Acid, alkali and peroxide pretreatments increase the cellulose accessibility and glucose yield of banana pseudostem

Abstract

Lignocellulosic biomasses such as banana pseudostem are attractive cellulose sources for bioenergy production, and for the use in biorefinery processes. However, pretreatment of lignocellulosic material is required to remove hemicellulose and lignin, while increasing cellulose accessibility to enzymatic hydrolysis (i.e., decreasing biomass recalcitrance). The effect of different concentrations of acid (H 2 SO 4), alkaline (NaOH) and peroxide (H 2 O 2) pretreatments on the chemical composition, cellulose accessibility, and enzymatic digestibility of banana pseudostem were studied. The water insoluble solids (WIS) recovery was low (∼30%) for the severe pretreatment conditions applied, indicating high material solubilization. Acid pretreatment completely removed the hemicellulose content, whereas alkaline and peroxide pretreatments reduced its amount to 4.38 and 8.68%, respectively. In contrast, the lignin content increased (from 17.26 to 39.99%) after severe acid pretreatment, while alkaline and peroxide pretreatments reduced the lignin content to 7.65% and 7.17%, respectively. In line with hemicellulose and lignin removal, the cellulose content increased from 60.84 to 75.48 and 74.37%, respectively for alkaline and peroxide pretreatments, with no alteration for acid. Dye adsorption assays showed that alkaline and acid pretreatments resulted in high internal and external specific surface areasindicative of high cellulose accessibilitywhen compared with peroxide pretreatments. Overall, alkaline and acid pretreatments resulted in the highest glucose yields from enzymatic hydrolysis of banana pseudostem, compared with peroxide pretreatment. In conclusion, concentrations of each pretreatment that led to the highest glucose yields was identified, confirming that the banana pseudostem is a great source of fermentable sugars, with high potential for biofuel production.

Utilization of banana crop residue as an agricultural bioresource for the production of acetone‐butanol‐ethanol byClostridium beijerinckiiYVU1

“…b). The indistinguishable SEM results were similar with acid, alkali and peroxide treated banana pseudo‐stem (Shimizu et al ). The pretreated BCR (10% w/v) was dried and subjected to saccharification with an enzyme mixture of cellulases and β‐glucosidases.…”

“…The cellulose, hemicelluloses and lignin contents of dried BCR were 44·3 ± 5·5%, 20·5 ± 3·0% and 16·3 ± 2·6% respectively (Table ). The pseudo‐stem part contained a good amount of cellulose ( c. 60–65%) and less amount of hemicellulose (10–15%) (Shimizu et al ; Srivastava et al ). In this work, the cellulose content of BCR was low because it’s leaf contained low amounts of cellulose and high amount of hemicellulose and lignin when compared with the pseudo‐stem.…”

“…The purpose of pretreatment was to solubilize and remove the lignin and hemicellulose from the BCR because the presence of these substituents prevents the enzymatic hydrolysis of cellulose to glucose for alcohol fermentation (Gabhane et al ; Srivastava et al ). Generally, acid pretreatment solubilizes the hemicelluloses fraction and the alkali solubilizes more lignin of the lignocellulosic biomass and enhances the cellulose accessibility to the enzymes during the saccharification (Franco et al ; Reddy et al ; Shimizu et al ). In this study, the proposed sequential alkali and acid pretreatment solubilized both lignin and hemicelluloses effectively.…”

Optimization of Alkaline, Acidic, Ionic Liquid and Oxidative Pretreatments for Coconut Waste Conversion into Fermentable Sugars

“…8 However, many methods (steam explosion, ammonia fiber explosion, alkali and acid solutions, organosolv process, and wet oxidation in combination with alkaline hydrolysis) have led to high sugar yield (above 90%). 9 Literature describes several pretreatments based on dilute acid, 10,11 dilute alkaline, 3,7 as well as on oxidative 12 and ionic liquid. 13,14 Thus, it is necessary analyzing pollution-free and economically feasible methods capable of shortening the duration and reducing the costs of the process before selecting the best pretreatment.…”

Experimental Investigation, Techno-Economic Analysis and Environmental Impact of Bioethanol Production from Banana Stem

“…The current study unveiled that 24 h additional hydrolysis enhanced glucose yield, 8.84 g/L more compared to 48 h hydrolysis. Apart from that, this study determined the highest amount of glucose content among all the previous studies done for the banana stem in other countries, such as Taiwan, Brazil, India, and Indonesia [21,26,37,41]. Applications of efficient catalysts and nano-catalysts may enhance the effectiveness of cellulase enzyme and lead to a higher rate of delignification.…”