College of Forestry, Guangxi University, Nanning 530004, China.
College of Resources Environment and Material, Guangxi University, Nanning 530004, China.
Molecules. 2020 Dec 4;25(23):5730. doi: 10.3390/molecules25235730.
Rice straw is a common agricultural waste. In order to increase the added value of rice straw and improve the performance of rice straw biochar. MgO-modified biochar (MRBC) was prepared from rice straw at different temperatures, pyrolysis time and MgCl concentrations. The microstructure, chemical and crystal structure were studied using X-ray diffraction (XRD), a Scanning Electron Microscope (SEM), Fourier transform infrared spectroscopy (FTIR), nitrogen adsorption desorption isotherms and Elementary Analysis (EA). The results showed that the pyrolysis temperature had significant influence on the structure and physicochemical property of MRBCs. MRBC-2 h has the richest microporous structure while MRBC-2 m has the richest mesoporous structure. The specific surface area (from 9.663 to 250.66 m/g) and pore volume (from 0.042 to 0.158 cm/g) of MRBCs increased as temperature rose from 300 to 600 °C. However, it was observed MgCl concentrations and pyrolysis time had no significant influence on pore structure of MRBCs. As pyrolysis temperature increased, pH increased and more oxygen-containing functional groups and mineral salts were formed, while MgO-modified yield, volatile matter, total content of hydrogen, oxygen, nitrogen, porosity and average pore diameter decreased. In addition, MRBCs formed at high temperature showed high C content with a low O/C and H/C ratios.
稻草是一种常见的农业废弃物。为了提高稻草的附加值并改善稻草生物炭的性能，采用不同热解温度、热解时间和 MgCl2浓度制备了 MgO 改性生物炭（MRBC）。采用 X 射线衍射（XRD）、扫描电子显微镜（SEM）、傅里叶变换红外光谱（FTIR）、氮气吸附脱附等温线和元素分析（EA）对其微观结构、化学和晶体结构进行了研究。结果表明，热解温度对 MRBC 的结构和理化性质有显著影响。MRBC-2 h 具有最丰富的微孔结构，而 MRBC-2 m 具有最丰富的中孔结构。MRBC 的比表面积（从 9.663 到 250.66 m2/g）和孔体积（从 0.042 到 0.158 cm3/g）随着热解温度从 300°C 升高到 600°C 而增加。然而，MgCl2浓度和热解时间对 MRBC 的孔结构没有显著影响。随着热解温度的升高，pH 值升高，形成了更多的含氧官能团和矿物质盐，而 MgO 改性产率、挥发分、总含氢量、氧、氮、孔隙率和平均孔径降低。此外，高温下形成的 MRBC 具有较高的 C 含量，较低的 O/C 和 H/C 比。
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