目前,微生物降解低阶煤技术已经取得显著的研究成果,但低阶煤的组成复杂,微生物降解低阶煤的机理仍然不明晰。因此,根据煤岩学的原理,分离得到富集镜质组的低阶煤(镜质组煤样),从而简化煤的组成,再利用微生物降解镜质组煤样,进而推知微生物对镜质组煤样的降解特性。采用重力分选法分离得到富集镜质组的新疆大南湖低阶煤,利用铜绿假单胞菌对硝酸预处理镜质组煤样进行降解,通过单因素实验和正交实验研究煤浆质量浓度、菌浓度、降解时间对铜绿假单胞菌降解镜质组煤样的影响。结果表明:三种因素按对降解效果的影响由大到小为降解时间、煤浆质量浓度、菌浓度,分析正交实验结果可知,铜绿假单胞菌降解预处理镜质组煤样的最优工艺条件为煤浆质量浓度6g/L、菌浓度6.37×106CFU/mL、降解时间11d,最大降解率为57.1%;对镜质组煤样、预处理镜质组煤样及降解后剩余镜质组煤样进行工业分析和元素分析,发现预处理镜质组煤样经过铜绿假单胞菌降解后,C元素和N元素的质量分数减小,H元素和O元素的质量分数增大;由红外分析结果可知,预处理镜质组煤样经过铜绿假单胞菌降解后,镜质组煤样中芳香结构发生变化,烷基侧链被降解;通过XRD分析发现,预处理镜质组煤样经过铜绿假单胞菌降解后,芳香层片的间距d002、堆砌高度Lc、微晶宽度La均减小,芳香层数N增大,表明铜绿假单胞菌能够降解预处理镜质组煤样中的芳香结构;采用气相色谱-质谱联用仪对铜绿假单胞菌降解预处理镜质组煤样后的液相产物进行分析,发现在二氯甲烷与甲苯萃取物中,质量分数最高的物质为烷烃类物质(均超过50%),其次为酯类物质(质量分数均在30%以上),相对分子质量均集中在142~394,说明铜绿假单胞菌可以将镜质组煤样降解为小分子;液相产物两种萃取物中还检测到部分胺类和硫取代基类化合物,综合元素分析结果得出铜绿假单胞菌能降解预处理镜质组煤样中的含氮结构和硫元素。

At present, the technology of microbial degradation of low-rank coal has achieved remarkable research results. However, the composition of low-rank coal is complex, and the mechanism of microbial degradation of low-rank coal is still unclear. Therefore, accor- ding to the principle of coal petrology, the low-rank coal enriched vitrinite (vitrinite coal sample) was separated, so as to simplify the composition of coal, and then used microorganisms to de- grade the vitrinite coal sample, and then inferred the degradation characteristics of microorga- nisms on the vitrinite coal sample. A gravity separation method to extract the Xinjiang Dananhu low-rank coal enriched vitinite was employed. Subsequently, degradation experiments on the vi- trinite coal sample were conducted using Pseudomonas aeruginosa. Through both single-factor experiments and orthogonal experiments, the influences of coal slurry mass concentration, bacte- ria concentration, and degradation time on the ability of Pseudomonas aeruginosa to degrade the vitrinite coal sample were systematically investigated. The results show that the factors affecting the degradation effectiveness followed the order (from large to small) of degradation time, coal slurry mass concentration, bacteria concentration. The orthogonal experimental results indicate that the optimal conditions for Pseudomonas aeruginosa to degrade the vitrinite coal sample are the coal slurry mass concentration of g/L, the bacteria concentration of 6.37×10 CFU/mL, and the degradation time of d, resulting in a maximum degradation ratio of 57.1%. Proximate and ultimate analyses were subsequently conducted on the vitrinite coal sample and pretreated coal sample and remaining coal sample after degradation by Pseudomonas aeruginosa. The analy- ses reveal that following degradation, the carbon (C) and nitrogen (N) mass fraction decrease, while the hydrogen (H) and oxygen (O) mass fraction increase. Infrared analysis indicates struc- tural changes in the vitrinite coal sample, including the degradation of alkyl side chains. X-ray diffraction results show alterations, including a decrease in the spacing between aromatic layers (d002), a decrease in the stacking height of aromatic layers (Lc), a decrease in the microcrystal- line width of aromatic layers (La), and an increase in the number of aromatic layers (N). These findings indicate the ability of Pseudomonas aeruginosa to degrade the aromatic structure within the vitrinite coal sample. Furthermore, gas chromatography-mass spectrometry was employed to analyze the liquid-phase products resulting from the degradation of the vitrinite coal sample by Pseudomonas aeruginosa. The analysis reveal that in both dichloromethane and toluene extracts, alkanes are the predominant compounds, comprising over 50% of the mass fraction. Ester com- pounds are the second most abundant, exceeding 30%, with relative molecular mass concentrate in the range of This indicates the capacity of Pseudomonas aeruginosa to degrade the vitrinite coal sample into smaller molecular compounds. Additionally, the liquid-phase products contain some amine compounds and sulfur-substituted compounds. Comprehensive ultimate anal- ysis results indicate that Pseudomonas aeruginosa can degrade nitrogen-containing structures and sulfur elements in the vitrinite coal sample.