Preparation Of Amidoxime Modified X Zeolite And Its Adsorption Properties For Ru³⁺ And Cs⁺ In Simulated Seawater

Radioactivity pollution has aroused widespread concern in society since the leakage of the Fukushima nuclear power plant have caused a large number of radionuclides to enter the sea in 2011.Ru and Cs are common pollution elements in radioactive waste liquids.From the perspective of environmental protection,it is of great practical significance to effectively separate Ru and Cs in seawater.In this study,zeolite X was prepared by hydrothermal method.the hydrazine-amidoxime group was loaded on the zeolite X to prepare ammonium modified zeolite X,which zeolite X was used as the carrier and iminodiacetonitrile?IDAN?was the nitrile-based precursor.It was used to remove radioactive ¹⁰⁶Ru and ¹³⁷Cs in seawater and to study the adsorption mechanism.The main research content is as follows:?1?The optimal reaction conditions for the preparation of ammonium modified zeolite X is:the dosage of IDAN is 1.5 g/g?zeolite X?;the optimal dosage of hydroxylamine hydrochloride is 1 g/g?zeolite X?;the optimal reaction temperature is70°C.;the optimal reaction time is 1h.XRD?X-ray diffraction pattern?,FTIR?Fourier infrared spectroscopy?,SEM?scanning electron microscopy?,and XPS?X-ray photoelectron spectroscopy?characterization were performed on adsorbent.It can be seen from the XRD pattern that NaX type zeolite exists.It can be seen from the SEM image that there is a unique regular octahedral crystal structure of the zeolite X before and after the modification.Amamoxime group is loaded on the zeolite X.From the BET test,the specific surface area of the adsorbent was 298.071 m²/g and the pore volume was 0.071 cm³/g.?2?The effects of pH,time,dosage and Initial concentration on the adsorption of Ru³⁺and Cs⁺on amoxime modified zeolite X were discussed by single factor experiments.The results showed that the best pH for adsorbents to adsorb Ru³⁺and Cs⁺were 3 and 7 respectively.When the initial concentration of Ru³⁺and Cs⁺is 12.4mg/L and 10mg/L,the removal rate of Ru³⁺and Cs⁺in 30 min can reach more than 99%.The optimum dosage of adsorbents to adsorb Ru³⁺and Cs⁺are 0.1g/L and 0.2g/L,respectively.?3?The adsorption kinetics and adsorption isothermof Ru³⁺and Cs⁺which is adsorbed by amidoxime modified zeolite X was studied.The results show that pseudo two order kinetics has the higher correlation?R²>0.99?,It can be seen that the mechanism of adsorption of Ru³⁺and Cs⁺by amidoxime modified zeolite X is based on chemical adsorption.The correlation coefficient?R²=0.98,0.94?of the linear fitting of Langmuir model with two kinds of ion adsorption is better than the correlation coefficient?R²=0.88,0.91?of Freundlich model.The maximum adsorption capacity of adsorbent for Ru³⁺and Cs⁺is 175.4 mg/g and192.8 mg/g respectively.?4?The effects of several common interference ions?Na+,K+,Ca2+,Mg2+,Cl-,SO42-,etc.?in seawater on the adsorption of Ru³⁺and Cs⁺with amidoxime modified zeolite X were investigated.The results show that the effect of Cl^-on adsorption is negligible.Ca²⁺and Mg²⁺have a great influence on the adsorption of Ru³⁺and have little effect on the adsorption of Cs⁺.The effects of Na⁺and K⁺on the adsorption of Ru³⁺and Cs⁺are small,.SO₄^2-has a certain inhibitory effect on the both adsorption.?5?The amidoxime modified zeolite X spheres were prepared to study the dynamic tests for removing Ru³⁺and Cs⁺.The results show that the amidoxime modified zeolite X spheres reach the point of exhaustion at 8h and 14h,respectively.,when the pH of Ru³⁺and Cs⁺were 3 and 7,when the initial concentrations were 30 mg/L and 50 mg/L,respectively.?6?The adsorption mechanism of amidoxime modified zeolite X on Ru³⁺and Cs⁺was studied.The results showed that the group of the amidoxime modified zeolite X which is reacted with Ru³⁺was a amidoxime group.The disappeared NO bond was observed from the FTIR spectrum and the characteristic peak of amidoxime group was weakened in the XPS-N1s spectrum.The mechanism is that the hydroxyl group in the zeolite was broken,and the Ru³⁺in solution reacts with the exposed N atoms and is adsorbed by the adsorbent.The adsorption mechanism of amidoxime modified zeolite X on Cs⁺is mainly based on chemical adsorption,and the adsorption mode is mainly ion exchange.