Preparation Of XCTS/ZX Composites And Its Adsorption Properties For Ru(?)

In recent years,radioactive pollution has aroused widespread concern in society.Ruthenium is one of the main pollutants in marine radioactive pollution.And because of its long half-life,high activity and water solubility,it will pose a threat to environmental safety and human health.Therefore,how to remove ruthenium ions from water efficiently has become the focus of research.Adsorption is considered as the most potential removal method because of its high efficiency,low cost and simple process.Therefore,the synthesis of highly efficient adsorbent materials is the most important in the field of radioactive wastewater treatment.The main purpose of this study is to develop a new type of adsorbent with good adsorption performance,strong anti-interference ability,good mechanical strength and chemical stability,low cost,especially for the radionuclide Ru³⁺with excellent selective adsorption performance.Considering the physical and chemical properties of chitosan and zeolite X and its practical application in adsorbing nuclides and other pollutants,XCTS/ZX composite microspheres and xanthan acidification modified crosslinked chitosan were prepared on the basis of chitosan.And the physical and chemical properties of the prepared materials were characterized by means of SEM-EDS,FTIR,XRD,BET and XPS.Static and dynamic adsorption experiments were designed to study the removal of Ru³⁺from seawater by the two materials,and the adsorption mechanism was discussed.The main research contents and results are as follows:1.Xanthic acid modified cross-linked chitosan powder adsorbent?XCTS?was prepared by two-step method.The factors influencing static adsorption of ruthenium ions?pH,dosage,temperature,reaction time,initial concentration,interference ions?by XCTS were discussed.The results showed that when the initial ruthenium concentration was 15 mg/L,the optimum conditions for ruthenium adsorption were pH 7,adsorbent dosage 0.5g/L,the removal rate reached 97.87%when the adsorption equilibrium time was 30 min.and it has a strong anti-jamming ability.When the initial concentration was 40 mg/L,the adsorption capacity of XCTS to Ru³⁺increased by 33.69 mg/g after modification.By fitting the adsorption data,it is found that the adsorption behavior of XCTS is more in line with the pseudo-second-order kinetic model?R²=1?and Langmuir model?R²=0.9758?.It shows that the adsorption of Ru³⁺by XCTS is spontaneous endothermic reaction and mainly chemical adsorption.2.The results showed that the surface of XCTS was uneven and aggregated,and the number of active adsorption sites increased.It had better surface characteristics of adsorbing Ru³⁺.XRD,FTIR and XPS showed that CS₂ was successfully used to modify cross-linked chitosan,and the adsorption capacity of modified chitosan for Ru³⁺was greatly improved.BET analysis showed that the specific surface area of CS₂was 0.7149 m/g,the pore volume was 2.654×10^-3 cm/g,and the pore diameter was226.223 nm.Comprehensive thermal analysis showed that XCTS powder had good thermal stability.3.The adsorption mechanism of Ru³⁺by XCTS was studied.The results of EDS and XPS characterization show that the surface complexation reaction of S-containing functional groups with Ru³⁺and ion exchange with Na⁺in XCTS are the main adsorption modes.4.XCTS/ZX composite microspheres were prepared with XCTS as the core,polyvinyl alcohol/calcium alginate mixture as the framework and X zeolite as the reinforcement.The effects of filler height,solution flow rate and initial concentration on the adsorption of ruthenium by XCTS/ZX composite microspheres were studied by designing dynamic adsorption column experiments.The results show that the adsorption regularity of composite microspheres is that the penetration time and exhaustion time of the adsorption column increases with the increase of the height of the packing,the decrease of the inlet velocity and the decrease of the initial concentration.Linear fitting analysis of dynamic experimental data using three models shows that Thomas and Yoon-Nelson models can predict the adsorption and penetration process of Ru³⁺to a certain extent,but Thomas model has better fitting effect?R²>0.9?.