Study On The Mechanism Of Bacteria Substrate Selectivity For The Production Of Hydrogen From Coal

In the world,there are different sources of usable energy in order to answer the demand of the population,which increases from day to day.These energy demands include transport,heating,electricity,etc.Coal is a complex and highly variable substance that can be converted into a variety of products.Coal is made up of some elements in which microorganisms feed on.These microorganisms,during their nutrition convert macromolecules of coal to micro molecules,a process that results in production of gases.The aim of this study was to develop a methodology to investigate dark fermentation process of five different coal samples collected in different coal mines in China,the yielding capability of each sample was also determined.These productions are done in small-volumes in the laboratory;the starting point is coal sampling i.e.sample preparation process,which involve crushing and sieving（200μm）.The preparation helps to increase the sample surface area,which favor chemical reaction efficiency.Utilizing the p H monitor（p HS-3C）to detect the p H of each coal solution,3g of coal sample is weighed and put into a beaker;10ml of distilled water was added then stirred for 5 minutes.The beaker is covered with a glass cover and allowed to stand for 8 hours and it is then stirred again before testing.If the final p H varies between 5.5 and 6,it means the coal samples are moderately acidic.Serum bottles with a volume of 500 m L were tightly sealed with a rubber septum connected to a gasbag then followed by the addition of microbial for the treatment of the coal solution.Incubators provide a controlled temperature（37℃）,six parallel of all the solution were done making six bottles for one sample,stock A（medium A）was placed in three bottles same with stock B also introduced in three other bottles of the coal sample.The optimum measurement was collected daily by removing the biogas through the septum pierced with a glass syringe needle.Stock B represented with a positive sign,showed that only anthracite coal（FHS and GXM）sample had a high yielding productivity with stock A but stock B had high yielding ability with LZY,LHT and XZH meaning that coal with carbon content less than 91%produced more with medium B.These five coal samples had different coal rank,that is Guangxi and Feng huang Shan are anthracite with a carbon content of 93-97%,Xuzhou is a gas fat coal with carbon content of 90-92%,Lao hu tai is a fat coal with a carbon content of 84-89%while Liziya is a lean coal with a carbon content of 93-97%.The enzyme efficiency of five different coal samples was determined using（α-amylase,Cellulase and Amyloglucosidase）.Taking 1g of enzyme into the test tube,100m L of distilled water was added with an adjustable mixer to shake,the amount of enzyme used is 0.1 m L per10 m L of coal solution and the temperature during the reaction period of coal was 55^oC.Benedict’s solution was used test the presence of reducing sugar in each coal.The macroscopic observation showed color difference in the coal solution before and after heating,these color difference does not imply that amylase and amyloglucosidase reacted positively with the coal sample,but these coal samples contains impurities.Absorbance of coal sample mixed with cellulase of each of the tubes was constant indicating the presence of cellulose in all the coal samples,whileα-amylase and amyloglucosidase sample did show neither a constant absorbance nor effective color change.These results indicated that there is no starch or glucose present in the five coal samples.The microbial analyzed by major cloud for taxonomy,presented one main family for the production of bio-H₂.According to the phylogenetic tree（Figure 3-14）,it makes it possible to show the links of relationship between microbial.This Phylogenetic tree indicate two main microbial genus i.e.Clostridium＿sensu＿stricto Sp.,Caproiciducens sp.and a trace proportion of Sporolactobacillus Sp.The scale bar indicated 0.1substitution per genus position.Numbers at the nodes are the bootstrap values（25,50）between Clostridium＿sensu＿stricto and other genus like Caproiciducens,sporolactobacillus.and Clostridium＿sensu＿stricto.These genus are highly exhibited in this Phylogenetic tree by elevated demonstration bars.The two pie charts（Figure3-15and Figure3-16）describe the percentage of each microbial genus present in the experiment before and after bio-H₂ production respectively.The pie chart revealed that Clostridium＿sensu＿stricto and other microbial genus reduced their percentages to 6.31%and 0.52%respectively after gas production while Caproiciducens increased its percentage to 1.82%.This result showed that microbial genus that highly took part in the production are Clostridium＿sensu＿stricto,that is why they experienced a high reduction in their genus after gas production.The modified Gompertz model with the use of SPSS software permit us to have predictive data values of each coal sample.These data revealed that FHS and GXM had the highest average bio-H₂ prediction capacity 77,67 m Lday-1and 68,90 m Lday-1 while LHT,XZH and LZY had 63,8m Lday-1,50.3 m Lday-1 and 49,01 m Lday-1respectively.This dissertation includes 56 figures,6 tables and 122 of references.