Physical properties of potassium pyrophosphate and its use in osmotic evaporation
Abstract
This work determined the effect of concentration on the refractive index, electrical conductivity and water activity of potassium pyrophosphate (K4P2O7) aqueous solutions. These properties were evaluated at several solute mole fractions between 0.01 and 0.09 at constant temperature. Besides, we determined the density and viscosity of these solutions at temperatures between 283.15?K and 313.15?K, in 10?K increments and mole fractions of solute between 0.06 and 0.11. Some correlations of these physical properties of K4P2O7 solutions were developed that can be adopted with confidence due to their excellent adjustment to the data. Osmotic evaporation experiments were performed at the same conditions to compare the usage of K4P2O7, NaCl and CaCl2 as osmotic agents. The permeate flux obtained was 0.32, 0.86 and 0.84?kg?m?2?h?1 for NaCl, CaCl2 and K4P2O7, respectively, with no statistical significant difference between the results for K4P2O7 and CaCl2.