Development of immobilized cellulase through functionalized gold nano-particles for glucose production by continuous hydrolysis of waste bamboo chopsticks

• Cellulase was immobilized on silica through functionalized gold nano-particle.
• Continuous hydrolysis of waste bamboo chopsticks powder gave 82.9% conversion rate to glucose.
• Immobilized cellulase can be reused at least 6 cycles for a period of 90 days with no loss of activity.

Cellulase immobilized on silica through the assistance of l-cysteine functionalized gold nano-particle was applied for the continuous hydrolysis of waste bamboo chopsticks powder to produce glucose. The optimal conditions for the continuous hydrolysis were pH 8.0, 50 °C. A 4-day reaction with an initial 0.3 g L−1 waste bamboo chopsticks powder, a feed containing 0.2 g L−1 waste bamboo chopsticks powder at a continuous feed and draw rate of 0.5 mL min−1, and an enzyme loading of 40 mg cellulase (g silica)−1, has 72.0–76.6% conversion rates of repeated hydrolyses that correspond to a total production of 630.5–671.2 mg glucose and are much better than batch hydrolyses. At higher enzyme loading (117 mg cellulase (g silica)−1), higher initial concentration (0.5 g L−1), and higher feed concentration (0.42 g L−1) the conversion rate increases to 82.9% and a total amount of 1418 mg glucose. The immobilized cellulase can be recovered easily by filtration and used repeatedly at least 6 times over a period more than 90 days with a recovered activity approximately the same as or better than previous reactions. Thus the process is promising for scaling up.

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