The relative basicity of trioctylamine (TOA), pKa,BS, in protic polar diluent (1-octanol), non-protic polar diluent [methyl iso-butyl ketone (MIBK)] and inert diluent (CCl4) were determined for 11 mono-carboxy...The relative basicity of trioctylamine (TOA), pKa,BS, in protic polar diluent (1-octanol), non-protic polar diluent [methyl iso-butyl ketone (MIBK)] and inert diluent (CCl4) were determined for 11 mono-carboxylic acids, and the dependence of PKa,BS on the nature of solute and diluent type was discussed. The results show that pKa,BS determined by half neutralization with the solute carboxylic acid is in the order of 1-octanol〉MIBK〉CCl4 for a fixed TOA concentration, and it increases with increasing acidity and hydrophobicity of the carboxylic acid. Compared with two parameters of the solute extracted (acidity and hydrophobicity), pKa,BS is more sensitive to hydrophobicity of the acid. A mathematic equation representing relationship between the apparent extraction equilibrium (K11) and the system properties (PKa,BS and pKa) was proposed: 1g K11 = 2pKa,BS=pKa. It is proved that the extraction equilibrium of mono-carboxylic acids can be predicted by the above equation with reasonable accuracy.展开更多
Tertiary amines dissolved in diluents are attractive extractants for recovery of carboxylic acids from dilute aqueous solutions. Quantitative Fourier transform infrared (FTIR) analysis of organic solutions containin...Tertiary amines dissolved in diluents are attractive extractants for recovery of carboxylic acids from dilute aqueous solutions. Quantitative Fourier transform infrared (FTIR) analysis of organic solutions containing various concentrations of trioctylamine (TOA), n octanol, and propionic acid was carried out, and liquid liquid equilibrium was investigated using TOA in n octanol as the solvent. The fraction of ion pair association between TOA and propionic acid in the organic phase was quantitatively determined by FTIR. The apparent reactive extraction equilibrium constant, K 11 , was calculated using the quantitative FTIR spectrum and the equilibrium data. The results show that the fraction of ion pair association depends on diluent concentration, complex dissolution for propionic acid, and association between TOA and propionic acid. The K 11 based on quantitative FTIR has the same loading trend as that from the equilibrium data.展开更多
基金Supported by the National Natural Science Foundation of China (No. 29836130).
文摘The relative basicity of trioctylamine (TOA), pKa,BS, in protic polar diluent (1-octanol), non-protic polar diluent [methyl iso-butyl ketone (MIBK)] and inert diluent (CCl4) were determined for 11 mono-carboxylic acids, and the dependence of PKa,BS on the nature of solute and diluent type was discussed. The results show that pKa,BS determined by half neutralization with the solute carboxylic acid is in the order of 1-octanol〉MIBK〉CCl4 for a fixed TOA concentration, and it increases with increasing acidity and hydrophobicity of the carboxylic acid. Compared with two parameters of the solute extracted (acidity and hydrophobicity), pKa,BS is more sensitive to hydrophobicity of the acid. A mathematic equation representing relationship between the apparent extraction equilibrium (K11) and the system properties (PKa,BS and pKa) was proposed: 1g K11 = 2pKa,BS=pKa. It is proved that the extraction equilibrium of mono-carboxylic acids can be predicted by the above equation with reasonable accuracy.
基金the National Natural Science Foundationof China(No. 2 9836 130 )
文摘Tertiary amines dissolved in diluents are attractive extractants for recovery of carboxylic acids from dilute aqueous solutions. Quantitative Fourier transform infrared (FTIR) analysis of organic solutions containing various concentrations of trioctylamine (TOA), n octanol, and propionic acid was carried out, and liquid liquid equilibrium was investigated using TOA in n octanol as the solvent. The fraction of ion pair association between TOA and propionic acid in the organic phase was quantitatively determined by FTIR. The apparent reactive extraction equilibrium constant, K 11 , was calculated using the quantitative FTIR spectrum and the equilibrium data. The results show that the fraction of ion pair association depends on diluent concentration, complex dissolution for propionic acid, and association between TOA and propionic acid. The K 11 based on quantitative FTIR has the same loading trend as that from the equilibrium data.