Study On Preparation Of N235 Impregnated Resins And Its Adsorption Characteristics For Vanadium

Solvent-impregnated resin combines the advantages of ion exchange and solvent extraction technology,and has the advantages of simple preparation,excellent selectivity,high utilization rate of the impregnated extractant and low environmental pollution,which is widely used for separation and recovery of metal ions.However,during the preparation and adsorption processes,there are problems such as long impregnation equilibrium time,low equilibrium adsorption amount,long adsorption equilibrium time,and low adsorption stability.Therefore,in this study,the effects of traditional method（constant temperature oscillation）,ultrasonic method,double extractant method and preparation conditions on the preparation process of N235impregnating resin and the adsorption of vanadium were investigated,and the optimal preparation conditions for the those preparation methods were obtained.The prepared N235 impregnating resin was characterized by scanning electron microscopy（SEM）and Fourier transform infrared spectroscopy（FTIR）.The promotion mechanism for preparation and adsorption performance of N235 impregnating resin prepared by the two new preparation methods was revealed.The adsorption and separation characteristics of vanadium and impurity ions in simulated acid leaching solution were studied by static adsorption test and dynamic column test.The main conclusions were listed as follows:（1）The optimum preparation conditions for N235 impregnating resin by the traditional method are as follows:N235 concentration 50%,impregnation time 240min;N235 impregnated resin prepared by traditional method（NIR-CI）has relative excellent adsorption performance for vanadium（V）at 25°C,pH=1.8,liquid-solid ratio 40:1 mL/g,V（V）concentration of 1350 mg/L,the adsorption equilibrium time for V（V）10 h,and the equilibrium adsorption amount reaches 46.5 mg/g.（2）The optimal preparation conditions for N235 impregnated resin by ultrasonic method are as follows:ultrasonic power 100 W,ultrasonic impregnation time 5 min,N235 concentration 40%;Under the same adsorption conditions,the adsorption equilibrium time of N235 impregnating resin prepared by ultrasonic method（NIR-UI）for V（V）is 14 h,and the equilibrium adsorption capacity is 49.4 mg/g.The acoustic cavitation of ultrasonic wave enhances the impregnation effect of the extractant in the resin pores,that is,improving the diffusion rate of extractant in the resin pores.Thus,the impregnation equilibrium time of the N235 impregnating resin is greatly shortened;SEM-EDS analysis imply that the extractant can enter the deeper pores of the resin under ultrasound irradiation,and distributes more uniformly,thereby enhancing the adsorption capacity and adsorption stability of N235 impregnated resin.（3）The optimum preparation conditions for N235-TBP impregnated resin by double extractant method are as follows:extractant ratio of 9:1,extractant concentration of 1.6 mol/L,impregnation time of 5 min;Under the same adsorption conditions,the adsorption equilibrium time of the N235-TBP impregnated resin（N-TIR）for V（V）is 6 h,and the equilibrium adsorption capacity is 50.9 mg/g;The addition of TBP can accelerate the impregnation rate of the extractant on the resin and greatly shorten the impregnation equilibrium time of N-TTIR,and the impregnation rate of N-TIR is improved.The FTIR analysis shows that N235 interacts with TBP during the impregnation process,thereby improving the extraction performance of the impregnated N235 for V（V）in the resin,that is,improving the equilibrium adsorption capacity of NIR for V（V）;SEM-EDS analysis shows that the addition of TBP increases the amount of extractant reacting with vanadium in N-TIR,and the extractant can enter the deeper pores of the resin during the impregnation process.Further,the adsorption stability of the N-TIR is improved.（4）The results of static adsorption test show that the adsorption capacity of N235 impregnated resin for V（V）increases with the increase of the initial V（V）concentration.Under the same adsorption conditions,the equilibrium adsorption capacity of those three impregnated resins for V（V）is ranked as:N-TIR>NIR-UI>NIR-CI;The adsorption process of those three impregnated resins for V（V）are more in line with the Freundlich isotherm adsorption model,and the Freundlich isotherm adsorption equilibrium constants of NIR-UI and N-TIR（n and K_F）are both higher than that of NIR-CI,indicating that vanadium is more easily adsorbed on the former two impregnatied resins,and the adsorption capacity of those two impregnating resins for V（V）are higher than the latter;The rate control step of NIR-CI and NIR-UI for V（V）adsorption process is the particle diffusion process,and the chemical reaction model has a higher goodness of fit（R²）for the adsorption process of N-TIR,indicating that the addition of TBP makes the rate control step of NIR-CI transform from particle diffusion to chemical reaction.（5）The column adsorption test of NIR-UI shows that the optimal adsorption conditions for adsorption of simulated acid leaching solution by NIR-UI are:pH=1.8,flow rate 1.0 mL/min,column height 12 cm;The optimum eluting conditions during the dynamic separation process are:12 Bed volume（BV）2 wt%Na2SO4;The optimum desorption conditions are:1 BV 14 wt%Na₂CO₃（circulating desorption）;The composition of the vanadium-rich liquid obtained after desorption are 4069 mg/LV（V）,9.19 mg/L Al（III）,17.16 mg/L Fe（III）,7.61 mg/L P（V）,1.80mg/L Si（IV）,indicating that V（V）can be effectively separated from impurity ions by NIR-UI in the simulate the acid leaching solution.