College of Engineering, Jiangxi Agricultural University, Nanchang 330045, PR China.
College of Engineering, Huazhong Agricultural University, Wuhan 430070, PR China; Key Laboratory of Agricultural Equipment in the Mid-lower Yangtze River, Ministry of Agriculture, Wuhan 430070, PR China.
Waste Manag. 2020 Oct;116:157-165. doi: 10.1016/j.wasman.2020.08.004. Epub 2020 Aug 13.
Hydrothermal treatment for dairy manure into value-added hydrochar and bio-oil is a potential technology for its resource utilization. During the process of treatment, extractant is applied to the separation of hydrochar and bio-oil. In this study, three polar extractants (ethyl acetate, dichloromethane, diethyl ether) and two nonpolar extractants (n-hexane and petroleum ether) were used, and the physico-chemical properties of hydrochar and the composition of bio-oil were investigated. Compared with nonpolar extractants, polar extractants could extract the bio-oil absorbed on the hydrochar exterior and interior surface, resulting in more mass loss of hydrochar and better extraction performance on the production of bio-oil. The decrease of H/C atomic ratio and the increase of O/C atomic ratio indicated the demethanation tendency to occur during the extraction process, and enhanced the hydrochar stability. The scanning electron microscope and specific surface area analysis revealed that polar extractant had a more positive effect than nonpolar extractant on the occurrence of disperse spherical microparticles and the augment of hydrochar specific surface area. The bio-oil from polar extractant mainly consisted of N-containing compounds, ketones, phenols and acids, while the bio-oil from nonpolar extractant mainly consisted of esters, alkanes and aromatics. These results reveal that the hydrochar extracted by polar solvent exerts a greater potential for the production of carbon-based material.
水热处理牛奶粪肥为增值水炭和生物油是其资源利用的一种潜在技术。在处理过程中，采用萃取剂分离水炭和生物油。本研究选用三种极性萃取剂（乙酸乙酯、二氯甲烷、乙醚）和两种非极性萃取剂（正己烷和石油醚），考察了水炭的物理化学性质和生物油的组成。与非极性萃取剂相比，极性萃取剂可以提取吸附在水炭内外表面的生物油，导致水炭的质量损失更大，对生物油的生产具有更好的萃取性能。H/C 原子比的降低和 O/C 原子比的增加表明在萃取过程中发生了脱甲烷倾向，增强了水炭的稳定性。扫描电子显微镜和比表面积分析表明，极性萃取剂比非极性萃取剂更有利于分散球形微粒子的产生和水炭比表面积的增加。极性萃取剂得到的生物油主要由含氮化合物、酮、酚和酸组成，而非极性萃取剂得到的生物油主要由酯、烷烃和芳烃组成。这些结果表明，极性溶剂萃取的水炭在生产碳基材料方面具有更大的潜力。
