The Effect of Water Quality on the Brightness Properties of Chemimechanical Pulp of Northern Iranian Hardwoods

摘要

Some metal ions present in water used for papcrmaking could affect the brightness of paper and cause a significant decrease in brightness and brightness stability. In this paper we qualified the effect of transition metal ions on optical properties of hydrogen peroxide bleached CMP pulp prepared from mixture of northern Iranian hardwoods. Also, the effect of DTPA on minimizing the impact of these metal ions in process water on brightness and its stability were investigated. Complementary study was done using lignin model compounds such as guaiacol, pyrogalol, resorcinol, benzyl alcohol and the effect of transition metal ions on absorbency of the compounds measured. The results showed that brightness loss due to metal ions is as high as 4-5 points. We also reported that using DTPA in small amount could recover the brightness loss in the presence of transition metal ions .Also, the results indicated that transition metal ions in complexation with lignin -like structures cause considerable increase in the light absorbency in visible region.