(567d) Kinetics of the Enzymatic Hydrolysis of Paper Pulp Fibers

Papermaking fibers, particularly waste fibers from recycling operations can be a valuable resource for bioenergy and products such as ethanol, bioplastics or biochemicals. The amount of lignin in such fibers is much lower than native wood or other plant based lignocellulosic resources eliminating the need for pretreatment steps. Moreover, waste fibers are readily available in the waste streams rejected from the papermaking operations to improve paper strength and runnability of the paper machines.

The present work develops a model for the kinetics of the enzymatic hydrolysis of cellulosic pulp fines based on the physico-chemical interactions. The cellulolytic enzymes adsorb to the outer surfaces of the fines after which they diffuse into the interior pores. The fine particles are assumed to be spherical, containing two distinct kinds of pores: one at the macro-scale and another at a micro-scale allowing slow progression of the enzymes into the solid cellulosic matrix. Enzymatic hydrolysis reactions are assumed to occur at the micro-scale within the cellulosic matrix. Convective mass transfer boundary layers reduce the enzyme transport across the external particle surfaces. The main utility of this model is in estimating the optimal reaction conditions and assist in scaling studies of these enzymatic hydrolysis processes.

Keywords: Enzymatic hydrolysis, cellulose, pulp fibers, fines, rejects, paper mill waste solids