Selective lithium recovery from simulated shale gas produced water using an ionic liquid extraction system

Abstract

Hydraulic fracturing to extract shale gas generates produced water containing high concentrations of lithium, along with interfering divalent ions and organic matter which originate from both the reservoir and the fracturing fluid. To selectively recover lithium from this complex matrix, we employed sequential pretreatment steps—adsorption and precipitation followed by solvent extraction using a bi-functional ionic liquid composed of Cyphos IL 101 and D2EHPA. The integrated process achieved a maximum lithium extraction efficiency of 85.9 %, with a stripping efficiency of 89.6 %, resulting in an overall lithium recovery of 71.5 %. These results demonstrate the potential of ionic liquid-based extraction combined with pretreatment as an effective strategy for lithium recovery from high-salinity industrial wastewater such as shale gas produced water.