Shanghai Key Laboratory of Atmospheric Particle Pollution and Prevention (LAP3), Department of Environmental Science and Engineering, Fudan University , Shanghai 200433, China.
Department of Civil, Environmental, and Architectural Engineering, University of Colorado , Boulder, Colorado 80309, United States.
Environ Sci Technol. 2017 Sep 19;51(18):10756-10764. doi: 10.1021/acs.est.6b06594. Epub 2017 Aug 28.
Hydrochar derived from hydrothermal carbonization (HTC) has been recognized as a promising carbonaceous material for environmental remediation. Organic solvents are widely used to extract bio-oil from hydrochar after HTC, but the effects of solvent extraction on hydrochar characteristics have not been investigated. This study comprehensively analyzed the effects of different washing times and solvent types on the hydrochar properties. The results indicate that the mass loss of hydrochar by tetrahydrofuran washing occurred mainly in the first 90 min, and the loss ratios of elements followed a descending order of H > C > O, resulting in a decrease in the H/C atomic ratio and an increase in the O/C atomic ratio. The use of various solvents for washing brought about hydrochar loss ratios in a descending order of petroleum ether < dichloromethane < acetone < tetrahydrofuran. The results from the Van Krevelen diagram and Fourier transform infrared, C nuclear magnetic resonance, and X-ray photoelectron spectroscopies further confirmed that demethanation controlled this washing process. Most importantly, the surface area of hydrochar increased after bio-oil removal via washing, which promoted the surface area development for hydrochar-derived magnetic carbon composites, but to some extent decreased the microporosity. Additionally, hydrochar washing by organic solvent has important implications for the global carbon cycle and its remediation application.
水热碳化衍生的水炭（HTC）已被认为是一种很有前途的环境修复用碳质材料。有机溶剂广泛用于 HTC 后从水炭中提取生物油，但溶剂萃取对水炭特性的影响尚未得到研究。本研究全面分析了不同洗涤时间和溶剂类型对水炭性质的影响。结果表明，四氢呋喃洗涤时水炭的质量损失主要发生在前 90 分钟，元素的损失率按 H > C > O 的顺序递减，导致 H/C 原子比降低，O/C 原子比升高。各种溶剂的洗涤使水炭的损失率按石油醚 < 二氯甲烷 < 丙酮 < 四氢呋喃的顺序递减。范克里夫图谱、傅里叶变换红外、C 核磁共振和 X 射线光电子能谱的结果进一步证实，脱甲烷控制了这一洗涤过程。最重要的是，通过洗涤去除生物油后，水炭的表面积增加，促进了水炭衍生磁性碳复合材料的表面积发育，但在某种程度上降低了微孔。此外，有机溶剂洗涤水炭对全球碳循环及其修复应用具有重要意义。
