The Ostwald solubility coefficient, L of 17 volatile organic compounds (VOCs) from the gas phase into water and dilute aqueous ammonia solutions was determined by the equilibrium partitioning in closed system-solid phase micro extraction (EPICS-SPME) method at 303 K and at 0-2.5 mol dm-3 ammonia concentrations. Ammonia increased the solubility of all VOCs nearly linearly, but to a different extent. The difference in the solubility values in aqueous ammonia solutions (Lmix) compared to pure water (L) is explained on the basis of a Linear Solvation Energy Relationship (LSER) equation made applicable for solvent mixtures, logLmix-logL=x((s NH3-sH2O)π2H+(a NH3-aH2O)Σα2H+(b NH3-bH2O)Σβ2H+(v NH3-vH2O)Vx). sNH3-s H2O,aNH3-aH2O,bNH3-b H2O,vNH3-vH2O are the differences of solvent parameters, x is the mole fraction, π2H is the solute dipolarity-polarizability, Σα2H is the effective hydrogen bond acidity of the solute, Σβ2 H is the effective hydrogen bond basicity of the solute and V x, the McGowan characteristic volume. The most significant term was v, the phase hydrophobicity. The solubility behavior was explained by the change in structure of the aqueous solution: the presence of ammonia reduces the cavity effect. These findings show that the presence of compounds such as ammonia, frequently observed in environmental waters, especially wastewaters, affect the fugacity of VOCs, having consequences for the environmental partitioning of VOCs and having technical consequences towards wastewater treatment technologies.
- Aqueous ammonia
ASJC Scopus subject areas
- Environmental Engineering
- Environmental Chemistry
- Health, Toxicology and Mutagenesis