 50mg The filter paper was added 2ml of 0.05% mol/l NaAC buffer solution at pH 4.8, and 0.5ml appropriately diluted enzyme solution was added. After reacting at 50°C for 30min, 2ml of DNS reagent was added to terminate the reaction. After boiling, the volume was adjusted to 15 ml, and the amount of reducing sugar (measured by glucose) was measured at 50 nm.
Xylanase activity: xylanase was dissolved in NaAC buffer solution at pH 4.8 and 0.05 mol/l to prepare a 0.5% xylan solution, 2 ml of this solution was added, and 0.5 ml of an appropriately diluted enzyme solution was added. The reaction was terminated with 2 ml of DNS reagent after 30 min at 40° C. After cooling, the volume was brought to 15 ml and the amount of reducing sugars (measured with xylose) was determined at 550 nm.
The above enzyme activity unit is defined as the amount of enzyme required to produce 1 μmol of product per minute under the reaction conditions is an enzyme activity unit.
1.4.2 Evaluation of Pulp Performance Whiteness, light absorption coefficient and opacity were measured on a YQ-Z-48B digital display whiteness meter. The physical properties of the pulp or paper and the determination of the COD and BOD of the waste water are all according to the relevant national standards. (To be continued)