Ethanol biofuel production and characteristics optimization from wheat straw hydrolysate: Performance and emission study of DI-diesel engine fueled with diesel/biodiesel/ethanol blends

Bioethanol has been classified as the most widely utilized biofuel globally because it helps greatly decrease crude oil consumption and pollution. In this study, bioethanol production improved by 3.6-fold after optimization conditions for commercial Saccharomyces cerevisiae on hydrolysate obtained from enzymatic saccharification of Aspergillus niger to 1% NaOH pretreated wheat straw. 26.0% bioethanol was obtained after 96 h at 30 °C using 10% (W/V) inoculum size of Saccharomyces cerevisiae at pH 5.0 and 2% molasses additives under static condition. After optimization, bioethanol was produced on a large scale, and distillation was carried out, then bioethanol was characterized using Gas chromatography (GC) analysis and ¹H NMR. On large-scale production, 1 kg NaOH pretreated wheat straw was fermented with Aspergillus niger to produce 10 L of hydrolysate that concentrated to 4 L using a rotary evaporator. After concentration, reducing sugar became 35.08 mg/ml, then 2% molasses were added, and the final sugar concentration became 41.7 mg/ml. Finally, reducing sugar was fermented by Saccharomyces cerevesiae to produce 1 L of bioethanol. In addition, the obtained bioethanol was blended by the commercial diesel#1/WCO biodiesel commixture with 10% and 20% by volume. The blends of 50%diesel/50%biodiesel, 10% bioethanol/45%diesel/45%biodiesel, and 20%bio ethanol/40%diesel/40%biodiesel were tested as new fuel blends in a single cylinder air-cooled direct injection diesel engine. The engine performance and emission have been recorded at different engine loads and fixed speeds of 1500 rpm. The obtained results reveal that the engine BTE has been enhanced where the engine NOx was reduced if 10% of bioethanol has been added. While increasing bioethanol to 20% by volume base increases the combustion of unburned hydrocarbon and CO emission.