不同原料生物炭理化性质的对比分析

为研究不同原料生物炭理化性质的差异,以苜蓿秸秆生物炭、小麦秸秆生物炭、棉花秸秆生物炭、葡萄藤生物炭、污泥生物炭和褐煤生物炭6种生物炭为测试材料,利用傅里叶红外光谱仪和Boehm滴定法对生物炭表面官能团进行定性和定量分析,用电子扫描显微镜观察生物炭表面形貌,并测定生物炭的pH值、有机碳含量和阳离子交换量等基本理化性质。结果表明,除污泥生物炭呈弱酸性外(pH=6.76),其他生物炭均呈碱性(pH=8.49~9.96)。苜蓿秸秆生物炭有机碳含量最高(588.43 g·kg~(-1)),污泥生物炭最低(168.17 g·kg~(-1))。阳离子交换量大小排序为,苜蓿秸秆生物炭、棉花秸秆生物炭葡萄藤生物炭小麦秸秆生物炭污泥生物炭褐煤生物炭。FTIR图谱表征显示,生物炭表面存在芳香烃类和含氧基团,生物炭的结构以芳环骨架为主。苜蓿生物炭表面官能团总数最多,污泥生物炭最少。扫描电镜(SEM)结果表明,苜蓿秸秆生物炭、小麦秸秆生物炭、棉花秸秆生物炭、葡萄藤生物炭表面有明显孔隙结构,褐煤生物炭和污泥生物炭表面并无明显的孔隙结构。综上,苜蓿秸秆生物炭、小麦秸秆生物炭、棉花秸秆生物炭、葡萄藤生物炭适用农田土壤改良与培肥,褐煤生物炭和污泥生物炭可尝试用于污染土壤的修复,同时污泥生物炭可用于盐碱土的改良。

Comparison of Biochars Characteristics from Different Raw Materials

Biochar is the carbon-rich product from biomass under limited supply of oxygen. Biochar has been well recognized in enhancing terrestrial carbon sequestration and greenhouse gas mitigation as well as in improving soil fertility and plant productivity. To explore the differences of biochars produced from different raw materials, six biochar samples made from alfalfa straw , wheat straw, cotton straw, grape vines, sludge and lignite were selected as test material. Qualitative and quantitative analysis by fourier transform infrared spectroscopy (FTIR)and Boehm titration were used to determine the amount of the surface functional groups of biochars. Meanwhile the scanning electron microscopy(SEM)was used to characterize the surface morphology of biochar samples. In addition, the basic physicochemical characteristics of biochar samples, such as pH value, organic carbon content and cation exchange capacity were also determined. The results showed that all of the biochar were alkaline except the sludge biochar was acidic. The organic carbon content of alfalfa biochar was the highest(588.43 g·kg-1) and sludge biochar was the lowest(168.17 g·kg-1). Furthermore, the rank of cation exchange capacity was alfalfa straw biochar, cotton straw biochar>grape vine biochar>wheat straw biochar>sludge biochar>lignite biochar. FTIR spectrum showed that there were the aromatic hydrocarbon and the oxygen group on the surface of biochar and the structure of biochar was mainly based on the aromatic rings skeleton. The total functional groups content of alfalfa straw biochar was the highest, but that of sludge biochar was the lowest. The SEM results showedthat there were obvious pore structure on the surface of plant-based biochar, but none on the surface of mineral-based biochar. Alfalfa straw biochar, wheat straw biochar, cotton straw biochar and grape vine biochar can be applied to improve farmland soil quality and increase soil fertility, and lignite biochar and sludge biochar can be used to remediate contaminated soil, moreover sludge biochar can be used for reclamation of saline-alkali soils.