Study On The Material Charactistics Of Red Mud And Its Inter-reaction Mechanism With Uranium(Ⅵ)

Uranium wastewater is toxic and radioactive drainage that would harm the public health,in this case,the study aims to explore the red mud,the by-product of Aluminum industry,as a potential adsorbent in the acid uranium wastewater treatment field.From the result of the physical and chemical analysis of red mud,it was known that red mud contained a high ratio of ferric,aluminum,and other metal components as well as high alkalinity,which have negative effect on the adsorption.Therefore,this study used nitric acid and metal nitrate reagents to modify red mud under the heating-bath condition.The U(VI)adsorption capability of red mud raised after modifying.In order to clarify how the interaction of the metal components in red mud would influence the adsorption capacity of red mud,the study synthesized some metal oxide aggregates to restructure and simulate the metals’ interaction mechanism.In addition,the study also established some immobilization-modified methods to optimize the adsorption capacity of modified red mud.In addition,SEM,XRD,and FTIR were utilized to analyze the characteristic of red mud and its modified adsorbents.From the results of uptaking the uranium from solution by raw red mud and modified red mud,the solid p H,surface area,pore distribution tendency and composition of adsorbent were studied.Raw red mud has very limited adsorption amount around 1.32 mg/g.Within the proper condition,DRM,FRM,and ARM could show their advanced adsorption capability under the low,middle and high uranium concentration range,which adsorption amount reach 1.24 mg/g,12.74 mg/g,and 32.92 mg/g,respectively.As the SEM and p H measure displayed,those materials would have mineral dissolved,and the modified process would transfer the surface of raw red mud into a snow-like structure which was benefited for ions adsorbing and mineral dissolving.Hence,the solution p H raised with the reaction time was extended.And,when the solution p H reached above 5.5,the calcium carbonate in red mud would influence the adsorption ability of modified red mud negatively.According to the modeling and single-factor experimental results of metal oxide aggregates,AOA material has a more stable treatment ability compared with FOA material when they contacted with the acid solution.Besides,AFOA material which Fe(III)/Al(III)ratio was 2:1,also has good stabilization capacity.As the modeling result of line pseudo-second-kinetics model showed,the calcium components would display its negative effect on the adsorption amount of AFSOA,especial when the Fe: Al rate of the oxide raises above 50:1.That is,AFSOA and AFSCOA material could show its saturation situation at 80 min and 120 min,and its saturation amount would be predicted as 42.5 mg/g and 18.10 mg/g,respectively.At the same time,the contrast experiment result showed that the added of manganese components would optimize the stability and adsorption ability of metal oxide aggregates.Manganese contained material(AFSMOA)can reach adsorption equilibrium at 60 min,and its adsorption amount is 29.04 mg/g.Two improvement methods were chosen for the immobilization experiment of the red mud.Depending on the analysis result,the surface area of immobilized red mud doubled.Meanwhile,C-RM-600 and Fe C-RM-600 exhibited excellent adsorption capacity,that is,the adsorption amount of C-RM-600 and Fe C-RM-600 could reach 48.85 mg/g and 59.45 mg/g,respectively,when the initial concentration of uranium was 250 mg/L.Although calcining red mud can effectively improve the adsorption capacity of red mud and inhibit the dissolution of red mud minerals within a short time(5 h),the immobilized red mud return instability when the contact time extended to 24 h.From adsorption behavior of the chelated immobilized red mud,it showed that the above adsorbents have stability and strong adsorption performance to U(VI)even when the contact time extended to 24 h,and contact temperant increased to 55 °C.When the reaction time was 60 min,the adsorption equilibrium of ET-RM and PT-RM could achieve 38.54 mg/g and 28.30 mg/g,respectively.According to the isothermal adsorption experiments of ET-RM series,when the ratio of chelation agent to red mud was 1:20,the ET-RM could reach the saturated adsorption amount of 46.64 mg/g.Through the study of red mud and its modified materials,this paper demonstrated the interaction effect of Fe,Al and Ca components in red mud by comparing the adsorption performance,adsorption behavior and surface characterization of those metal oxide aggregates.After that,the study formed a basic reaction mechanism between red mud and acidic uranium-containing wastewater.To sum up,red mud has the advantages of large adsorption amount,fast adsorbing and low cost,on the treatment of uranium-containing solution.By further investigate the mechanism between red mud adsorbents and uranium adsorbate,the study may provide a reliable theoretical basis for the effective treatment of uranium pollutants wastewater and comprehensive utilization of red mud.