Degradation of Xinjiang Wudong low rank coal based on ultrasonic crushing fluid of Pseudomonas japonicus

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 N2 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.