Effect Of Surfactant On The Diffusion Of Tracer Bacteria In Coal Samples

Bacteria inhabiting coal seams have a significant impact on the coal matrix and surrounding fluids.Understanding the behavior and dynamics of bacteria in coal samples,particularly the diffusion of tracer bacteria,can provide insights into transport and colonization patterns within the coal seam environment.This thesis investigates the effect of surfactants on tracer bacteria diffusion in coal samples.An experiment was conducted using coal samples from Zhongmacun Coal Mine in Jiaozuo and p MJ67 L.acidophilus SP.fluorescent tracer bacteria.Bacterial liquid infiltration was limited by surface tension,affecting bacterial diffusion and species distribution.To address this,the study evaluated the effects of different surfactants on bacterial infiltration and diffusion in coal seams.The experiment comprised several stages.The first stage involved surface liquid seepage experiments using deionized water and different coal particle sizes as the matrix.Surfactants such as sodium dodecyl sulphate(SDS),sodium dodecyl benzene sulfonate(SDBS),fatty alkyd polyoxyacetate(PPJ),sodium stearate(SS),and sucrose(Su)were tested to improve coal seam seepage.The effects of temperature at 30℃,45℃,and 60℃ and surfactant molarity,2.50%,3.75%,and 5.00% on liquid surface tension were explored.The second stage used a multifactor,multi-level linear regression experiment method to determine optimal surfactant configurations.Composite ratio experiments explored the improvement and optimal levels of two surfactants on bacterial tracer seepage.In the third stage,the coal column test method simulated composite liquid column-shaped coal bodies to study seepage characteristics and infiltration effects.The percolation efficiency,uniform distribution,and migration of the bacterial agent were analyzed using fluorescence microscopy.The saturation of the complex p MJ67 L.acidophilus SP.fluorescence solution decreases proportionally with the decrease of dilution coefficient,1/10,1/20 and 1/100.The 1/100 dilution factor,1% of the p MJ67 L.acidophilus SP.Fluorescent stock solution offered a suitable identification and saturation of p MJ67 L.acidophilus SP.Fluorescent cells under an optical microscope.Coal samples were crushed,ground,and screened to obtain particles of different sizes ranging from 0.280 to 0.450 mm,0.154 to 0.180 mm,0 to 0.125 mm of coal samples,respectively named Coal Sample 1,Coal Sample 2 and Coal Sample 3.Surfactants increased wetness and liquid tracer infiltration in coal samples.Penetration of p MJ67 L.acidophilus SP.fluorescent-contaminated water droplets did not occur in any coal particle samples.The penetration time of surfactant solutions varied between extremely infiltrated(0.2 s)and noninfiltrated(>3600 s).Surfactant concentration increased bacterial liquid infiltration,except for sucrose,which had no effect.SDS and PPJ increased infiltration at room temperature,while SS and SDBS required higher temperatures(>50 °C).Infiltration increased with low surfactant concentration,but high concentration negatively impacted infiltration.Surfactant solutions infiltrated coal samples more effectively at higher temperatures.The optimal result(droplet penetration time: 0.098 s)was obtained at 45 °C using a 5.00% concentration of SDS solution and a 3.75% concentration of PPJ solution.Smaller coal particle sizes decreased surfactant solution infiltration.Liquid tracers composed of 1.88% SDS,1.88% PPJ,and a mixture of 1.88% PPJ + SDS both percolated coal samples 1 and 2,allowing the study of hydraulic properties.Hydraulic conductivity,water retention,and moisture content were investigated.The PPJ 1.88% tracer liquid showed higher retention volume,2.50 m L in both coal samples.The SDS 1.88% tracer liquid had a greater impact on permeability.Coal sample 1 exhibited shorter infiltration time,the hydraulic conductivity was 0.37 cm/s using PPJ 1.88% tracer liquid,0.35 cm/s using SDS1.88%,and 0.30 cm/s using a mixture of 1.88% PPJ + SDS tracer liquid.Diffusion of tracer bacteria depended on coal particle size.Moisture content increased from top to bottom in the column,from 10.47% to 21.80% in coal sample 1,from 29.56% to 30.52% in coal sample 2.Fluorescence microscopy detected p MJ67 L.acidophilus SP.fluorescent cells in liquid tracer samples.The SDS 1.88% tracer liquid failed to detect fluorescent cells,while PPJ and PPJ +SDS 1.88% tracer liquids successfully identified fluorescent cells.This study confirms the effect of surfactants on the diffusion of tracer bacteria in coal seams.The addition of surfactants can improve the permeability of liquids in coal samples and enhance the uniform distribution and diffusion ability of bacteria in coal seams.Column experiments have demonstrated that p MJ67 L.acidophilus SP.fluorescent cells,as a biological tracer,can successfully migrate in coal samples,allowing for the analysis of coal seam hydrological diffusion and seepage points.These findings provide a novel technical approach for studying the hydrogeology of coal seams and evaluating the effectiveness of hydraulic operations.They hold great significance in improving the reliability and accuracy of hydrological observations,coal seam water injection design and evaluation,and other related work.This dissertation includes 68 figures,25 tables,and 114 sets of references.