光谱学与光谱分析, 2019, 39 (11): 3475, 网络出版: 2019-12-02  

生物炭中溶解性有机质的光谱分析

Spectral Analysis of Dissolved Organic Matter from Biochar
作者单位
1 安徽科技学院资源与环境学院, 安徽 凤阳 233100
2 上海交通大学中英国际低碳学院, 上海 201306
摘要
稻壳和木屑是农林业废物处理与利用的重点, 将稻壳和木屑制备成生物炭并用于环境污染与防治成为研究热点, 但对稻壳和木屑生物炭中溶解性有机质(DOM)的研究还较少。 以稻壳和木屑为生物质原料, 在不同温度(200~700 ℃)下制备稻壳和木屑生物炭, 利用紫外-可见光谱、 三维荧光光谱和红外光谱技术对生物炭DOM的光谱特征进行分析, 研究不同热解温度对生物炭DOM光谱特征的影响。 结果表明, 随着热解温度升高, 稻壳和木屑生物炭DOM中溶解性有机碳(DOC)浓度逐渐降低, 且木屑生物炭的DOC浓度远高于相同温度下的稻壳生物炭。 稻壳和木屑生物炭DOM的紫外吸收均随着波长的增大而逐渐降低, 且随着热解温度升高, 稻壳生物炭DOM的吸光度先增加后降低, 而木屑生物炭DOM则持续降低。 紫外光谱的特征参数值(SUVA254和SUVA260)随着热解温度升高变化趋势相同, 且在相同温度下, 稻壳生物炭DOM的特征参数值均高于木屑。 三维荧光光谱表明稻壳和木屑生物炭DOM的荧光峰主要出现在λex/em=300~315/400~425 nm和λex/em=210~245/380~435 nm波段, 分别代表类腐殖质荧光峰和富里酸荧光峰, 可用来表示生物炭DOM的腐殖化程度和疏水组分含量。 随温度升高, 稻壳生物炭DOM的腐殖化程度和疏水组分含量先升高后降低, 而木屑生物炭DOM则逐渐降低。 三维荧光参数表明稻壳和木屑生物炭DOM的自生源指标(autochthonous index, BIX)不强, 生物可利用性和类蛋白比例较低; 随着温度升高稻壳生物炭DOM腐殖化指数(humification index, HIX)先增加后降低, 而木屑生物炭DOM的HIX则逐渐降低。 此外, 红外光谱结果表明, 随着热解温度的升高, 稻壳和木屑生物炭DOM中—OH逐渐降低, —CH2、 —CH3变化不明显, 芳环CC, C—H增强, 芳香化程度增强。
Abstract
Rice husk and sawdust are the focus of agricultural and forestry waste treatment and utilization. It has become a hot topic of research to make rice husk and sawdust into biochar and use it in environmental pollution and prevention, but there are little studies of dissolved organic matters in rice husk and sawdust biochar. Rice husk and sawdust biochars were prepared under different temperatures from 200 to 700 ℃. The characteristics of DOM from the biochars were analyzed by UV-Vis spectroscopy, three-dimensional fluorescence spectroscopy and infrared spectroscopy, in order to find the influence of different pyrolysis temperature on biochar DOM. The results showed that DOC concentration in rice husk and sawdust biochar decreased with the increase of pyrolysis temperature, and the DOC concentration in sawdust biochar was much higher than that in rice husk biochar at the same temperature. The UV-Vis spectrum curve of the biochar DOM of rice husk and sawdust gradually decreased with the increase of wavelength, and the absorbance of biochar DOM of rice husk first increased and then decreased with the increase of pyrolysis temperature, while the biochar DOM of sawdust continued to decrease. At the same time, the ultraviolet characteristic parameters (SUVA254 and SUVA260) of DOM from rice husk and sawdust biochar had the same changing trend with the increase of pyrolysis temperature, and the parameters of rice husk biochar DOM were higher than those of sawdust DOM at the same temperature. Three dimensional fluorescence spectra showed that the fluorescence peaks of rice husk and sawdust biochar DOM were mainly in the bands of λex/em=300~315/400~425 and λex/em=210~245/380~435, respectively representing humic and fulvic acid fluorescence peaks, which could be used to represent humic degree and hydrophobic component content of biochar DOM. With the increase of temperature, the humation degree and hydrophobic component content of the biochar DOM of rice husk first increased and then decreased, while the biochar DOM of sawdust gradually decreased. Moreover, the autochthonous index (BIX) of those DOM was not strong, indicating that the bioavailability and protein-like ratio of those DOM were low. The humification index (HIX) of DOM from rice husk biochar increased first and then decreased with the increase of temperature, while that of sawdust decreased gradually. In addition, the infrared spectrum results showed that, with the increase of pyrolysis temperature, the content of —OH in DOM of rice husk and sawdust biochar decreased gradually, the —CH2 and —CH3 did not change significantly, the aromatic ring CC, C—H was enhanced, and the degree of aromatization was enhanced.

李飞跃, 桂向阳, 许吉宏, 马吉然, 文正午, 范行军, 蔡永兵, 汪建飞. 生物炭中溶解性有机质的光谱分析[J]. 光谱学与光谱分析, 2019, 39(11): 3475. LI Fei-yue, GUI Xiang-yang, XU Ji-hong, MA Ji-ran, WEN Zheng-wu, FAN Xing-jun, CAI Yong-bing, WANG Jian-fei. Spectral Analysis of Dissolved Organic Matter from Biochar[J]. Spectroscopy and Spectral Analysis, 2019, 39(11): 3475.

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