Papadaki S., Krokida M., Economides D., Vlyssides A., Koukios E., 2012, Dyeing Capacity of Eucalyptus globulus L. on Chemical Pulp: An Overview, Chemical Engineering Transactions, 29, 7-12.
This paper presents a study on the dyeing capacity of Eucalyptus globulus L. bark on chemical pulp. Eucalyptus globulus L. bark is a natural source of polyphenolic compounds such as tannins and flavonoids, which are natural colourants. First of all, the effect of the bark granulometry on dyeing capacity was investigated. The greater dyeing capacity noted in the range between 1.4 and 1.0 mm. Subsequently, the effect of conventional aquatic extraction and ultrasound assisted extraction were studied in a wide range of different conditions such as temperature and residence time. Ultrasound assisted extraction gave evidence of being the most effective method. Furthermore, the effects of conventional dyeing (impregnation of the pulp in the dye bath) and ultrasound assisted dyeing were evaluated, with the last one showing a significant improvement of dyeing capacity. Also, the effect of the change in the ratio of the weight of extractable quantity of the plant to the weight of dry pulp on the dyeing capacity of eucalyptus was examined. In addition, tests about the colour stability took place by measuring the colour difference of the dyed paper in several time periods. The estimation of dyeing capacity occurred through the determination of colour coordinates of the dyed paper, according to CIE L*a*b* system. By controlling these parameters we can optimize the dyeability of chemical pulp which is critical for the paper industry.
