Assessing the potential of lignocellulosic energy crops as an alternative resource for bioethanol production using ultrasound assisted dilute acid pretreatment

Abstract

Abstract Nowadays, more research is directed towards the development of sustainable and eco-friendly technology for the bioethanol production using lignocellulosic biomass to address the global energy requirement. The present study was focused on evaluating the chemical composition and bioethanol production potential of four different lignocellulosic biomass viz., Typha angustifolia, Saccharum arundinaceum, Arundo donax, and Ipomoea carnea. The study exploits the application of ultrasound (US) assisted dilute acid pretreatment for delignification of lignocellulosic biomass. The compositional analysis of biomasses, before and after pretreatment, showed that lignin structure was degraded and more cellulose was exposed for enzymatic saccharification. During enzymatic hydrolysis, Saccharum arundinaceum yielded the highest value of 309.75 ± 3.98 mg/g for total reducing sugar (TRS) among all the biomasses. Typha angustifolia yielded a higher percentage of ethanol of 81.91 ± 8.17% when compared to other biomasses. After the pretreatment, the changes in the morphological features, functional groups, and cellulose crystallinity were examined using various characterization techniques. The variations in peak intensity of functional groups in FTIR and decrease in crystallinity index in XRD indicate that cellulose content was increased with a decrease in lignin content due to the synergistic effect of dilute acid and cavitational effect of US shock waves. Among the lignocellulosic biomass examined, Typha angustifolia resulted a maximum bioethanol production of 5.12 ± 0.87% (w/v) during fermentation. The outputs of the present study showed that the four lignocellulosic perennial energy crops could be utilized as a potential feedstock for the production of bioethanol.