Aqueous solutions of propylene glycol, glycerol and glycerol-salt mixtures are investigated as alternative to Calcium Chloride, normally employed to concentrate aqueous mixtures by osmotic distillation. These extractants can overcome the problems of corrosion and scaling associated with the use of brines. The proposed extractants are compared in terms of driving force available for mass transfer, flux achievable, viscosity, penetration pressure through the membrane pores, solvent entrainment. The water activities of the relevant solutions are calculated by predictive methods and, in the case of glycerol-salt mixtures, measured by an isopiestic technique. Propylene glycol and Glycerol solutions exhibit similar extractive power; the concentration has to be limited to 70-75 wt% in order to limit the viscosity, as a consequence these compounds are a bit less effective than highly concentrated CaCl2 solutions. Notwithstanding the good flux achievable, propylene glycol cannot be recommended as extractant for juice concentration, indeed, owing to the not negligible volatility, it diffuses toward the juice in considerable amount, in addition the penetration pressure through the membrane pores is quite small. The ternary mixture glycerol-salt-water allows to obtain the same flux achievable with glycerol alone, but with a substantially lower viscosity.

Osmotic distillation with propylene glycol, glycerol and glycerol-salt mixtures / M. CELERE; GOSTOLI C.. - In: JOURNAL OF MEMBRANE SCIENCE. - ISSN 0376-7388. - STAMPA. - 229:(2004), pp. 159-170. [10.1016/j.memsci.2003.10.025]

Osmotic distillation with propylene glycol, glycerol and glycerol-salt mixtures

GOSTOLI, CARLO
2004

Abstract

Aqueous solutions of propylene glycol, glycerol and glycerol-salt mixtures are investigated as alternative to Calcium Chloride, normally employed to concentrate aqueous mixtures by osmotic distillation. These extractants can overcome the problems of corrosion and scaling associated with the use of brines. The proposed extractants are compared in terms of driving force available for mass transfer, flux achievable, viscosity, penetration pressure through the membrane pores, solvent entrainment. The water activities of the relevant solutions are calculated by predictive methods and, in the case of glycerol-salt mixtures, measured by an isopiestic technique. Propylene glycol and Glycerol solutions exhibit similar extractive power; the concentration has to be limited to 70-75 wt% in order to limit the viscosity, as a consequence these compounds are a bit less effective than highly concentrated CaCl2 solutions. Notwithstanding the good flux achievable, propylene glycol cannot be recommended as extractant for juice concentration, indeed, owing to the not negligible volatility, it diffuses toward the juice in considerable amount, in addition the penetration pressure through the membrane pores is quite small. The ternary mixture glycerol-salt-water allows to obtain the same flux achievable with glycerol alone, but with a substantially lower viscosity.
2004
Osmotic distillation with propylene glycol, glycerol and glycerol-salt mixtures / M. CELERE; GOSTOLI C.. - In: JOURNAL OF MEMBRANE SCIENCE. - ISSN 0376-7388. - STAMPA. - 229:(2004), pp. 159-170. [10.1016/j.memsci.2003.10.025]
M. CELERE; GOSTOLI C.
File in questo prodotto:
Eventuali allegati, non sono esposti

I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.

Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11585/1663
 Attenzione

Attenzione! I dati visualizzati non sono stati sottoposti a validazione da parte dell'ateneo

Citazioni
  • ???jsp.display-item.citation.pmc??? ND
  • Scopus 23
  • ???jsp.display-item.citation.isi??? 20
social impact