Prediction of vapor-liquid phase equilibrium of nicotine+alcohol binary system based on COSMO-SAC model
The phase equilibrium of the nicotine system holds great significance in guiding the separation and purification of nicotine,as well as exploring the release laws of nicotine and active ingredients in heated cigarettes.The conductor-like screening model-segment activity coefficient(COSMO-SAC)enables the prediction of phase equilibria and other properties through quantum chemical calculations.In this study,the vapor-liquid phase equilibria of nicotine with binary systems consisting of mono-alcohols(methanol,ethanol,n-propanol,isopropanol,butanol,pentanol,hexanol,heptanol,octanol)and poly-alcohols(ethylene glycol,1,2-propanediol,1,3-propanediol,and glycerol)are predicted respectively using the COSMO-SAC model.The results show that alcohol molecules exhibit peaks in both the donor and acceptor regions of hydrogen bonds,whereas nicotine only exhibits a peak in the acceptor region.This suggests that nicotine can only act as a hydrogen bond acceptor to receive protons and form hydrogen bonds.The nicotine-alcohol binary systems are all positive deviation systems;specifically,the binary systems of mono-alcohols and nicotine exhibit general positive deviation systems and show a similar phase diagram profile,however,as the number of carbon chains of alcohols increases,the area of the gas-liquid coexistence region becomes smaller;the binary systems of poly-alcohols and nicotine exhibit the azeotropic phenomenon,which is a system with minimum azeotrope.As the temperature rises,the pressure and composition of the azeotrope increase accordingly.At 101.3 kPa,the temperature and composition of the azeotrope are 511.4 K and 0.261 for glycerol/nicotine,459.5 K and 0.857 for 1,2-propanediol/nicotine,483.0 K and 0.727 for 1,3-propanediol/nicotine,and 467.0 K and 0.889 for ethylene glycol/nicotine.These research results provide theoretical data to guide the purification and separation of nicotine and to understand the release law of nicotine.