Extraction of Bioethanol from Corn Husk

Abstract

Well over a century, bioethanol, the most largely used liquid biofuel is produced by the fermentation of starch-and sucrose based-sources. However, it appears unattractive producing biofuel from food/feed sources which have the potential of hyping the competitiveness of their prices. The extraction of bioethanol from corn husk in this research seeks to explore more on the production of bioethanol using lignocellulosic biomass, by optimizing the treatment conditions to obtain the highest yield possible, and to analyze the distillate (i.e., the product) and evaluates its prospects for a potential biofuel. This research adopts a chemical extractive model (acid hydrolysis) by pretreating the corn husk with concentrated sulphuric acid, followed by the post-hydrolysis step where the feed acid concentration is reduced to a predetermined value. The approach adopted gave a high Brix value of 33°. A 14-day fermentation period of the hydrolysate is performed using a genetic modified variant of the microbial strain, Saccharomyces cerevisiae. The raw powdered corn husk, the residual solid residue of the husk generated during hydrolysis, and the recovered bioethanol are subjected to a number of analytical and characterization techniques. These include X-ray powder diffraction (XRD) spectroscopy, Fourier transform infrared (FTIR) spectroscopy, Gas chromatography-mass spectrometry (GC-MS) analysis, and Ultraviolet-visible light (UV-Vis) spectroscopy. The XRD pattern shows four matching crystallographic peaks for both the raw powdered husk and residual solid residue at different intensities producing an average of 38.50 % breakdown of the crystalline cellulose. FTIR analysis shows three frequencies of absorption peaks at 3332.00 nm, 2107.87 nm, and 1635.07 nm for an O - H, C= O, and C-H bending of an aromatic source, respectively. The GC-MS analysis identifies about 41 different chemical components present in the distillate, comprising organic acids, inorganic compounds, and organic salts. The chemical component with the highest percent composition is n-Hexadecanoic acid, making 26 % of peak area. UV-Vis spectroscopy analysis qualitatively identifies ethanol in the distillate by comparing the spectrum of the distillate to the spectrum of standard grade ethanol at 99.8 wt % purity. The both graphs show absorption in the range 220 nm - 280 nm. Further UV-Vis