Study On Mechanism Of Uranium Removal By The Synergistic Effect Of Oxygen And Iron(?)

The mining process of uranium mining area produced uranium-containing waste water,causing groundwater polluted in the mining area.The process with the oxidation of iron-bearing minerals will release elevated levels of Fe???in groundwater.In the presence of O₂,whether the iron ion forms ferric hydroxide colloid or co-precipitates with U???,it will effectively remove U???.Thus,this experiment takes advantage of O₂ injecting into solution,Thus,this experiment takes advantage of the synergistic effect of Fe???and O₂ to investigate removal efficiency of uranium and mechanisms in the synergistic effect of Fe???and O₂,researching the effect of reaction time,ratio of initial Fe???concentration to U???,different initial pH values and HCO₃^-on U???removal efficiency.The mechanisms in the synergistic effect of Fe???and O₂ were analyzed by using scanning-electron microscope?SEM?,X-ray analysis?EDS?,X-ray power diffraction?XRD?and BCR sequential extraction experiments methods.The results from experiments show that in the neutral condition with the injection of O₂,the removal efficiency of U???was 60%.In the synergistic effect of Fe???and O₂,the removal efficiency of U???increased with p H values increasing.In the neutral condition,the removal efficiency of U???both reached 94%with the ratio of initial Fe???concentration to U???of 1/10,1/5,1/2,1/1,2/1 respectively.In acid condition,the optimal ratio of Fe???to U???was 1/2.The effect of HCO₃^-on U???removal efficiency was obviously.In the neutral condition,the removal rate of U???was 41%,47%,55%,58%,70%respectively with the ratio of initial Fe???concentration to U???of 1/10,1/5,1/2,1/1,2/1.The effect of HCO₃^-on U???removal was attributed to the combination of U???and HCO₃^-to form uranyl carbonate complexes such as UO₂?CO₃?₂^2-and UO₂?CO₃?₄^4-,retarding the he adsorption and co-precipitation of U???during the process.The results from BCR sequential extraction experiments show the average proportion of different speciation uranium to total uraniuma with a sequence of oxidation?46.45%?>adsorption?22.73%?>reduction?21.22%?>residual?9.6%?.The analysis of SEM,EDS and XRD indicated that the precipitates consisted of iron oxides and uranium oxide.The crystal form of iron oxides is stable,which can adsorb uranium into the surface of iron oxides.The mainly mechanisms of U???removal by the synergistic effect of Fe???and O₂ may be reduction absorption and the co-precipitation of uranium and iron oxides.