Experimental And Simulated Study On Bimolecular Reactive Solute Transport In Heterogeneous Porous Media

With the development of society,groundwater problem is becoming more and more serious.The study of the law and mechanism of reactive solute migration in groundwater is the premise of groundwater protection and treatment.The solute transport in underground water is mostly concentrated in pores.However,the influence of heterogeneity of porous media on solute transport and quantification of reactive solute transport in heterogeneous porous media is an outstanding problem.In order to explore the law and mechanism of inert and reactive solute transport under different heterogeneity conditions,the heterogeneous porous media was constructed by using glass beads of different particle sizes and organic glass plates.The experiments and numerical simulation of inert and reactive solute transport were carried out under different heterogeneity and flow conditions（For example,brilliant blue was used for inert solute migration,reactive solute migration was considered Cu SO₄+EDTA-Na→EDTA-Cu as the example）.The results of the experiment and simulation were compared,and the simulation results of IM-ADRE model on reactive solute transport in heterogeneous porous media were studied.Finally,the parameters of solute transport in porous media with different heterogeneity were analyzed.Through the analysis of the experimental results,the following results and conclusions were obtained:（1）In the inert solute migration experiment,the flow increased,which led to the more obvious dominant channel in porous media,which showed that the bright blue concentration penetration curve kept close;in the reactive solute migration experiment,the concentration penetration curve of EDTA-Cu of the product was"Gaussian distribution",and the peak concentration of EDTA-Cu increased with the flow rate and the heterogeneity of porous media.（2）ADE model could fit the migration process of inert solute in heterogeneous porous media well,and the effect of catching"tail"phenomenon decreased with the increase of flow rate;the concentration penetration curve of reactants and products simulated by IM-ADRE model was basically consistent with the experimental value.The larger the flow rate,the higher the heterogeneity of the medium,the more obvious the phenomenon of"trailing",the worse the fitting effect of IM-ADRE model to"trailing",but the closer the prediction of the peak concentration of the product by IM-ADRE model to the experimental value.（3）The diffusion coefficient D of inert solute migration increases linearly with the flow rate.The heterogeneity of flow and porous medium affects the diffusion coefficient of reactive solute transport,and the effect of flow plays a major role;the dispersion coefficient of reactants and products increases linearly with the flow rate;the greater the heterogeneity of porous media,the dispersion coefficient of flow to the material.The larger the influence of coefficient was,the linear decrease of dispersion coefficient of different substances was with the increase of relative molecular weight of the material.（4）The parameterβ₀ of IM-ADRE model increased linearly with the increase of flow rate,and the slope of linear fitting ofβ₀ decreased with the increase of heterogeneity of porous media.The linear fitting slope of M increased with the increase of the heterogeneity of porous media.IM-ADRE model was the most sensitive to parameter m value and was relatively sensitive toβ₀.For dispersion coefficient D,IM-ADRE model was relatively sensitive to Cu SO₄ and EDTA-Cu,but not to EDTA-Na.