Numbering-up Y-Y microfluidic chips for higher-throughput solvent extraction of platinum(IV) chloride

The application of microfluidic devices to industrial processing is relatively scarce due to the high volumetric throughputs that are generally required. One approach to increasing throughput is massive parallelisation ('numbering-up' or 'scale-out'), which involves the use of many microfluidic devices working in parallel to multiply the overall throughput. Numbering-up is attractive because it is modular and eliminates traditional 'scale-up' stages on the path towards full-scale processing. However, numbering-up presents other challenges, some of which are addressed here for liquid-liquid extraction using Y-Y chips. The theoretical limits were explored using the extraction of hexachloroplatinate(IV) ions as an industry-relevant system (extraction using a secondary amine). Experimental numbering-up from one channel to five, and then ten, in an extraction module is demonstrated, with extraction performance unchanged with increasing throughput. Calculations suggest that further numbering-up to at least a 1000-channel module could be facilitated by minor modifications to the present circuit.