Microwave-assisted Acid Hydrolysis of Starch Polymer in Cassava Pulp in the Presence of Activated Carbon

Cassava pulp contains significant amount of starch which can be hydrolyzed to glucose, and further converted to different kinds of chemicals, such as lactic acid, fumaric acid, and ethanol. Microwave irradiation is an alternative method for starch hydrolysis, and the addition of activated carbon has been reported could increase glucose yield at lower temperature in water medium. This research was to study the effects of two types of activated carbon on the acid hydrolysis of cassava pulp under microwave irradiation. The experiment was conducted at two microwave power level (30% and 50%), each with heating duration of 5, 7.5 and 10 min in 0.5% sulfuric acid medium. The addition of activated carbon with superior adsorption capacity in cassava pulp suspension resulted in lower glucose yield than the one without the addition of activated carbon at both power levels. On the other hand, the addition of activated carbon with inferior adsorption capacity resulted in much higher glucose yield than the one without the addition of activated carbon at microwave power 30% and slightly lower glucose yield at microwave power 50%. However, activated carbon with higher adsorption capacity was superior to the other one in suppressing the formation of colored secondary degradation materials. The highest glucose yield (91.52%) was obtained in the hydrolysates from the treatment at microwave power 50% for 10 min without the addition of activated carbon.