The Preparation Of Nano Emulsified Oil And Its Migrationand Release Simulation Experiment In Porous Media

Emulsified oil,as a slow release carbon source,has achieved good effectin situ remediate groundwater nitrate,perchlorate,hexavalent chromium,and halogenated hydrocarbon pollution.However,due to the larger oil particle size and higher viscosity of emulsified oil.It was easily causing permeability loss in varying degrees after emulsified oilinjected into aquifer for pollution remediation.Contaminated groundwater flowed around the reaction zone and would not be treated,resulted in the decrease or failure of remediation efficiency.In order to solve this problem.This article made reference totechnical methods in the field of food and drug,introduced the mixed emulsifier,adopted heating phase inversion method,prepared nano emulsified oil,and used one-dimensional column experiment to simulate migration and release of ordinary emulsified oil and nano emulsified oil in porous media.Contrast analysis of the permeability loss,emulsified oil carbon source release,and effective longevity.The main results are as follows:?Preparation experimental results show that,the ratio of tween 80 and span 80 is 7:3,the ratio between emulsifier and oil ratio is 1:2,1:1.5,and 1:1,internal phase content is 15%~25%,10~30%,and 5%~30%.Nano emulsified can be acquiredunder 55 ? for phase transformation temperature.Among them,the best ratio between emulsifier and oil is 1:1,internal phase content is 30%.In this preparation proportion,the average particle size of nano emulsified oil is 255.1 nm,dynamic stability index is 0.5,viscosity is 3.72×10-4 pa·s,and COD release content is 472 g/L.?Column experiment results show that the permeability loss in medium sand caused by nano and micro emulsified oilinjected were3.20% and 20.40%,respectively.Emulsified oil interceptionwere 20.15% and 28.51%,respectively.Obviously,emulsified oil interception is the important reason for porous media permeability loss,and the decrease of the emulsified oil droplets size can effectively reduce permeability loss in porous media.In addition,emulsified oil interception and permeability loss can also affect its migration distance in porous media.The migration distance of micro and nano emulsified oil in medium sand were6.53 m and 8.19 m,respectively.By contrast,the permeability loss of nano emulsified in fine sand was 10.70%,emulsified oil interceptionwas 25.71%,the migration distance was 7.36 m.Nano emulsified can be used in widermedia.?Phase content and particle size in emulsified oil is the important factors influencing the release ratio of COD.The experimental results show that the ratio between dissolved COD and total COD of nono and micro emulsified oil in medium sand were 61.95% and 87.61%,respectively.Effective longevity were 243.17 dand 98.80 d,respectively.Although theeffective longevity of nano emulsified oil was less than micron emulsified oil,COD release ratio was less than micron emulsified oil,releasing effect wasmuch better,and compared with congestion problem,nano emulsified oil is more acceptable.After nano emulsified oilinjectedinto fine sand,the ratio between dissolved COD and total COD was 77.23%,effective longevity was 197.41 d,which indicated thatnano emulsified oil can extend the effective longevity in fine sand.