Structural elucidation of humic acids extracted from Pakistani lignite using spectroscopic and thermal degradative techniques
Structural elucidation of humic acids extracted from Pakistani lignite using spectroscopic and thermal degradative techniques
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DOI：
10.1016/j.fuproc.2010.12.020
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发表时间：
2011-05-01
影响因子：
7.5
通讯作者：
Chaffee, A. L.
中科院分区：
文献类型：
--
作者：
Nasir, Saqib;Sarfaraz, Tahira B.;Chaffee, A. L.
本文描述了巴基斯坦褐煤、衍生腐殖酸（HAL）和硝基腐殖酸（NHA）沿着以及标准风化褐煤腐殖酸（LHA）的表征。该研究利用色谱和光谱技术来表征煤及其衍生材料的结构。在有和没有甲基化剂（四甲基氢氧化铵）的情况下，进行了热裂解-气相色谱/质谱联用。热解研究导致主要释放脂肪酸甲酯、不同系列的烃和α，ω-二羧酸甲酯。还检测到三萜类化合物、香豆酸和对香豆酸化合物以及来自木质素部分的芳香族化合物。傅里叶变换红外（FT-IR）和NMR数据有助于评估煤阶再生和硝化过程中的煤和衍生材料的化学结构组成的影响。四种材料的FT-IR光谱相似，除了NHA在1532 cm（-1）处显示吸收带，从而证实了-NO（2）基团的存在。(13)C NMR表明HAL比NHA具有更高的芳香度和更少的羟烷基物质。本文还报道了四种煤的元素组成和酸性官能团含量，不同分析方法的综合结果有助于加深对巴基斯坦煤性质的认识，并有助于其未来的利用。(c)2011 Elsevier B. V.保留所有权利。
The present paper describes the characterization of Pakistan lignite coal, derived humic acids (HAL) and nitrohumic acids (NHA) along with the standard leonardite humic acids (LHA). The study utilized chromatographic and spectroscopic techniques to characterize the structure of coal and derived materials. Pyrolysis coupled to gc/ms was conducted with and without methylating agent (tetramethyl ammonium hydroxide). The pyrolysis study resulted in releasing mainly fatty acid methyl esters, different series of hydrocarbons and alpha, omega-dicarboxylic acid methyl esters. Triterpenoids, syringic and rho-coumaric compounds and aromatic compounds derived from lignin moieties were also detected. Fourier transform infrared (FT-IR) and NMR data helped to evaluate the influence of coal rank on regeneration and nitration processes with respect to chemical structural composition of coal and derived materials. FT-IR spectra of four materials were similar except that NHA showed an absorption band at 1532 cm(-1), thus confirming the presence of -NO(2) groups. (13)C NMR indicated higher aromaticity and less hydroxylalkyl material in HAL than NHA. The elemental composition and acid functional group content of four materials were also reported.The combination of results from different analytical techniques gives an improved understanding of the Pakistan coal nature and helpful for its future utilization. (c) 2011 Elsevier B.V. All rights reserved.