Efficient bioconversion of rice straw to ethanol with TiO2/UV pretreatment

Bioprocess Biosyst Eng. 2012 Jan;35(1-2):43-8. doi: 10.1007/s00449-011-0589-9. Epub 2011 Sep 10.

Abstract

Rice straw is a lignocellulosic biomass that constitutes a renewable organic substance and alternative source of energy; however, its structure confounds the liberation of monosaccharides. Pretreating rice straw using a TiO(2)/UV system facilitated its hydrolysis with Accellerase 1000(™), suggesting that hydroxyl radicals (OH·) from the TiO(2)/UV system could degrade lignin and carbohydrates. TiO(2)/UV pretreatment was an essential step for conversion of hemicellulose to xylose; optimal conditions for this conversion were a TiO(2) concentration of 0.1% (w/v) and an irradiation time of 2 h with a UV-C lamp at 254 nm. After enzymatic hydrolysis, the sugar yields from rice straw pretreated with these parameters were 59.8 ± 0.7% of the theoretical for glucose (339 ± 13 mg/g rice straw) and 50.3 ± 2.8% for xylose (64 ± 3 mg/g rice straw). The fermentation of enzymatic hydrolysates containing 10.5 g glucose/L and 3.2 g xylose/L with Pichia stipitis produced 3.9 g ethanol/L with a corresponding yield of 0.39 g/g rice straw. The maximum possible ethanol conversion rate is 76.47%. TiO(2)/UV pretreatment can be performed at room temperature and atmospheric pressure and demonstrates potential in large-scale production of fermentable sugars.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Biodegradation, Environmental
  • Ethanol / chemical synthesis*
  • Ethanol / radiation effects
  • Oryza / chemistry*
  • Oryza / radiation effects*
  • Plant Components, Aerial / chemistry*
  • Plant Components, Aerial / radiation effects
  • Plant Extracts / chemistry*
  • Plant Extracts / radiation effects
  • Radiation Dosage
  • Titanium / chemistry*
  • Titanium / radiation effects*
  • Ultraviolet Rays

Substances

  • Plant Extracts
  • titanium dioxide
  • Ethanol
  • Titanium