Effect of enzymatic treatment on mechanical strengths of deinked pulp of old newspaper at neutral pH

This research was carried out to study the effect of Enzymatic deinking on strength properties of old newspaper deinked pulps. In order to perform this research, we did pulping operation with cellulase and lipase enzyme, in 4% consistency for 2.5 minutes in neutral PH, in two temperatures of 20 oC and 50 oC. Following pulp preparation, we started deinking process by washing on the 120 meshes. We did statistical analyses on the effect of enzymatic and temperature repairs on mechanical strengths of handsheets. The results showed that the enzymatic treatment increases the mechanical strengths of the treated pulps compared to the control pulp. Also, combined effects of cellulase and lipase on improvement of mechanical strengths of pulp were more than cellulase treatment alone. For handsheets made from control pulp the values of burst index, tear index, tensile index, breaking length and tensile stiffness were 1/43, 5/33 (mN.m2/g), 48/64 (Nm/g), 4/9 (km), 476/46 (kN/m), respectively. On the contrary, for enzyme treated pulps the optimum values were 1/92, 5/96 (mN.m2/g), 63/29 (Nm/g), 6/45 (km) and 584/31 (kN/m), respectively. This investigation showed that due to limited availability of woods, enzymatic deinking can be a suitable alternative instead of current deinking in paper recycling industries.