Investigation on using two types of sonoreactors for Kraft lignin fractionation

For a decreasing conventional pulp and paper industry, new products from wood are needed. As lignin is the second most abundant polymer on earth (cellulose is the first), many studies are oriented toward her utilisation. Lignin is rich in many carbon based polymer, phenolic groups, alcohol groups but the highly 3 dimensional structure prohibit easy usage of this material. Ultrasonic modifications were tried by a few researchers but success and horror stories were reported. The objective of this work is to study the potential in ultrasound fractionation on Kraft lignin in two high power flow-through sonoreactor. From our work, we can conclude that lignin modification is indeed possible with ultrasound but will be dependant of the system. Indeed, successful conditions were found for the small sonoreactor while the same condition tried in the semi-pilot sonoreactor was unsuccessful. This duality of results, as found in the literature, is indicating that ultrasonic modification of lignin is not evident but that the process, under specific conditions, could be successful.