复合菌剂转化褐煤产腐植酸机理研究

Mechnism of producing humic acid in lignite conversion via mixed microbial agent

以新疆褐煤为转化底物,构建复合菌剂(100 mL菌剂中枯草芽孢杆菌、苏云金芽孢杆菌、米曲霉和微紫青霉菌的体积分数分别为1.5%,1.5%,1.0%,2.5%)作为研究对象,通过工业分析、元素分析、X射线衍射分析、傅立叶红外光谱分析、X射线光电子光谱分析和紫外-可见光光谱分析等方法,研究了复合菌剂转化褐煤前后煤的腐植酸质量分数、元素组成、矿物组成、有机官能团、碳元素赋存形态的变化,以及转化褐煤过程中,复合菌剂和单一微紫青霉产生的锰过氧化物酶、木质素过氧化物酶、漆酶的活性变化。结果表明:经复合菌剂转化后,煤中总腐植酸和可溶性腐植酸质量分数分别由29.75%和6.24%增加到66.41%和33.44%;复合菌剂转化后,煤中灰分质量分数和固定碳质量分数分别由8.91%和55.72%降至8.07%和52.99%,而挥发分质量分数则由38.83%增加至42.36%。元素分析结果表明:经复合菌剂转化后,煤中C元素相对含量由71.56%降至69.93%;H,O,N等元素相对含量均升高,其中N元素相对含量上升最明显,由0.65%升至1.26%。经复合菌剂处理后,煤中无机矿物组成变化不明显,但C—C/C—H官能团和O C—O官能团增加,且部分不饱和C被饱和。微紫青霉产生的锰过氧化物酶、木质素过氧化物酶、漆酶的活性较单一,复合菌剂产生的锰过氧化物酶、木质素过氧化物酶、漆酶的活性均明显提高,其中漆酶活性达到16.09 U/mL。以上结果说明复合菌剂可将褐煤中大分子结构转化生成小分子腐植酸。与单一菌种相比,复合菌剂产生更多的胞外酶有助于腐植酸的产生。

Used the lignite obtained from Xinjiang as substrate and the mixed microbial agent constructed in the previous study as the research object(the volume fractions of Bacillus subtilis,Bacillus thuringiensis,Aspergillus oryzae and Penicillium janthinillum in 100 mL inoculum were 1.5%,1.5%,1.0%,2.5%).Bioconversion of lignite to produce humic acid with the mixed microbial agent was conducted by the batch shaking flask test.The humic mass fraction,element and mineral content,organic functional groups and carbon speciation in raw coal and residual coals,and the lignin peroxidase,manganese peroxidase and laccase enzyme activity of the mixed microbial agent as well as the single Penicillium janthinillum during bioconversion were investigated using the ultimate analysis,proximate analysis,X-ray diffraction analysis,Fourier transform infrared spectrum,X-ray photoelectron spectrum analysis and UV-visible spectrum analysis.The results show that the mass fraction of total and soluble humic acid increase from 29.75%and 6.24%to 66.41%and 33.44%;respectively.After bioconversion,the ash mass fraction and fixed carbon in lignite decrease from 8.91%and 55.72%to 8.07%and 52.99%,while the volatile matter increases from 38.83%to 42.36%.The results of ultimate analysis show that the C content decreases from 71.56%to 69.93%;while H,O,and N contents increase.N has the highest percentage of increase,from 0.65%to 1.26%.The mineral components almost remaine unchangeable after the treatment of the mixed microbial agent,but the C—C/C—H functional groups and O C—O functional groups increase and partial unsaturated C of lignite is saturated.The activities of lignin peroxidase,manganese peroxidase,and laccase produced by the mixed microbial agent exceed those produced by single strains,and the laccase activity is up to 16.09 U/mL.All these results show that some complex macromolecular structures in the lignite can be decomposed and transformed into the small molecule humic acid.Furthermore,compared to the single strain,the mixed microbial agent produces more extracellular enzymes for humic acid production.