340 / 2018-07-31 10:31:06

Ethanol production from Jerusalem artichoke tuber harvested from mining area and elucidating the heavy metals distribution during the conversion process

全体主题 > 生物质液体燃料

In order to use the Jerusalem artichoke cultivated in mining area, ethanol conversion and environmental risk control of heavy metals in the conversion process were investigated. Tuber hydrolysis was performed using diluted phosphoric acid. Based on the selected conditions for hydrolysis process, the contents of Cu, Zn, Pb, and Cd in the whole streams of ethanol conversion process were investigated using inductively coupled plasma mass spectrometry (ICP-MS). Results indicated that the optimized conditions for reducing sugar release of tuber was 4% phosphoric acid concentration at 90 °C for 180 min of hydrolysis time. A rather high reducing sugar concentration of 973 mg·g was obtained at the solid-liquid ratio of 1:6. The subsequent ethanol yield reached 53.04 g·L in 48 h with the corresponding conversion rate of 94%. As for the heavy metal distribution, 52.05% (Cu), 42.28% (Zn), 87.73% (Pb), 42.46% (Cd) in the tuber were transferred to the hydrolyzed solid residues while the rest part was transferred into the soluble sugar solution. At the ethanol fermentation process, 25.88% (Cu), 33.94% (Zn), 12.09% (Pb), 49.97% (Cd) of the corresponding heavy metals were remained in the broth, and much less of 11.84% (Cu), 1.54% (Zn), 2.08% (Pb), 1.94% (Cd) entered into the fermented residues. It was shown less than 2% heavy metal was remained in the ethanol product. These results indicated Jerusalem artichoke cultivated in heavy metal polluted soil was still feasible for bioethanol production. In the phosphoric acid hydrolysis-fermentation process, most of heavy metals were transferred into the waste streams, which should be paid more attention to decrease its overall environmental risks.