| dc.description.abstract | The objective of this research is to evaluate the physical and chemical properties of pulp from waste laser print paper. The waste paper was pretreated with 1 % lipase (based on oven-dried pulp) for repulping. After repulping, pulp slurry was floated at two conditions : alkaline flotation and acidic flotation. The result of the research shows that brightness increased in the added lipase, reach the maximum brightness after flotation by increased ash content. Residual ink area and particle size distribution decreased in the lipase addition. Furthermore, they can increase deinkability factor. The enzymatic deinking can change cellulose structure with the formation of carboxyl groups and increasing index of crystallinity. The Water Retention Value (WRV) with centrifuge method at 3000 G, increased in the added lipase with existence of carboxyl groups. Lipase and acidic treatment can increase the viscosity of pulp. Enzymatic treatment can increase strength properties of deinked pulp. | id |
