Fluid Phase Equilibria, Vol.233, No.2, 230-233, 2005
Isopiestic determination of the osmotic and activity coefficients of dilute aqueous solutions of symmetrical and unsymmetrical quaternary ammonium bromides with a new isopiestic cell at 298.15 K
The osmotic coefficients of Bu4NBr, sec-Bu4NBr, iso-Bu4NBr, Bu2Et2NBr and Bu3EtNBr were determined by isopiestic method at 298.15 K in dilute aqueous solutions. A branched isopiestic cell was used. The osmotic coefficients of tetra-alkyl-ammonium solutions were analyzed comparing these with the Debye-Huckel limiting law. The order of the osmotic coefficient variation is (BuEt2N+)-Et-2 > BuEt3N+ > sec-Bu4N+ > iso-Bu4N+ > n-Bu4N+. The results were fitted to the Pitzer equation and the parameters beta(0) and beta(1) were calculated. The results are discussed. (c) 2005 Elsevier B.V. All rights reserved.
Keywords:activity coefficient;osmotic coefficient;unsymmetrical quaternary ammonium bromides;Pitzer model