Removal Of Cu(?),Ni(?),Eu(?)and U(?) From Aqueous Solutions Using Synthesized ?-Zeolite And Its Ethylenediamine Derivative

With the improvement of relevant laws and the growing interest of human health,water pollution has became one of the most serious environmental problems.To protect the environment and human health,harmful metal ions must be disposed before discharge into wastewater.In this manuscript,?-zeolite with high Si/Al ratio and large specific surface area was choosed as an adsorbent,the cheap ethylenediamine was choosed to modify ?-zeolite,and the other adsorbent was the product(EDA@?-zeolite).The effect of pH,contact time,solid-liquid ratio and temperature on adsorption behaviors of Cu(II),Ni(II),Eu(III)and U(VI)were studied by batch experiment under different experimental conditions.The results obtained in this manuscript provided basic experimental data for the efficient removal of harmful ions in wastewater.This manuscript was divided into seven parts.Chapter 1 introduced the research background,the topic significance and the research objective.Chapter 2 introduced the physicochemical properties of the two kinds of adsorbent.In chapter 3,chapter 4 and chapter 5,the adsorption behaviors of Cu(II),Ni(II)and U(VI)onto ?-zeolite and EDA@?-zeolite in aqueous solution were studied,respectively.Chapter 6 described the adsorption results of Eu(III)onto ?-zeolite in aqueous solution.Last,in chapter 7 the general conclusions and perspectives were summarized.The research contents and the main results of this manuscript are described below.(1)XRD,SEM,FT-IR,N2-BET and TGA were choosen to characterization the synthesized ?-zeolite and EDA@?-zeolite.The results showed that the original structure of ?-zeolite was retained after the modification of ethylenediamine,but the specific surface area was reduced from 385.9182 m/g to 135.0794 m/g.(2)The adsorption of Cu(II)onto ?-zeolite and EDA@?-zeolite were studied by batch technique.The adsorption of Cu(II)onto ?-zeolite and EDA@?-zeolite was significantly influenced by pH,at pH 4.0-7.0,the adsorption of Cu(II)was increased with pH increasing,and compared with ?-zeolite,the ethylenediamine modification of?-zeolite significantly improved the adsorption capacity of Cu(II).The adsorption processes of ?-zeolite and EDA@?-zeolite needed 16 h and 24 h to reach equilibrium respectively,the adsorption kinetics matched the pseudo-second-order kinetics model,and the adsorption was mainly affected by intraparticle diffusion.When the solid-liquid ratio between 0.05 and 1.25 g/L,improve the solid-liquid ratio was beneficial to the adsorption of Cu(II).Increasing the temperature from 298 K to 318 K,the adsorption of Cu(II)was promoted,and the results can be well described by the Langmuir model.The adsorption processes of Cu(II)were endothermic and spontaneous.(3)The adsorption of Ni(II)onto ?-zeolite and EDA@?-zeolite were studied by batch technique.The adsorption of Ni(II)was significantly dependent on pH values,when pH between 5.0 and 8.5,the adsorption of Ni(II)increased with the increasing of pH gradually,and compared with ?-zeolite,EDA@?-zeolite showed better adsorption capacity.The adsorption of Ni(II)onto ?-zeolite and EDA@?-zeolite needed 12 h and 16 h to reach equilibrium,respectively,the adsorption processes matched the pseudo-second-order kinetics model,and the intraparticle diffusion was the main factor that influence the adsorption rate.When the solid-liquid ratio was 0.05-1.50 g/L,the adsorption of Ni(II)increased with the increasing solid-liquid ratio.Improving the temperature was favorable to the adsorption of Ni(II)in the range of temperature 298 K-318 K.Langmuir isotherm model can be used to described the adsorption results.The thermodynamic study showed the adsorption were spontaneous and endothermic.(4)The adsorption of U(VI)onto ?-zeolite and EDA@?-zeolite were studied by batch technique.The adsorption of U(VI)onto ?-zeolite and EDA@?-zeolite was increased with the increasing of pH in the range of 3.5-5.5 gradually,but the adsorption of U(VI)decreased with the increasing of pH at pH 6.5-8.0.The adsorption of U(VI)onto ?-zeolite and EDA@?-zeolite can be described by pseudo-second-order kinetics model,the adsorption needed 16 h and 48 h to reach equilibrium respectively,and the adsorption processes can be divided into exterior surface adsorption,interior surface adsorption,and equilibrium stage.There was an increase in the removal percentage of U(VI)with an increase in the amount of ?-zeolite or EDA@?-zeolite.The higher temperature was helpful to the adsorption of U(VI)at 298 K-333 K,and U(VI)was adsorbed onto ?-zeolite and EDA@?-zeolite by monolayer layer.The adsorption of U(VI)onto ?-zeolite and ?-zeolite-EDA were endothermic and spontaneous.(5)The adsorption of Eu(III)onto ?-zeolite was studied by batch technique.At pH 4.0-7.0,the adsorption of Eu(III)was strongly dependent on pH and ionic strength,indicating that the adsorption was mainly dominated by outer-sphere complexation and ion exchange,at pH>7.0,the adsorption was controlled by inner-sphere complexes.The equilibrium time of adsorption of Eu(III)onto ?-zeolite was 12 h in experimental conditions,the experimental results can be well described using the pseudo-second-order model,and Weber-Morris equation can be used to describe the adsorption process indicated that the adsorption process involves multiple steps.Results obtained from this study show the presences of different electrolyte ions can enhance or inhibit the adsorption of Eu(III)onto ?-zeolite in various degrees.Higher temperatures were found favoring U(VI)retention on ?-zeolite when the temperature between 298 K and 318 K,Langmuir isotherm model can be used to described the experimental results.The adsorption process of Eu(III)onto ?-zeolite was endothermic and spontaneous.