| Nuclear energy is an important way to solve the energy shortage crisis.Among them,uranium is the most critical nuclear fuel,so the demand for uranium has become particularly important.However,uranium-containing pollutants are carcinogenic,highly toxic and mutagenic.If uranium Released into the natural environment,the environment in which mankind lives will be severely threatened.Uranium cannot be biodegraded during the migration and transformation process of the environment,and it will be continuously enriched,causing lasting harm to the environment.In this paper,through the uranium adsorption experiments on several different natural clay minerals,the sepiolite with the best uranium adsorption performance was selected,and the uranium adsorption performance of the sepiolite was tested,and the different solution environments and competing ions were studied.Effect on the adsorption of uranium by sepiolite.X-ray diffraction(XRD)and scanning electron microscopy(SEM)characterization methods were used to analyze the morphology and properties of sepiolite.In this paper,the uranium migration path of soil-leaching solution-sepiolite was constructed to achieve the removal of uranium from soil and its enrichment in sepiolite.The effects of different leaching agents on the removal of soil uranium and the enrichment in sepiolite were studied,and the idea of remediation process of uranium-contaminated soil with uranium-bearing soil micro-acid leaching and sepiolite enrichment was put forward.(1)According to the adsorption experiment of sepiolite on uranium-containing solution,it can be concluded that sepiolite has the best adsorption effect on uranium when the dosage of sepiolite is 1 g/L,the adsorption reaction time is 50 min,and the initial concentration of uranium is 30 mg/L.The adsorption capacity reaches the peak of 24.4mg/g,which also saves the cost of sepiolite.Moreover,in the subsequent studies,p H,ions and ion concentration in the solution all affect the adsorption of uranium by sepiolite.The quasi second order kinetic model can reflect the adsorption process of sepiolite to uranium better.Langmuir isotherm model can better reflect sepiolite adsorption process of uranium.(2)This paper also selects the contaminated soil of uranium mines as the research object,and uses sepiolite to assist in chemical leaching of uranium-bearing soil.The contaminated soil containing uranium was screened,and the content of uranium in different particle sizes was studied.The soil was repaired by stirring leaching method,and the leaching effect of leaching time,eluent pair,temperature,ultrasonic heating and the enrichment of uranium by sepiolite were discussed.The experimental results of chemical cleaning of uranium-bearing soil assisted by sepiolite showed that with the increase of soil particle size,the amount of uranium in the soil decreased gradually,that is,the amount of uranium in the soil was inversely proportional to the soil particle size.Besides,except for sand and gravel,the contents of other uranium exceeded the target restoration value of uranium by 40 mg/kg.When the leaching time is 8 h,the leaching is more sufficient,the leaching effect is the best and the cost is appropriate.By raising the temperature and ultrasonic assisted methods,not only the leaching effect can be significantly improved,but also the enrichment effect of sepiolite can be promoted very well.In the aspect of leaching,citric acid had the best effect,while hydrochloric acid had the worst effect.In terms of enrichment of uranium by sepiolite,sulfuric acid eluent has the highest enrichment ratio,and citric acid has the worst enrichment ratio. |
PDF Full Text Request