(424a) Adsorption and Filtration of Lignocellulosic Hydrolyzates Using Fibrous Depth Filters

Mary Jennifer Puthota, Thomas Dwyer Stuart and Bandaru V. Ramarao

Empire State Paper Research Institute

Department of Paper and Bioprocess Engineering

State University of New York,

College of Environmental science and Forestry,

1 Forestry Drive, Syracuse, New York 13210, USA

Abstract

Lignocellulosic hydrolyzates contain lignin in dissolved and colloidal form which must be separated before fermentation to prevent inhibition of bioconversion of the sugars. The most common detoxification techniques to remove lignin involve acidification and precipitation followed by adsorption using activated carbons.

Depth filtration has emerged as a useful technology in Bioseparations to purify solutions containing colloidal particles and macromolecular species. Lignocellulosic hydrolyzates can be purified using fibrous depth filters effectively, especially by integrating a flocculation step ahead of depth filtration.

In this paper, the application of fibrous depth filters using unbleached and bleached kraft pulp fibers (hardwood and softwood) is presented. Since fibers are anionic, as are the lignin particles in hydrolyzates, it is necessary to cationize the fibers using polyelectrolytes such as poly DADMAC to cause filtration. Another route is the use of PEO polymers to attach the lignin particles to the fibers.

Both of these techniques are considered and preliminary experimental results on separations are presented. Mathematical models for depth filters of composed of such fibers are presented and analyzed to show the impact of different operating variables.