Study of di-hydrogen (Na; K or NH4) orthophosphates in aqueous solutions at temperatures from 298.15 K to 353.15 K

In this investigation, the thermodynamic properties of aqueous solutions Na, K or NH4 dihydrogenphosphate were determined at various temperatures ranging from 298.15 K to 353.15 K. The measurements of water activity were performed in the molality range from dilution to saturation using the hygrometr...

Full description

Saved in:
Bibliographic Details
Published in:Fluid phase equilibria 2016-01, Vol.408, p.223-231
Main Authors: El Guendouzi, Mohamed, Benbiyi, Asmaa
Format: Article
Language:English
Subjects:
Aqueous solutions
Concentration (composition)
Di-hydrogenphosphate
Dilution
Dissolution
Hygrometric
Mathematical models
Osmotic and activity
Phosphates
Solubility
Thermodynamic properties
Water activity
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:In this investigation, the thermodynamic properties of aqueous solutions Na, K or NH4 dihydrogenphosphate were determined at various temperatures ranging from 298.15 K to 353.15 K. The measurements of water activity were performed in the molality range from dilution to saturation using the hygrometric method. The modeling approach based on the ion interaction model was developed to determine the thermodynamic properties. From these measurements of phosphate salts, mixing parameters in binary solutions were evaluated at various temperatures, without considering formation of aqueous complexes. The osmotic and activity coefficients were determined for these aqueous solutions of orthophosphate salts. The measurements of the binary systems were combined with reference pure water, NaH2PO4(s), KH2PO4(s) and (NH4)H2PO4(s) solubility data to construct a chemical model that calculates solute and solvent activities from dilute to saturated solution concentration from 298.15 to 353.15 K respectively up to mmax(NaH2PO4(s)) = 7.90–18.29 mol kg−1; mmax(KH2PO4(s)) = 1.83–5.10 mol kg−1; and mmax((NH4)H2PO4(s)) = 4.93–12.62 mol kg−1. The thermodynamic characteristics, solubility products Ksp° and the standard molar Gibbs energy of dissolution ΔGdiss° were also given. [Display omitted] •Water activities of dihydrogen (Na; K or NH4) orthophosphates of aqueous solutions were measured from 298.15 K to 353.15 K.•Osmotic and activity coefficients were also determined at various temperatures.•The ion interaction model was developed to calculate Ksp° and ΔGdiss°.•Short and long-range contributions were evaluated in the aqueous solution of orthophosphates.
ISSN:0378-3812
1879-0224
DOI:10.1016/j.fluid.2015.08.035