Effects Of Oil And Suspended Sediment Characteristics On The Formation Of Oil-particle Aggregates

The frequent occurrence of oil spills in marine has brought great harm to the ecological environment.The spilled oil aggregates with suspended sediment in the water to form an oil-particle aggregations(OPA)that then settles down is the main source of sunken oil.At present,the commonly used methods of oil spill removal are aimed at the oil slick on the surface of the sea and fail to remove the sunken oil that has settled to the bottom of the sea,so sunken oil can cause serious influence on benthic and environment.Therefore,it is of great significance to explore the action mechanism of different influencing factors on the formation process of OPA for the theoretical study of sunken oil and the improvement of oil spill emergency response mechanism.In this paper,the mixing mode of "beaker with magnetic agitator" is adopted to simulate the turbulent energy in the offshore sea.Oman crude oil,Dalia crude oil,Roncador crude oil,Merey crude oil,180#fuel oil and 380#fuel oil for the test oil respectively,with quartz sand for the experiment particles,choose the GM-2 for experimental chemical dispersants.Studied the oil sinking efficiency and OPA size in different particle concentration and size,oil type,seawater temperature and the proportions of chemical dispersants.And according to the experimental data,a dispersion oil dissipation model based on OPA was established to simulate the dispersion process of dispersed oil in different marine environments.The main research results are as follows:(1)When the oil-particle interaction reaches a balance,the oil sinking efficiency and the polymerization rate of the whole process show an obvious linear growth trend with the increase of particle mass concentration within a certain range.(2)When the mass concentration of particles is the same,the number of small particles is higher,so more oil droplets can be consumed,and the large particles can combine with the oil droplets faster.The larger the particle size,the larger the OPA size and the higher the density of OPA.(3)The higher the polarity composition of the oil,the more conducive to the formation of OPA;The viscosity has a certain value corresponding to the maximum oil sinking efficiency.When the viscosity is less than this value,the larger the viscosity is,the more favorable it is for the formation of OPA.The particle size of OPA first increased with the increase of viscosity and asphaltene content and then remained stable.(4)Temperature mainly affects the viscosity of crude oil and oil-water interfacial tension.The higher the temperature,the lower the viscosity,and the smaller the interfacial tension.(5)An appropriate amount of chemical dispersants can reduce the oil-water interfacial tension,promote oil spill dispersion,and thus improve the amount of OPA formation.However,excessive chemical dispersants will increase the strength of the outer layer of the oil droplets and inhibit the effective adhesion between oil and particles.(6)Based on the theoretical model of dispersion oil concentration reduction,a prediction method of OPA formation is proposed,and the reliability of the theoretical model is verified by the above experimental data.Based on the application background of Bohai Sea environmental conditions,the change rules of OPA formation rate and dispersion oil concentration with time and suspended sediment concentration after oil spill accidents in the near shore and open sea areas are predicted.The research results can provide theoretical basis for further improvement and improvement of the oil spill polymerization settlement model and oil spill environmental behavior prediction.