Enzymatic Hydrolysis Of Cellulose And Acceleration Of Ultrasonic Energy To The Hydrolysis

The mechanism and the kinetics model of enzymatic hydrolysis of cellulose by cellulase, and the acceleration of ultrasonic energy to the hydrolysis were studied. The effect of various factors to the enzymatic hydrolysis and the deactivation of cellulase in ultrasonic field were also investigated.According to the structure of cellulosic material (crystal cellulose and non-crystal cellulose) and the hydrolysis specialty of cellulase, a new mechanism for enzymatic hydrolysis of cellulose was proposed. The mechanism can appropriately explain various phenomena in hydrolytic process of cellulose by cellulase. On the basis of the hydrolysis mechanism, a kinetic model was suggested, and the integral equation was derived. This kinetic equation expressed the effect of cellulase concentration, reaction rate constant, equilibrium constants, cellulosic material effective concentration, density, and size and hydrolysis time on the concentration of reducing sugar produced. When the kinetic equation was used to describe the relation between concentration of produced sugar and hydrolysis time, there are only 3 parameters in the equation, which can be regressed easily. To avert some nonlinear influence caused by composition of cellulose material and product inhibition, an equivalent hydrolysis time, which is proportional to reaction rate constant, was used io express enzyme reaction rate. The ultrasonic effect on chemical reaction and enzyme reaction was analyzed. The ultrasonic effect to chemical reaction is cavitation, and the ultrasonic effect on enzyme reaction is increasing kinetic energy of enzyme molecule and increasing its renewing frequency on the surface of cellulose material. Ultrasonic can accelerate reaction rale of enzyme reaction, but also can accelerate the deactivation rate of enzyme. If oxygen exits in the system, deactivation takes place more easily. Thus it was suggested to use nitrogen in the system to avoidthe deactivation.The experimental data of enzymatic hydrolysis of filter paper obtained by us and the experimental data of avicel and non-crystal cellulose obtained by other researchers were regressed with the kinetic equation suggested by us. The kinetic equation was conformable with these experimental data. It was proved that the model is reasonable to avicel, filter paper cellulose and amorphous cellulose.The acceleration of ultrasonic to enzymatic hydrolytic process of cellulose was obvious. The hydrolysis rate rises with increase of ultrasonic energy in 0-54mW/mL. The hydrolysis rate in the 28mW/mL ultrasonic field was 0.6 times higher than that in non-ultrasonic field.Cellulase was simplified as 3 ionization states in the investigation of effect of pH on the enzymatic hydrolysis. A relation between equivalent time and pH was obtained. The predicted values were consistent with experiment data under 10min, 40min, 70min within pH4-6.5, and optimal pH was obtained at 4.83 through regression computation. Reaction rate was raised with increasing temperature within 25-50C. Through calculating, the activity energy of cellulose hydrolysis by cellulase in ultrasonic field was 57.8 kJ/mol. The effect of enzyme concentration, glucose concentration, filter paper concentration and material kind on the enzymatic hydrolysis in ultrasonic field was also investigated. The effect rules of various factors in ultrasonic field were similar as that in non-ultrasonic field. It was showed that ultrasonic did not change the reaction mechanism. The deactivation of cellulase was studied briefly. It was found that hydrolysis rate under nitrogen higher than that under air. It was showed that cellulase deactivation was caused mainly by oxygen under the experimental condition.