Modular and Scalable Alluvial Cells for the Electroconversion of Poorly Soluble l -Cystine

A new cell design for the electrochemical reductive cleavage of l-cystine to l-cysteine has been presented. The so-called alluvial cell exploits the low solubility of l-cystine as a substrate by reducing a cystine suspension at a porous cathode, dissolving only small quantities of the substrate and separating the fully dissolved product by filtration. This setup avoids corrosive, highly concentrated acidic electrolyte systems, which is beneficial for the lifetime of the plant and improves the energy efficiency of the process. Additionally, several alloys were established as novel electrode materials suitable for the electroconversion of cystine. The alluvial cell achieved an almost quantitative yield of l-cysteine upon optimization and was scaled up to a small pilot range, highlighting its technical relevance.