Center for Renewable Carbon, 2506 Jacob Drive, University of Tennessee, Knoxville, TN 37996, United States.
Department of Biosystems Engineering & Soil Science, 2506 E.J. Chapman Dr., University of Tennessee, Knoxville, TN 37996, United States.
Chemosphere. 2013 Mar;90(10):2623-30. doi: 10.1016/j.chemosphere.2012.11.021. Epub 2012 Dec 13.
Surface properties of switchgrass-derived biochars produced at fast pyrolysis temperatures of 450, 600 and 800 °C were characterized at different solution pHs in order to determine the structural and chemical changes of artificially-weathered biochars when incorporated into soil. As biochars were acidified from pH 7 to 3, crystalline minerals dissolved slowly releasing nutrients; however, residual minerals were still detected in biochars produced at higher pyrolysis temperatures after pH treatment. Moreover, the amount of exchangeable bases and other inorganic compounds released from the biochars increased when pH decreased. As minerals dissolved from the biochars, total surface area and pore volume were found to increase. Surface functional groups and water vapor adsorption capacity at 0.8 P/Po also increased, whereas the potential CEC of biochars decreased due to the replacement of exchangeable sites by hydrogen ion. Therefore, during the aging process, it is predicted that soil-incorporated biochars will slowly release nutrients with changes in surface functionality and porosity, which are expected to enhance water holding capacity of soil and provide a beneficial habitat for microbial colonization.
为了确定在土壤中添加人工老化生物炭时其结构和化学性质的变化，对在 450、600 和 800°C 快速热解温度下制备的柳枝稷衍生生物炭在不同溶液 pH 值下的表面性质进行了表征。随着生物炭从 pH 7 酸化至 3，结晶矿物缓慢溶解并释放养分；然而，在 pH 处理后，仍在较高热解温度下制备的生物炭中检测到残留的矿物质。此外，随着 pH 值降低，从生物炭中释放的可交换碱基和其他无机化合物的量增加。随着生物炭中矿物质的溶解，总表面积和孔体积被发现增加。表面官能团和在 0.8 P/Po 下的水蒸气吸附能力也增加，而由于氢离子取代了可交换位点，生物炭的潜在 CEC 降低。因此，在老化过程中，预计土壤中添加的生物炭将随着表面官能团和孔隙率的变化而缓慢释放养分，这有望提高土壤的持水能力并为微生物定殖提供有利的生境。
