| The unique physical and chemical properties of rubidium(Rb)and cesium(Cs)make their widely applications in many aspects,especially in the new energy and high-tech fields.There are abundant rubidium and cesium resources in salt lake and geothermal brine,and the exploitation and utilization of rubidium and cesium in brine will be an effective solution of present dilemma.In this thesis,we investigated the extraction methods for rubidium and cesium in geothermal brine and solar pond brine.The extraction of rubidium and cesium in geothermal brine by crown ether and ionic liquid system was firstly demonstrated after synthesis and identification for three kinds of crown ethers.Meanwhile,the extraction of rubidium and cesium in solar pond brine by t-BAMBP was also preliminary studied.Main conclusions presented in this thesis are summarized as follow.① Three crown ethers including 18-crown-6(DB18C6),24-crown-8(DB24C8)and 21-crown-7(DB21C7)were synthesized,and the synthesis parameters for the potential extractive reagent of DB21C7 were optimized.The productive rate of DB21C7 reached to 57.00%through 25 h reaction at 110℃.After purifying and identifying combines with melting point determination,fourier transform infrared spectrometry,H-nuclear magnetic resonance(1HNMR)and gas chromatography mass spectrometry(GC-MS),it indicated that pure target product was finally acquired.② The parameters for cesium extraction from geothermal brine by crown ether*and ionic liquid system were optimized.It is found that the single stage extraction rate of cesium was larger than 75%,while it was only about 30%for potassium under the optimum condition of 0.02 mol/L 21-crown-7 + 20%sulfonated kerosene + 80%1-butyl-3-methylimidazolium hexafluorophosphate at phase ratio O/A=1,extraction time t=5 min,and the original pH of brine,.However,the back extraction of cesium was quite difficult,and it cannot be effectively back extracted under all proper conditions.③ The parameters for rubidium and cesium extraction from solar pond brine by t-BAMBP + cosmetic grade white oil were optimized.It is found that the extraction rates of rubidium,cesium and potassium were 69.75%,97.48%and 15.79%,respectively,and the separation factor between rubidium、cesium and potassium respectively reached to 12.3 and 213.8 at 1 mol/L t-BAMBP,phase ratio O/A=2.5,and extraction time t=5 min.Based on the elution study of extract organic phase of solar pond brine,it is found that the elution rate of potassium was higher than 94%after four-stage elution with the elution condition of 0.1 mol/L NaOH,phase ratio O/A=3,and elution time t=5 min.However,only 40%rubidium can be back extracted no matter changing the acidity,phase ratio or extraction stage.Meanwhile,multistage back extraction had not obvious improved this situation.It is worthy of saying that some problems are still existed for the back extraction of rubidium and cesium after extracting by the two investigated extration systems although the extraction for rubidium and cesium in geothermal brine and solar pond brine with both extractive systems of 21-crown-7 + sulfonated kerosene + 1-butyl-3-methylimidazolium hexafluorophosphate and t-BAMBP + cosmetic grade white oil.Therefore,further studies are still needed. |
