原料和热解温度对生物炭中可溶性有机质的影响

Effects of Feedstock Material and Pyrolysis Temperature on Dissolved Organic Matter in Biochars

以水稻秸秆和杉木凋落物为原料,选择不同热解温度(350、500和650℃)制备生物炭,研究原料与热解温度对生物炭中可溶性有机质(dissolved organic matter,DOM)含量和光谱特征的影响.结果表明,随着热解温度的升高,两类生物炭pH值分别从8.10和6.56上升至10.53和8.23;热解温度对生物炭全碳(TC)含量的影响并不明显,但原料及其与温度交互作用的影响显著(P<0.05).两类生物炭中可溶性有机碳(dissolved organic carbon,DOC)含量呈先降低后升高的趋势,相同热解温度下水稻生物炭的显著高于杉木生物炭的(P<0.05).原料对DOM芳香化指数(SUVA254值)无显著影响,但温度及其与原料交互作用的影响显著(P<0.05),在500℃时该值最大,芳香化程度最高.三维荧光光谱表明,DOM组分以类富里酸和类腐殖酸为主,但这两种物质对热解温度的响应不同.傅里叶红外光谱分析发现,两类生物炭DOM在5个区域的相似位置存在吸收峰,其中,脂肪族C—H的伸缩振动随着热解温度的升高逐渐减弱.因此,高温(500℃和650℃)与低温(350℃)制备的生物炭相比,DOC含量降低,但其芳香化和腐殖化程度升高,稳定性增强.

The aim of this study was to investigate the effects of feedstock material and pyrolysis temperature on the content and spectral properties of dissolved organic matter(DOM)in biochars.Biochars were produced from the pyrolysis of rice straw and Cunninghamia lanceolata litter at three temperatures(350,500,and 650℃).The results showed that the pH values of the two biochars with pyrolysis temperature increases were improved from 8.10 and 6.56 to 10.53 and 8.23,respectively.The pyrolysis temperature had no significant effect on the total C content of biochar,but the feedstock material and their interaction had significant effects on the total C content of the biochar(P<0.05).The dissolved organic carbon(DOC)content of the two types of biochar first decreased and then increased with increasing pyrolysis temperature,and the content of DOC of the biochar derived from rice straw was significantly higher than that from Cunninghamia lanceolata litter under the same temperature(P<0.05).The feedstock material had no significant effect on the SUVA254 value of DOM,but temperature and its interactive effect with the feedstock material had a significant effect on the SUVA254values(P<0.05).Maximum DOC SUVA254 values occurred at 500℃in the two types of biochar,indicating the highest degree of aromatization.Three-dimensional fluorescence spectra showed that the DOM components of the two types of biochar were dominated by fulvic acid-like and humic acid-like material,which had different responses to pyrolysis temperature.FTIR spectra suggested that the DOM of the biochars had absorption peaks at similar positions,in five regions,and the stretching vibration of aliphatic C—H gradually weakened with an increase in pyrolysis temperature.Therefore,the biochars produced at higher pyrolysis temperatures(500℃and 650℃)had lower DOC contents but a higher aromatization degree and humification degree,and were more stable,compared to the biochars produced at a lower pyrolysis temperature(350℃).