(24a) Development Of A Universal Solvent Selection Methodology For In-Situ Extraction

At TNO a Pseudomonas Putida S12 strain was developed which produces phenol from glucose as a carbon source[1]. However, this strain was severely hindered by product inhibition. To alleviate product inhibition from fermentation broths the product must be removed from the environment of the micro-organism. One way of achieving product removal is in-situ extraction. In this project so-called solvent impregnated resins (SIRs) are developed which are able to selectively remove phenol from fermentation broths. An extractant is impregnated in a carrier polymer which separates the solvent from the fermentation broth. These SIRs are then applied inside the fermentor to remove the product from the fermentation broth into the extractant phase of the particle. This new application of SIRs puts extra constraints on the solvent selection, requiring a novel approach. The selection of an extractant for a certain product should include parameters for fermentation biocompatibility, product separation and extractant regeneration. Toxicity, melting/boiling point, biodegradability, logPo/w, solubility, charge, and hydrogen bond acceptor/donor ability [2] are therefore important factors to take into account for both the product and extractant. We have constructed a database including more than 180 extractants which are a wide range of alcohols, amines, phosphates, aromatics, alkanes, alkenes, thiols, aldehydes and other extractant families. A two-step approach is employed that includes a decision model to obtain a short-list of extractants and an experimental part that consists of measuring and predicting phenol partition coefficients. A quick first selection out of all possible extractants can be made using a 2-step model. For making a final decision between several extractants we use an automated solvent screening system which is able to measure partition coefficients of aromatics over any two-phase system. Using the combination of known physical properties, molecular interaction predictions and measured data an optimal solvent choice can be made. This solvent selection methodology will be developed towards all other uncharged solutes. Results for the model compound phenol will be presented.

1. Wierckx N.J.P., et al., Engineering of solvent-tolerant Pseudomonas Putida S12 for bioproduction of phenol from glucose. Applied and environmental microbiology, 2005. 71(12): p. 8221-8227. 2. Abraham M.H. and Platts J.A., Hydrogen bond structural group constants. Journal of organic chemistry, 2001. 66: p. 3484-3491.