Immobilisation of laccase for polymerisation of commercial lignosulphonates

The oxidoreductive enzyme laccase has previously been shown to be able to increase the average molecular weight of lignosulphonates through generation of phenoxy radicals on end groups and the subsequent radical-radical coupling reactions that cross-link individual lignosulphonate molecules. Utilisation of laccases for this purpose is a potential industrial process not only to improve the properties of technical lignosulphonates but also to expand their utilisation to new areas. Immobilisation of the laccase is an interesting technique to enable reusage of the enzyme and thus reduce costs involved with such process. In this work, we demonstrate the potential of immobilised laccase to polymerise technical lignosulphonates. A number of factors that limits re-utilisation of the immobilised catalyst such as lignosulphonate adsorption onto the carrier and laccase deactivation have been identified and are discussed. However, by using a low-porosity support and lower reaction temperatures these problems can be limited. (C) 2011 Published by Elsevier Ltd.