Optimization of ionic liquid recycling in Ionic Liquid-based Three Phase Partitioning processes

Abstract

The economic viability of Ionic Liquid-based Three Phase Partitioning (ILTPP) processes, which have been proposed to recover proteins from waste streams, highly depends on the recyclability of the salt and, especially, the ionic liquid used in this technique. For this reason, the economic optimization of the recovery of ILTPP reagents is carried out, considering the main operational costs (reagents and energy). Results show that the process configuration with which costs are minimized is based on the use of vacuum evaporation to remove water from the salt-rich phase of the process. Therefore, the increase of salt concentration is not an economically efficient alternative to recycle the ionic liquid, even though this alternative is usually proposed in the literature. The optimum costs vary between 51.5 – 307 € kg protein−1 for almost all protein concentrations in the feed stream, which are significantly lower than the lowest price reported for the target protein (lactoferrin), so ILTPP processes seem to be economically viable. In addition, the price of reagents and energy has very little influence on the optimum solutions, because very large changes of prices are required to modify the obtained results.