Study On Preparation Of Magnesium Iron Hydrotalcite And Its Adsorption Properties For Uranium In Wastewater

Uranium-containing wastewater produced in the process of uranium mining,it will harm the ecological environment around the mine and human health.Hydrotalcite?LDHs?materials are widely used in the field of environmental pollution control due to their excellent layered structure,inter-layer anion exchangeability and metal laminate controllability.In this paper,magnesia-iron hydrotalcite?Mg-Fe LDH?was prepared by hydrothermal synthesis.The microstructure and phase composition of the material were characterized by SEM,TEM and XRD,the adsorption properties and mechanism of Mg-Fe LDH for uranium were studied,the effects of preparation conditions and different influencing factors on the adsorption properties of Mg-Fe LDH for uranium were discussed The main knowledge is as follows:?1?The results of SEM,TEM,EDS and XRD characterization show that the Mg-Fe LDH materials have typical layered structure,the size of the wafer is about 20 nm,and the crystal phase structure is uniform and complete.By means of FT-IR and XPS techniques,it was found that Mg-Fe LDH contained Mg-O metal oxygen-containing bonds and non-metallic oxygen-containing functional groups such as interlayer–OH and CO₃^2-,which provided a large number of active sites for uranyl ion adsorption in uranium-containing wastewater.The adsorption performance of uranium in Mg-Fe LDH is better than that Fe?OH?3 and Mg?OH?2,under the conditions of Mg/Fe molar ratio of 3:1,pH=12,temperature of 150?and preparation time of 2 h,the removal rate of 5mg/L uranium solution by Mg-Fe LDH was up to 98.89%.?2?The effects of Mg/Fe molar ratio,pH,temperature and reaction time on the adsorption properties of Mg-Fe LDH materials were studied,the results showed that the Mg/Fe molar ratio had the greatest effect on the adsorption properties of Mg-Fe LDH materials.Under the optimum conditions of Mg/Fe molar ratio of 4:1,pH is 12.0,temperature of 180?and reaction time of 3 h,the actual saturated adsorption capacity of uranium on the Mg-Fe LDH material reached 710 mg/g.The uranium adsorption performance of Mg-Fe LDH is better than that of hydrotalcite materials reported in related literatures.?3?The effects of the pH,the dosage of Mg-Fe LDH and the initial concentration of uranium on the removal rate of uranium were studied.The results showed that when the initial concentration of uranium was 50 mg/L,pH is 5.0,and the dosage of Mg-Fe-LDH was 0.3 g/L,the removal rate of uranium was up to 95.01%after 2 h adsorption.The adsorption process was in accordance with Langmuir model and pseudo-second-order kinetic model,which indicated that the adsorption was a monolayer chemisorption process.?4?The effect of Mg-Fe LDH on the treatment of uranium-containing wastewater from uranium mines was studied.The results showed that when the concentration of uranium was 2.799 mg/L,pH is 5.0,and the dosage of Mg-Fe LDH was 0.3 g/L,the removal rate of uranium reached 98.28%after 15 min adsorption.The low adsorption efficiency of Ca²⁺,Al³⁺,Mg²⁺and Fe³⁺in uranium-containing wastewater indicates that Mg-Fe LDH has selective adsorption characteristics for U???in wastewater.The removal efficiency of uranium was 82.14%after sodium carbonate was used as elution agent and reused for five times,which indicated that Mg-Fe LDH material had good adsorption stability.It can be concluded that the research results can provide theoretical and technical references for efficient green treatment of uranium-containing wastewater.