The Influence Of Adsorption And Migration Of Uranium By The Suspended Solids And Colloids From The Alar River

As a radioactive element,uranium?U?is the basic raw material for the development of China's nuclear industry,which is of great significance to national security and sustainable development of national economy.However,due to its high radioactivity,toxicity and long half-life period,U poses a serious threat to human survival and ecological security.Therefore,it is necessary to study the migration and enrichment mechanism of uranium in nature.Among them,the adsorption of uranium by suspended solids and colloids in rivers is particularly important.Gaskule Salt Lake is located in the west part of Qaidam Basin,and the U content in the lake is much higher than the average value of seawater and other saline lakes.It has great research value.In the mean time,the Alar River is both the main freshwater recharge source and important gate of U into the salt lake.Therefore,the research results of this paper are helpful to enrich and develop the theory of U migration and enrichment.It is of great significance for the rational exploitation,prevention and control of pollution of U resources in brine of salt lakes in arid areas.In this paper,the effects of reaction time,solution pH value,temperature,initial concentration of uranium,solid-liquid ratio and Zeta potential on the adsorption of U by suspended solids and colloids from the Alar River were studied by static adsorption method.Finally,combined with the physicochemical properties of suspended matters,colloids and spectroscopic means,following results have been achieved through implementation from various adsorption models into deep mechanism study.1.The physicochemical properties of suspended solids in the Alar River are analyzed by various characterization methods.BET analysis results show that the surface area of suspended solids decreases with little change due to the internal diffusion of adsorption reaction.XRF results indicate that the suspended solids have more Aluminium,iron hydrate oxides and a small amount of manganese oxides and organic matter.It has strong adsorption capacity for U.XRD and FTIR results show that the main adsorption mechanism of U by suspended solids is surface complex adsorption.In the adsorption process.U mainly chelates with the surface-active groups of suspended matters to form complexes.Active groups such as associative hydroxyl,carboxyl,carbonyl and Si-OH play a leading role.2.Reaction time,temperature,solution pH value,solid-liquid ratio,initial concentration of U and coexistence of anions and cations effect on the adsorption of U by suspended solids.The adsorption equilibrium reaches balance after 16 hours;the solution pH effect greatly on the adsorption of U by suspended solids;when pH=5⁷,the adsorption capacity performs the best;the maximum adsorption rate is 95.48%;increasing temperature is beneficial to U adsorption;with increase of initial U concentration C₀,the adsorption capacity floats while the adsorption rate falls.3.Quasi-second-order kinetic model can better describe the kinetic process of U adsorption on suspended solids.It indicates that the adsorption is not controlled by external diffusion,surface adsorption and internal diffusion rather than a single step.The adsorption is more in line with Langmuir isothermal adsorption model,which shows that the adsorption of U by suspended solids is a spontaneous endothermic process.As monolayer adsorption process,surface complexation adsorption is in a dominant position.4.In this paper,the author uses tangential flow ultrafiltration filter to extract apparatus from river water in Alar colloid to carry out static adsorption experiments of uranium.In the meantime,through determination of Zeta potential?stability?of colloids,pH is the most important factor affecting the adsorption of uranium,which is mainly related to the change of colloidal stability under different pH conditions.5.The content of humic acid in suspension was 0.517%by potassium dichromate titration.According to the static adsorption of uranium by humic acid under different conditions,the adsorption of uranium by humic acid is in accordance with that by suspended solids,which promotes the adsorption of uranium by suspended solids.