From Screening to Scale-Up: The DoE-Based Optimization of Electrochemical Reduction of <scp>l</scp>-Cystine at Metal Cathodes
Johannes Seidler, Rebecca Bernhard, Stefan Haufe, Caroline Neff, Tobias Gärtner, Siegfried R. Waldvogel
Abstract
Design of experiment (DoE) is a powerful statistical tool in establishing improved chemical processes. An optimization and scale-up of the electrochemical reduction of l-cystine to l-cysteine is presented. Subsequent to an electrode screening of 17 metals and alloys in divided batch-type cells, the lead electrode was selected for a systematic optimization in flow cells with a geometric cathodic surface area ranging from 10 to 100 cm2. Using two consecutive factorial designs, parameters like substrate concentration, current density, electrode gap, amount of applied charge, and number of cell passages were screened for significant effects onto the l-cystine conversion. A multiresponse optimization combining the product conversion and Faradaic efficiency was performed to account for economic considerations.