2024年7月21日 星期日
不同热解温度和升温速率下杨树枝条生物质炭产率和理化性质分析
Analyses on yield and physicochemical properties of poplar branch biochars at different pyrolysis temperatures and heating rates
2023年 第32卷 第3期 页码[71-82]    下载全文[6.5MB]  
摘要

以杨树(Populus sp.)枝条为原材料,研究不同热解温度和升温速率下制备的生物质炭产率和理化性质的变化。结果表明:热解温度对杨树枝条生物质炭的产率,灰分含量,pH值,电导率,C、N、H、K、Ca、Na和Mg含量以及C/H比均有极显著(P<0.01)影响,升温速率对K、Ca和Mg含量以及C/H比有显著(P<0.05)或极显著影响,二者的交互作用对灰分含量,pH值,电导率以及H、K、Ca、Na和Mg含量有显著或极显著影响。同一升温速率下,生物质炭产率随着热解温度的升高而降低,热解温度700 ℃条件下的生物质炭产率较热解温度300 ℃降低了68.93%~70.76%;生物质炭的灰分含量、pH值和电导率总体随着热解温度的升高而升高。同一升温速率下,随着热解温度的升高,生物质炭C含量升高,N含量先升高后降低,H含量降低。与热解温度300 ℃相比较,热解温度700 ℃条件下的生物质炭C含量的增幅在50%以上,H含量的降幅在80%以上,差异达显著水平。同一升温速率下,生物质炭的K、Ca、Na和Mg含量总体随着热解温度的升高而升高,且热解温度700 ℃条件下这4个元素含量较热解温度300 ℃显著升高。同一升温速率下,随着热解温度的升高,生物质炭表面层状结构逐渐明显,比表面积和总孔容总体呈增大的趋势,平均孔径、微孔面积和微孔体积的变化趋势存在差异。总体上看,生物质炭的表面官能团种类在不同热解温度和升温速率下基本相同;随着热解温度的升高,-CH3和-CH2等官能团数量减少,C=C数量增加,生物质炭稳定性增加;随着升温速率的增加,-OH数量增加,C/H比下降,生物质炭稳定性下降。综上所述,热解温度400 ℃、升温速率10 ℃·min-1条件下制备的杨树枝条生物质炭呈弱碱性,C和N含量损失较少,较适合改良碱性土壤;热解温度500 ℃~700 ℃条件下制备的生物质炭pH值、灰分含量以及K和Na含量较高,更适合改良酸性土壤;热解温度600 ℃和700 ℃条件下制备的生物质炭比表面积较高,适合改良重金属和有机物污染的土壤。

Abstract

 Taking branches of poplar (Populus sp.) as raw materials, changes of yield and physicochemical properties of biochars prepared at different pyrolysis temperatures and heating rates were studied. The results show that pyrolysis temperatures have extremely significant (P<0.01) effects on yield, ash content, pH value, electric conductivity, contents of C, N, H, K, Ca, Na and Mg, and C/H ratio of poplar branch biochars, heating rates have significant (P < 0.05) or extremely significant effects on contents of K, Ca and Mg and C/H ratio, and the interactions of pyrolysis temperatures and heating rates have significant or extremely significant effects on ash content, pH value, electric conductivity, and contents of H, K, Ca, Na and Mg. When at the same heating rate, biochar yield decreases with the increase of pyrolysis temperature, biochar yield at the pyrolysis temperature of 700 ℃ decreases by 68.93%-70.76% compared with that at the pyrolysis temperature of 300 ℃; ash content, pH value, and electric conductivity of biochar increase with the increase of pyrolysis temperature in general. When at the same heating rate, C content in biochar increases, N content first increases and then decreases, and H content decreases with the increase of pyrolysis temperature. Compared with the pyrolysis temperature of 300 ℃, the increment of C content and decrement of H content of biochar at the pyrolysis temperature of 700 ℃ are greater than 50% and 80% respectively, and the differences reach significant levels. When at the same heating rate, contents of K, Ca, Na and Mg of biochar increase with the increase of pyrolysis temperature in general, and contents of these four elements  at the pyrolysis temperature of 700 ℃ all significantly increase compared with those at the pyrolysis temperature of 300 ℃. When at the same heating rate, with the increase of pyrolysis temperature, the surface lamellar structure of biochar gradually becomes evident, specific surface area and total pore volume show a tendency to increase, and the variation tendencies of average pore width, micropore area, and micropore volume have differences. In general, the types of surface functional groups of biochar are basically the same at different pyrolysis temperatures and heating rates; with the increase of pyrolysis temperature, the number of functional groups such as -CH3 and -CH2 decreases, the number of C=C increases, and the stability of biochar increases; with the increase of heating rate, the number of -OH increases, and the C/H ratio decreases. Overall, the  poplar branch biochar prepared at the pyrolysis temperature of 400 ℃ and heating rate of 10 ℃·min-1 is weakly alkaline, and its losses in contents of C and N are relatively less, which is suitable for remediating  alkaline soil; pH values, ash contents, and contents of K and Na in biochars prepared at pyrolysis temperature of 500 ℃-700 ℃ are relatively high, which are more suitable for remediating  acid soil; specific surface areas of biochars prepared at pyrolysis temperature of 600 ℃ and 700 ℃ are relatively high, which are suitable for remediating  heavy metal and organic matter contaminated soil.

关键词杨树; 枝条; 生物质炭; 热解温度; 升温速率; 产率; 理化性质
Key wordspoplar (Populus sp.); branch; biochar; pyrolysis temperature; heating rate; yield; physicochemical property
作者孙玲1, 贾明云2, 刘壮壮2, 薛建辉1,2, 于金平2
所在单位1. 南京林业大学生物与环境学院, 江苏 南京 210037; 2. 江苏省中国科学院植物研究所(南京中山植物园) 江苏省植物资源研究与利用重点实验室, 江苏 南京 210014
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基金项目江苏省碳达峰碳中和科技创新专项资金(BE2022306)