Department of Chemistry, Faculty of Science, University of Dhaka, Dhaka, 1000, Bangladesh.
Environ Sci Pollut Res Int. 2022 Mar;29(14):21012-21022. doi: 10.1007/s11356-021-17220-z. Epub 2021 Nov 8.
A laboratory-scale experiment was conducted to determine the light absorption properties of brown carbon (BrC) produced from the incomplete combustion of 14 different biomasses. Particulate matters (PM) emitted from biomass burning were collected on the quartz fiber filters with a low volume sampler. BrC from filter samples was extracted with two different solvents (methanol and water), and absorption characteristics of BrC were determined using a UV-Vis spectrophotometer. The absorption coefficient (b), mass absorption efficiency (MAE), absorption angstrom exponent (AAE), and absorbing portion of refractive index (k) were calculated for each biomass from the absorbance of the extracted solution. Methanol-soluble BrC (MeS-BrC) showed higher absorbance than water-soluble BrC (WS-BrC) in all biomasses. MeS-BrC has higher b than WS-BrC, suggesting that the rate of light absorption on BrC extracted in methanol was higher. The absorption coefficients (b) were varied among biomasses-rain tree had the highest value of b, whereas jute stick had the lowest. The mass absorption efficiency of BrC (MAE) was evaluated in both water and methanol extracts, and it was found that the MAE for MeS-BrC in the biomasses was greater than that of WS-BrC. The highest MAE value (13.02 mg) was identified in the jackfruit tree, whereas the lowest MAE value (0.1 mg) was observed in the jute stick. The absorption angstrom exponent (AAE) of both WS-BrC and MeS-BrC was determined which represents the light absorption capacity of the aerosol particles. The highest AAE value was found in cow dung, and the lowest was found in rain tree. The increasing pH of the WS-BrC solution increased its optical absorption. However, this study revealed that the light absorption properties of brown carbon emitted from commonly used biomasses were varied significantly.
进行了一项实验室规模的实验，以确定来自 14 种不同生物质不完全燃烧产生的棕色碳（BrC）的光吸收特性。使用体积较小的采样器在石英纤维滤纸上收集生物质燃烧产生的颗粒物（PM）。使用两种不同的溶剂（甲醇和水）从滤膜样品中提取 BrC，并使用紫外可见分光光度计测定 BrC 的吸收特性。从提取溶液的吸光度计算每种生物质的吸收系数（b）、质量吸收效率（MAE）、吸收消光系数指数（AAE）和折射率吸收部分（k）。在所有生物质中，甲醇可溶 BrC（MeS-BrC）的吸光度均高于水溶 BrC（WS-BrC）。MeS-BrC 的 b 值高于 WS-BrC，表明在甲醇中提取的 BrC 的光吸收速率较高。吸收系数（b）在不同的生物质之间有所不同——雨树的 b 值最高，而黄麻棒的 b 值最低。评估了 BrC 的质量吸收效率（MAE）在水和甲醇提取物中的情况，发现生物质中 MeS-BrC 的 MAE 大于 WS-BrC。MAE 值最高（13.02mg）的是菠萝蜜树，而 MAE 值最低（0.1mg）的是黄麻棒。测定了 WS-BrC 和 MeS-BrC 的吸收消光系数指数（AAE），该指数代表气溶胶颗粒的光吸收能力。牛粪便中的 AAE 值最高，雨树中的 AAE 值最低。WS-BrC 溶液的 pH 值增加会增加其光吸收。然而，本研究表明，来自常用生物质的棕色碳的光吸收特性差异很大。
