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| Selection of optimal conditions for maize straw pretreatment by SPORL method |
| Received:September 01, 2017 |
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| KeyWord:SPORL method;maize straw;response surface methodology;humification |
| Author Name | Affiliation | E-mail | | YAO Yan-ying | College of Resources and Environment Sciences, Jilin Agricultural University, Changchun 130118, China | | | WU Jing-gui | College of Resources and Environment Sciences, Jilin Agricultural University, Changchun 130118, China | wujingguiok@163.com | | LI Jian-ming | College of Resources and Environment Sciences, Jilin Agricultural University, Changchun 130118, China | | | ZHAO Xin-yu | College of Resources and Environment Sciences, Jilin Agricultural University, Changchun 130118, China | | | WANG Cai-yun | College of Resources and Environment Sciences, Jilin Agricultural University, Changchun 130118, China | |
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| Abstract: |
| In this study, we explored the possibility of producing organic fertilizer with the solid product from maize straw treated by the Sulfite Pretreatment to Overcome Recalcitrance of Lignocelluloses(SPORL) method. The acidic ammonium sulfite was chosen as a catalyst because it could generate a solid product with the highest organic matter content. The catalyst is composed of nitric acid and ammonium sulfite, and the pretreatment process is affected by temperature. Thereafter, a single-factor experiment was carried out to assess the application rate of nitric acid and ammonium sulfite, and reaction temperature. The results showed that the solid product had a higher organic matter content when maize straw was treated with 10%~20% ammonium sulfite(relative to dry weight of the solid, m/m) and 3%~7% of nitric acid(V/V) at 130~150℃. Accordingly, the response surface methodology was applied to redesign and optimize the pretreatment conditions using organic matter content of the solid product as a response index. Under the optimized reaction conditions, the maize straw treated with 5.4% nitric acid and 18% ammonium sulfite at 150℃ could yield a solid product with an organic matter content as high as 794.40 g·kg-1, which was 5.70 g·kg-1 more than that obtained in the validation tests. Analysis of humification of the solid product showed that SPORL could promote the formation of humic acid and improve the degree of humification. Therefore, when the maize straw was treated with acidic ammonium sulfite a catalyst in a reactor at high temperature and high pressure, lignosulfonates could be formed, which could subsequently convert into humic substances that contains a mixture of lingohumic acids and a smaller proportion of low-molecular-weight organic compounds. This method can add to the value of maize straw resource reuse. |
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