Abstract
Investigation of an alternative source of the nonrenewable energy is attracting the world attention nowadays. The fruits and leaves biomass of
Calotropis procera
were exposed to sequential pretreatment processes. First, a successive pretreatment with an organic solvent (hexane/methanol) yielded biocrude and plant spent residues fractions. The plant spent residues fractions were exposed to successive acid/alkali (1% H
2
SO
4
/2% NaOH) pretreatment to yield spent residues of fruits (SRF) and leaves (SRL). The amount of cellulose content of the sequential pretreated SRF and SRL were 87.3 and 83.4%, respectively. The hydrolysis process of 10 g of the sequential pretreated SRF and SRL by Sternzym cellulase produced 80.2 and 50.4 g/L of total reduced sugars, respectively. The reduced sugars were then fermented by
Saccharomyces cerevisiae
(MN901244) for bioethanol production. The HPLC analysis showed 38.9 and 23.8 g/L of bioethanol yields from sequential pretreated SRF and SRL, respectively. The GC/MS analysis of methanol and hexane biocrude fractions revealed the presence of 20 and 12% of fatty acids, respectively, which would be promising amounts for biodiesel production after esterification. So, the present study suggested a low-cost nonedible plant biomass (
Calotropis procera
) as a biorefinery for production of renewable bioethanol.
Graphical abstract