The Adsorption Of Uranium Reconstructed By Amide-Based Non-Ionic Surfactants On Two-Dimensional Transition Metal Dichalcogenides

In this paper,molybdenum disulfide（MoS₂）was prepared by molten salt electrolysis,while tungsten disulfide（WS₂）and molybdenum diselenide（MoSe₂）were prepared by ultrasonic stripping,respectively.The non-ionic surfactant N,N-Dimethyl-9-decenamide（NNA）was added to reconstruct the adsorption behavior of uranyl ions on the adsorbent surface.The systems of NNA/MoS₂,NNA/WS₂and NNA/MoSe₂were prepared by a simple co-blending method and used to adsorb uranyl ions from aqueous solution.The microstructure and physicochemical properties of the materials were analyzed by Scanning Electron Microscopy and X-ray Energy Spectroscopy（SEM-EDS）,Fourier Transform Infrared Spectroscopy（FT-IR）,X-ray Diffraction（XRD）,X-ray Photoelectron Spectroscopy（XPS）,Contact angle and Zeta potential.MoS₂,WS₂and MoSe₂are layered structures,and NNA covered on the surface of the adsorbents without destroying the morphological structure of them.NNA reduces the static contact angle of MoS₂,WS₂and MoSe₂,increases the surface negative charge,improves the hydrophilicity and dispersion stability of the adsorbents,and makes it easier to bind uranyl ions.The analysis results showed that UO₂²⁺mainly interacted with S atoms,Se atoms and the hydrophilic group of NNA.The effects of the content of surfactant,p H,contact time,initial uranium concentration,temperature,coexisting metal ions and irradiation intensity on the adsorption of uranium by NNA/MoS₂,NNA/WS₂and NNA/MoSe₂were systematically investigated.The properties and mechanism of uranium adsorption by NNA/MoS₂,NNA/WS₂and NNA/MoSe₂were studied by adsorption kinetics model,isothermal adsorption model and thermodynamic model.The adsorption performance of NNA/MoS₂,NNA/WS₂and NNA/MoSe₂for uranium was influenced by p H,the types and amount of surfactant.The kinetic fitting results indicated that the uranium adsorption by NNA/MoS₂,NNA/WS₂and NNA/MoSe₂was dominated by chemisorption,and the fast adsorption rate made them reach the adsorption equilibrium within a short time;the results of the adsorption isotherm model showed that the processes of uranium adsorption by NNA/MoS_2,NNA/WS₂and NNA/MoSe₂conformed to the Langmuir adsorption isotherm model,and the maximum adsorption capacities were 551.84 mg/g,180.27 mg/g and150.86 mg/g,respectively.The adsorption processes of MoS₂,WS₂and MoSe₂changed from spontaneous endothermic to spontaneous exothermic processes,and the order degree of the adsorption reaction process increased after adding NNA.The results prove that NNA/MoS₂,NNA/WS₂and NNA/MoSe₂can be potentially used in emergency treatment of radionuclide leakage with irradiation stability,adsorption selectivity for U（VI）,fast adsorption rate and high adsorption capacity.