基于日本假单胞菌超声破碎液对新疆乌东低阶煤的降解

Degradation of Xinjiang Wudong low-rank coal based on ultrasoniccrushing fluid of Pseudomonas japonicus

低阶煤的微生物降解过程条件温和、能耗低,是煤炭绿色转化的途径之一,但降解率较低、降解时间较长的难题阻碍了其工业化的进程。近年的研究发现微生物主要是利用其分泌的胞外液来降解煤,但胞外液的提取过程繁杂,不利于工业生产。因此,本实验选取对煤降解能力较好的日本假单胞菌,采用超声波对其进行破碎获取菌种超声破碎液,利用超声破碎液降解新疆乌东低阶煤,并以未经处理的菌种细胞培养液作为对照。结果显示:当日本假单胞菌生长状态处于稳定期及稳定期以后时,进行超声波破碎细胞培养液,所获得的破碎液对煤样有较好的降解效果;选取培养60 h达到稳定期的菌种进行超声波破碎,破碎液对煤样的降解率为48.97%,较对照组提高了13.13%。细胞培养液主要依靠分泌的胞外液降解煤,而菌种超声破碎液中既含有胞外液又含有胞内液,GC-MS分析可知,胞外液和胞内液组成相似,主要为胺类和醇类等物质,因此,菌种经超声波破碎后,胞内液释放,胞外液和胞内液共同参与了降解过程,从而提高了煤样的降解率。采用FTIR、XRD、低温N_(2)吸附和GC-MS对降解后的固、液相产物进行分析,与对照组相比发现:日本假单胞菌超声破碎液对煤样分子结构中羟基、羧基和酯基等官能团的降解作用更强,从而使微晶结构中芳香层片的间距更大,堆砌高度更低,碳层数更少,并且固相产物中19~23 nm微孔所对应的比表面积增加;液相产物的物质种类数增加,主要成分为烷烃、酮、醇和酯类等,分子量为154~546。利用菌种超声破碎液代替细胞活体降解低阶煤,不仅提高了煤样的降解率,还为低阶煤生物降解的工业化提供了一条新的途径。

The microbial degradation process of low-rank coal has mild conditions and low energy consumption,which is one of the ways for coal green transformation.However,the problems of low degradation rate and long degradation time hinder its industrialization process.Recent studies have found that microorganisms mainly use their secreted extracellular fluid to degrade coal,but the extraction process of extracellular fluid is complex,which is not conducive to industrial production.Therefore,Pseudomonas japonicus(P.japonicus)with good coal degradation ability was selected and crushed by ultrasonic wave,the ultrasonic crushing fluid was employed to degrade Xinjiang Wudong low-rank coal,and the untreated strain cell culture fluid was used as the control.The results showed that when the growth state of P.japonicum was in the stable stage and after the stable stage,the cell culture fluid was broken by ultrasonic wave,and the crushing fluid obtained had a good degradation effect on the coal sample.The strains which reached the stable stage after 60 h culture were selected to be broken by ultrasonic crushing,and the coal degradation rate by the crushing fluid was 48.97%,which was 13.13%higher than that of the control group.The cell culture fluid mainly depends on the secreted extracellular fluid to degrade coal,and the strain ultrasonic crushing fluid contains both extracellular fluid and intracellular fluid.The GC-MS analysis shows that the compositions of extracellular fluid and intracellular fluid were similar,mainly including amines and alcohols.Therefore,after the strain was broken by ultrasonic wave,the intracellular fluid was released,and the extracellular fluid and intracellular fluid participated in the degradation process together.Thus,the degradation rate of the coal sample was improved.The solid and liquid products after coal biodegradation were analyzed by FTIR,XRD,low temperature N_(2) adsorption,and GC-MS.Compared with the control group,it was found that the strain ultrasonic crushing fluid of P.japonicum had a stronger degradation effect on hydroxyl,carboxyl,and ester groups in the molecular structure of the coal sample.This resulted in the larger spacing of aromatic layers,lower stacking height,and fewer carbon layers in the microcrystalline structure,and the specific surface area corresponding to 19-23 nm micropores in solid product increased.The number of substances in liquid product increased,the main components were alkanes,ketones,alcohols and esters,and the molecular weight is about 154-546.Strain ultrasonic crushing fluid was used to degrade low-rank coal instead of living cells,which not only improves the degradation rate of coal sample,but also provides a new way for the industrialization of biodegradation of low-rank coal.