Effect of enzymatic treatment on Eucalyptus globulus vessels passivation

Abstract

Hardwood vessel elements generate problems in industrial uncoated wood-free printing paper operation, causing vessel picking and ink refusal. These problems are mitigated using mechanical refining at the cost of paper quality. Vessel enzymatic passivation, altering its adhesion to the fiber network and reducing its hydrophobicity is a way of improving paper quality. The object of this paper is to study how the enzymatic treatment by xylanase and by an enzymatic cocktail containing cellulases and laccases affect elemental chlorine free bleached Eucalyptus globulus vessel and fiber porosities, bulk, and surface chemical compositions. Thermoporosimetry revealed the vessel structure to be more porous, surface analysis showed its lower O/C ratio and bulk chemistry analysis its higher hemicellulose content. Enzymes had different effects on porosity, bulk and surface composition of fibers and vessels, affecting vessel adhesion and hydrophobicity. Vessel picking count decreased 76% for papers containing vessels treated with xylanase and 94% for the papers with vessels treated with the enzymatic cocktail. Fiber sheet samples had lower water contact angle (54.1º) than vessels rich sheets (63.7º), that reduced with xylanase (62.1º) and cocktail (58.4º). It is proposed that differences in vessel and fiber porosity structures affect the enzymatic attacks, eventually causing vessel passivation.

Microwave Treatments and Their Effects on Selected Properties of Portuguese Pinus pinaster Aiton. and Eucalyptus globulus Labill. Wood

“…Wood is one of the most commonly used materials in construction since it is abundant, sustainable, and presents a great strength-to-weight ratio compared with other materials such as concrete and steel [1]. In Portugal, many wood species have been tested for either construction or non-construction applications (e.g., pulp industry) [2][3][4][5][6][7][8][9], but maritime pine (Pinus pinaster Aiton.) and eucalyptus (Eucalyptus globulus Labill.)…”