EXTRACTION EQUILIBRIA OF NICOTINIC ACID USING ALAMINE 300/DILUENT AND CONVENTIONAL SOLVENT SYSTEMS

摘要

Distribution of nicotinic acid between water and Alamine 300 (tri-n-octylamine) dissolved in various (proton-donating and -accepting, polar and non-polar) diluents, as well as a comparison with the extraction equilibria of pure diluent alone have been studied at 298 K and the phase ratio of 1:1 (v/v). Cyclic alcohol/amine system yields the highest synergistic extraction efficiency. The strength of the complex solvation was found to be reasonably high for halogenated aliphatic hydrocarbons and nitrobenzene, activating mainly the formation of acid_1-amine_1 structure. The influence of the acid structure over distribution has been evaluated through comparing the extractabilities of three acids containing different functional groups, i.e., nicotinic, benzoic and valeric acids. The results were correlated using various versions of the mass action law, i.e., a modified Langmuir equilibrium model and a chemical modeling (chemodel) approach comprising one or two acid-amine complex formation.