25 ℃ NaCl-Na2SO4-C2H5OH-H2O体系相平衡及应用研究

Phase Equilibrium and Application of NaCl-Na2SO4 -C2H5OH-H2O System at 25 ℃

中文关键词:  乙醇  混合溶剂  溶析结晶法  等温溶解平衡

英文关键词:Ethanol  Mixedsolvent  Solutioncrystallization  Isothermalsolutionequilibrium

中文摘要:

      溶析结晶法是无机盐分离纯化的重要方法之一。通过等温溶解平衡法测定了两个三元体系 NaCl-CH3CH2OH-H2O，Na2SO4-CH3CH2OH-H2O和一个四元体系 NaCl-Na2SO4-CH3CH2OH-H2O的部分溶解度数据，并根据溶解度数据绘制了相图。通过对实验数据的分析得出以下结论: 1)随着乙醇含量的增加硫酸钠和氯化钠的单盐含量均下降。 2)随着乙醇含量的增加硫酸钠和氯化钠共饱和溶液中两盐的含量均下降，但是趋势有所不同，氯化钠的下降趋势较缓和，而硫酸钠一开始下降速度比较快之后趋于平缓。 3)乙醇含量为 10%时硫酸钠和氯化钠的溶解度差值最大，大于纯水中两盐溶解度差值，这为溶析结晶法分离氯化钠和硫酸钠奠定了理论基础。 4)设计了溶析结晶法分步分离盐硝的路线，并用相图进行了分析计算，结果表明硫酸钠和氯化钠的一次循环收率分别为 68.68%、66.61%。

英文摘要:

      Salt lake brine in China is rich in inorganic salt resources. Dissolution crystallization is one of the importantmethodsto separatesodium sulfate and sodium chloride from brine.In thispaper，the solubil-ity data of two ternary systems NaCl-CH3CH2OH-H2O，Na2SO4-CH3CH2OH-H2O and a quaternary system NaCl-Na2SO4-CH3CH2OH-H2Owere determinedbyisothermal solution equilibrium method，andphase dia-grams have been drawn based on the solubilitydata.Through the analysis of experimentaldata，the follow-ing conclusions were obtained:1)The solubility of sodium sulfate and sodium chloride decreased with the increase of ethanol content.2)Withthe increase of ethanolcontent，the solubility of sodium sulfate and so-dium chloride in the co-saturated solution both decreased，but the trends were different. The decline trend of sodium chloride was moderate，while the decline rate of sodium sulfate was relatively fast at the begin-ningandthentendedtobegentle.3)Whentheethanolcontentis10%，thesolubilitydifferencebetweenso-dium sulfate and sodium chloride is the largest，which is greater than the solubility difference between the two salts in pure water，which lays a theoretical foundation for the separation of sodium chloride and so-dium sulfate by solution crystallization. 4)The method of solution-crystallization for the separation of salt and nitrate was designed. The results of Phase diagram analysis and calculation showed that the primary cycleyieldsofsodiumsulfateandsodiumchloridewere68.68%and66.61%，respectively.