Synthesis and evaluation of new surfactants for enhancing simultaneous saccharification and fermentation of natural cellulosic materials to bioethanol.

Abstract

Sorbitan monolaurate (Span 20) was ethoxylated by four different molar ratios of ethylene oxide

(20, 40, 60, and 80) and named E (20), E (40), E (60), and E (80). The structure ofthe prepared • nonionic surfactants was elucidated using; FT-IR and 1H NMR spectroscopies. The surface tension

measurements were recorded. The effect of the prepared nonionic surfactants on the simultaneous saccharification and fermentation (SSF) of microwave/alkali pretreated rice and wheat straws to produce ethanol were investigated. From the obtained data, it was found that the addition of the nonionic surfactants at 2.5 g/1 had positive effect on SSF. The maximum ethanol yield (82 and 76 %) was obtained after 72 hat 42 °C using Kluyveromyces marxianus for wheat and rice straws ,

respectively, while Saccharomyces cerevisiae exhibited a maximum ethanol yield (61 and 55 %) at 37 oc and 72 h for wheat and rice straws , respectively. The ethanol yield increases with increasing the Hydrophile-Lipophile Balance (HLB) of the prepared nonionic surfactants by increasing ethylene oxide units.

Keywords: Span 20- ethylene oxide-nonionic surfactants- SSF- rice straw- wheat straw- ethanol- Kluyveromyces marxianus- Saccharomyces cerevisiae- HLB.