Separation Of Zirconium And Hafnium

The separation of zirconium and hafnium is a global problem, the traditional separation method is solvent extraction. The progress in solvent extraction and separation of zirconium and hafnium is reviewed. For that the solvent extraction makes environmental pollution and poor separation, so urgently need to develop environment-friendly separation method. This text is committed to research new methods of separation of zirconium and hafnium. The metal ion-imprinted technology is the rise of o new method of separation of metal ion in recent years, and that is reviewed. Preparation of zirconium ion-imprinted polymers separate zirconium and hafnium using the metal ion-imprinted technology, it has no pollution and low cost. Tributyl phosphate and N-phenylanthranilic acid as the complexing agent respectively, 4-vinylpyridine and styrene as functional monomer, divinylbenzene as crosslinking agent, zirconium ion-imprinted polymers (Zr-IIPsⅠand Zr-IIPsⅡ) is prepared by using bulk polymerization, and Zr-IIPsⅠand Zr-IIPsⅡare characterized by FT-IR, XRD. Study pH and adsorption time effect on the property of zirconium ion-imprinted polymers, and the optimal conditions are: pH=2.67, t=20min, Ci=1.0ppm, V=20mL, m=10g. The separation results of titanium, zirconium and hafnium are: Zr-IIPsⅠ:βTi/Zr =2.11,βHf/Zr =1.43; CPsⅠ:βTi/Zr = 1.58,βHf/Zr = 1.15; Zr-IIPsⅡ:βTi/Zr=1.05,βHf/Zr=1.03; CPsⅡ:βTi/Zr=1.01,βHf/Zr=0.96.In addition, zirconyl citrate and hafnyl citrate are prepared firstly, their chemical composition respectively are: [(ZrO)3(C6H5O7)2] and [(HfO)3(C6H5O7)2] through the elemental analysis. They are characterized by FT-IR, TG-DTG, XRD. The solubility of zirconyl citrate and hafnyl citrate are carried out at 30℃in water by static equilibrium method, 1.37×10-4 mol/L and 2.32×10-4 mol/L respectively. To get a better crystallinity of zirconyl citrate and hafnyl citrate, we use hydrothermal method, urea hydrolysis, gel method, crystalline form has improved, but not ideal.When prepared zirconyl citrate and hafnyl citrate, we find that zirconium and citric acid form white precipitation immediately, but hafnium form slowly. So we can use citric acid as precipitant to separate zirconium and hafnium by precipitation method. This article examines the molar ratio of zirconium or hafnium and citric acid, preicipitation time, the initial concentration of zirconium or hafnium effacting on precipitation rate. The best conditions for separation of zirconium and hafnium are: M/H3cit(M=Zr or Hf)=1.7, t=30min, CM=0.01mol/L, pH(M)=1.3. The separation coefficient of zirconium and hafnium is up to 9.3. We also study the precipitation kinetics of zirconium and citric acid.