Enzymatic deinking of laser and xerographic printed wastepaper
2002
Torres, A.S., Forest Products Research and Development Inst., College, Laguna (Philippines). Cellulose Technology Section | Razal, R.A., Philippines Univ. Los Banos, College, Laguna (Philippines). Coll. of Forestry and Natural Resources
Laser and xerographic printed papers (LXPP) were deinked with a commercial enzyme preparation (mixture of cellulases and hemicellulase) at different pH levels, enzyme dosages and flotation times. Deinking was done by repulping shredded LXPP at 60 deg C in an aqueous solution (10 percent consistency) containing enzyme. After enzymatic treatment, the mixture was transferred to a flotation cell to remove the ink. The temperature in the flotation cell ranged from 35 to 45 deg C, consistency was 1 percent and pH was 6.5-7.5. The deinked stock samples were washed with water at room temperature and deactivated with hot water (90-95 deg C) for 10 min. The resulting pulps were formed into handsheets and tested for brightness, effective residual ink concentration (ERIC) and srength properties (burst, tear and tensile indices). The enzyme-deinked pulps exhibited higher brightness and lower ERIC than the untreated and conventionally-deinked paper. Gain in brightness ranged from 2 to 8 units while ERIC reduction was up to 70 percent. Tear and burst strengths of the enzyme-deinked LXPP were not adversely affected by the treatment while tensile strength increased. The average burst, tensile and tear indices were 4.36 kPa. sq m/g, 48.42 N.m/g and 11.47 mN.sq m/g, respectively. Both the enzyme and deinking chemicals were able to reduce toner ink from LXPP. However, the enzyme preparation showed greater efficiency than the deinking chemicals in removing the ink particles.
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