The Effect of Different Concentrations of Cellulase Enzyme on Optical and Physical Properties of ONP Deinked Pulp

Abstract

Enzymes are protein molecules with complex structures that accelerate the biochemical reactions. Activity of these chemical compounds is accomplished at limited range of pH, temperature and concentration. In this study, the effects of different concentrations of cellulose enzyme were investigated on deinking of old newsprint. Old newsprint (ONP) was repulped at 5% consistency for 10 minutes in disintegrator with total revolution number of 26500. Enzymatic treatments of recycled ONP pulp were done under constant conditions (10% consistency,treatment time of 15 minutes, pH range of 5-5.5) at different cellulose concentrations of 0.025, 0.05, 0.1 and 0.2% (based on oven-dry waste paper). The optical and physical properties of the standard paper (60g/m2) made at different concentrations of cellulose were evaluated in comparison with control pulp (untreated ONP pulp with cellulase). Overall, the results achieved by comparison the optical properties of the paper produced indicated that using cellulase in deinking of ONP led to increase the brightness and the yellowness and decrease the opacity. The brightness was improved to a maximum level of 47.5 ISO %, but the yellowness was decreased to a minimum level of 11.3 ISO %, while the brightness reduced and the yellowness increased at higher concentrations than 0.05% cellulase. The highest opacity of 99.3 ISO % was achieved using 0.1% cellulase even higher than control pulp. The results gained by comparison the physical properties of the paper showed that using cellulase resulted in decrease of paper calliper, air resistance and density and improve the freeness of pulp

Keywords

• : cellulase Enzyme
• Deinking
• Old Newsprint
• Optical properties
• Physical properties