Department of Environmental Hydrology and Microbiology, Zuckerberg Institute for Water Research, Ben Gurion University of the Negev, Campus Sde Boqer, Midreshet Ben Gurion, Israel.
French Associates Institute for Agriculture and Biotechnology of Drylands, Jacob Blaustein Institutes for Desert Research, Ben Gurion University of the Negev, Campus Sde Boqer, Midreshet Ben Gurion, Israel.
PLoS One. 2018 Oct 26;13(10):e0206299. doi: 10.1371/journal.pone.0206299. eCollection 2018.
Detailed assessment of hydrochar wetting properties, which could provide an essential understanding of underlying mechanisms during its application to soils, is lacking. We characterized hydrochar produced from hydrothermal carbonization (HTC) performed on poultry litter at various temperatures and for different times in terms of hydrophobicity and surface free energy properties. Hydrochar was more hydrophobic than untreated poultry litter, and its hydrophobicity increased with increasing HTC temperature (contact angle > 130°). These changes were correlated with degradation of hemicellulose and cellulose. Hydrochar produced at 250°C contained mostly lignin and displayed high hydrophobicity over both prolonged wetting periods and repeated wetting cycles. Surface free energy was calculated using the Owens-Wendt-Rabel-Kaelble and Wu models, with the latter resulting in lower standard errors. The surface free energy decreased as HTC treatment severity increased from 26 mJ/m2 in the poultry litter to 8 mJ/m2 after treatment at 250°C for 60 min. The dispersive component fraction of the surface free energy increased with increasing treatment severity. This study demonstrated that changes in the physical composition of hydrochar due to increased treatment severity increase its hydrophobicity and decrease its surface free energy. Moreover, due to non-persistent hydrophobicity, hydrochar produced at temperatures lower than 250°C will likely not show adverse effects on soils.
详细评估水炭的润湿性能，这可以为其在土壤中应用时的基础机制提供重要的理解。我们以疏水性和表面自由能特性为指标，对在不同温度和不同时间下通过水热碳化（HTC）处理家禽粪便得到的水炭进行了表征。水炭比未经处理的家禽粪便更疏水，其疏水性随 HTC 温度的升高（接触角>130°）而增加。这些变化与半纤维素和纤维素的降解有关。在 250°C 下生成的水炭主要包含木质素，在长时间润湿和反复润湿循环中均表现出高疏水性。使用 Owens-Wendt-Rabel-Kaelble 和 Wu 模型计算表面自由能，后者的标准误差更低。随着 HTC 处理严重程度从家禽粪便中的 26 mJ/m2 增加到 250°C 处理 60 分钟后的 8 mJ/m2，表面自由能降低。表面自由能的色散分量分数随处理严重程度的增加而增加。本研究表明，由于处理严重程度增加导致水炭物理组成的变化，增加了其疏水性并降低了其表面自由能。此外，由于非持久性疏水性，在低于 250°C 的温度下生产的水炭不太可能对土壤产生不利影响。
