Adsorption Characteristics Of U（Ⅵ） And Cd²⁺ In Waste Water By Fe（Ⅱ）-Al LDH

Uranium mining and metallurgy industry produce a large number of uranium containing radioactive wastewater,which potentially threats to the natural environment seriously. So the treatments of this kind of wastewater become a research hotspot. Among the heavy metal wastewater treatment method, the adsorption method is highly concerned because of its high efficiency and other advantages. Having a large specific surface area, thermal stability, and anion exchangeable, hydroxides is widely studied.Fe（Ⅱ）–Al layered double hydroxides（Fe（Ⅱ）–Al LDHs） were prepared by the ultrasound-assisted co-precipitation method and used for the adsorption of uranium（Ⅵ） from aqueous solution. The effects of initial p H, adsorbent dosage, temperature, adsorption time and initial U（Ⅵ） ions and Cd²⁺ concentration on adsorption of U（Ⅵ） and Cd²⁺ were investigated. The prepared composites were characterized by SEM, FTIR.The consequencesindicated that the maximum adsorption of Fe（Ⅱ）–Al LDHs occurred at p H of 6 and the adsorption reached equilibrium within 120 min. Meanwhile the removal rate is up to 98.08% for initial U（Ⅵ） concentration of 10 mg/L and adsorbent dosage of 1.0g/L at 25℃,and the maximum adsorption capacity for U（Ⅵ） ions reached 117.13mg/g. The experimental data fitted well with the Langmuir isotherm model and pseudo-second-order kinetic model（R2≈1）,Adsorption of U（Ⅵ） on Fe（ Ⅱ）-Al LDH is primarily due to spontaneous exothermic reaction. The results of SEM、FTIR and XPS showed that the structure of Fe（ Ⅱ）-Al LDH has no changed, chemisorption played a major role and regradation took subsidiary function.The experiment consequences of Cd²⁺ adsorption by Fe（Ⅱ）–Al LDHs indicated that the maximum adsorption occurred at p H of 7 and the adsorption reached equilibrium within 80 min. Meanwhile the removal rate is up to 98.3% for initial Cd²⁺ concentration of 10 mg/L and adsorbent dosage of 1.0g/L at 30℃,and the maximum adsorption capacity for Cd²⁺ ions reached 122.3mg/g. The experimental data fitted well with the Langmuir isotherm model and pseudo-second-order kinetic model（R2≈1）, Adsorption of Cd²⁺ on Fe（Ⅱ）-Al LDH is primarily due to spontaneous exothermic reaction. The results of SEM、FTIR showed that the structure of Fe（Ⅱ）-Al LDH has no changed, chemisorption played a major role in the adsorption and desorption experiments indicates Fe（Ⅱ）-Al LDH sorbent is reusable.