| The migration of heavy metal cadmium ions in saturated porous media is influenced by temperature,concentration,seepage velocity and suspended particles,in this paper,the present research situation of heavy metal ions transfer in saturated porous media is used,and the experimental device developed by ourselves is utilized to acid environment(ph=5.4)Experimental study on the transport characteristics of heavy metal cadmium ions in saturated porous media,including experimental research and mechanism analysis.(1)To study the influence of temperature,seepage velocity and ion concentration on the migration characteristics of single cadmium ions in saturated porous media,3 kinds of seepage velocities(0.087,0.173,0.260cm/s),3 kinds of cadmium ion concentrations(100,300,500ng/mL)and 3 kinds of test temperatures(20,40,60?),the experiment law of soil column infiltration with single cadmium ions was investigated.The results show that under the same test conditions,the peak value of cadmium ions in the flow fluid is almost unchanged,even negligible,with the change of temperature.The results show that the temperature has no much effect on the migration of single cadmium ions.In the same way,the influence of seepage velocity and injected ion concentration on the migration of single cadmium ions in saturated porous media is studied,and the seepage velocity and ion concentration are taken as variables,others as control quantities,and the results show that under the same test conditions,with the change of seepage velocity,The peak of the relative concentration of cadmium ions in the flow fluid was not much changed,it can be neglected that the seepage velocity has little influence on the migrateon of single cadmium ions,and the concentration of cadmium in the discharge fluid decreases with the increase of ionic concentration,which indicates that the concentration range of the experiment is not more than the adsorption limit of porous media,the change of ion concentration of injected liquid can significantly change the concentration of cadmium ion in leachate.(2)To study the influence of temperature,seepage velocity,ionic concentration and silica particle size on the migration of cadmium ions in saturated porous media,3 kinds of temperature(20,40,60?),3 kinds of seepage velocity(0.087,0.173,0.260cm/s),3 kinds of cadmium ion concentrations(100,300,500ng/mL),The effect of suspended particles on the infiltration test of cadmium ions under 3 kinds of silicon powder particle size(2.8,10.9,8.7?m)was studied.The results show that under the same test conditions,with the increase of temperature,the relative concentration of cadmium ions in the discharge fluid decreases,which indicates that temperature inhibits the migration of cadmium ions under the influence of suspended particles.The same method studies the velocity of seepage,Effect of implanted ion concentration and silica particle size on the migration of cadmium ions in saturated porous media under the influence of suspended particles,the results show that,with the change of seepage velocity in the same test condition,the peak value of cadmium ion concentration in the flow fluid is not much changed,the results show that the flow velocity has no great influence on the transfer of cadmium ions,and the concentration of cadmium in the discharge liquid decreases with the increase of ion concentration,which is consistent with the single cadmium ion test,which indicates that the ionic concentration range of the experiment is not more than the adsorption limit of porous media,the change of ion concentration of injected liquid can significantly change the concentration of cadmium ion in leachate;with the increase of silica particle size,the relative peak concentration of cadmium ions in the flow fluid decreases gradually,and the suspended particles in porous media greatly promote the migration of cadmium ions,but decrease with the increase of silica particles.(3)By means of the analytic solution of the convection-diffusion equation of first-order sedimentary coefficients under the corresponding conditions,the test penetration curves of heavy metal cadmium ions under the influence of suspended particles are fitted.The related motion parameters(dispersion coefficient DL,deposition rate Kdep,average velocity u)are determined by comparing the parameters above,and the DL and u and Kdep increase with the increase of seepage velocity.The recovery rate of heavy metal cadmium ions was higher than that of single cadmium ions,and the decrease of particle size was decreased. |
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