Modeling vapour-liquid phase equilibrium for the aqueous solutions of formaldehyde and electrolyte

• Published in: The Journal of chemical thermodynamics 2020-11, Vol.150, p.106181, Article 106181
• Main Authors: Yin, Liuyi, Li, Yongbo, He, Yanlin, Jiao, Yongjuan, Chang, Ying, Song, Nizi
• Format: Article
• Language: English
• Subjects: Formaldehyde; Salt effect; Thermodynamic model; Vapor−liquid equilibria
• ISSN: 0021-9614; 1096-3626
• DOI: 10.1016/j.jct.2020.106181

•Modeling for the vapor-liquid equilibria in (HCHO–H2O–salt) system was developed.•Isobaric vapor-liquid equilibrium data for (HCHO–H2O–salt) system were measured.•New MR interaction parameters of the model were regressed.•Salts effect on the vapor-liquid equilibria in (HCHO–H2O–salt) system was uncovered. Modeling of vapor-liquid equilibrium for the aqueous solutions of formaldehyde and electrolyte is required for the extractive distillation of formaldehyde-containing multicomponent mixtures using salt as entrainers. Here a revised physicochemical model, which integrates the advantages of the physicochemical model for the vapor-liquid and the chemical equilibria in aqueous formaldehyde solution and the LIFAC model for the phase behavior in mixed-solvent electrolyte systems, has been proposed. The new vapor-liquid equilibrium data in (HCHO–H2O–salt) were systematically measured and utilized to determine newly-introduced model parameters. Comparisons of model calculated and experimental measured values proved that the model presented here provides a reliable method for correlating the vapor-liquid equilibria data in (HCHO–H2O–salt) system. Furthermore, the model established in this work was used to study salts effect on vapor-liquid equilibria. Both the model calculations and the VLE experiments uncover that Zn(NO3)2 is the most promising among all of the entrainers investigated.