Microwave-Assisted Alkali Delignification Coupled with Non-Ionic Surfactant Effect on the Fermentable Sugar Yield from Agricultural Residues of Cassava

Abstract

Abstract-

Bioethanol production from microwave-assisted acid or alkali-pretreated agricultural residues of cassava using separate hydrolysis and fermentation (SHF)

“…It was reported earlier that in the case of MW-assisted alkali-pretreated cassava leaves saccharified with Cellic alone without or with Tween 20 in the system, RS values of 41.60 and 46.23 g/L were, respectively, obtained (Pooja and Padmaja 2017), which showed that the effect of triple enzyme cocktail or detoxification chemical mix used in the present study was not highly significant for cassava leaves. MW-assisted dilute acid-pretreated cassava leaves on saccharification with triple enzyme (C + S + OBG) without (D0) or with (D+) detoxification chemical mix gave RS values of 30.28 and 33.95 g/L, respectively, after 120 h (Fig.…”

“…However, when MW-assisted alkali-pretreated cassava stems were saccharified using Cellic alone with or without Tween 20, much lower RS contents were reported (Pooja and Padmaja 2017), which indicated that the triple enzyme cocktail was beneficial in enhancing RS release from MWassisted alkali-pretreated stems. Optimash BG used in the cocktail had component activities such as β-glucanase and xylanase, while Stargen had high amylolytic activity and these might have facilitated high hydrolysis of both hemicelluloses and starch.…”

“…The slurries were then exposed to microwave irradiation power of 300 W and irradiation time of 7 min in a Microwave oven (M/s Samsung, Thailand) as reported (Mithra et al 2017). MW-assisted alkali pretreatment was carried out by preparing the alkaline biomass slurry (20 g in 200 ml 3% NaOH) for each sample, which was then exposed to MW irradiation at 300 W for 7 min (Pooja and Padmaja 2017).…”

“…Microwave-assisted alkali (3% NaOH) pretreatment was earlier found to be reasonably effective in enhancing the fermentable sugar yield from cassava residues during saccharification with Cellic alone, which otherwise was only poorly deconstructed after steam pretreatment (Pooja and Padmaja 2017). Hence, it was thought worthwhile to compare the effects of MW-assisted dilute acid or alkali pretreatments on fermentable sugar yield during saccharification with the triple enzyme cocktail comprising Cellic + Optimash BG + Stargen to find out the improvements over Cellic alone-aided saccharification (with or without Tween 20).…”

“…Further studies using another cellulolytic complex, Cellic CTec2 showed that very high yield of sugars was possible from peels, while optimum hydrolysis of polysaccharides could not be achieved for the other two biomasses using the single enzyme (Pooja and Padmaja 2015b). MWassisted alkali pretreatment followed by saccharification with the enzyme complex Cellic in the presence of Tween 20 could convert as high as 83-93% potential sugar yielding carbohydrates to reducing sugars (Pooja and Padmaja 2017). Previous studies showed that a mix of detoxification chemicals such as Tween and Polyethylene glycol was highly effective in eliminating soluble phenolics from the pretreated root crop residues (Mithra and Padmaja 2016).…”