A model compound study: The formation of colored metallic extractive complexes and their effect on the brightness of TMP pulp

Flavonoids, such as Quercetin, are the main polyphenol compounds found in e xtractives. When complexing with transition metal ions, these extractives m ay induce a significant discoloration to mechanical pulps. In this study, t he effect of metallic extractive complexes was investigated using a model c ompound, Quercetin. It was confirmed that the complexes formed between some metal ions and Quercetin are strongly colored. However, most of the strong absorbance in visible light due to metallic Quercetin complexes, can be el iminated by the addition of diethylenetriaminepentaacetic acid (DTPA). The metal ions studied were Fe(III), Cu(II), Mn(II) and Al(III).