Modelling of CCC/CPC Experiments and Running Modes
The main techniques used for CCC modeling are the Craig theory (CCD) and diffusion theory. Diffusion theory is commonly used to model other types of chromatography such as solid-liquid chromatography.
There is clearly a need for a model which is versatile enough to take into account the numerous operating modes and pump out procedures that can be used with counter-current chromatography (CCC). This paper will describe a universal model for counter-current chromatography based on counter-current distribution. The model is validated with real separations from the literature and against established CCC partition theory. This universal model is proven to give good results for isocratic flow modes, as well as for cocurrent CCC and dual flow CCC, and will likely also give good results for other modes such as intermittent CCC.
Figure: Output of the CCD Model
Chromatography models, liquid-liquid models and specifically Counter-Current Chromatography (CCC) models are usually either iterative, or provide a final solution for peak elution. This paper describes providing a better model by finding a more elemental solution. A completely new model has been developed based on simulating probabilistic units. This model has been labelled ProMISE: Probabilistic Model for Immiscible phase Separations and Extractions, and has been realised in the form of a computer application, interactively visualising the behaviour of the units in the CCC process. It does not use compartments or cells like in the Craig based models, nor is it based on diffusion theory. With this new model, all the CCC flow modes can be accurately predicted. The main advantage over the previously developed model, is that it does not require a somewhat arbitrary number of steps or theoretical plates, and instead uses an efficiency factor. Furthermore, since this model is not based on compartments or cells like the Craig model, and is therefore not limited to a compartment or cell nature, it allows for an even greater flexibility.
Figure: Screenshot of ProMISE Output (same in high res)
ProMISE: Download / Installation
Free for non-commercial purposes (after free registration).
Version 2: Download ProMISE2 here, download ProMISE2 user manual here
System requirements: Windows XP or higher
2. Dynamic modelling of coil planet centrifuges
2.1 Non-Synchronous Centrifuge Model
For the Non-Synchronous model, email email@example.com
2.2 g-level Calculations for All Coil Planet Centrifuges
Calculation of the g-level is often used to compare CCC centrifuges, either against each other or to allow for comparison with other centrifugal techniques. This study shows the limitations of calculating the g-level in the traditional way. Traditional g-level calculations produce a constant value which does not accurately reflect the dynamics of the coil planet centrifuge. This work has led to a new equation which can be used to determine the improved non-dimensional values. The new equations describe the fluctuating radial and tangential g-level associated with CCC centrifuges and the mean radial g-level value. The latter has been found to be significantly different than that determined by the traditional equation. This new equation will give a better understanding of forces experienced by sample components and allows for more accurate comparison between centrifuges. Although the new equation is far better than the traditional equation for comparing different types of centrifuges, other factors such as the mixing regime may need to be considered to improve the comparison further.
The programme to calculate the g-levels in coil planet centrifuges can be obtained from firstname.lastname@example.org
Figure: Screenshot of the g-level modelling application (same in high res)
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