CAJ | 학술논문

以核桃壳为生物质炭生产原料，研究热解温度（200～700℃）对生物质炭产率、元素组成、表面官能团分布及其稳定性的影响，以期探明生物质炭基本性质随热解温度变化的规律，为全面了解生物质炭固碳减排效果提供理论参考。结果表明，生物质炭的C含量随温度升高而增加，H和O元素含量却随温度升高而降低。此外，生物质炭的H/C和O/C随着温度增加而减少。生物质炭的产率及碳保留量随着温度的升高而降低。红外光谱分析结果表明，经过热解核桃壳原材料分子中所含的-C-O和O-CH3基团消失，随着热解温度升高，生物质炭中的烷烃基团-CH逐渐减少，芳香化程度逐渐升高。500℃制备生物质炭的K2Cr2O7和KMnO4氧化碳损失量均最低，分别为10.4%和1.66%。相关分析表明，生物质炭的产率、碳保留量及稳定性与热解温度之间均具有显著相关关系。
이핵도각위생물질탄생산원료，연구열해온도（200～700℃）대생물질탄산솔、원소조성、표면관능단분포급기은정성적영향，이기탐명생물질탄기본성질수열해온도변화적규률，위전면료해생물질탄고탄감배효과제공이론삼고。결과표명，생물질탄적C함량수온도승고이증가，H화O원소함량각수온도승고이강저。차외，생물질탄적H/C화O/C수착온도증가이감소。생물질탄적산솔급탄보류량수착온도적승고이강저。홍외광보분석결과표명，경과열해핵도각원재료분자중소함적-C-O화O-CH3기단소실，수착열해온도승고，생물질탄중적완경기단-CH축점감소，방향화정도축점승고。500℃제비생물질탄적K2Cr2O7화KMnO4양화탄손실량균최저，분별위10.4%화1.66%。상관분석표명，생물질탄적산솔、탄보류량급은정성여열해온도지간균구유현저상관관계。
Turning biomass wastes into biochar under the conditions of low temperature and limited oxygen has recently proven to be a promising approach for long-term carbon sequestration. However, the ultimate carbon sequestration efficiency of biochar depends not only on the feedstock type and production condition, but also on the environmental conditions of soil. In order to reveal the effects of pyrolysis temperature which is main parameter of biochar production condition on carbon retention and biochar stability, and provide more information for further improvement of carbon sequestration potential by turning biomass into biochar, the characteristics of biochar derived from walnut shell under lab condition were analyzed. During a typical slow pyrolysis process, the biochar was heated at a speed of approximately 20℃/minin a Muffle Furnace under limited oxygen and held at 200-700℃ for 2 h; then, biochar yield, elemental composition, functional groups distribution using Fourier transform infrared spectroscopy (FTIR) analysis and its chemical stability determined by potassium dichromate (K2Cr2O7) and potassium permanganate (KMnO4) oxidation methods, were all analyzed. The results showed that the carbon (C) content of biochar increased with the rise of the pyrolysis temperature from 54.0% at 200℃ to 83.7%at 700℃, on the contrary, thehydrogen (H) and oxygen (O) contents decreased with the rise of the temperature from 6.31% to 2.22% for H content and 45.1% to 10.6% for O content, respectively. Moreover, the H/C and O/C, usually used as two indexes to estimate carbon aromaticity for biochar, also decreased with the rise of the pyrolysis temperature from 1.25 to 0.32 for H/C and 0.54 to 0.09 for O/C, respectively, which indicated the carbon aromaticity of biochar was strengthened with the rise of the pyrolysis temperature, which is beneficial for the improvement of biochar stability. After the pyrolysis of walnut shell, especially when pyrolysis temperature was above 200℃,compared to the feedstock, the -C-O and O-CH3 groups did not exist and the aliphatic-CH gradually disappeared while more aromatization were shown by new aromatic compounds with the increasing of pyrolysis temperature based on FTIR analysis. Biochar yield decreased with the rise of the pyrolysis temperature from 79.1% at 200℃ to 19.4%at 700℃. The carbon retention, defined as the proportion of the original carbon, which was from plant photosynthesis and sequestrated the CO2 in feedstock from atmosphere, was retained in the biochar after the pyrolysis, and also decreased with the rise of the pyrolysis temperature from 69.4% to 11.0%, all of which indicated that high pyrolysis temperature aggravated carbon loss. However, high pyrolysis temperature strengthened the carbon stability, and especially for biochar derived from 500℃, the carbon loss of biocharoxidated by K2Cr2O7and KMnO4 were 10.4% and 1.66%, respectively, which were smaller than the other biochars derived from other pyrolysis temperatures. There was significant negative correlation between pyrolysis temperature and the yield and carbon retention of biochar, while there was significant positive correlation between pyrolysis temperature and biochar stability. The stability of biochar in real soil and the optimal temperature of biochar for maximizing its carbon sequestration capacity need to be researched in the future.