Enzymatic deinking of laser printed office waste papers: Some governing parameters on deinking efficiency

The protocol for the enzymatic deinking of laser printed waste papers on a laboratory scale using cellulase (C) and hemicellulase (H) of Aspergillus niger (Amano) was developed as an effective method for paper recycling. A maximum deinking efficiency of almost 73% by the enzyme combination of C:H was obtained using the deinking conditions of pulping consistency of 1.0% (w/v) with the pulping time of 1.0 min, temperature of 50 degrees C, pH = 3.5, agitation rate of 60 rpm, pulp concentration of 4% (w/v), concentration of each enzyme of 2.5 U/g air dried pulp and the enzyme ratio of 1:1. The deinking efficiency was further enhanced to 95% using the optimized flotation system consisting of pH = 6.0, Tween 80 of concentration 0.5% (w/w), working air flow rate of 10.0 L/min and temperature of 45 degrees C. The deinked papers were found to exhibit properties comparable to the commercial papers suggesting the effectiveness of the enzymatic process developed. (c) 2006 Elsevier Ltd. All rights reserved.