The study of novel aspects of solution

• Main Author: Summers, D. M.
• Published: Swansea University 1979
• Subjects: 541
• Online Access: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.639135

The work presented in this thesis deals with the liquid chromatographic (CLC) measurement of the liquid/gas partition coefficients (KKR) and specific retention volumes (V°) of a number of solutes, of varying chemical types, with each of three binary solvent mixtures. The objective of this study was to attempt to establish further evidence in favour of the Microscopic Partition (MP) model of solution behaviour, proposed by Purnell and Laub. This model is based on the observation, of Purnell and Vargas de Andrade, that the relationship between KR and volume fraction (b), for a mixture of two solvents is strictly linear. The solvent systems studied, together with the solutes used, were as follows: (1) tri-n-butyl phosphate/ethylene glycol (at 21°C) (2) ethyl benzoate/propyleno glycol (at 30°C). For both these systems, Kp~ values were calculated for each of the following solutes: Furan, diethyl ether snd methyl formate. (3) octadecanol/octadecylamine (at 60°C, 70°C and 80°C) Vo values were calculated for the following solutes: n-pentane, n-hexane, n-heptane, furan, gthiopbene, chloroform, di-chloromethane, ethyl acetate, diisopropyl ether and propanol. Solvent systems (1) and (2) were studied, in particular, in order to provide a test for the proposed MP model of solution behaviour. As there remained a remote possibility that all the binary systems dealt with previously were ideal, the present work was also aimed at the elimination of the above objection, as well as testing the overall generality of the basic equation. The two systems presented in this section of the work involved partially miscible binary solvent mixtures, since, not only would such a liquid pair be highly non-ideal but, in addition, would fit closely to the proposed model of solutions. This is because, while over some composition range the system will be single phased, over some other range it will definitely be two phased and highly aggregated. In both oases, columns were studied spanning the whole composition range i.e. b = 0-i 1. For each of the partially miscible pairs, it was found that, within the limit of reasonable experimental error, the data obtained obeyed the basic equation of Purnell et al, and hence must be taken as strong evidence in support of the proposed MP model of solution behaviour. (2)system (3) was studied in order to compare the results obtained for a solvent pair in which a specific interaction might be expected to occur with those of the two previously mentioned solvent pairs. For this supposed interacting solvent system there was found to be some curvature, at the pure ootadeoanol end of the composition range.