生物炭的制备及其性能研究

Preparation and Properties of Biochar

以生物质(小麦秸秆、稻壳和木屑)为原料,KOH为浸渍剂,采用控制热分解的方法制备生物炭,并利用差热/热重分析、Boehm滴定、红外光谱、X射线衍射、碘吸附及亚甲基蓝吸附等方法对原料和生物炭的结构及性质进行了表征。实验结果表明:木屑在热解过程中质量损失最大,其次是稻壳和小麦秸秆;不同原料在相同炭化温度下制得的生物炭所含表面含氧官能团种类和总量相近,均含有烷基、芳香基及一些含氧官能团,但pH值和吸附能力差别较大,其中小麦秸秆制备的生物炭pH值最大,木屑制备的生物炭吸附能力最强;随着炭化温度的升高,生物炭表面含氧官能团总量减少,pH值升高,芳构化程度增加;生物炭吸附性能总体呈上升的趋势。

Biochar was a carbonaceous product which is derived by controlling pyrolysis of biomass（wheat straw,rice husk and sawdust） under specifically gaseous circumstance with KOH intercalation. The structure and properties of biochar were characterised by thermogravimetric analysis,Boehm titration,Fourier transform infrared spectroscopy,X-ray diffraction,iodine adsorption and methylene blue adsorption. The results show that sawdust has the highest mass loss,followed by those of the wheat straw and rice husk. The total quantity of surface oxygen containing functional groups in biochar made from different raw materials at the same temperature is similar,all containing alkyl group,aromatic group and some oxygen containing functional groups,but pH value and adsorption capacity have larger differences,in which biochars derived from wheat straw have the highest pH value and derived from sawdust have the highest adsorption ability. Results of characterization of biochars derived from the same raw material show that with the increase of carbonization temperature,the content of surface oxygen containing functional groups decreases;pH value increases;the aromatization degree of biochars increases. As a whole,the adsorption properties of biochar are on the rise.