Enzyme Adsorption Equilibria and Kinetics for Recycling - Experimental and Modeling Studies

Cellulase enzymes are used to depolymerize cellulose fibers from waste paper and paper fines to produce monomeric glucose sugars for further conversions into different biofuel and bioplastic products. Optimal utilization and economic feasibility of enzyme catalyzed cellulose hydrolysis can be enhanced by recycling the enzyme cocktails after their first use. This study shows that cellulase enzymes from waste paper hydrolyzates can be adsorbed on to zeolite β under typical hydrolysis conditions. The adsorbed enzyme can then be recovered by applying polyethylene glycol (PEG) or salt (NaCl) or by changing the pH. The application of the PEG (20 kDa MW) appeared to give the best recovery while also maintaining the activity of the enzyme. The adsorption and desorption processes of the enzymes on zeolite β using PEG as an eluent was evaluated using mathematical modelling.