Sequential Centrifugal Partition Chromatography (sCPC) is a new process in the portfolio of continuous liquid separation processes. sCPC is a cyclic liquid-liquid chromatographic process performed in two adjacent columns. Its particularity is that the feed mixture is introduced continuously between the columns, whereas the two product streams are collected sequentially at the opposite ends of the columns, in each step of the cycle. The components are separated based on their different partitioning between the phases of the used biphasic liquid system. One reason for the lack of industrial applications of this process is the limited number of published data on experimental demonstrations of its advantages.
In this work, sCPC is used to fractionate a multicomponent mixture of compounds with similar molecular structure into two fractions. A quaternary mixture of parabens (methyl-, ethyl-, propyl- and butylparaben) was selected as model feed mixture. The fractionation of the quaternary mixture was regarded as a separation of a pseudo-binary mixture. The approach for designing a sCPC process to separate of binary mixtures [1-3] was extended and used to select the unit operating parameters.
Three fractionation tasks were performed: (i) methylparaben was separated from the rest of parabens, (ii) methyl- and ethylparaben were separated from propyl- and butylparaben, and (iii) butylparaben was separated from the rest of parabens. Even though the separation factors of the parabens were relatively low (ca. 1.6), all desired fractions were recovered with purities higher than 99.9%.
The presented results demonstrate the potential of sCPC technology for fractionations of multicomponent mixtures containing components that are difficult to separate.
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