Pyrolysis temperature affects pore characteristics of rice straw and canola stalk biochars and biochar-amended soils
Pyrolysis temperature affects pore characteristics of rice straw and canola stalk biochars and biochar-amended soils
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DOI：
10.1016/j.geoderma.2021.115097
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发表时间：
2021
期刊：
影响因子：
6.1
通讯作者：
Cai-di Yang;Jing-jing Liu;Shenggao Lu
中科院分区：
文献类型：
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作者：
Cai-di Yang;Jing-jing Liu;Shenggao Lu
土壤物理性质可能会受到生物炭的影响。这种效果在很大程度上取决于生物质炭的孔隙特性，特别是生物质炭的原料和热解过程。研究了250 ° C、350 ° C、450 ° C、550 ° C和650 °C热解条件下稻草和油菜秸秆生物炭的孔隙特征，并评价了生物炭对土壤孔隙性质的影响。采用氮气吸附等温线（NAI）、压汞法（MIP）和扫描电镜（SEM）对生物炭的孔结构进行了表征。每种生物炭以1%（w/w）的比例混合到两种土壤（Ultisol和Alfisol）中，然后将土壤-生物炭混合物培养90天。随着热解温度的升高，生物炭的比表面积（SSA）和总孔容（TPV）均增大。在450 °C热解的生物炭具有最高的孔隙率和由MIP测量的TPV。RSB的最大孔隙类型为大孔（>75 μm），而CSB的主要孔隙类型为微孔（5-30 μm）和超微孔（0.1-5 μm）。培养实验结果表明，生物炭的加入改变了淋溶土和淋溶土的孔径分布。RSB提高了土壤的总孔隙度和微孔隙度，而CSB降低了土壤的总孔隙度、大孔隙度和中孔隙度。生物质炭增加了土壤贮水孔隙，提高了土壤的持水能力。对生物炭热解温度、孔隙特征和保水能力之间的相关性进行热图分析，结果表明，生物炭热解温度与CSB改良的淋溶土孔隙特征和CSB改良的淋溶土水分特征具有较好的相关性。研究结果表明，生物质炭中孔和微孔结构对土壤生物质炭添加反应有重要影响。基于孔隙性质，热解温度在450 °C左右是制备具有较大孔隙率的多孔生物炭的最佳条件。
Soil physical properties are potentially affected by the addition of biochar. The effect is largely determined by the pore characteristics of biochar, especially the biochar’s feedstocks and pyrolysis processes. This study examined the pore characteristics of rice straw biochars (RSB) and canola stalk biochars (CSB) produced at pyrolysis temperatures of 250, 350, 450, 550, and 650 °C, and evaluated the effects of biochars on soil pore properties. The pore characteristics of biochars were characterized by nitrogen adsorption isotherm (NAI), mercury intrusion porosimetry (MIP), and scanning electron microscope (SEM). Each biochar was mixed into two soils (Ultisol and Alfisol) at the rate of 1% (w/w), then the soil-biochar mixtures were incubated for 90 days. The specific surface area (SSA) and total pore volume (TPV) measured by NAI technique increased with increasing pyrolysis temperature of biochar. Biochars pyrolyzed at 450 °C had the highest porosity and TPV measured by MIP. The largest pore class for RSB was the macropore (>75 μm), while the main pore classes for CSB were micropore (5–30 μm) and ultramicropore (0.1–5 μm). Incubation experimental results showed that biochar addition altered the pore size distribution of the Alfisol and Ultisol. RSB enhanced the total porosity and microporosity of soils, whereas CSB decreased total porosity, macroporosity, and mesoporosity. The water-holding capacity of soil was increased by increasing the amount of soil storage pores caused by biochar. Heatmap analysis on the correlation among pyrolysis temperature of biochar, pore characteristic and water retention capacity of biochar-amended soils illustrated that the pore properties of the Ultisol amended with CSB and the water properties of the Alfisol with CSB were highly correlated with pyrolysis temperature of biochar. Our results suggested the meso- and micro-pores in biochars played an important role to affect the soil response to biochar addition. Based on pore properties, pyrolysis temperature around 450 °C was found to be the optimal condition for producing porous biochar with larger porosity.