Yang Yan, Li Yanhong, Zhang Yuanqin, Wang Miao, Wang Pingyan, Liu Donghui
Faculty of Chemical Engineering, Kunming University of Science and Technology, Kunming 650500, People's Republic of China.
ACS Omega. 2024 Sep 3;9(37):38409-38422. doi: 10.1021/acsomega.4c01840. eCollection 2024 Sep 17.
In this study, response surface methodology (RSM) was adopted to investigate the optimization of process conditions for extracting humic acid (HA) from coal, aiming to enhance the yield of humic acid. Additionally, UV-vis spectroscopy, FTIR, XRD, TG-DTG, CP/MASCNMR, XPS, and molecular fluorescence were utilized to examine the properties of HAs. The extraction time significantly influenced the yield from Lishi weathered lignite, while the liquid-solid ratio had a significant impact on the yield from Wuhai weathered lignite. The interactive effect between factors did not have a significant effect on the yield. The optimal extraction conditions for Lishi humic acid (LSHA) were determined to be an extraction time of 4.4 h, NaOH concentration of 0.30 mol/L, and liquid-solid ratio of 21 mL/g, while those for Wuhai humic acid (WHHA) were 3.1 h, 0.21 mol/L, and 12 mL/g, respectively. Under these optimal conditions, the true yield values closely matched the predicted value obtained from the model optimization. Comparative analysis of the HAs revealed similarities in their chemical properties, including the degree of aromaticity, molecular weight, and distribution of functional groups. The aromaticity of WHHA was higher compared to that of LSHA. The higher hydrophilic-hydrophobic index of LSHA contributed to its relatively high biological activity compared to that of WHHA. Both humic acids belong to terrestrial humic acids. The results of the study provide a reference for further application of humic acid.
在本研究中，采用响应面法（RSM）来研究从煤中提取腐殖酸（HA）的工艺条件优化，旨在提高腐殖酸的产率。此外，利用紫外可见光谱、傅里叶变换红外光谱、X射线衍射、热重-微商热重、交叉极化/魔角旋转核磁共振、X射线光电子能谱和分子荧光来研究腐殖酸的性质。提取时间对离石风化褐煤的产率有显著影响，而液固比对乌海风化褐煤的产率有显著影响。各因素之间的交互作用对产率没有显著影响。离石腐殖酸（LSHA）的最佳提取条件确定为提取时间4.4小时、NaOH浓度0.30mol/L、液固比21mL/g，而乌海腐殖酸（WHHA）的最佳提取条件分别为3.1小时、0.21mol/L和12mL/g。在这些最佳条件下，实际产率值与模型优化得到的预测值紧密匹配。对腐殖酸的比较分析表明，它们在化学性质上具有相似性，包括芳香度、分子量和官能团分布。与LSHA相比，WHHA的芳香度更高。LSHA较高的亲水-疏水指数导致其与WHHA相比具有相对较高的生物活性。两种腐殖酸均属于陆地腐殖酸。该研究结果为腐殖酸的进一步应用提供了参考。
