Abstract
BackgroundLignocellulose biomass such as agricultural residues is increasingly important for biofuel production. Using agricultural residues like rice straw for biofuel production has dual purposes of utilizing the huge waste generated. The abundant availability and high polysaccharide contents are the main reason for biofuel production. However, the use is limited due to the reluctant nature of lignin in the biomass. Therefore, sodium hydroxide was used for solubilizing lignin and preserving the polysaccharides.ResultsAbout 71.29% of lignin (maximum amount of lignin) was removed after 7% sodium hydroxide (NaOH) pretreatment followed by 3% pretreatment (about 67.13%). Also, maximum cellulose (about 71.33%) was preserved after 7% NaOH pretreatment. Results of reducing sugars obtained by spectrophotometric analysis (3,5-dinitrosalycilic acid method) of pretreated rice straw show about 88.27% conversion (753 mg/g) after the 13th day of hydrolysis by bacteria isolated from a termite. FE-SEM, XRD, FTIR, and TGA analyses show a significant amount of lignin was removed which helps in releasing cellulose tangled in lignin.ConclusionRice straw pretreatment at 7% NaOH and hydrolysis by Bacillus sp. BMP01 achieved the release of a high yield of fermentable sugars that increased the yield of bioethanol. This study demonstrates the potential of alkali pretreatment coupled with microbial hydrolysis for efficient bioethanol production from agricultural residues like rice straw.
Highlights
Lignocellulose biomass such as agricultural residues is increasingly important for biofuel production
The effect of different concentrations of sodium hydroxide treatments is described by comparing it with raw/
Characterization of pretreated rice straw Scanning electron microscopy analysis (SEM) The effect of different concentrations of Sodium hydroxide (NaOH) treatments on surface morphology and the microstructure of rice straw were characterized by scanning electron microscopy (SEM)
Summary
Lignocellulose biomass such as agricultural residues is increasingly important for biofuel production. Using agricultural residues like rice straw for biofuel production has dual purposes of utilizing the huge waste generated. Rice is one of the most common staple foods in the world in which half of the world population relies on it. Both in terms of consumption and growth, Asia alone accounts for about 90%. From every 4 tons of rice grain produced, 4–6 tons of straw is obtained (Poornejad et al 2013). About 550 million tons of straw and 110 million tons of husks are produced in Asia alone.
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