炭化温度对小麦秸秆炭化产率及理化特性的影响

研究了炭化温度对小麦秸秆生物炭产率及理化特性的影响,为小麦秸秆生物炭的制备及还田作用机制提供理论依据。通过低氧炭化法,以20℃/min的升温速度将小麦秸秆炭化至特定温度(100,200,300,400,500,600,700,800℃),然后对其炭化产率和理化性质(孔隙状况、全碳及无机碳含量、CEC含量、表面含氧官能团情况及p H值、FTIR)进行分析,结果表明,低温炭化时小麦秸秆生物炭呈酸性,400℃之后呈碱性;随热解温度的升高,小麦秸秆生物炭的炭化程度逐渐增大,100~400℃产率自91.32%降至18.52%;炭化过程中,小麦秸秆生物炭孔隙增加,结构疏松;比表面积、孔径和比孔容均表现出先增大后减小的趋势,且均在400℃时达到最大,分别为6.675 m2/g、13.992 nm、0.015 cm3/g;有机碳含量在200~400℃较高;CEC含量于400~800℃维持在较高水平,处于69.13~84.35 cmol/kg;FTIR和表面含氧官能团的结果显示,小麦秸秆生物炭的芳香化程度随着热解温度的升高而增大,结构也愈加稳定。小麦秸秆的制备以400℃左右的炭化温度条件较为理想。

Effects of Carbonization Temperature on Biochar Yield and Physicochemical Properties from Wheat-straw

The paper studied the effects of carbonization temperature on biochar yield and the physicochemical properties from wheat-straw improved the application of wheat-straw biochar,in order to further expound the mechanism of action of wheat straw biochar.The effects of different carbonization temperatures(100,200,300,400,500,600,700,800 ℃)on wheat-straw biochar yield and the physicochemical properties (porosity condition,the content of total carbon and inorganic carbon,CEC content,oxygen-containing functional group,pH and FTIR) were studied through mionectic carbonization with the heating rate of 20 ℃/min.Fourier transform infrared spectrometer was used to obtain infrared spectra and the reasons for the changes of biochar physicochemical properties were analyzed.The wheat-straw of low temperature carbonization was acidic,after 400 ℃,was alkaline.The degree of wheat straw biochar carbonized increased with the increased of carbonization temperature,and the yield decreased from 91.32% to 18.52% in 100-400 ℃.In the carbonization process,the wheat-straw biochar porosity increased,the structure was loose.Pore size,specific surface area and specific pore volume showed first increased and then decreased trend,and all reached the maximum at 400 ℃,were 6.675 m2/g,13.992 nm,0.015 cm3/g respectively.In 200-400 ℃,the content of organic carbon was high.The content of CEC was maintained at a high level in 400-800 ℃,between 69.13-84.35 cmol/kg.The analysis of infrared spectrum and surface oxygen functional groups showed that,with the increase of pyrolysis temperature,the degree of aromatization of wheat-straw biochar increased,and the structure became more stable.The carbonization temperature of wheat-straw is more ideal at about 400 ℃.