Utilization of waste cellulose. 7. Kinetic study of the enzymatic hydrolysis of spruce wood pretreated by sodium hypochlorite

Spruce wood sawdust has been pretreated with sodium hypochlorite at pH 8 and hydrolyzed into glucose by cellulases of Trichoderma viride at different initial concentrations of substrate and enzyme. The initial rate of hydrolysis was shown to obey a Michaelis type equation and the limiting yield is very high. The kinetics are different for the untreated substrate hydrolyzed under the same conditions; low conversion into glucose is obtained even at very long reaction times. The higher reactivity of the pretreated substrate is explained by a significant increase in the number of accessible anhydroglucose units due to oxidation of the lignin network by sodium hypochlorite. Inhibition of the hydrolysis by glucose and by enzyme adsorption is considered. A simple kinetic scheme is proposed to explain the results.