Determination and correlation of solubilities of lithium chloride and sodium chloride in NMP
In order to recover the additive lithium chloride in the polyphenylene sulfide production,the disolution of lithium chloride and sodium chloride in solvent N-methyl pyrrolidone(NMP) was studied.By using laser diffraction assistance method,solubility data of lithium chloride and sodium chloride in NMP were measured between 297.95 K and 364.75 K.Empirical formula,λh equation and improved NRTL equation were used to correlate the solubility data of lithium chloride in NMP.The results show that the solubility of lithium chloride increases with temperature while that of sodium chloride almost keeps unchanged.The improved NRTL equation can predict the solubility data well and the relative average error is 0.41%.Thus the K-NRTL equation is most suitable for description of solid-liquid equilibrium of lithium chloride in NMP at high temperature.