Thermodynamics of liquid mixtures containing N-methyl-2- pyrrolidone.
Naicker, Pavanandan Kista.
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This thesis involves a study of the thermodynamics of liquid mixtures containing N-methyl-2pyrrolidone (NMP) and hydrocarbons or ethers. NMP is a polar liquid which is used in liquid extraction procedures for the separation of polar and nonpolar hydrocarbons. It was considered important enough to devote an entire thesis to the properties of NMP related to its interactions with simple hydrocarbons and ethers. The thesis consists of four parts: Part one is devoted to liquid-liquid equilibria. Experimental results at 298.2 K, are presented for the mixtures: NMP + an aromatic hydrocarbon + an n-alkane. Firstly, the effect increasing the chain length of the alkane has on the liquid-liquid equilibria was investigated, by studying mixtures of the type: an n-alkane + toluene + NMP; where the n-alkane refers to n-hexane or n-nonane or n-tetradecane or n-hexadecane. Secondly, the effect of substitution on the benzene ring on the equilibria was studied by measuring the liquid-liquid equilibria for the mixtures: n-hexadecane + an aromatic hydrocarbon + NMP; where the aromatic hydrocarbon refers to toluene or o-xylene or m-xylene or p-xylene or mesitylene or ethyl benzene. The chain length of the n-alkane had a significant effect on the liquid-liquid equilibria. Methyl substitution on the benzene ring had a small effect on the liquid-liquid equilibria. Part two is devoted to activity coefficients at infinite dilution. Experimental results at 298,15 K, determined using gas-liquid chromatography, are presented for the mixtures: NMP (solvent) + n-pentane or n-hexane or n-heptane or n-octane or cyclopentane or cyclohexane or cycloheptane or I-hexene or 1-heptene or l-octene or diethyl ether or diisopropyl ether. The magnitudes of the infinite dilution activity coefficients had the following order: n-alkanes > cycloalkanes > l-alkenes > ethers. Part three is devoted to excess molar enthalpies. Experimental results at 298.15 K are presented for the mixtures: NMP + an aromatic hydrocarbon. Here, an aromatic hydrocarbon refers to one of benzene or toluene or o-xylene or m-xylene or p-xylene or mesitylene or ethyl benzene. Isothermal flow microcalorimetry was used to determine the excess molar enthalpies. Increased methyl substitution on the' benzene ring manifests itself as a reduction in the association between NMP and the aromatic hydrocarbon. Part four is devoted to excess molar volumes. Experimental results at 298.15 K are presented for the mixtures: NMP + an aromatic hydrocarbon. Here, an aromatic hydrocarbon refers to one of benzene or toluene or o-xylene or m-xylene or p-xylene or mesitylene or ethyl benzene. Densitometry was used to determine the excess molar volumes. The excess molar volumes were negative for all the mixtures.