Anodic modification of lignins during electrolysis in the organocell process

Pulping liquor from the 5 t/day demonstration plant of Organocell GmbH, Munich, was electrolyzed with different current densities. The analysis of the isolated lignins revealed considerable changes of lignin structure during electrolysis. These changes included polymerization reactions involving the formation of C- and O-condensed interunit linkages and reactions of the side-chain such as decomposition of enol ethers and increase of COOH, CO and OH_ali. groups. The extent of the observed reactions was found to be highly dependent on the current density. With the exception of OH_ali.groups and residual sugars, the degree of structural modification was inversely proportional to current density.