Delignification of rapeseed straw using innovative chemo-physical pretreatments

• Published in: Biomass & bioenergy Vol. 95; pp. 92 - 98
• Main Authors: Brahim, M., El Kantar, S., Boussetta, N., Grimi, N., Brosse, N., Vorobiev, E.
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.12.2016; Elsevier
• Subjects: Delignification; Engineering Sciences; Enzymatic hydrolysis; High-voltage electrical discharges; Microwaves; Rapeseed straw; Ultrasounds; Rapeseed straw; Ultrasounds; Delignification; High-voltage electrical discharges; Enzymatic hydrolysis; Microwaves
• ISSN: 0961-9534; 1873-2909
• DOI: 10.1016/j.biombioe.2016.09.019

Rapeseed straws are recoverable lignocellulosic biomass for second generation bioethanol production. Therefore, a pretreatment step is recommended in order to increase accessibility of enzymes to sugars. As a pretreatment step in this study, several innovative technologies have been performed in order to investigate their efficiency for delignification and enzymatic hydrolysis purposes: microwaves (MW), high voltage electrical discharges (HVED) and ultrasounds (US). As a key processing parameter, different levels of energy input were studied MW (1832–7328 kJ/kg), US (916–3664 kJ/kg) and HVED (204–814 kJ/kg) corresponding to a treatment duration range of 10–40 min. Treatment temperature (60–90 °C) and medium alkalinity (0.125–0.5 M) impact was also investigated and optimized based on sugar and soluble lignin contents in black liquor, and lignin removal yields. Delignification yields increased from 28.3%, 28.6% and 31.2% for 10 min of treatment to 38.4%, 41.5% and 42.3% for 40 min of treatment, respectively for MW, US and HVED. However, in order to achieve the same efficiency the energy required by HVED is 9 times and 4.5 times less than that required by MW and US respectively. Treatment temperature also revealed to be important as sugars yields increased by 41.6% when temperature increased from 60 °C to 90 °C for HVED and the optimal medium alkalinity was found to be 0.3 M. Finally, better enzymatic hydrolysis yields were obtained and correlated to better delignification performances improving material accessibility. •Physical treatments were applied on rapeseed straw for delignification purposes.•The effect of the duration, the treatment energy input, the temperature and the alcalinity of the medium were studied.•The impact of physical treatments on enzymatic digestibility was investigated.•Physical treatments allow the lignin removal and improve the enzymatic hydrolysis with less energy consumption for HVED.