Role of Tween 80 in biobleaching of unbleached hardwood kraft pulp with manganese peroxidase

The role of Tween 80 in biobleaching of unbleached hardwood kraft pulp (HWK P) with manganese peroxidase (MnP) was investigated. Among the surfactants (e.g., Tween 80, Tween 20, CHAPSO) the most significant brightness increase was obtained with Tween 80, Tween 80 and Tween 20 exhibited several effect s, such as dispersion of degraded lignin and activation of MnP, that partly contributed to the brightening of HWKP during MnP treatment. However, thes e characteristics did not explain the most appreciable effect on the bright ness increase by Tween 80. Lipid peroxidation of surfactants during MnP bio bleaching was determined by measuring the peroxide value (POV). The order o f the POV increase was consistent with that of the brightness increase of p ulp during MnP treatment in the presence of various surfactants or linoleni c acid. However, radicals and peroxides derived from lipid (linolenic acid) peroxidation by lipoxidase hardly brightened the HWKP by themselves. These results suggested that Tween 80 was peroxidized by Mn(III), and that Mn(II I) and lipid peroxidation of Tween 80 synergistically brightened HWKP.