NaBH4 Pretreatment in Bioethanol Production of Corn Stalks

Corn stalks, which are an abundant agricultural waste product in Turkey, have a high carbohydrate structural content and could be a valuable raw material for bioethanol production. In this study, stalks with crystalline cellulose and complex lignin and hemicellulose distribution in their structure were first steam-exploded and then chemically treated to achieve efficient hydrolysis. The conventional chemicals sodium hydroxide (NaOH), sulfuric acid (H2SO4), hydrogen peroxide (H2O2), and an alternative chemical, sodium borohydrate (NaBH4), were utilized in the chemical treatment procedure. Results showed that the samples treated with NaOH (83.9%) and NaBH4 (82.9%) gave higher glucan conversion in enzymatic hydrolysis compared to those treated with H2O2 (74.5%) and H2SO4 (56.6%). The highest ethanol yield from untreated stalks (97.4g/kg) was obtained when the stalks were pretreated with 4% NaBH4 for 90min; the theoretical ethanol yield was found to be 72.5%