NaBH₄ Pretreatment in Bioethanol Production of Corn Stalks

Abstract

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 (97.4 g/kg) was obtained when the stalks were pretreated with 4% NaBH₄ for 90 min; the theoretical ethanol yield was found to be 72.5%.

Keywords:

• Chemical pretreatment
• corn stalks
• enzyme
• ethanol production
• hydrolysis
• steam explosion

Acknowledgments

This work was supported by The Scientific and Technological Reseach Council of Turkey (TUBITAK Project: 109O200).