Cassava Pulp Hydrolysis under Microwave Irradiation with Oxalic Acid Catalyst for Ethanol Production

Abstract

Abstract.Microwave irradiation is an alternative method of starch hydrolysis that offers a rapid process. The aim of this research was to improve microwaveassisted hydrolysis of cassava pulp by using oxalic acid as a catalyst. Suspension of cassava pulp in 0.5% oxalic acid (1 g/20 mL) was subjected to microwave irradiation at 140-230°C for 5 minutes, with 4 minutes of pre-heating. One gram of fractured activated carbon made of coconut shell was added into a number of suspensions that were subjected to the same conditions of microwave irradiation. The soluble fraction of the hydrolysates was analyzed for its total soluble solids, malto-oligomer distribution, glucose content, pH value, and formation of brown compounds. The effects of the combined severity parameter at a substrate concentration of 5-12.5% on the glucose yield were also evaluated. The highest glucose yield (78% of dry matter) was obtained after hydrolysis at 180°C without activated carbon addition. Heating above 180°C reduced the glucose yield and increased the pH and the formation of brown compounds. The use of activated carbon in microwave-assisted acid hydrolysis of cassava pulp reduced the glucose yield, but suppressed the formation of brown compounds. The highest glucose yield (70-80% of dry matter) was attained at a severity parameter of 1.3-1.5.

Disruption of Oil Palm Empty Fruit Bunches by Microwave-assisted Oxalic Acid Pretreatment

“…The irradiation power was controlled automatically by monitoring the inner temperature of the reactor. MAOxAc pretreatment was conducted according to Hermiati, et al [9] with modification. An amount of 3.0 g (oven-dry weight) of OPEFB was immersed in 1% w/v oxalic acid in a Teflon tube with liquid to solid ratio of 10 and degassed at -20 bar for 5 min.…”