Experimental Study On Microbial Degradation Of Baoji Linyou Long Flame Coal

Coal is the main source of China's energy and raw materials for chemical industry. It is a topic that worthy of further study, about how efficient and rational use of a large amount of low rank coal resource. Biotransformation of coal is a kind of chemical reaction, which degrade of coal macromolecules under the action of microorganisms. This technology has many advantages, such as easy operation, low cost, low energy consumption, environmental friendly, biodegradation products of higher value. Since the 1980 s, more and more domestic and foreign researchers have engaged in the study of biotransformation of coal technology.In this paper we selected four kinds of fungi: Phanerochaete chrysosporium, Trametes versicolor, Schizophyllum commune, White rot fungi; and four kinds of bacteria: Paenibacillus polymyxa, Bacillus thuringiensis, Staphylococcus aureus, Salmonella as the experimental microorganisms. And investigated the ability of the eight microorganisms to degrade Linyou long flame coal; We found that among these four fungus, Phanerochaete chrysosporiumwas the strongest in biodegradation of linyou long flame coal, the biodegradation rate can be as high as 27.45 percent. In the four kinds of bacteria, Paenibacillus polymyxa got the highest efficiency in biodegrading of linyou long flame coal, can up to 69.97%. It can be seen that for the same coal sample, Paenibacillus polymyxa has the better biodegradation ability.We have studied the effects of several factors on the efficiency of microbial degradation of coalby Phanerochaete chrysosporium and Paenibacillus polymyxa, such as the concentration of nitric acid used when oxidized coal samples, experimental time, the amount of bacteria, coal particle size. And found that the higher the concentration of nitric acid used when oxidized coal samples, the higher biodegradation efficiency got; As time increases, the efficiency of microbial degradation first increases and then slowly stabilized, so is the amount of bacterial suspension; For the fungal degradation of coal, coal particle size has no significant effect on the degradation efficiency, while for bacteria, the smaller the particle size is, the higher the degradation efficiency are.In order to optimize the experimental conditions of biodegradation of coal by Paenibacillus polymyxa, Response Surface Methodology was used. We studied the effects of the interaction between the three factors, experimental time, the amount of bacteria, the concentration of nitric acid used when oxidized coal samples, on the efficiency of biodegrade coal. The best experimental condition and the degradation rate under the best condition was obtained. The experimental result obtained under the optimal experimental condition was consistent with the expected values of the response surface model.In order to understand the characteristics of biodegradation products, a variety of modern analytical techniques were used for the analysis of raw coal, oxidized coal, coal residues after degradation and liquid products of degradation of coal, such as Proximate, Ultimate analysis of coal, Ultraviolet-visible spectrum analysis, FTIR, thermal gravimetric analysis, GC-MS analysis, UPLC-MS analysis. The results showed that the molecular structure of Linyou long flame coal have greatly changed after biodegradation and the character of caloric has changed too; The liquid product of the degradation of coal mainly consists of alkanes, alkenes, Oxygen-containing compounds such as carboxylic acids, esters, ketones, Nitrogen-containing compounds and Sulfur-containing compounds. And in most of the heteroatom compounds contain benzene ring structure. The m/z value of molecular ions or fragment ions of liquid productions are distributed in about 300-800, we can predict that the relative molecular mass of various substances contained in the liquid product is much less than the relative molecular weight of coal macromolecules, which may account for microbial degradation of coal produced, some coal macromolecules are degraded into smaller molecular weight substances.