Low concentration of NaOH/Urea pretreated rice straw at low temperature for enhanced hydrogen production

• Published in: International journal of hydrogen energy 2020-01, Vol.45 (3), p.1578-1587
• Main Authors: Dong, Lili, Wu, Jiwen, Zhou, Chunshuang, Xu, Cheng Jiao, Liu, Bingfeng, Xing, Defeng, Xie, Guojun, Wu, Xiukun, Wang, Qi, Cao, Guangli, Ren, Nanqi
• Format: Article
• Language: English
• Subjects: Hydrogen; Low concentration NaOH/Urea; Low temperature; Pretreatment; Rice straw
• ISSN: 0360-3199
• DOI: 10.1016/j.ijhydene.2019.11.037

In lignocellulose-to-hydrogen bioconversion, reducing the concentration of chemical agents in pretreatment is of great interest. In this study, rice straw (RS) pretreated at reduced NaOH and urea (NU) concentrations was evaluated. Results showed that the composition of RS exhibited excellent pretreatment performance at a reduced concentration of NU. When the concentration of NaOH was decreased to 3 wt% in combination with 6 wt% urea, the lignin was reduced by 59.52% with a cellulose and hemicellulose loss of less than 17%. Moreover, extending the pretreatment time at a low concentration of NU could effectively promote the biodegradability of RS. Upon fermentation by Thermoanaerobacterium thermosaccharolyticum M18 for H2 production, the H2 production increased up to 213.06 mL/g with a substrate treated by 3 wt% NaOH/6 wt% urea at low solid loading for 15 d, which was 16.31% higher than the counterpart subjected to a 7 wt% NaOH/12 wt% urea pretreatment. The present results suggest the NU pretreatment can be carried out at low concentrations to improve the conversion of RS into bio-H2 production. [Display omitted] •Low concentration NU pretreatment could enhance the biodegradability of RS.•Extending time could promote the effciciency of pretreatment at low concentration NU.•The maxmium H2 production reached 213.06 mL/g substrate at 3%–6% NU for treated 15 d.•This study provides a promising and technically way for biomass pretreatment.