Adsorption Of Cs⁺ And Sr²⁺ In Simulated Radioactive Wastewater By MOFs And Their Composites

The development of nuclear power has been accompanied by the production of radioactive waste,which is one of the main components of radioactive waste.How to treat radioactive wastewater economically and effectively is a hot spot for scientists all over the world.In this paper,HKUST-1/KCoFC composites were prepared by coprecipitation method and hydrothermal method,UiO66-COOH?MOFs?materials were prepared by solvothermal method and used to adsorb Cs⁺and Sr²⁺in simulated radioactive wastewater.The main experimental work and conclusions of this paper are as follows:?1?The copper-based MOFs material?HKUST-1?was synthesized by hydrothermal method,and the HKUST-1/KCoFC composite was synthesized by vacuum precipitation.The structure of the sample was studied by means of SEM,XRD,FTIR and other analytical methods,and it was used to remove the cerium ions in the simulated radioactive wastewater.The results show that the initial cesium ion concentration is 200mg/L at room temperature,and the saturated adsorption capacity of Cs⁺is about 44.2mg/g when the amount of HKUST-1/KCoFC sample is 1g/L.At pH=8,the optimum adsorption capacity can reach 49 mg/g.In the presence of other cations in the solution,the adsorption effect of HKUST-1/KCoFC on Cs⁺is affected to varying degrees.When Na⁺and NH⁴⁺in solution together with strontium ions,the adsorption of cesium ions by the sample is inhibited,and the NH⁴⁺inhibition is more pronounced.The adsorption of Cs⁺by the composite conforms to the pseudo-second-order kinetic model.The adsorption of Cs⁺by HKUST-1/KCoFC sample is mainly chemical adsorption.The specific chemical change is that Cs⁺in the solution replaces the position of K⁺in some samples.The adsorption process of composites to Cs⁺is more suitable for the Langmuir model,which indicates that the HKUST-1/KCoFC composites are single-layer adsorption for the Cs⁺adsorption process,and the adsorbed ions have no interaction.?2?Zirconium-based MOFs?UiO66-COOH?was prepared by solvothermal method.The structure of the sample was studied by SEM,FTIR and other methods,and it was used to remove the strontium ions in the simulated radioactive wastewater.At room temperature,the adsorption of strontium ions by this sample can reach the adsorption equilibrium within 3 hours.At pH 8-12,the UiO66-COOH sample has a strong adsorption capacity for strontium ions,and at pH=8,the optimal adsorption amount is 49.3 mg/g.The adsorption kinetics and adsorption isotherms were used to treat the experimental results.It was found that the adsorption process of strontium ions by UiO66-COOH samples is more in line with the quasi-secondary kinetic model and the Langmuir isotherm model,which indicates the adsorption of ruthenium ions on UiO66-COOH samples.The process is a single layer of chemical adsorption.