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 °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 °C. The deinked papers were found to exhibit properties comparable to the commercial papers suggesting the effectiveness of the enzymatic process developed.