The reactions of lignins with high temperature hydrogen peroxide - Part 2.The oxidation of kraft lignin

A technical pine kraft lignin was subjected to alkaline hydrogen peroxide o xidation in the presence of DTMPA and molecular oxygen at various temperatu res. In the presence of DTMPA the lignin was found to undergo increasing le vels of oxidation and degradation with increasing temperature. At 110 degre es C over 80% of the kraft lignin was degraded. Analyses of the degraded li gnins indicated that both phenolic and nonphenolic lignin moieties were deg raded. At 90 degrees C the addition of molecular oxygen resulted in further lignin demethoxylation, but did not decrease the amount of phenolic hydrox yl groups or hydrogen peroxide consumed. In the absence of DTMPA the hydrog en peroxide was rapidly degraded, and accompanied by only minimal lignin ox idation.